The Roll2Rail project aims to develop key technologies and to remove already identified blocking points for radical innovation in the field of railway vehicles, as part of a longer term strategy to revolutionize the rolling stock for the future. The results will contribute to the increase of the operational reliability and to the reduction of the life cycle costs

This deliverable describes the motivation and methods for the characterization of the railway environment for radio transmission. After a thorough review of existing measurements and channel models in the railway domain, the gaps for a detailed characterization of the radio environment are identified and based on this analysis, a common methodology is defined. Since channel measurements require a considerable technical effort and experience, the methodology for channel sounding is described in detail. For the preparation and the execution of the measurement campaigns, a strong effort both in terms of equipment as well as trained staff is required. For this reason, the measurement campaign planning is outlined in detail in Chapter 4. Chapter 5 describes the actual three different measurement campaigns carried out. Two measurement campaigns were carried out in the field, i.e. the high-speed line and the urban/metro measurements. These included measurements with one or two trains in the operational environment. The third measurement campaign conducted stationary measurements in a depot for the 60 GHz measurements and a regional train. Finally, Chapter 6 describes the post processing and analysis of the channel measurements. For the high speed line measurements, the large scale and small scale fading parameters are estimated in Section 6.1 for the inter-vehicle channel measurements and the parameters for a tap-delay line channel model are provided. Similarly, Section 6.2 provides the large scale and small scale fading parameters of a channel model for the Metro for inter-consist, intra-consist, and train-to-train scenarios as well as parameters for a tap-delay line channel model for the first two scenarios. Finally, Section 6.3 analyses and estimates parameters for a regional train at 60 GHz carrier frequency for various measurement scenarios such as intra-vehicle and outdoor-to-roof.

To conclude, the results of Chapter 6 provide the basis for channel models which are then used in Task 2.7 to simulate and evaluate selected wireless technologies and in channel emulations in Task 2.8 to validate suitable radio technologies for wireless TCMS.

LIST OF TABLES

INTRODUCTION

This Roll2Rail project covers different rolling stock topics such as Traction (WP1), TCMS (WP2), Car-Body-Shell (WP3), Running-Gear (WP4), Brakes (WP5), Vehicle Interiors (WP6) and transversal activities such as Noise (WP7) and Energy Management (WP8).

In that context, WP2 work package's concrete goal is to make research on technologies and architectures to allow new generation of train communication systems based on Wireless Transmission for Train Control and Monitoring System (TCMS), functions and Infotainment, CCTV applications, thus reducing or even completely eliminating, on board communication cables and simplifying the train coupling procedure.

The goal of this deliverable (D2.2 within WP2) is to study and characterise the railway environment in order to elaborate models for later simulation of radio communications technology for railways. Most relevant scenarios, where reflections, radio collisions or EMI may play a role, will be analysed. Therefore metro and mainline tunnels and stations, different power supply (i.e. AC, DC) and signalling systems will be considered.

The objective of this deliverable is the faithful characterization of the railway environment for radio transmission. In order to avoid duplication of work load and results, Chapter 2 gives a thorough overview of existing channel measurements and channel models in the railway domain and identifies the missing pieces which are required for a complete characterization of the radio environment. Chapter 3 defines a common methodology which will be applied in the different measurement campaigns and reports relevant aspects and experiences from already finalized measurements. In Chapter 4, the measurement campaigns are described in quite some detail.

Chapter 5 describes the actual three different measurement campaigns carried out, i.e. the highspeed line measurements and the urban/metro measurements in the field as well as 60 GHz measurements for a regional train in a depot. Finally, Chapter 6 reports the post processing and analysis of the channel measurements as well as parameters for channel models considering large scale and small scale channel characteristics. These channel models are the basis for the simulations in Task 2.7 to evaluate selected wireless technologies and in channel emulators in Task 2.8 to validate suitable radio technologies for wireless TCMS. In recent years, power line communication technology for communications inside vehicles in the field of aerospace and automotive industries experience important developments. This is also true for public transport vehicles.

STATE-OF-THE-ART ON MEASUREMENTS AND MODELS IN RAILWAYS

CURRENT AND FUTURE RAILWAY COMMUNICATION SYSTEMS

Outside Train Communication

Communication between vehicles in the public transport sector covers several applications. The first one, often referred to as the concept of carrier pigeon, consists in providing information on the fly between two vehicles. The use case is often a disabled vehicle, out of range of a communication network, that will transmit information to another vehicle passing nearby [START_REF] Van Den Abeele | Procédé de transfert de données d'alerte entre un véhicule ferroviaire en panne et un centre de contrôle, dispositif associé[END_REF], [START_REF] Hilali | Enhanced high data rate communication system using embedded cooperative radar for intelligent transports systems[END_REF].

Another use case, still in the research labs, is virtual coupling of two vehicles (car trains, subways, trams) this means no mechanical coupling but only wireless coupling for Train-to-Train (T2T) communications. Indeed, in the case of mechanical coupling of two vehicles (subways, trams, trains, High Speed Railway (HSR)), it is also necessary to interconnect high-speed networks embedded in both vehicles. This is now carried out mechanically using specific connectors that deteriorate quickly under hard railway operation conditions. One of the candidate technologies is UWB (Ultra Wide Band) such as the IEEE 802.15.4a standard. A survey of possible UWB applications in the railway domain is given in [START_REF]IGR-D-WIF-007-06 -Ultra Wide Band Application report[END_REF]. The UWB links are deemed more robust to frequency selective fading [START_REF] Benedetto | Understanding UWB radio fundamentals[END_REF]. New technologies in the 60 GHz range like IEEE 802.11ad and machine-to-machine type communication systems as being defined in 4G and 5G may also be considered.

Current Wireless Systems

Apart from legacy systems (usually analog) that started its development in the early 80s, wireless systems in railways is a trend that is still on its first decade of life. GSM-R is the most famous system of the second type because it is based on GSM standard phase 2+ [START_REF] Cellmer | Le réseau GSM-R de RFF[END_REF], but with major modifications to fulfil many railway-based needs, like functional or regional addressing and many more. In subways, it is very likely to have some implementations of IEEE 802.11g with optimizations at certain levels to improve its performance, e.g. mobility aspects, like the TEBATREN solution already in service in Metro de Madrid and in some others. In the signalling field, the use of IEEE802.

Possible Directions for Future Wireless Systems

The future wireless systems for railways need to address many issues like costs, interoperability and spectrum allocation. Depending on the point of view, actual technology is very expensive and sometimes it is not interoperable at all. GSM-R is a possible exception in terms of interoperability only. However, open standards like 3GPP LTE imply also heavy costs and possible dependence on mobile operators, which is something unlikely to be accepted by railway operators apart from other disadvantages. 10/12/2016 Despite of all these issues, one of the aims of several research groups in Asia and Europe and projects all over the world, including Roll2Rail, is to study feasible wireless communication technologies for both T2G, T2T, and inside train communications (cf. Figure 1). At the current stage of WP2, it is not possible to jump to the conclusions, but some technologies are more feasible than others. It is not a secret that 3GPP LTE has introduced some functionality on its last release that targets the railway sector, like mobile relays, public safety issues, Device-to-Device (D2D) communications, etc. On the other hand, for Car-to-Car (C2C) communications, IEEE 802.11p is planned to be deployed in the smart cars field in the near future. So, it could be an option for T2T communications if high data rates are not required. Other solutions based on UWB technology or millimetre wave solutions in the range of 60 GHz are foreseen.

Furthermore, spectrum allocation is always a challenge. Industrial Scientific and Medical (ISM) bands at 2.4 and 5 GHz are always a possibility, but also imply potential problems, not only for security. Also there is some discussion on the possibility of using the Intelligent Transportation System (ITS) band at 5.9 GHz for urban rail systems. Facing the problem from the business perspective, partnerships with mobile operators to deploy mobile networks and also provide some non-safety services to operators and stakeholders is possible but implies some regulatory challenges that should be addressed, too.

Moreover, it is also important to account for the ongoing work on cognitive radio. The concept of cognitive radio was highlighted as an attractive solution to the problem of congestion of the radio spectrum occupied by licensed users [START_REF] Mitola | Cognitive radio: making software radios more personal[END_REF], [START_REF] Palicot | De la radio logicielle a la radio intelligente[END_REF]. Cognitive Radio (CR) is a radio or a system capable of analysing its electromagnetic environment and able to dynamically and independently operational radio parameters to modify the operation of the system, i.e. throughput, interference cancellation, the interoperability, access to other radio networks. This field of research is very active at European and international level. For instance, the French project CORRIDOR (COgnitive Radio for Railway through Dynamic and Opportunistic spectrum Reuse) is paving the way for the development of Cognitive Radio technologies for railway applications. The project objectives were to design, develop and evaluate fundamental bricks of a CR system adapted to the requirements and constraints of HSR, e.g. high speed, electromagnetic interference, poor coverage of systems in rural area, etc.. More details and publications can be found in [START_REF] Ifsttar | Cognitive Radio for Railway through Dynamic and Opportunistic spectrum Reuse[END_REF]. 10/12/2016

To summarize this section, the main focus for future train wireless communications as depicted in Figure 1 needs to be on providing reliable and real-time data links with the required data rate for safety critical applications while providing best-effort high data rate links to other applications. In a first step research should focus on removing cabling and connectors that suffer from mechanical and environmental stress: Consist-to-consist autocoupler, car-to-car cabling, and bogie-to-carbody cabling. In conjunction with new railway applications such as virtual coupling, future train wireless communications will enable the railway operators to reduce downtime of trains and increase efficiency and safety of the railway system.

EXISTING CHANNEL MODELS AND MEASUREMENTS

Types of Channel Models

One can distinguish three main categories of channel modelling approaches for performance evaluation that are used within the context of vehicle to vehicle channels: deterministic, geometrical-stochastic and stochastic.

Deterministic channel models

Deterministic channel models characterize the C2C or car-to-infrastructure (C2I) channels in a completely deterministic way. They may be based on rigorous solving of Maxwell's equations like Method of Moments (MoM) and Finite Difference Time Domain (FDTD) or on asymptotic approaches introducing the concept of "rays", i.e. ray tracing. [START_REF] Castiblanco | Time-domain methods to model electromagnetic wave propagation in confined environments[END_REF] and [16] present a new and original methodology to model electromagnetic wave propagation and to find antenna specifications and positions in tunnels of arbitrary cross-section bases on the use of transmission line matrix.

The ray tracing approach that is computationally-wise able to simulate much bigger scenarios compared to MoM or FDTD is the most widely used technique in characterizing channels in a deterministic manner. The main idea of ray tracing is to regenerate 'rays' from the transmitter to the receiver, taking into consideration reflections and diffractions occurring due to objects in the environment. Therefore, it is required to define the shape, properties and location of all the involved objects in the transmission environment. Hence, the detailed description of the environment and the following intensive computations are time and effort consuming, and the extracted Channel Impulse Response (CIR) cannot be easily generalized to different scenarios. In [START_REF] Maurer | A new inter-vehicle communications (IVC) channel model[END_REF] ray tracing was applied to the car-to-car channel. The implementation was divided into three distinguishable parts. The first part was the modelling of the road traffic, i.e. other cars. To characterize the channel's Doppler shift and Doppler spread accurately, the dynamic behaviour of the transmitting and receiving vehicles as well as the adjacent vehicles have to be characterized in a realistic manner. Authors considered microscopic modelling to simulate each vehicle separately, resulting in a realistic instantaneous position and velocity for each vehicle at each snapshot in the simulation. The Wiedemann traffic model was implemented to describe road traffic for different scenarios. The second part was the modelling of the environment, where a stochastic model was chosen to draws the environmental surroundings such as buildings, parked vehicles and trees. The third and last part is the modelling of the wave propagation. Here, ray tracing was used to simulate the multipath propagation from the transmitter to the receiver. A carrier frequency of 5.2 GHz was used in the simulation. Results were validated against measurement data obtained using a RUSK ATM vector channel sounder operating at the same carrier frequency. The comparison between 10/12/2016 measurement and simulation showed that the proposed deterministic channel model fits well to measurement results and real-life scenarios. Ray tracing for T2G environments was investigated in the mm-wave band in [START_REF] Chang | Propagation Analysis with Ray Tracing Method for High Speed Trains Environment at 60 GHz[END_REF], where a HSR environment was considered including a transmitter mounted on the top of a fence while the receiver antenna is located on the top of the train. For the scenario, the ray tracing simulator RapLap was used to simulate the wireless propagation channel. Results, such as received power, delay spread and angular spread, were provided. A dynamic channel model was also proposed using obtained statistical parameters from the deterministic simulation method. A comparison to measurement data was omitted. In [START_REF] Arruti | A Novel WINNER Based Model for Wireless Communications inside Train Carriages[END_REF] the authors focused on the propagation channel inside a train wagon using ray tracing based on the EM CUBE software simulator from Emag Technologies Inc. [20].

It is important to notice that ray tracing techniques work only for plane surfaces. For curved surfaces the image theory which is used in ray tracing approach is no more valid and a ray launching approach associated with for example analytical description of the surfaces should be consider. Detailed are given in [START_REF] Didascalou | Ray optical wave propagation modelling in arbitrarily shaped tunnels[END_REF] and [START_REF] Masson | Ray Launching Modeling in Curved Tunnels with Rectangular or Non Rectangular Section[END_REF]. [START_REF] Masson | Ray Launching Modeling in Curved Tunnels with Rectangular or Non Rectangular Section[END_REF] focuses on radio wave propagation modelling for metro tunnels. The case of arched and curved tunnels is treated. Theoretical results obtained are compared with experimental results in various tunnels.

Geometry-based stochastic channel models (GSCM)

In GSCM, scatterers, representing propagation paths are distributed in a virtual geometrical environment. Using the geometrical relations between the transmitter, a scatterer and the receiver, the delay and angle of arrival of different propagation paths can be calculated according to a simplified ray tracing procedure. Diffuse multipath contributions may be included by considering clusters of points as scatterers. GSCM can be easily adapted to different scenarios by changing the geometrical distribution of the scatterers, making a good compromise between complexity and accuracy. Furthermore, GSCM can be easily adapted to non-stationary environments based on the geometrical relations, making them a good candidate to describe T2T and T2G channels. In recent years, GSCM gained a lot of research interest in the C2C domain; their flexibility makes it tempting to extensively develop them in the T2T and T2G domains. Authors in [START_REF] Karedal | A Geometry-Based Stoachastic MIMO Model for Vehicle-to-Vehicle Communications[END_REF] adopted a GSCM to characterize the MIMO channel in the C2C domain. Distributed scatterers were divided into three different groups. The first group represents paths occurring due to wave interactions with moving objects, i.e. other vehicles. A second group represents propagation paths from static objects like road signs or other structures next to the road or in the middle between both traffic lanes. The last group describes diffuse components originating from trees, buildings or walls. Each group is given different stochastic and deterministic properties (such as geometrical density, path-loss exponent and reference power). The model was validated by comparing simulations to measurements performed with the RUSK LUND channel sounder in both rural motorway and highway environments. Detailed discussion on vehicular channel characterization was presented in [START_REF] Mecklenbräuker | Vehicular Channel Characterization and Its Implications for Wireless System Design and Performance[END_REF] and [START_REF] Cheng | Wideband Channel Modeling and Intercarrier Interference Cancellation for Vehicle-to-Vehicle Communication Systems[END_REF], where the authors discussed C2C channel and GSCM in detail. A GSCM for HSR was developed in [START_REF] Ghazal | A Non-Stationary MIMO Channel Model for High-Speed Train Communication Systems[END_REF] where a non-stationary wideband MIMO channel model was proposed that includes the Line-Of-Sight (LOS) component and propagation paths occurring due to one-time scattering. 10/12/2016

Stochastic channel models (SCM)

SCM tend to describe the propagation channel based on stochastics without considering the underlying geometrical relations. In this type of channel models a certain structure (such as tapped delay line structure, Saleh-Valenzuela structure or finite state Markov chains structure) is assumed and modelled by random processes. Stochastic parameters for the characterization depend on pre-defined generalized environments (such as rural or highway environments) as well as different assumptions. To parameterize a model, intensive measurements in different scenarios have to be performed. Channel model parameters are then tuned to fit the results of the measurements. A tapped delay-Doppler profile model was proposed in [START_REF] Acosta-Marum | Six time-and frequency-selective empirical channel models for vehicular wireless LANs[END_REF] and [START_REF] Acosta-Marum | Doubly selective vehicle-to-vehicle channel measurements and modeling at 5.9 GHz[END_REF] for the C2C channels. This model was also adopted by the IEEE 802.11p standards group for the development of its system. However, the Wide-Sense Stationary Uncorrelated Scattering (WSSUS) assumption in the channel model does not reflect the non-stationarity of the channel impulse responses reported in the measurements for the C2C environments. Authors in [START_REF] Sen | Vehicle-vehicle channel models for the 5-GHz band[END_REF] provided parameters for C2C channel models based on the tapped-delay structure. Three model types were provided, where two are non-WSSUS based and the third one was based on the WSSUS assumption. Parameters were given for channel bandwidths of 5 and 10 MHz using measurements performed by the authors in both highway and urban scenarios. These measurements were taken at different times and under different traffic conditions. The model was updated by results in [START_REF] Wu | 5-GHz-Band Vehicle-to-Vehicle Channels: Models for Multiple Values of 10/12/2016 Channel Bandwidth[END_REF] using the same type of channel model to characterize propagation for channel bandwidths of 1, 20, 33.33 and 50 MHz, where the same data from the measurement campaign in [START_REF] Sen | Vehicle-vehicle channel models for the 5-GHz band[END_REF] was used. In [START_REF] Wang | Finite-state Markov channel-a useful model for radio communication channels[END_REF], the Rayleigh fading channel was modelled using a finite-state Markov structure as an evolution of the two-state Markov channel known as the Gilbert-Elliot channel [32] [33]. Finite-state Markov models were later developed to model tunnel channels [START_REF] Wang | Finite-state Markov modeling of tunnel channels in communication-based train control (CBTC) systems[END_REF] and the fast time-varying C2G channels [START_REF] Lin | Finite-state Markov channel modeling for vehicle-toinfrastructure communications[END_REF]. Measurements of T2G in viaduct environment and agricultural environment were performed in [START_REF] Min | Analysis and Modeling for Train-Ground Wireless Wideband Channel of LTE on High-Speed Railway[END_REF] and [START_REF] Min | A two-dimensional integrated channel model for train-ground communications[END_REF]. In [START_REF] Min | Analysis and Modeling for Train-Ground Wireless Wideband Channel of LTE on High-Speed Railway[END_REF] an evaluation and development of LTE technology for HSR communications was presented. In [START_REF] Min | A two-dimensional integrated channel model for train-ground communications[END_REF], authors proposed a two-dimensional Ricean K-factor channel model based on the measurement results.

Measurements inside Vehicle

An important issue for wireless networks in railway environments is the presence of a severe multipath due to the reflections in the metallic train structures; in order to tackle this, wireless propagation features need to be obtained through channel measurements and the results need to be carefully considered for the selection, design and deployment of the physical layer of the wireless network.

Concerning the characterization of the wireless propagation channel for railway environments, literature about this topic usually includes research papers about the propagation in different scenarios and at different frequency bands [38] [39]. The effect of certain structures like viaducts and terrain cuttings (canyons) onto a train-to-ground communication link (GSM-R) has been taken into account in [START_REF] Liu | Position-based modeling for wireless channel on high-speed railway under a viaduct at 2.35 GHz[END_REF] [41] [42] [START_REF] Ruisi He | An Empirical Path Loss Model and Fading Analysis for High-Speed Railway Viaduct Scenarios[END_REF]. Results show that the classical models for propagation loss are not accurate for attenuation prediction.

All these works are related to the propagation study of the train-to-ground link, but wireless network applications require the characterization of the on board propagation. In [START_REF] Kita | Experimental study of propagation characteristics for wireless communications in high-speed train cars[END_REF] [45], intra-vehicle and inter-vehicle communication links are analysed using the 2 and 5 GHz bands. Measurement results show that the transmitted signal can re-enter vehicles through windows and that its contribution to inter-vehicle propagation is more relevant than the line-of-sight (LOS) signal. On the other hand, 10/12/2016 wideband propagation analysis with a 2.35 GHz channel sounder using planar and omnidirectional antennas placed at different locations is done in [START_REF] Weihui | Channel properties of indoor part for high-speed train based on wideband channel measurement[END_REF]. The performance of both antennas is compared, obtaining a larger path-loss in the case of the planar antenna, and showing a similar performance regarding delay spread.

The authors in [START_REF] Mariscotti | Characterization of the radio propagation channel aboard trains for optimal coverage at 2.45 GHz[END_REF] analyse the path loss and delay spread for both inter-vehicle and intra-vehicle communication links. All the measurements are done for a 100 MHz signal bandwidth using a VNA for the 2.45 GHz band, where results show that path loss is slightly smaller than free space. In [START_REF] Gruden | Reliability experiments for wireless sensor networks in train environment[END_REF], the authors study the wave propagation around the train, focusing on the wireless sensor network application, and taking into account that the wireless devices need to be installed under the train, e.g. bogie monitoring. They use a narrowband approach at 434 MHz band for wireless channel characterization by means of a signal generator and a spectrum analyser. Results show how the path loss increases for the case where the antennas are located below the train, in contrast to the case where the antennas are inside the train.

Apart from reviewing inside vehicle channel models for trains, we also summarize the literature on similar environments, i.e. bus and airplane cabins. Whereas only [START_REF] Matolak | 5 GHz Intra-Vehicle Channel Characterization[END_REF] measured channels inside a bus, [START_REF] Chetcuti | Wireless propagation modelling inside a business jet[END_REF], [START_REF] Chiu | Characterization of UWB Channel Impulse Responses Within the Passenger Cabin of a Boeing 737-200 Aircraft[END_REF], [START_REF] Diaz | Wideband channel characterization for wireless communications inside a short haul aircraft[END_REF], [START_REF] Errico | UHF radio channel characterization for Wireless Sensor Networks within an aircraft[END_REF], [START_REF] Jacob | Influence of passengers on the uwb propagation channel within a large wide-bodied aircraft[END_REF], [START_REF] Matolak | Aircraft intra-vehicular channel characterization in the 5 GHz band[END_REF], [START_REF] Moraitis | Radio Channel Measurements and Characterization inside Aircrafts for In-Cabin Wireless Networks[END_REF], [START_REF] Schmidt | UWB propagation channels within an aircraft and an office building environment[END_REF], [START_REF] Spiliotopoulos | Path-Loss and Time-Dispersion Parameters of UWB Signals in a Military Airplane[END_REF], [START_REF] Spiliotopoulos | UWB channel parameters in a C130 airplane[END_REF] measured channels inside airplanes. All measurements have been conducted for stationary vehicles. Further, [START_REF] Matolak | 5 GHz Intra-Vehicle Channel Characterization[END_REF], [START_REF] Jacob | Influence of passengers on the uwb propagation channel within a large wide-bodied aircraft[END_REF], [START_REF] Matolak | Aircraft intra-vehicular channel characterization in the 5 GHz band[END_REF] consider the influence of passengers on the channel measurements. For the large wide-body cabin of an A380 airplane with two aisles, [START_REF] Jacob | Influence of passengers on the uwb propagation channel within a large wide-bodied aircraft[END_REF] shows a reduced delay spread for UWB measurements between 3-8 GHz. Clearly, these results are not directly applicable to the train environment as passenger trains usually are single aisle. In contrast [START_REF] Matolak | 5 GHz Intra-Vehicle Channel Characterization[END_REF] and [START_REF] Matolak | Aircraft intra-vehicular channel characterization in the 5 GHz band[END_REF] conclude that human movement causes larger delay spreads at 5 GHz for a measurement bandwidth of 50 MHz inside a bus or medium-sized airplane with a single aisle. The airplane cabin measurements of [START_REF] Chetcuti | Wireless propagation modelling inside a business jet[END_REF], [START_REF] Chiu | Characterization of UWB Channel Impulse Responses Within the Passenger Cabin of a Boeing 737-200 Aircraft[END_REF], [START_REF] Errico | UHF radio channel characterization for Wireless Sensor Networks within an aircraft[END_REF], [START_REF] Jacob | Influence of passengers on the uwb propagation channel within a large wide-bodied aircraft[END_REF], [START_REF] Moraitis | Radio Channel Measurements and Characterization inside Aircrafts for In-Cabin Wireless Networks[END_REF], [START_REF] Schmidt | UWB propagation channels within an aircraft and an office building environment[END_REF] show consistently a path loss exponent between two and three for medium to large aircrafts depending on the measurement setup, carrier frequency, and bandwidth. As an exception to these findings, the estimated path loss exponents are below one in the cargo bay of a military airplane [START_REF] Spiliotopoulos | Path-Loss and Time-Dispersion Parameters of UWB Signals in a Military Airplane[END_REF], [START_REF] Spiliotopoulos | UWB channel parameters in a C130 airplane[END_REF]. Here, the different behavior stems from the metallic cabin containing no equipment that absorbs the UWB signals. Similar behavior could be expected inside an empty cargo compartment of a train vehicle.

When considering the bandwidth of the measurements, we can distinguish narrow band, wide band and UWB measurements. For the UWB measurements [START_REF] Chiu | Characterization of UWB Channel Impulse Responses Within the Passenger Cabin of a Boeing 737-200 Aircraft[END_REF], [START_REF] Jacob | Influence of passengers on the uwb propagation channel within a large wide-bodied aircraft[END_REF], [START_REF] Schmidt | UWB propagation channels within an aircraft and an office building environment[END_REF], [START_REF] Spiliotopoulos | Path-Loss and Time-Dispersion Parameters of UWB Signals in a Military Airplane[END_REF], [START_REF] Spiliotopoulos | UWB channel parameters in a C130 airplane[END_REF], the findings vary greatly depending on the exact measurement setup, often requiring a large number of multipath components to model the channel characteristics accurately, e.g. [START_REF] Spiliotopoulos | Path-Loss and Time-Dispersion Parameters of UWB Signals in a Military Airplane[END_REF]. The wide band models exhibit for carrier frequencies around 2 or 5 GHz frequency selective fading [START_REF] Matolak | 5 GHz Intra-Vehicle Channel Characterization[END_REF], [START_REF] Diaz | Wideband channel characterization for wireless communications inside a short haul aircraft[END_REF], [START_REF] Matolak | Aircraft intra-vehicular channel characterization in the 5 GHz band[END_REF] [56] and contain both Ricean and Rayleigh fading paths. A 3-path tapped delay line model can be sufficient to describe the in-cabin channel behavior [49] [55]. For the narrow band measurements, the resulting channel model is a flat fading model [START_REF] Errico | UHF radio channel characterization for Wireless Sensor Networks within an aircraft[END_REF]. The influence of signals propagating outside the cabin and then re-entering it are not considered, apart from the environment description in [START_REF] Matolak | 5 GHz Intra-Vehicle Channel Characterization[END_REF].

Ray tracing simulators can also be used for characterizing in-vehicle propagation [START_REF] Aguirre | Characterization of wireless channel response in in-vehicle environments[END_REF] [61]; however, results are highly dependent on the accuracy of the simulation model.

Measurements outside Vehicle

Several works exist related to the characterization of train to ground wireless propagation [START_REF] Zhou | High-speed railway channel measurements and characterizations: A review[END_REF], [START_REF] Liu | Survey of wireless channel measurement and characterization for high-speed railway scenarios[END_REF]. This is an active field of research these last years. The effect of structures like viaducts and terrain cuttings (canyons) onto a train-to-ground communication link with GSM-R has been analysed in [START_REF] Liu | Position-based modeling for wireless channel on high-speed railway under a viaduct at 2.35 GHz[END_REF], [START_REF] Zhang | Measurement-Based Delay and Doppler Characterizations for High-Speed Railway Hilly Scenario[END_REF], [START_REF] Tian | Small scale fading characteristics of wideband radio channel in the Ushape cutting of high-speed railway[END_REF], [START_REF] Ruisi | An empirical path loss model and fading analysis for highspeed railway viaduct scenarios[END_REF]. Overall results show that the classical models for propagation loss are not accurate for attenuation prediction.

While the research of the T2G channel is comprehensive, the propagation channel of the T2T is hardly described in literature. A measurement and analysis of a T2T channel was done in [START_REF] Lehner | On the Performance of TETRA DMO Short Data Service in Railway VANETs[END_REF] considering the use of TETRA. Authors in [START_REF] García | Channel Model for Train to Train Communication using the 400 Mhz Band[END_REF] describe a channel model for a direct T2T link at 400°MHz centre frequency based on known communication models.

In order to characterize the propagation environment for inter-vehicle communications, a wireless channel measurement campaign was carried out in [START_REF] Val | Time-synchronized Wireless Sensor Network for structural helath monitoring applications in railway environments[END_REF]. This campaign was done at La Sagra maintenance facilities in Mocejón, Spain. For these measurements the train was positioned in an open field in order to obtain the multipath coming from the train itself and not from reflections on surrounding objects. It was observed that in absence of reflections outside the train, the radio communication between the inside of the car and the bogie occurs due to the diffraction of the signal on the window edge and on the bottom edge of the car. Electromagnetic simulations were carried out with CST Microwave Studio [START_REF]CST Microwave Studio[END_REF] that confirms this behaviour (see Figure 2). As an example, Figure 3 shows the simulated and measured power-loss results at 2.45 GHz between two vertically-polarized antennas placed with a separation of 3 meters following the setup described in Figure 2. A good agreement is observed between simulations and measurements; the main difference is that in simulations higher power rays are received after the first 20 meters, which are due to the perfect conducting structures used in the car for obtaining reasonable simulation times, which make the car more reflective than in the real situation. On the other hand, it can be noted that the losses of -75 dB for the first ray are a combination of 50 dB free-space losses (i.e. 3 meters at 2.45 GHz) plus 25 dB of diffraction losses at the window edge. From these results it was concluded that positioning the base station under the vehicle provided a more stable link, with lower delay spread and higher 𝐵 𝑐 . However, it must be noted that wireless sensor networks operating with a bandwidth lower than the 𝐵 𝑐 will suffer from flat fading, and therefore spatial antenna diversity and/or frequency agility will need to be implemented to overcome this issue.

Identified Gaps of Existing Measurements and Models

The summary of existing channel measurements and models shows that important aspects for modern wireless T2T applications are missing. Most of the measurements and the resulting channel models refer to T2G. The small amount of investigations on T2T aspects are limited on either low train speed or lower frequency bands. In several publications cellular channel models are used for C2C communications. Apart from the points mentioned in Section 2.1.4, the following gaps have been identified.

Railway Environment

The railway environment differs depending on the type of track significantly to a road environment. Furthermore, the shape of cars on a street differs much more severely compared to the profile of trains for wave propagation. On the other side, most of the artificial and non-artificial obstacles that are found next to roads (see Table 1) may occur also next to railways.

One of the most challenging and diverse environments for communications in railway traffic are tunnels. Especially underground trains but also HSR and commuter trains are operating in tunnels.

The shape and the material of the tunnel is heavily influencing the propagation: tunnels excavated with boring machines (i.e. smooth walls, with almost no changes on their cross-section -see Figure 4a), man-made tunnels (i.e. frequent changes on tunnel section, walls made of bricks, etc.), one-track tunnels (Figure 4b), stations (both pit-shaped and tunnel-shaped, Figure 4c and Figure 4d respectively). Some tunnels are also made with metal (some case in new-York and London). In this case the propagation rules inside these types of tunnels are completely different.

High Total Velocity

Previous measurements reported in underground or general railway environments have been mostly focused on the T2G links. Future measurements shall focus on intra-vehicle, inter-vehicle, inter-consist and T2T links from mid velocities in subway networks up to high total velocities for HSR.

The Intra-vehicle scenario investigates the wireless link between different elements inside a single vehicle (see Figure 5 left). These will be LOS links, mostly affected by the internal structure of the vehicle and passengers. Here several scenarios shall be measured, such as person presence/movement, narrow/wide train gauge, as well as vehicles with/without corridor in-between (i.e. continuous and non-continuous trains -see Figure 6). Inter-vehicle scenarios include wireless links that go beyond a single vehicle, involving both the next vehicle and the exterior of the vehicle (both roof and bogie) -see Figure 5 right. In this case the environment inside (see Figure 6) and outside of the train in combination with the velocity is influencing the propagation channel. Hence, it will be necessary to measure and model different propagation environments with different speeds.

An inter-consist connection establishes a wireless link between one consist to another one, with the antennas located on the roof of the train. The antenna position may vary between the centre and the edge of the cars (see Figure 7). In case of omni-directional antennas, high Doppler shifts resulting from the high speed of the train in combination with reflected or scattered multipath components located in the surrounding environment may cause the main influence on the received signal. If directional antennas are used curve radii and train vibrations need to be considered for the beam-width of the employed antennas.

High Relative Velocity

The channel between two moving trains regarding the T2T communications as well as the interference between adjacent trains using the same wireless technology is hardly discussed in literature. The scenarios differ from two trains stopped and located in parallel on depot (i.e. continuous interference) to two trains driving next to each other on parallel tracks in the same or opposite direction. The antennas can be placed both inside and on the roofs of the vehicles. Highly interesting is the influence of the Doppler shift on the receiver side. Due to possible relative speeds of 600 km/h and above, high Doppler shifts may occur.

COMMON METHODOLOGY DEFINITION

REQUIREMENTS FOR MEASUREMENT SCENARIOS

The objective of the channel measurement campaigns is the characterization of the physical channel between the transmitting and the receiving antenna for a given frequency band. The outcome of these measurements is generic in the sense that it does not depend on the selected transmission technology but only on the frequency band and the chosen scenario. This approach, which is known as channel sounding, requires a careful preparation of the measurement campaign and involves a considerable amount of professional measurement equipment. In order to obtain good measurements of the channel itself, the absence of any interfering transmitters is highly desirable. The obtained measured data with channel sounding can be used as direct input for simulations or it can be applied to derive one or multiple channel models. The impact of interference can be included in simulations, based also on channel models derived from the channel sounding measurements.

In other words, measurements based on channel sounding only depend on antenna locations and the relevant environment (scatterers, reflecting material and movement) but not on transmit parameters like data rates, packet sizes of modulation formats.

A simpler approach for channel measurements applies a selected wireless technology and directly provides results like packet error rates, delay, data rates for this technology. This has been the method for the measurement with ITS-G5 equipment reported in Section Error! Reference source not found.. The obtained results are naturally specific for the equipment deployed during the measurements, including transmitter, receiver, antennas and cabling.

SOURCES OF EM NOISE

The railway environment increasingly makes use of more innovative applications and seeks to develop new technologies. This requires using more sophisticated equipment for each application.

In an environment where different kind of equipment and applications can be found (power electronics, communications links, sensing applications…), all the electric and electronic equipment is required to be electromagnetically compatible, in such a way that the operation of one equipment does not disturb other equipment. This is known as EMC (Electromagnetic Compatibility), and is defined as the ability of an electronic equipment/system to operate as designed in its electromagnetic environment without affecting other equipment/system or being affected by the interferences from other equipment/system. Thus the design of an equipment/system is required to comply with the emission and immunity requirements of the environment in which it is intended to run. Compliance with these requirements is usually demonstrated by testing using the harmonized standards.

For the development of a Wireless TCMS, the effect of the electromagnetic interferences of the environment should be considered for wireless communications. The Electromagnetic Interference, EMI, is defined as the unwanted EM (electromagnetic) energy, which may or may not affect the victim equipment. Disturbances may be produced by either intentional or spurious sources from equipment, or by natural causes (e.g. lightning, electrostatic discharge).

Regulations and Standards

EMC is regulated by the 2004/108/EC directive and the new directive 2014/30/EU, which is applicable from 20 April 2016. According to these EMC directives, for railway environment, the European harmonized standards series EN 50121 is to be used in order to show that the essential EMC requirements are fulfilled. Part 3-2 of EN 50121 corresponds to apparatus on board the rolling stock and sets the requirements for emission and immunity for all equipment on board the rolling stock [START_REF]Railway applications -Electromagnetic Compatibility[END_REF].

Additionally to this, within the rolling stock there are also equipment/systems (e.g. radios) covered by the R&TTE 1999/5/EC directive and the new directive 2014/53/EU which is applicable from 13 June 2016. This directive calls for ETSI (European Telecommunications Standards Institute) to set the corresponding EMC requirements.

EMI Environmental Characterisation

For the environmental characterization, a classification of the different EMI sources should be done depending on the nature of the source. Internal EMI sources to the rolling stock cover all EMI sources, both intentional and unintentional, from equipment installed on board the rolling stock and destined to be used in railway applications. External EMI sources to the rolling stock cover all sources from equipment not destined for railway but which may affect the electromagnetic compatibility of the victim equipment.

Mainly there are four ways where EMI can couple into systems. These coupling mechanisms are radiated, conductive, capacitive and inductive. For this activity we will focus in radiated emissions as a source EMI.

Internal EMI sources

Unintentional EMI sources

Within this category are included the equipment on board the rolling stock which do not have an electromagnetic radiating functionality (antenna) and their radiated emissions correspond to a spurious emission.

The requirements for radiated emissions for the on board apparatus (non-intentional) of rolling stock are defined in EN 50121-3-2 [START_REF]Railway applications -Electromagnetic Compatibility[END_REF]. Under this classification are considered equipment as: The EN 50121-3-2 standard sets the following requirements for the radiated emissions: In March 2015, the new version of EN 50121-3-2 was published and which includes additional requirements for the radiated emissions [START_REF]Railway applications -Electromagnetic Compatibility[END_REF]. The new requirements cover the gap between 1 GHz to 6 GHz which is currently in use for several applications. More detailed information is presented below for the different equipment/system: ERTMS. The European rail traffic management system has two basic components, ETCS, the European Train Control system, and GSM-R, a radio system for providing voice and data communication.


 GSM-R is an international communication system for railway applications based on GSM and EIRENE specification. GSM-R is standardized in 900 MHz or 1800 MHz GSM frequency bands to be used around the world, but depending on the country GSM-R can use specific frequency bands.

 ETCS -

Fleet Management Systems -Train to wayside communication (TWC)

Technologies used are mobile phone networks for the train to wayside communications. Also there are systems using inductive loops for vehicle detection (VETAG) that work between 10-100 kHz.

Passenger Information Systems

The information is received from an automatic vehicle location system and from control systems. Technologies used are GPS (reception) and mobile data phone network (GPRS, 3G or LTE) or Wi-Fi for data reception.

External EMI sources

As informative, external EMI sources to the rolling stock include sources like:

 Intentional emitters: radio, TV or mobile phone networks.

 Natural EMI: lightning and electrostatic discharge.

 Illegal jamming.

Summary and additional information

In the following table a summary of the identified EMI sources is presented including additional information of working frequencies and emission power R2R-T2.

Equipment Location

Following two examples of different vehicles are presented with the on board location of the EMI sources from the main equipment.

Non-intentional equipment fulfilling EN 50121-3-2 are placed in the different cabinets along the train (passenger area or cabin), on roof or underframe depending on the equipment and the type of train.

RFID readers are placed near doors as this technology is used mainly for ticket validation application.

Wi-Fi and Radio/Mobile Technology antennas are placed on roof, mainly in the cabin, but also can be found in other places of the vehicle roof. Generally, the preferred location for these antennas is away from pantograph location because the sparks in the pantograph -catenary interface are the biggest interference source for this kind of equipment.

AVAILABLE MEASUREMENT EQUIPMENT

IK4-IKERLAN has the following equipment for channel measurements:

 For static measurements, a Keysight E5071A network analyser (frequency range up to 8.5 GHz) equipped with Electro-Metrics EM-6865 omnidirectional UWB (2-18 GHz) antennas is used (see Figure 12). This setup has the advantage of allowing a perfect synchronization between transmitter and receiver units, as they are both housed in the same equipment; conversely, having both units together limits the measurement distance, as long cables need to be run to transmitter and receiver antennas. The maximum 0 dBm output power of the VNA also limits the measurement distance. This setup has been used for indoor measurements with medium transmitter-receiver distances (e.g. office environments).  For static and dynamic measurements, a setup made of a Keysight E4438C signal generator as transmitter and a 89600 Vector Signal Analyser (VSA) as receiver is used (see Figure 13). This setup also uses Electro-Metrics EM-6865 antennas. A multicarrier OFDM signal is programmed in the generator, and it is equipped with an external power amplifier (MiniCircuits TVA-11-422) in order to reach 1 W output power; on the other hand, a downconversion stage is added before the VSA in order to fit the signal into a 70 MHz Intermediate Frequency. Furthermore, in order to allow the synchronization of the oscillators in transmission and reception without running cables between them, Rubidium oscillators (Stanford Research Systems PRS10) with GPS receivers (Acutime GG Smart Antenna by Trimble) are used. This setup has been used for medium-long distance indoor and outdoor measurements. We have also used a Medav RUSK channel sounder for channel measurement campaigns [START_REF] Medav | RUSK Multidimensional Channel Sounder[END_REF] (Figure 14). This sounder can measure RF channels up to 6 GHz with a bandwidth of 240 MHz, a minimum period of 1.6 microseconds, and a maximum output power of 2W. For channel excitation, RUSK uses a Multi-Carrier Spread Spectrum Signal (MCSSS) with an almost rectangular shape in the frequency domain. This approach allows concentration of the transmitted signal energy in the band of interest (see Figure 16).  Rusk Channel Sounder: The most accurate measurement results would be available by using the Rusk Channel Sounder. For further channel models these data would be the best choice. This measurement system implicates the highest technical effort.

 Signal Generator + Signal Analyzer: This setting is a slimmed channel sounder. The data would be not as accurate as with the Rusk Channel Sounder and the effort would be negligible smaller.

 IEEE 802.11p Cohda MK5:

The Cohda MK5 boards are working with the IEEE 802.11p standard and the measurement results would represent the error rates of a communication between two boards. This data is not useable to generate a channel model. Nevertheless, the effort is very small and these measurements could be done in parallel to the channel sounding. 10/12/2016

MEASUREMENT EXPERIENCE KNOW-HOW IN RAILWAYS

IFSTTAR

IFSTTAR has ample experience in channel measurements for a wide range of scenarios for railway and automotive communications in the 2.45 GHz and 5.8 GHz bands, in the 10 GHz and 60 GHz band for anti-collision radar applications. The measurements concerns V2I configurations in outdoor or in tunnels and also V2V configurations [START_REF] Masson | MIMO Channel Characterization in Subway Tunnel for Train-to-Wayside applications[END_REF], [START_REF] Kaltenberger | Broadband wireless channel measurements for high speed trains[END_REF], [START_REF] Hilali | Enhanced high data rate communication system using embedded cooperative radar for intelligent transports systems[END_REF]. IFSTTAR have also experience on EMC measurements in general [START_REF] Dudoyer | Study of the Susceptibility of the GSM-R Communications to the Electromagnetic Interferences of the Rail Environment[END_REF].

IFSTTAR has also experience in measurements for GSM-R and also for GSM-R deployment along high speed line in the context of works realized for CERTIFER the notify body in France.

Here after the various types of equipment already available.

DLR

DLR has ample experience in channel measurements for a wide range of scenarios, including  Maritime communications in the 5-6 GHz band, with measurements on the Baltic Sea [START_REF] Wang | Propagation Channel at 5.2 GHz in Baltic Sea with Focus on Scattering Phenomena[END_REF]  Aeronautical communications [START_REF] Schwinzerl | Wide-Band Characterization of Antennae Plus Aircraft Platform Patterns in L-and Ka-Band[END_REF] [74] [START_REF] Schneckenburger | An Aeronautical Air-Ground Channel Investigation for APNT Applications[END_REF]  Mobile radio outdoor-to-indoor for positioning [START_REF] Wang | A Comparison of Outdoor-to-Indoor Wideband Propagation at S-Band and C-Band for Ranging[END_REF] [77]

 Airport channel measurements for AeroMACS [START_REF] Gligorevic | Airport Channel Measurements at 5.2GHz[END_REF]  Mobile vehicle-to-vehicle channel measurements [START_REF] Walter | Experimental Verification of the Non-Stationary Statistical Model for V2V Scatter Channels[END_REF]  Modelling of MIMO satellite channel with measurements from a zeppelin [START_REF] Lehner | Spatial Dynamic Wideband Modeling of the MIMO Satellite-to-Earth Channel[END_REF] [81]

In the railway domain, measurements have been performed to characterize the train-to-train channel in the 70 cm UHF band [START_REF] Lehner | Measurement and Analysis of the Direct Train to Train Propagation Channel in the 70 cm UHF-Band[END_REF] and for the TETRA system [START_REF] Lehner | On the Performance of TETRA DMO Short Data Service in Railway VANETs[END_REF]. These measurements formed the basis for the development of the Railway Collision Avoidance System (RCAS) [START_REF] Dlr | RCAS -Railway Collision Avoidance System[END_REF], which takes advantage of direct train-to-train communication to increase the safety.

R2R-T2.

IK4-Ikerlan Experience

IK4-Ikerlan has experience executing wireless channel measurement campaigns in two particular scenarios for railway applications.

La Sagra maintenance facilities

A wireless channel measurement campaign has been carried out on a high speed train located at La Sagra maintenance facilities in Mocejón, Spain. The goal was the characterization of the propagation environment where a wireless sensor network will be operating.

CAF facilities

A wireless channel measurement campaign has been carried out on a metro train located at CAF facilities in Beasain, Spain. The goal was the characterization of the propagation environment where a wireless sensor network will be operating. The equipment used in this campaign was RUSK, where the measurements were performed at a centre frequency of 2.53 GHz with a signal bandwidth of 100 MHz, spanned by 161 subcarriers. The transmitted signal was repeated with a period of 1.6 microseconds. At each spatial position, a block of ten snapshots was recorded for enhancement of the measurement signal-to-noise ratio through coherent averaging.

The measurements were done in the interior of the train, where two different scenarios have been considered, according to the localization of the sensor nodes either on the bogie or inside the car.

For both measurement groups, the localization of the access points (AP) or data recollections has been the same, where eight different locations (APx) have been taken into account for these measurements. The AP3 and AP4 were located under the car, whereas the rest of the APs were installed inside the car. Figure 19 shows the access point placements, where Sx points the bogie where all the sensor nodes were located (see Figure 20). 10/12/2016 As stated above, the sensor nodes have been placed under and inside the car. Figure 20 depicts the location of six different node sensors on the bogie of the train, where Figure 21 shows an example of the antenna located on the gearbox. On the other hand, the location of another six sensor nodes inside the car is shown in the Figure 22.

Channel Sounding Methodology

A channel sounder is a system consisting of a transmitter and a receiver that is designed to measure the properties of the wireless propagation channel. One can distinguish channel sounders working in the time domain or in the frequency domain [START_REF] Salous | Radio propagation measurements and channel modelling[END_REF]. In the following description, we will describe the principle operation of a channel sounder, using the Medav RUSK channel sounder owned by the German Aerospace Center (DLR) as an example. 10/12/2016 . In order to avoid aliasing effects and to allow for a moderate roll-off of the transmit Nyquist filter 𝑔(𝑡) (cf. Figure 24), the discrete-time signal 𝑠[𝑛] is generated as a bandlimited signal in an Orthogonal Frequency Division Multiplex (OFDM)-like fashion, i.e. a multi-tone signal [START_REF] Thomä | Mutlidimensional high-resolution sounding measurement[END_REF]. First, the symbols 𝐗 ̃= [𝑋 ̃0, 𝑋 ̃1, … , 𝑋 ̃𝑁c -1 ] are generated with constant amplitude and a phase chosen such that the peak-to-average power ratio of the signal 𝑠[𝑛] is minimized. These 𝑁 c < 𝑁 symbols are zero-padded to yield the vector

𝐗 = [𝟎 (𝑵-𝑵 𝐜 )/𝟐 , 𝐗 ̃, 𝟎 (𝑵-𝑵 𝐜 )/𝟐 ] (1)
where 𝟎 𝑛 denotes a vector with 𝑛 zero entries. The vector 𝐗 is transformed by an 𝑁-point inverse Fast Fourier Transformation (FFT) to yield 𝑥 = [𝑥 0 , 𝑥 1 , … , 𝑥 𝑁-1 ] with

𝒙 𝒏 = ∑ 𝑿 𝒎 𝒆 𝒋 𝟐𝝅 𝑵 𝒏𝒎 𝑵-𝟏 𝒎=𝟎 (2)
and this signal is parallel-serial converted to

𝒔[𝒏] = 𝒙[𝐦𝐨𝐝(𝒏, 𝑵)] for ∈ ℤ . (3)
The continuous-time baseband signal in Figure 24 is then

𝒔(𝒕) = ∑ 𝒔[𝒏] ⋅ 𝒈(𝒕 -𝒏𝑻 𝐬 ) ∞ 𝒏=-∞ . ( 4
)
Note that the same symbols 𝐗 ̃, 𝐗, 𝐱 are transmitted in every FFT-block and therefore the signal 𝑠[𝑛] is periodic. We can therefore consider 𝑠[𝑛] as an OFDM-like signal, for which the cyclic prefix is as long as the FFT-size and hence the CIR may be as long as 𝑁𝑇 s without causing inter-symbol interference. Since the discrete-time signal 𝑠[𝑛] is already bandlimited due to the zero subcarriers in 𝐗, there are only mild requirements on the transmit filter 𝑔(𝑡). The maximum bandwidth of the transmit signal is strictly limited by the transmit filter, which operates at the sampling frequency 𝑓 𝑠 = 1 𝑇 s ⁄ which for the available equipment is given by 𝑓 s = 320 MHz [START_REF] Medav | RUSK Channelsounder[END_REF]. However, since some bandwidth has to be reserved for the filter roll-off and the "OFDM-like signal" 𝑠[𝑛] is not strictly bandlimited, the effective bandwidth has to be selected significantly smaller. In the case of the Medav RUSK channel sounder owned by DLR, the maximum effective bandwidth is 120 MHz.

Given the sampling frequency of 𝑓 s = 320 MHz, the sampling interval is 𝑇 𝑠 = 3.125 ns. To obtain long OFDM-like symbols and hence to allow for a long CIR, 𝑁 = 8192 is selected, which leads to an OFDM-like symbol time of 𝑇 OFDM = 𝑁𝑇 s = 25.6 μs. This corresponds to a maximum excess length of a multipath component of 𝑑 max = 𝑇 OFDM ⋅ 𝑐 0 = 7680 m. The subcarrier spacing is fixed by the choice of 𝑁 and 𝑓 s and is given by

Δf = 1 T OFDM = 1 NT s = 39 063 Hz . (5)
Out of the 𝑁 = 8192 subcarriers, only 𝑁 𝑐 = 3072 are non-zero, and these define the actual bandwidth of the transmit signal 𝑠(𝑡), which is given by 𝐵 = 𝑁 𝑐 ⋅ Δ𝑓 = 120 MHz.

Post Processing

The data obtained from the measurement campaign is processed in order to get characteristic parameters of the wireless channel. This information is used to model its statistical behaviour in simulation / emulation, and improve the physical layer design of the wireless communication system. Let's summarize the signal post-processing steps:

 Antenna and cable effect calibration. The response of the antenna and cables used during the measurement campaign must be suppressed from measured signal in order to get the channel response between the transmitter and receiver antenna. Figure 25 shows the radiation pattern of a particular antenna measured in a semi-anechoic chamber, whereas the Figure 26 shows the frequency response of the same antenna for a defined frequency band.

N-IFFT

s(t) P S x[0]
x [START_REF]IEEE-SA Standards Board, IEEE STd 1473-1999 Standard for Communications Protocol Aboard Trains[END_REF] x

[N-1] … … … … X[0] X[N-1] g(t)
s

where 𝑑 is the Tx to Rx distance, 𝐺 0,𝑑𝐵 is the path power gain at the reference distance 𝑑 0 , and 𝑛 is the path loss exponent. 𝑋 𝑆𝑆𝐹,𝑑𝐵 is the small-scale fading contribution (random signal variations due to multipath observed over one small scale area), and 𝑋 𝐿𝑆𝐹,𝑑𝐵 is the large-scale fading contribution (random variation in local average of received power observed over a spatial extent of multiple small scale areas.

Figure 27: Channel power gain along the frequency and space

For small scale fading analysis, these contributions must be extracted for each measurement (see Figure 28), obtaining the normalized channel frequency response

𝐻 𝑛𝑜𝑟𝑚 = √ 𝑑 𝑛 𝐺 0 1 𝑋 𝐿𝑆𝐹 𝐻 ( 7
)
where 𝐻 is the measured channel frequency response, and 𝐻 𝑛𝑜𝑟𝑚 is the small scale fading contribution. For each of the transmitter-receiver spatial combination, the total of PDPs are averaged the averaged PDP (see Figure 30) as

𝐴𝑃𝐷𝑃(𝜏) = 𝐸{𝑃𝐷𝑃(𝜏)} (9)
where 𝐸{•} denotes the expectation over the measurement points.

while the coherence bandwidth is related to the inverse of the delay spread.

 Envelope autocovariance. The autocovariance of the envelope is commonly used to characterize the spatial selectivity of the channel, and therefore the possibility of using spatial diversity techniques, such as antenna diversity. The Figure 31 shows the autocovariance curve of a channel, which states that the decorrelation distance is nearly 30 spatial samples. In this example, each sample equals one millimeter, therefore it means that two channel responses separated this distance will be decorrelated. Doppler spectrum of the received signal (see Figure 33). The spectrum width is conventionally expressed in terms of the root-mean-square Doppler-spread.

MEASUREMENT CAMPAIGN 1: HIGH-SPEED TRAINS IN ITALY

The main objective for this measurement campaign is to characterize the channel for moving trains, both for communications within the same train (vehicle-to-vehicle), as well as for train-totrain communication. This is important for evaluating the interference coming from trains on adjacent tracks. At the same time, these measurements will be useful for future train-to-train communication. The measurements are planned to be conducted in a way that the outcome will not depend on the communication technology but will be general enough to derive channel models for more than one application.

Overview of Environments

Terrestrial propagation is highly affected by the environment. The channel characteristic is one of the key points for radio communication, also in case of wireless railway communication. On a track from A to B, a train can pass different scenarios as mentioned in Table 6; combinations of those scenarios (see Table 7) are defining the environment for the propagation path. Most of the given scenarios are common for T2G as well as for T2T communications. From experience on past railway measurements, the following aspects should be considered:

 Pylons/masts that support the catenary can have a significant impact (all metallic and periodically installed). They are very close from the antennas and can be seen as reflectors with a high speed.  The tunnel case is specific but it can be described as an urban canyon with a roof. Indeed, with a rectangular cross-section, tunnel walls can be seen as buildings along the track.

Manoeuvres

The possible movement of trains is listed in Table 8. Within the communication range of a T2T system, trains can drive these different manoeuvres depending on the amount of tracks.

Flow of two trains

In this scenario, two trains drive in the same direction on parallel tracks (cf. Figure 35). One manoeuvre could be set up as virtual coupled trains. The variables are the common velocity and the distance between the two trains. The relative velocity should be zero. The other possibility would be an overtake manoeuvre as described in Figure 36.

Opposing of two trains

The goal of the scenario opposing traffic is to measure two trains passing each other with high relative speed (see Figure 37). For this manoeuvre both trains are stopped at the same distance from the foreseen crossing point, at which they should cross with constant velocity in opposite directions, as depicted below in Figure 38. For the fast counter-direction manoeuvre, 𝑥 2 = 12 km, while for slow one, 𝑥 2 ≈ 5 km is sufficient.

x 0 x 1 x 2 -x 1 -x 2

One train pass another

In this manoeuvre one moving train passes with a certain velocity another train standing still (yellow train in Figure 39 with v2=0).

Inter-Vehicle measurements

The inter-vehicle measurements can scope 3 different placements of the antennas (red dots). For consist to consist measurements, the antennas can be placed as shown in Figure 40 a). In this way we meet the proposal of T2.5 and use directional antennas right on the edge of the vehicle, but the antenna cable is not mounted on the roof itself. Another possibility would be to mount the antennas on the bottom of the train next to the chassis.

The possibility to install antennas in the middle of the vehicle Figure 40 b) needs to be investigated concerning security aspects regarding the antenna feeding cable in case of a catenary emergency. To extend the distance between the antennas, a blank consist could be between the two "active" consists. In case of a Front-to-End channel characterization Figure 41 For all measurements it is mandatory to install GPS antennas or use existing GPS antennas to track the measurements.

Scenarios

Out of the favourite environments in Table 7 (red marked) and the manoeuvres shown in Figure 34 a list of the most interesting scenarios was established (Table 9). The measurements are weighted by 1 to 4 for each manoeuvre.

Measurement Equipment Channel Sounder

The Rusk channel sounder is the primary measuring equipment. This system consists of a transmitter and a receiver and is rather bulky, as can be seen in Figure 42. Both parts are mounted in a 19" rack of approximate dimension 60 cm x 90 cm x 135 cm and a weight of over 90 kg.

Transmitter and receiver have to be connected by a cable of at most 100 m length for synchronization before the measurements could be started (in the morning). They also have to be connected after the measurements (in the evening) to ensure that synchronization is not lost. Due to the dimension of the equipment, they first have to be placed in the trains and then they have to be connected for ca. 1 hour for synchronization.

Figure 42: Receiver (left) and transmitter (right) of the channel sounding equipment

The racks for the channel sounder (see Figure 42) need to be placed as close as possible to the measurement antennas to minimize the antenna cable length. The racks need to be fixed in the train with tension belts. The actual position depends on the possibilities of fixing, the power supply and the antenna cables. The channel sounder is represented as cubes (TX in yellow, RX in orange) in the Figure 46, Figure 47 and Figure 48.  Frequency bands: GSM, DCS, GPS  Usage: GPS  Green star ( ), will be used for every measurement

Additional sensors

Several additional sensors were mounted in the train: a) Next to the channel sounder or on the floor of the locomotive an IMU was placed to record the acceleration and turn rate of the train. In Figure 42 the IMU is placed on the top of the channel sounder for illustration.

b) For a detailed distance recording between the trains a distance-radar was mounted in the nose of the train next to the directional antennas.

Installation

For the different measurement scenarios different antennas is fixed mounted on the train and stay there after finishing the measurements. All the other equipment is replaced afterwards. The blue lines represent the antenna cables.

a) Day 1 Vehicle-to-Vehicle measurement For the V2V measurement 3 SWA-0859 antennas will be used (see Figure 46). The TXchannel sounder rack and antenna are placed in/on car 3. One receiving antenna is placed on car 2, in a distance of approximately 4 m from TX-antenna and the second RX-antenna is on car 1 approximately 30 m away from TX. The sounder rack is placed as close as possible to the antenna in car 1 due to link budget reasons. For measurements, the two RX-antennas are time-multiplexed which leads to a slightly longer measurement period time. The advantage of this method is that one environment is measured with both antenna settings at one run with a negligible time shift in comparison to the slowly changing environment. 10/12/2016  Behind the front nose at the bottom of the locomotive. This front fairing is made of plastic and offers enough space behind. Advantage would be the position itself and the plastic in the beam direction of the antenna. A higher effort of installation needs to be considered.  Behind the front glass of the drivers cab. In this way, the antenna would be mounted inside the drivers cab. An advantage would be the easy installation. The biggest disadvantage is the unknown RF-specification of the window. This could ruin the whole measurement. As GPS reference the SWA-0459 antenna should be mounted on top in front of the locomotive.

The rack needs to be placed in the coach next to the locomotive as shown in Figure 48, because next to the antenna and in the drivers cab there is no space for the measurement equipment.

Trajectory of Measurements

The measurements take place on the track between the station Roma Termini and Napoli Centrale as shown with the red line in Figure 49. On this track all interesting scenarios are covered in different sections. The track is doubled tracked and trains are operating with speeds up to 300 km/h.

Figure 49: Track map

The train Frecciarossa ETR 500 (see Figure 50) is used for measurements. These trains are composed of 11 couches for a total of 574 seats:



Measurement data

The raw data is recorded on each device itself and is downloaded after each run by the corresponding staff. A copy of the files and one backup copy is stored separately.

Protocols

Every procedure should follow prescribed protocols. Incidents and additional steps need to be recorded.

Audio-Visual

The environment during the measurement runs should be recorded with video systems. Due to the night conditions it is difficult to record the surroundings of the track.

All the processes of preliminary work (e.g. installations), the measurement itself and parts of the post processing should be documented with videos and pictures

MEASUREMENT CAMPAIGN 2: METRO IN MADRID

The main objective of this measurement campaign is to characterize the channel in underground trains, which is a completely different scenario compared to both regular and high speed trains. The measurements will be conducted in such a way that the outcome will not depend on the communication technology but will be general enough to derive channel models for more than one application. The outcome of the measurements will be delay spread and transfer functions for each of the measured wireless links. The measurements are scheduled for 30th May -3rd June 2016.

A representative subset of wireless links and scenarios will be selected taking into account the inputs coming from Tasks T2.1 (requirements), T2.5 (architecture), and the documentation provided by Metro de Madrid for Task T2.2. They are described in the following sections.

Measurement Procedure

The following measurement equipment will be used: a channel sounder for channel characterization, and a Vector Network Analyzer (VNA) with horn antennas for material characterization. The channel sounder is depicted in the next figure, and its main features are summarized in Table 16. For each measurement, two antennas will be connected to the channel sounder: a) At one end, a wideband monopole antenna (Mobile Mark MGRM-WHF) will be placed (see Figure 52). This is a magnetic-mount antenna with 3-meter coaxial cable and SMA connector.

Tuesday 31 st May

On Tuesday afternoon, first the effect of multipath in inter-consist links due to train-crossing will be measured at Cuatro Vientos depot. After that, the Train-to-Train measurements will be prepared. The aim of the train-to-train scenario is to simulate either the interference of adjacent trains that use the same wireless TCMS technology, or a vehicle-to-vehicle communication. The following picture shows the location of transmitter and receiver antennas for these measurements:

Wednesday 1 st June

This day will focus on Intra-Consist measurements. The preparation of the setup will be done in the afternoon. The following picture shows the location of transmitter and receiver antennas.

Figure 56: Intra-Consist measurements on Continuous train

The measurements will be done at night in Line 10 or Line 11, at the following environments:

Thursday 2 nd June

The measurements on Thursday will be focused on Intra-Consist links in wide gauge noncontinuous trains (Series 5000), in order to check the impact of the separation between cars in this type of links. The preparation will be done in the afternoon: first, both transmitter and receiver units of the channel sounder will be mounted on a continuous train in Cuatro Vientos depot, and it will be moved to Laguna depot; once there, the channel sounder and the antennas will be placed on a non-continuous train for intra-consist measurements. The following picture shows the location of transmitter and receiver antennas.

Figure 57: Intra-Consist measurements on Non-Continuous train

The measurements will be done at night in Line 6, at the following locations:

Table 21: Intra-Consist measurement environments

Type of Environment

Number of Locations per Environment

Tunnel (wide) -Straight 3 Tunnel (narrow) -Straight 3

Station (pit-shaped) 3

Open Air 3

Friday 3 rd June

On Friday afternoon, the measurement equipment will be dismounted and packed. In parallel, glass characterization measurements will be done with Vector Network Analyzer (VNA) and horn antennas.

Friday night has also been planned as backup, in case delays from previous nights do not allow finalizing some of the measurements.

Available Measurement Equipment

Channel sounder IFSTTAR will use the VµBIQ equipment described here after. This equipment allows to obtain information on the channel at 60 GHz in a SISO configuration.

Mmw antenna 60 GHz 2

Tektronix AWG 7102 10 GS/s 1 The channel sounder consists of a transmitter sending a known signal, and a receiver which analyses the received signal, and stores information to files. The supported bandwidth is up to 1.2 GHz, while RF modules are built to be operated at 60 GHz. The maximum measurable delay is 1.33 s. The channel sounder is capable of conducting measurement of power and delay domain.

The transmitter and the receiver are synchronized by using a RF cable to set a Marker. The channel sounder is modular and flexible, and can easily be configured for different measurement scenarios. The detailed description will be given in the following content. Two identical horn antennas with 15 dBi gain are utilized in the system. The antenna beam width is 22 o , which is the same as our motion control sweep step. The detailed information can be found in the above Figure 61.

Signal waveform

The default transmitter signal is a repetitive chirp signal, where the amplitude and the phase of signal are continuous at the transition from one chirp to another. The phase continuity is achieved by rounding the wanted chirp bandwidth and center frequency to give a whole number of signal periods during the duration of one chirp. Input to the chirp generation routine is:

 fs -Sample frequency  fc -Centre frequency  B -Chirp bandwidth  A -Amplitude  N -Number of samples
The chirp is defined by:

    1 ,...., 1 , 0 , 2 cos 1 mod 2     N i i k i k A c c i   (11)
Where:

N N f B f k s c            5 . 0 2  (12) and 2 5 . 0 2 N N f B k s c         ( 13
)
  is the floor function. The intention of the modulo 1 -function in (11) is to avoid taking modulo 2 of large numbers in the cosine function, since modulo 1 can be implemented by using the floor function. The chirp is generated directly on Arbitrary Wave Generator (AWG), which could be any frequency as long as the chirp fits within half the sampling frequency. In our case, the AWG sampling rate is set to be 2.5 Gs/s, which is more than two times of bandwidth (1.2 GHz). The maximum samples supported by the AWG in one chirp duration are 3333 due to the memory size, which results in the maximum delay time of 1.

Data recording system

The transmitter (Tx) keeps on sending the chirp signal continuous. The main challenge is to record these measurement data from scope to disk, even though the scope can demonstrate the received signal on the screen. GPIB port introduced by Tektronix is used to record the data from scope to laptop disk by using IO control program and Matlab. The scope setups are shown in the following Table 23: 10 s measurement continuous data can be transferred to the laptop local disk at one time due to the memory size limitation, which includes 7 continuous chirps. The next 7 chirps will be recorded in the next row of our file. 20 rows will be written in one file and the next file will be written repeatedly. All the chirp data has been converted to channel impulse response (CIR) after match filtering before restored.

The Scope setups are also recorded for each measurement campaign, which can be for the measurement campaign description and data analysis.

Back-to-back measurement

In order to verify the system accuracy and calibrate the absolute power level, a Back-to-Back (B2B) measurement is conducted. First, we connect the AWG and Oscilloscope directly to verify the baseband system and chirp signal (Figure 63). The complex impulse response measurement result is demonstrated in the Figure 64, from which it can be found that the chirp signal shows a good autocorrelation property and the signal-to-noise ratio (SNR) is over 50 dB. IFSTTAR is trying to provide the following equipment for channel measurements. The availability will depend on the budget needed to rent the equipment.

For 60 GHz, in order to obtain accurate channel information like received signal level, power-delay profile and Doppler spectrum, a dedicated mmw channel sounder comprising a transmitter (TX) and a receiver (RX) is needed, which can "sound" the channel by sending predefined signals and obtain the channel properties based on the post signal processing on the received signal. The sounder which was designed to operate at 60 GHz and emits a repetitive frequency chirp signal with 368 MHz bandwidth, which leads to a delay resolution of about 3 ns. The maximum transmit power is 16dBm and the antenna gain is 7.5 dBi, yielding an EIRP of 23.5 dBm. The antenna is integrated with the transceiver (AiP) and the opening angle is in the order of 60 degrees. There is a tradeoff between the maximum Doppler band and the maximum delay spread, which can be configured due to the requirements of the scenarios. Since this sounder is still under development, the current working mode is SISO and synchronization system is realized by using a 25 m connecting cable. Therefore, the maximum distance between transmitter and receiver is about 25 meters. However, both MIMO and synchronization system can be updated based on customer's request. The channel sounder's parameters are summarized in details:

R2R-T2.

Measurement Scenario Description

It needs to be pointed out that the mmw radio technology is feasible only for the short-range radio link due to the high propagation loss. Besides, the mmw sounder system with integrated antennas is fragile. By taking the feasibility into consideration, the related measurement campaigns should be performed for short-distances (maximum 25 m) with limited mobility. As a result, the following scenarios are proposed.

Intra-Vehicle Communication (Metro and HSR)

Links: This scenario will consist of measuring the wireless link between different elements inside a single vehicle. These will be Line-Of-Sight (LOS) links, mostly affected by the internal structure of the vehicle.

Figure 67: Intra-vehicle links

Measurement locations:

It can be measured on depot.

Variations:

1. Person presence (a single metro car can handle up to 200 people; for measurements, a group of 10-20 people will be available). 2. Person movement. 3. Train gauge (narrow and wide), as well as vehicles with/without corridor between (i.e. continuous new trains, and non-continuous old trains). 4. Impact of material properties (this could be measured on old trains -it will be put as a low priority action).

Intra-Consist Communication (Metro and HSR)

Links: This scenario will include wireless link that go beyond a single vehicle, involving both the next vehicle and the exterior of the vehicle (both roof and bogie). Although different environments can affect the communication link, especially for vehicles without a corridor between cars, it could be difficult to mount the sounder outside the train due to integrated antenna systems. However, if a firmed and secured mounting solution can be proposed, it may be feasible for the measurement campaigns with mobility.

Note: additional measurements will be made on roof and bogie in order to characterize EMI noise coming from catenary and engine (DC old engines and AC new engines). These measurements will be done with a wideband antenna and a spectrum analyzer, and will be used as an input for task T2.7.

Variations

Inter-Consist Communication (Metro and HSR)

Links: It will include wireless links that go from one consist to another one, locating the antennas on the roof of the train (both at the centre and at the edges -see Figure 69).

Figure 69: Inter-Consist links

If mm-wave measurement equipment is available, the channel at mm-waves will be characterized for the edge configuration.

Measurement locations:

The mmw channel sounding is suggested to be performed when the vehicle is still. However, if a firmed and secured mounting solution can be proposed, it may be feasible for the measurement campaigns with mobility.

Inter-Vehicle Measurement

One train, the transmitter and receiver of the channel sounder were located in the same train but on different cars (see Figure 46). The installation of the equipment had to be done at Napoli Centrale. At 23:15 Train 28 arrived at the station on platform 18. At 23:30 the measurement start was shifted to 00:45. Due to the delay, phase 1 was shortened to PK 60. From PK 60 to PK 36 the speed was 100 km/h. Phase 2 was done as planned. Within these measurements a multiplexer was used. Two antennas were measured at the receiving side in parallel, i.e. measurements were performed in Single-Input Multiple-Output (SIMO) mode.

Intra-Consist Measurements

The intra-consist measurements were done inside the train from one coach to another with the ITS-G5 system (cf. Figure 71). In this case, the intra-consist and intra vehicle measurements could be performed in parallel to the inter-vehicle measurements. A data set of 1.5 hours was collected.

Intra-Vehicle Measurements

The smallest measured distance with ITS-G5 was within one vehicle. This measurement represents an intra-vehicle link, Figure 71 shows the setup. The GPS fix is used for the timestamp of the transmitted and received data.

Night 2

Two trains: The transmitter and receiver were located in different trains. The measurements were done with directional antennas. For the calibration measurements, the two trains needed to be placed in a way that TX and RX were on the same level next to each other to minimize the length of additional cables. This manoeuvre resulted in a total length of necessary railway track of around 640 m. This length was not available at the station Napoli Centrale or the Depot of Naples. Therefore, the calibration had to be done on the high speed line.

During this calibration measurement strange calibration values occurred. Using the same Rubidium frequency normal, the phase spectrum was time variant. Additionally, the phase was symmetric around the IF instead of linear over the transfer function. The reason might be a different electrical ground between either trains or problems with the inverter from DC to AC used inside the train. A later check of the channel sounder at the hotel could not verify the problems during the measurement campaign. Due to these calibration problems on the track, the channel sounder measurements were cancelled. In addition the ITS-G5 measurement equipment was set up for T2T measurements with omni-directional antennas as shown in Figure 73. A reduced and adapted amount of manoeuvres (Table 13, phase 1 and 3) were complete with ITS-G5 equipment and RCAS measurements from 3:00 to 5:30. Two trains: The transmitter and receiver were located in different trains. The measurements were done with omni-directional antennas (see Figure 74). For an easier realization of the calibration measurement, Train 07 was turned around. In this case, Locomotive B of Train 07 was located next to Locomotive A of Train 28. Hence, the calibration measurement was performed in the Station Napoli Centrale with a platform between the trains. Within this setting, no problems with the phase in the calibration arose. All manoeuvres were performed as planned in Table 14. The measurement setup is shown in Figure 74 and the settings are explained below.

Cohda Tx

Night 4

Two trains: The transmitter and receiver were located in different trains. The planned measurements setting were using omni-directional antennas. Because of the cancelled channel sounder measurements in night 2, in night 4 directional antennas were used. The calibration measurement was performed in the same way as in night 2. Within the calibration, similar phase problems were recorded as in night 2, even with powering all the equipment from one train. Nevertheless, the measurement run was performed with the setup shown in Figure 75 and started with this calibration on time. All manoeuvres were performed as planned listed in Table 15.

R2R-T2.

URBAN / METRO (METRO DE MADRID)

Measurements were carried out in Line 6, Line 10 and Line 11 of Metro de Madrid. The specific lines and stations measured are highlighted in Figure 76 (L6 in grey, L10 in blue, and L11 in green). Narrowband measurements where done transmitting an unmodulated carrier frequency with a signal generator, and using as a receiver a National Instruments USRP 2901 Software Defined Radio equipment, which has two receiver ports. The following configuration was used for these narrowband measurements:

Transmitter Power (dBm) 19 Carrier Frequency (MHz) 2600 Bandwidth (MHz) Continuous wave

Night 1

The preparation of the antennas and measurement equipment was done in the afternoon at Cuatro Vientos depot of Metro de Madrid. Two Mobile-Mark MGRM-WHF antennas were placed on the roof of a Series 8000 continuous train, at the edges of two cars, and spaced 1 meter apart (see Figure 77).

Figure 77: Omnidirectional antennas for inter-consist measurements

These antennas were connected to the transmitter and receiver equipment, placed inside the cars; an additional antenna was also placed on a tripod inside the train, in order to check the roof-toindoor link (see Figure 78).

Figure 78: Inter-consist measurement setup

At night, the train was moved to Line 10, and both wideband and narrowband measurements were done between Cuatro Vientos and Tribunal stations. This line has tunnels, stations and also open air environments.

After doing the inter-consist measurements, two MGRM-WHF antennas were placed inside the train at a distance of 15m from each other (5m and 10m from the connection of two cars, respectively) for intra-consist measurements. The measurement setup is shown in Figure 79 and the antennas in Figure 80. With this setup, wideband measurements were carried out. After completing these measurements, the wideband transmitter was checked and an unexpected behaviour was observed, so it was decided to repeat the wideband measurements in Line 10; they were rescheduled for Night 3.

T R 2 1

Night 2

The second night, measurements were done in Line 11 between La Fortuna and Pan Bendito stations. This line covers tunnel and station environments, but open air was also measured on the way from the depot to the first station (La Fortuna). First, wideband intra-consist measurements were done using a six-antenna array (Figure 81). Then, narrowband intra-consist measurements were done using two monopole antennas, as in Figure 80. Finally, with the monopole antennas which were already installed on the roof, wideband and narrowband inter-consist measurements were also taken.

Figure 81: Antenna array for intra-vehicle measurements

After returning to the depot, narrowband intra-consist measurements were done to check the impact of people movement on intra-consist links. The path loss along the train was also measured moving one of the indoor antennas in narrowband configuration (Figure 82).

Night 3

In preparation for the train-to-train measurements to be done at night, in the afternoon of the third day monopole antennas were installed on a second train, both on the roof and inside the train (Figure 83). Additionally, the properties of the glass of the trains were measured using a measurement setup with horn antennas (Figure 84).

Figure 84: Glass characterization setup

At night, narrowband train-to-train measurements were done in Line 10. For these measurements, one of the trains was kept at a fixed location, while the other train crossed it at the next track. One tunnel, one station and one open air locations were used for this. Additionally, before starting the train-to-train measurements, wideband and narrowband inter-consist measurements were taken while moving to the first location in Line 10.

REGIONAL TRAINS (ALSTOM)

The 60 GHz mmw radio technology is usable only for the short-range radio link due to the high propagation loss. Besides, the mmw sounder system with integrated antennas is fragile. By taking the feasibility into consideration, the related measurement campaigns should be performed for short-distances (maximum 25 m) with limited mobility. As a result, the following scenarios are proposed.

Thanks to ALSTOM, we had access to the regional trains in Alstom's factory in Valenciennes in a garage. Under these conditions, only some configurations can be measured.

CHANNEL MODELS

This chapter presents the post processing and analysis of the channel measurements described in Chapter 5. For the high speed line measurements, the large scale and small scale fading parameters are estimated in Section 6.1 for the inter-vehicle channel measurements and the parameters for a tap-delay line channel model are provided. Similarly, Section 6.2 provides the large scale and small scale fading parameters of a channel model for Metro inter-consist, intraconsist, and train-to-train scenarios as well as parameters for a tap-delay line channel model for the first two scenarios. Finally, Section 6.3 analyses and estimates parameters for a regional train at 60 GHz carrier frequency for various measurement scenarios such as intra-vehicle and outdoorto-roof.

HSR INTER-VEHICLE CHANNEL MODEL

In this section a channel model for data communication between train wagons is presented. Based on the channel sounder data collected in the first night of the HSR-measurements in Italy, an intervehicle channel model was developed. A description of the measurement scenario can be found in Section 4.1.3 and the detailed measurement setup in Section 5.1.1.

Data Post Processing

In the post processing, as described in Section 3.5, the calibration measurements need to be taken into account. One calibration measurement was done from the N-connector of the antenna cable to the N-connector of the MUX-LNA cable at the receiver side (see "calibration" in Figure 70). This calibration was done before the measurement run and is respected within the measurements automatically. The calibration measurements for the cables connecting MUX rx1 and rx2 with the antennas (see Figure 70) and the MUX itself were done before the measurement run, but need to be considered in the post processing. Therefore, the output of the channel sounder H_rawt(,t) is divided with the transfer function of the MUX H_muxt(,t) to cancel out the cable and MUX effects. The Fourier transformation of Ht(,t) gives the time-variant channel impulse response (CIR) h(,t). Any other equivalents of the CIR can be calculated as illustrated in Figure 87.

Owing to the SISO measurement setup, an angle of arrival cannot be derived. Hence, the antenna pattern cannot be taken into account and the antennas need to be considered as part of the channel. This is a common approach for channel sounder measurements.

Channel Characteristics

Large scale fading

The measurement antennas are placed on the roof of the train as for commercial train applications (see Figure 43). Due to the conditions of same height and short distance, shadowing effects cannot occur. The short range link is 3 m and the long range link is 29 m. The path loss results to a constant average PRx of the LOS link with minor variation. The theoretical received power was calculated as in ( 14) before the measurement and the transmit power PTx was adjusted not to saturate the input of the channel sounder receiver. The cable losses Lcable were measured for every used cable and considered with the calibration measurements. The antenna gains GTx and GRx can be found in the datasheet of the used antennas.

𝑃 𝑅𝑥 = 𝑃 𝑇𝑥 -𝐿 𝑐𝑎𝑏𝑙𝑒 + 𝐺 𝑇𝑥 -10 • log ( 4𝜋•𝑟•𝑓 𝑐 ) 𝑘 + 𝐺 𝑅𝑥 -𝐿 𝑐𝑎𝑏𝑙𝑒 (14)

b) Power Delay Profile

The power delay profile (PDP) is calculated out of the CIR of one scenario normalized in two dimensions. First, the CIR is normalized in power with respect to the theoretical free space path loss (FSPL) and is indexed with F. Second, the delay 𝜏 is normalized w.r.t. the maximum such that τ G = 0 s. For communication aspects the absolute delay is not important and therefore a normalization of the delay is not adding any error. To reduce the effect of small scale fading on the PDP analysis, the CIRs are averaged over distances in blocks of d = 40 • λ; l G represents the blocks and N l the number of snapshots in each block [START_REF] Wei | Channel Measurement and Modeling for Mobile Radio Based Positioning[END_REF].

𝑃 𝜏 𝐺 ,𝐹 (𝑙 𝑔 , 𝜏 𝑛 ) = 1 𝑁 𝑙 ∑ |ℎ 𝜏 𝐺 ,𝐹 (𝑡 𝑘 , 𝜏 𝑛 )| 2 𝑡 𝑙 𝑔 +1
𝑡 𝑘 =𝑡 𝑙 𝑔 [START_REF] Castiblanco | Time-domain methods to model electromagnetic wave propagation in confined environments[END_REF] Figure 88 shows the normalized PDP for the two measured link distances of 3 m and 29 m for a slow and fast manoeuvre during the first night. The probability density functions (PDF) of the PDP is presented in Figure 89

Small scale fading

The strongest variation of the received power is caused by multipath propagation. The railway environment and also the train cause reflections and scattering. For the analysis a sliding average window is used to cancel out the large scale fading. For the slow ride the window is 40 snapshots for the 3 m for the 29 m link. The small scale fading is analysed for each tap within a delay of 100 ns.

Tapped delay line model

Bandwidth

The bandwidth of the measurement signal of the RUSK DLR Channel Sounder is 𝐵 = 120 𝑀𝐻𝑧. This results in a minimum spacing of the measurement samples of ∆𝜏 = 8.33 𝑛𝑠. The delay spacing of the measurements is the lower bound of the delay in the tapped delay line model. With the delay spacing of the taps the bandwidth of the model is set. To achieve a technology independent channel model the maximum bandwidth of 𝐵 = 120 𝑀𝐻𝑧 is used for the model.

Significant taps

The PDP in Figure 88 shows a decrease in power of 20 dB or more within a delay of 100 ns. Samples within this range can be considered as significant for the channel model. W.r.t the chosen bandwidth the amount of significant taps is equivalent to the measurement samples within 100 ns.

Tap model fitting parameters

In the following tables and figures the parameters of the fitted channel model for the 3 m and 29 m link for low speed are presented. Three of the most common distributions were used to fit to the measurement data:

 Rician distribution: The Rician distribution is used for modelling multipath propagation with a strong dominant path (LOS). The shape fitting is adjusted with the mean  and the variance 𝜎 2 ; 𝐼 0 is the zero-order modified Bessel function of the first kind [START_REF] Rice | Mathematical Analysis of Randon Noise[END_REF].

𝑝 𝑥 = I 0 ( x•μ σ 2 ) * x σ 2 * e -( x 2 +μ 2 2σ 2 ) (16)
The Rician k-factor is defined as the ratio of the dominant to the scattering path for one multipath component (in the case of tapped delay line, for one tap) [START_REF] Wei | Channel Measurement and Modeling for Mobile Radio Based Positioning[END_REF]:

k = 10 • 𝑙𝑜𝑔 10 ( 𝑃 𝑚𝑒𝑎𝑛 𝑃 𝑓𝑎𝑑 ) = 10 • log 10 ( μ 2 2•σ 2 ) (17)
 Rayleigh distribution: For dense scattering propagation environments the Rayleigh distribution is used. The mean 𝜇 = 0 and the variance 𝜎 2 is the tuning parameter for the fitting.

p x = x σ 2 * e -( x 2 2𝜎 2 ) (18)
 Nakagami distribution: The Nakagami distribution is used to model scattering channels as well. With the shape parameter  and the scale parameter  this distribution was originally used for ionospheric links [START_REF] Nakagami | The m-Distribution-A General Formula of Intensity Distribution of Rapid Fading[END_REF].

p x = 2 ( 𝜇 𝜔 ) 𝜇 * 𝑥 (2𝜇-1) Γ(μ) * e -( μ•x 2 ω ) (19)
In Table 28 29. For both models (3 m and 29 m link) the normalized power in Table 28 and Table 29 is describing the average received power normalized to the FSPL. Due to the nature of these short links on the roof of HSRs, shadowing effects or other effects described by large scale fading do not appear. The small scale effects are described by the fading distribution for each tap, in which each tap is normalized to its own maximum.

METRO CHANNEL MODEL

In this Section the channel models obtained for metro environment will be described, including Inter-consist, Intra-consist and Train-to-train links. For each type of link, separate models will be obtained for tunnel, station and open air environments. First of all, the post-processing of the data will be described.

Data Post Processing

Regarding narrowband measurements, in order to model the channel it is necessary to analyze statistically the small-scale fading of the signal. This has been done by removing the large-scale fading of the channel, and checking which theoretical Probability Density Functions (PDF) fits best with the result. In order to obtain the large-scale fading of the channel, narrowband data have been averaged every 40 samples.

Regarding wideband measurement results, RMS Spread and Mean Delay have been calculated. Then, the Power Delay Profile (PDP) of the channel has been calculated, and an 8-tap channel model has been obtained, where each tap is spaced 12.5 ns, corresponding to the receiver bandwidth of 80 MHz. It can be observed that the signal is attenuated 30-35 dB when one of the antennas is placed inside the train, compared to the outdoor case. This is because in this situation there is no Line of Sight between the two antennas, and the signal from the antenna on the roof reaches the antenna 10/12/2016 in the train through diffraction on the train structure (e.g. window frames, car interconnection structure, etc) and also through reflections on the tunnel walls. It can also be observed that the amplitude of the small-scale fading is lower for the case of the outdoor antennas, and mainly slow signal variations are observed; this is due to the influence of the large Line Of Sight component and the stability of the surrounding reflections. On the contrary, for the case of the indoor antenna fast signal variations are observed.

Inter-consist Model

In order to illustrate the effect of the windows of the car, the electrical properties of the glass have been obtained (see measurement setup in Figure 84). Figure 94 and Table 30 show the result of this characterization. It can be observed that the losses due to the glass are not significant (1.8 to 4.4 dB), and a phase variation is observed due to the permittivity of the glass. Regarding wideband results, the evolution of each of the 8 taps of the channel model is presented in Figure 95 for a tunnel in Line 10, and in Figure 97 It can be observed that the value of attenuation is slightly higher at the station, when it should have been similar to tunnel or open air. However, the amount of data recorded at the station is lower, due to the lower distance covered (120m), and therefore the obtained average value is less accurate. On the other hand, it can be observed that there is a 34-35 dB difference between the outdoor and indoor receiver antennas in station and tunnel environments; this value rises up to 43 dB in open air, as there is less energy coming from external reflections.

The measured narrowband data with the external antennas fit statistically to Rice distribution, where the LOS component is substantially higher than the multipath components. The Probability Density Functions (PDF) and their parameters are shown in Figure 109 and Table 32. As can be observed, the link with external antennas shows clearly a Rician PDF, due to the excellent LOS in this type of link. The lower value of the K-Rice coefficient in the station environment is due to a higher multipath.

On the other hand, the link from the antenna in the roof to the antenna inside the train fits statistically to a Rayleigh distribution, as there is no LOS between the antennas (see Figure 110 and Table 33). The standard deviation is lower for open air and station, due to less reflections coming from the environment (the station is the opposite case, with a higher value of standard deviation due to a higher level of reflections and signal fading). These values are summarized in Table 34. It can be observed that the RMS spread is very similar in all environments. However, there is a difference in the mean delay (up to 15% higher in tunnel compared to station).

Equivalent results have been obtained for Line 11 (Station and Tunnel) and Line 6 (Station). They are presented in Figure 112, Table 37, Table 38 and Table 39 for Line 11, and Figure 113, Table 40, Table 41 and Table 42 for Line 6.

Tunnel

Wideband measurements were done in Line 11 using a six-antenna array. This allows distinguishing the angle of arrival of the different groups of rays. Figure 114 shows the obtained response in a tunnel, where each antenna covers an angle of 60 degrees. It can be observed that most of the energy comes from the antenna facing the transmitter antenna, which is located on the left side, and most multipath is received by the two antennas on its sides. On the other hand, if the transmitting antenna was fixed and the receiver array was moving, it would be possible to obtain the Doppler spectrum of the train with this measurement. In this case, both antennas were moving at the same time, and therefore it is not possible to separate the reflections due to the train from those due to the environment; the first ones do not produce Doppler, while the second ones do. However, the plots show that most of the energy in the intraconsist link comes from the reflections inside the train, what implies that there is little influence of the environment and therefore little influence of the Doppler spectrum.

Station

Figure 115 shows the results of the measurements with the array in a station environment. Afterwards, in order to obtain the path loss of the intra-consist link in a continuous train, the receiver antenna was moved along the train and narrowband measurements were taken. Figure 116 shows the average of the received signal and the path loss model. It can be observed that near the transmitter the path loss exponent (n) is very small (less than 0.5), and therefore the path loss can be estimated with a constant value. Afterwards, the path-loss exponent is 3.1, higher than the free-space value, due to the reflections in the various inner structures of the train (e.g. walls, vertical hand-hold bars, interconnections between cars, etc). A statistical modeling has also been done for these narrowband measurements, obtaining a fit to a Rician model, due to the high LOS component (see Figure 117 and Table 43). The presence of people inside the train has also been measured at the depot. Figure 118 shows a narrowband measurement over time with random people movement (even blocking the LOS link). The statistical modeling is shown in Figure 119 and Table 44. Signal fading up to 30 dB is observed, as well as averaged variations of 10 dB. It is also observed that the impact of the environment is higher when the LOS is blocked; therefore, for this kind of situations the use of MIMO solutions or solutions with spatial diversity would be advisable. 10/12/2016 45 and Table 46)

Intra-consist Model (Non-Continuous Train)

Narrowband measurements were done at Laguna station (Line 6) for obtaining the path loss inside a non-continuous train. Figure 121 shows the result.

The statistical modeling of these narrowband measurements is presented in Figure 122 and Table 47. 10/12/2016 RMS spread and Mean Delay values have also been extracted from wideband measurements in Line 6, as well as the statistical distributions of the different taps (see Table 48 and Table 49). On the other hand, the magnitude of each of the 8 multipath components (taps) with respect to the LOS component is shown in

Train-to-Train Model

In this Section the results of train-to-train measurements of Line 10 are presented, along with the proposed models.

Tunnel

Figure 125 shows the averaged narrowband result for the train-to-train link in tunnel environment. The receiver train was stopped inside a tunnel, while the transmitter train crossed it. 10/12/2016 For the case of the outdoor antennas, a model is obtained for the path loss (see Figure 126).

Open Air

The crossing in open air was done between Batán and Casa de Campo stations. The receiver train was stopped, while the transmitter train crossed it. Figure 129 shows the averaged narrowband result, while Figure 130 shows the path loss model. 10/12/2016 In order to analyze the small-scale fading in Train-to-Train links, the averaged part of the signal has been removed to the recorded waveform, and it has been fitted with theoretical PDFs. Figure 132 and Table 51 show the results for the outdoor receiving antenna, while Figure 133 and Table 52 show the result for the indoor receiving antenna. These results indicate the presence of a strong LOS component, both for outdoor and indoor antennas. 10/12/2016 where n is the path loss index, P0 is the path loss at 1m, and d is the distance. The values of these parameters for the different propagation environments are summarized in Table 53. It can be observed that in all cases the propagation index is lower than 2 (free space value), due to the reflections coming both from the environment (tunnel and station) and from the train structure itself. 55 and Table 56 summarize the values of Mean delay and RMS delay in ns for different angle positions. The tables show that the mean delay and RMS delay at downstairs location is much larger than at upstairs location. It shows more reflection paths at downstairs location.

Inter Car Scenario

The scenarios are illustrated by the scheme on Figure 138 The following In the Table 57 and Table 58 the mean delay and RMS delay at downstairs location is much larger than at upstairs location. It shows more reflection paths at downstairs location. In addition, the RMS and mean delay value turn out to be small when the RX antenna point at the TX while the RMS and mean delay value is large at the other angles due to high mount of reflections when the door of the driver car is closed.

Penetration through the train window

In this paragraph we present the results obtain by measuring the penetration losses through the train window as illustrated on Figure 143 The mean delay and RMS delay become larger gradually with the increase of the Tx-Rx distance, which means that more radio waves are reflected accordingly.

Outdoor to Driver's room

Virtual coupling is considered to be feasible in the further railway. To support it, it is important to investigate the radio channel for this application. One of these scenarios is to mount the system antenna inside the car. This Outdoor-to-Driver (O2D) scenario is designed to study this case.

In this scenario, the transmitter is located inside the driver cabin as illustrated in the photography We observe that from position P1 to P5 (up to 17 m), the highest RSLs are received at the angle of 0 degree. When the Tx-Rx distance is more than 17 m, the highest RSLs are received at the angel of -22 0 . However, the difference between the largest RSL and the smallest RSL are within 5 dB. Figure 150 shows that the RSL difference between different angles decrease with the increase of the Tx-Rx distance, which means the antenna directivity in 60 GHz band at short Tx-Rx distances is sensitive. A larger antenna pattern can be needed for this case.

Outdoor to Driver (Centre)

This scenario is designed for the virtual coupling as the previous one, in which the transmitter is located inside the driver cabin. The only difference is that Rx is located in the middle of the track (see Figure 147 63 and Table 64. In the above two tables we observe that the RMS delay and the Mean delay at large Tx-Rx distance (Position P5, P6 and P7) are much larger at the angle of -22°, which is consistent with the previous scenario. Similarly, the above Figure 153 shows that the RSL difference between different angles decrease with the increase of the Tx-Rx distance. It will be more efficient to point antenna beam towards the Tx than any other angle at all the locations.

Outdoor to Outdoor (O2O)

It is feasible that Tx and the Rx are outside the train near the mechanical coupling system (see photography on Figure 154 (b) in order to simulate a future transmission in the context of virtual coupling. In this scenario, the receiver is located at several positions on the same longitudinal axis as indicated on the scheme Figure 154 The above Table 65 and Table 66 show that the RMS delay and the Mean delay is small and consistent, which shows that the RMS delay and the Mean delay is uncorrelated with the Tx-Rx distance. It can also be concluded few reflections from environment are found. We can observe on the above Figure 157 that there is a big fading at P4 for all the angles. It will be more efficient that the antenna pattern is pointing to Tx than the other angles at all the locations. 10/12/2016

Train to Infrastructure

As described in [START_REF] Ai | Future railway services-oriented mobile communications network[END_REF], two kinds of links between the access points (APs)/ transceivers of the train and the infrastructures of fixed networks are required. These links have following requirements: high data rates, low latencies, bidirectional streams, less than 100 ms latencies and 98-99 percent availability. It will be important to exploit the feasibility of mmw system to fulfil these requirements. Therefore, in this configuration, the transmitter is located on the roof of the train as illustrated on the photography given on Figure 158 (b). The receiver is situated on the ground and takes different positions as shown on the scheme given in Figure 158 (a).

Both the Tx and the Rx antenna height are 4.5 m. The azimuth angles at the Rx antenna were swept in 22° steps from 0 to 360°, while the Tx antenna is fixed on the roof of the train. All the location and surrounding information is given in detail in the Figure 158 (a). Figure 159 gives the angular power distribution at the 5 different positions. Then in Figure 160 we present the received power level for each angle for the 5 positions. Table 67 and Table 68 give the values of the mean delay and RMS delay for each angle at each position. We remind that for each transmitter position, the antenna is rotated overs 360°. 0° corresponds to the case where Tx and Rx are in LOS (same axis for the antennas). Figure 161 shows that the largest RSL difference between different angles is within 15 dB and uncorrelated with the Tx-Rx distance. In this scenario, the transmitter is located on the roof of the train while the receiver is situated at the same height to simulate the virtual coupling when both Tx and Rx antennas are installed on the roof of the two cars. It needs to be mentioned that in our measurement campaign, there is only one car in the station which can be used in our measurement campaign. However, the Outdoor-to-Roof (O2R) still provide good information for the virtual coupling. The transmitter is located on the roof of the train as illustrated on the photography given on Figure 163 Similar with the O2O scenario, the two Table 69 and Table 70 highlight that the RMS delay and the Mean delay are small and consistent, which shows that the RMS delay and the Mean delay is uncorrelated with the Tx-Rx distance. It can also be concluded that few reflections from environment are found. 10/12/2016 In Figure 166 we observe that the RSL difference at the angle of 0° and 22° is small. However, the RSL difference between these two angles and -22 o increase with the increase of the Tx-Rx distance. 10/12/2016

Outdoor to Roof

To conclude, the results of Chapter 6 provide the basis for the channel models which are used in simulations in Task 2.7 to evaluate selected wireless technologies and in channel emulators in Task 2.8 to validate suitable radio technologies for wireless TCMS.

In case of HSR and Metro measurements the tapped delay line channel models of roof top measurements will be used as input for Physical Layer simulations in T2.7. As discussed in T2.7 meeting, a mapping-table of channel models with channel parameters for different scenarios will be evaluated in different Physical Layer link simulations to obtain system performance parameters in terms of delay time and packet error rate, which can be further evaluated as inputs in higher-layer system simulations.

The results of Chapter 6 show that the HSR, the METRO and the mmWave measurements have been successful to provide the necessary generic tapped delay line channel models for evaluating wireless TCMS. Further analysis of the measurement data beyond Roll2Rail will confirm this and enable new applications such as virtual coupling in addition to wireless TCMS.

R2RFigure 1 :

 1 Figure 1: Future train wireless communications ............................................................................

Figure 2 :

 2 Figure 2: Diffraction phenomena around car: electromagnetic simulation model (left); simulated electric field (right) .................................................................................................................

Figure 3 :

 3 Figure 3: Simulated and measured power-loss results for 3-meter setup with vertical polarization at 2.45 GHz ...........................................................................................................................

Figure 4 :

 4 Figure 4: Different lateral cuts of tunnels .......................................................................................

Figure 5 :

 5 Figure 5: Intra-vehicle (left) and inter-vehicle (right); note that the vertical gray lines depict the boundaries between rail vehicles...........................................................................................

Figure 6 :

 6 Figure 6: Continuous (left) and non-continuous (right) trains .........................................................

Figure 7 :

 7 Figure 7: Inter-consist: (a) centre; (b) edge ...................................................................................

Figure 8 :

 8 Figure 8: Train-to-train: inside (left), roof (right) .............................................................................

Figure 9 :

 9 Figure 9: Vehicle Example A (Tram) .............................................................................................

Figure 10 :

 10 Figure 10: Vehicle Example B (Tram) ...........................................................................................

Figure 11 :

 11 Figure 11: Vehicle Example C (Metro Madrid) ...............................................................................

Figure 12 :Figure 13 :

 1213 Figure 12: VNA-based measurement setup for static channels: VNA (left); UWB antennas (right) Figure 13: VSA-based measurement setup: transmitter (left); receiver (right) ...............................

Figure 14 :

 14 Figure 14: RUSK Channel Sounder in railway environment ..........................................................

Figure 15 :

 15 Figure 15: MEDAV RUSK block diagram ......................................................................................

Figure 16 :

 16 Figure 16: Broadband multicarrier spread spectrum signal (MCSSS) magnitude in time (left) and frequency domain (right) .......................................................................................................

Figure 17 :

 17 Figure 17: Antennas on wheel and bogie for channel measurements ...........................................

Figure 18 :

 18 Figure 18: Base station antenna located inside the train ...............................................................

Figure 19 :

 19 Figure 19: Access Point locations .................................................................................................

Figure 20 :

 20 Figure 20: Sensor node locations under the car ............................................................................

Figure 21 :

 21 Figure 21: Sensor node located on gearbox (S2) ..........................................................................

Figure 22 :

 22 Figure 22: Sensor node locations inside the car ............................................................................

Figure 23 :

 23 Figure 23: Principle of channel sounding ......................................................................................

Figure 24 :

 24 Figure 24: Waveform generation at transmitter side ......................................................................

Figure 25 :

 25 Figure 25: Radiation pattern of Mobile Mark MGRM-UMB-1C antenna at 2.45 GHz .....................

Figure 26 :

 26 Figure 26: Frequency response of Mobile Mark MGRM-UMB-1C antenna from 2 to 3 GHz ..........

Figure 27 :

 27 Figure 27: Channel power gain along the frequency and space ....................................................

Figure 28 :

 28 Figure 28: Small scale fading extraction ........................................................................................

Figure 29 :

 29 Figure 29: Small scale envelope distribution .................................................................................

Figure 30 :

 30 Figure 30: Averaged power delay profile .......................................................................................

Figure 31 :

 31 Figure 31: Spatial autocovariance .................................................................................................

Figure 32 :Figure 33 :

 3233 Figure 32: Temporal power variations ...........................................................................................

Figure 34 :

 34 Figure 34: Manoeuvres .................................................................................................................

Figure 35 :

 35 Figure 35: Flow traffic of two trains ...............................................................................................

Figure 36 :

 36 Figure 36: Timeline for overtake manoeuvre .................................................................................

Figure 37 :

 37 Figure 37: Opposing traffic of two trains ........................................................................................

Figure 38 :

 38 Figure 38: Time line for counter manoeuvre ..................................................................................

Figure 39 :

 39 Figure 39: One train pass a second train ......................................................................................

Figure 40 :

 40 Figure 40: Consist-to-Consist (Bombardier) ..................................................................................

Figure 41 :

 41 Figure 41: Front to End measurement ...........................................................................................

Figure 42 :

 42 Figure 42: Receiver (left) and transmitter (right) of the channel sounding equipment ....................

Figure 43 :

 43 Figure 43: Omni-directional (red marked) antenna on train 28, coach 3 ........................................

Figure 44 :

 44 Figure 44: Installation of the directional antenna ...........................................................................

Figure 45 :

 45 Figure 45: Tetra antenna on locomotive ........................................................................................

Figure 46 :

 46 Figure 46: Vehicle-to-Vehicle setup ..............................................................................................

Figure 47 :

 47 Figure 47: Train-to-Train with omni-directional antennas ...............................................................

Figure 48 :

 48 Figure 48: Train-to-Train with directional antennas .......................................................................

Figure 49 :

 49 Figure 49: Track map ....................................................................................................................

Figure 50 :

 50 Figure 50: Frecciarossa ETR 500 .................................................................................................

Figure 51 :

 51 Figure 51 : Channel Sounder ........................................................................................................

Figure 52 :

 52 Figure 52: Mobile Mark MGRM-WHF Wideband Monopole Antenna.............................................

Figure 53 :

 53 Figure 53: Monopole Array antenna ..............................................................................................

Figure 54 :

 54 Figure 54: Inter-Consist measurements ........................................................................................

Figure 55 :

 55 Figure 55: Train-to-Train Measurements .......................................................................................

Figure 56 :

 56 Figure 56: Intra-Consist measurements on Continuous train .........................................................

Figure 57 :

 57 Figure 57: Intra-Consist measurements on Non-Continuous train .................................................

Figure 58 :

 58 Figure 58: Photos of the mmw measurement setup -VµBIQ ........................................................

Figure 59 :

 59 Figure 59: mmw measurement setup -VµBIQ ..............................................................................

Figure 60 :

 60 Figure 60: Scheme of the equipment ............................................................................................

Figure 61 :

 61 Figure 61: Characteristics of the mmw antenna ............................................................................

Figure 62 :

 62 Figure 62: Real and imaginary part of the chirp signal ..................................................................

Figure 63 :

 63 Figure 63: Back-to-Back measurement setup without RF module .................................................

Figure 64 :

 64 Figure 64: Channel Impulse Response from B2B measurement without RF module .....................

Figure 65 :

 65 Figure 65: (a) waveguide attenuator (b) attenuation loss measurement ........................................

Figure 66 :

 66 Figure 66: mmw measurement setup ............................................................................................

Figure 67 :

 67 Figure 67: Intra-vehicle links .........................................................................................................

Figure 68 :Figure 69 :

 6869 Figure 68: Intra-Consist links ........................................................................................................

Figure 70 :

 70 Figure 70: Measurement setup for inter-vehicle measurements ....................................................

Figure 71 :

 71 Figure 71: Measurement setup for inside ITS-G5 measurements .................................................

Figure 72 :

 72 Figure 72: Intra vehicle/consist measurement ...............................................................................

Figure 73 :

 73 Figure 73: Measurement setup for outside ITS-G5 measurements ...............................................

Figure 74 :

 74 Figure 74: Measurement setup for T2T omni-directional measurements .......................................

Figure 75 :

 75 Figure 75: Measurement setup for T2T directional measurements ................................................

Figure 76 :

 76 Figure 76: Measured metro lines and stations ...............................................................................

Figure 77 :

 77 Figure 77: Omnidirectional antennas for inter-consist measurements ...........................................

Figure 78 :

 78 Figure 78: Inter-consist measurement setup .................................................................................

Figure 79 :

 79 Figure 79: Intra-consist measurement setup .................................................................................

Figure 80 :

 80 Figure 80: Omnidirectional antennas for intra-consist measurements ...........................................

Figure 81 :

 81 Figure 81: Antenna array for intra-vehicle measurements .............................................................

Figure 82 :

 82 Figure 82: Path loss measurement ...............................................................................................

Figure 83 :

 83 Figure 83: Train-to-train measurement setup ..............................................................................

Figure 84 :

 84 Figure 84: Glass characterization setup ......................................................................................

Figure 85 :

 85 Figure 85: Monopole antennas on a Series 5000 train ................................................................

Figure 86 :

 86 Figure 86: View of the train for measurements in Valenciennes ..................................................

Figure 87 :

 87 Figure 87 : The time-variant impulse response and its frequency-domain equivalents [89] .........

Figure 88 :

 88 Figure 88: Normalized PDP for 1. Night: scenario 1 (slow), scenario 2 (fast) ..............................

Figure 89 :

 89 Figure 89: PDF of Normalized PDP for 1. Night ..........................................................................

Figure 90 :

 90 Figure 90 : Tapped delay line model ...........................................................................................

Figure 91 :

 91 Figure 91: 3 m measurement, distribution fitting for different taps ...............................................

Figure 92 :

 92 Figure 92: 29 m measurement, distribution fitting for different taps .............................................

Figure 93 :

 93 Figure 93: Narrowband Results for Inter-Consist link in Tunnel (Line 10) ....................................

Figure 94 :

 94 Figure 94: Glass characterization: losses (blue graph); phase deviation (yellow graph) ..............

Figure 95 :

 95 Figure 95: Channel taps vs distance for Inter-Consist link in Tunnel (Line 10) ............................

Figure 96 :Figure 97 :

 9697 Figure 96: Probability Density Function of channel taps for Inter-Consist link in Tunnel (Line 10) Figure 97: Channel taps vs distance for Inter-Consist link in Tunnel (Line 11) ............................

Figure 98 :Figure 99 :

 9899 Figure 98: Probability Density Function of channel taps for Inter-Consist link in Tunnel (Line 11) Figure 99: Narrowband Results for Inter-Consist link in Station (Line 10) ....................................

Figure 100 :

 100 Figure 100: Channel taps vs distance for Inter-Consist link in Station (Line 10) ..........................

Figure 101 :

 101 Figure 101: Probability Density Function of channel taps for Inter-Consist link in Station (Line 10) ............................................................................................................................................

Figure 102 :

 102 Figure 102: Channel taps vs distance for Inter-Consist link in Station (Line 11) ..........................

Figure 103 :Figure 104 :

 103104 Figure 103: Probability Density Function of channel taps for Inter-Consist link in Station (Line 11) ............................................................................................................................................

Figure 105 :

 105 Figure 105: Probability Density Function of channel taps for Inter-Consist link in Station (Line 6) Figure 106: Narrowband Results for Inter-Consist link in Open Air (Line 10) ...............................

Figure 107 :

 107 Figure 107: Channel taps vs distance for Inter-Consist link in Open Air (Line 10) .......................

Figure 108 :

 108 Figure 108: Probability Density Function of channel taps for Inter-Consist link in Open Air (Line 10) ............................................................................................................................................

Figure 109 :

 109 Figure 109: Probability Density Function with External Antennas ................................................

Figure 110 :

 110 Figure 110: Probability Density Function with External and Internal Antenna ..............................

Figure 111 :

 111 Figure 111: Power Delay Profile (PDP) for Inter-Consist link in Line 10 ......................................

Figure 112 :

 112 Figure 112: Power Delay Profile (PDP) for Inter-Consist link in Line 11 ......................................

Figure 113 :

 113 Figure 113: Power Delay Profile (PDP) for Inter-Consist link in Line 6 ........................................

Figure 114 :

 114 Figure 114: PDP vs angle of arrival for Intra-Consist link in Tunnel (Line 11) ..............................

Figure 115 :

 115 Figure 115: PDP vs angle of arrival for Intra-Consist link in Station (Line 11) ..............................

Figure 116 :

 116 Figure 116: Path loss model for the Intra-Consist link (continuous train) .....................................

Figure 117 :

 117 Figure 117: Probability Density Function of Intra-Consist link in station (continuous train) ..........

Figure 118 :

 118 Figure 118: Impact of people movement on Intra-Consist link (continuous train) .........................

Figure 119 :

 119 Figure 119: Probability Density Function of Intra-Consist link (continuous train) with people movement ...........................................................................................................................

Figure 120 :

 120 Figure 120: PDP vs angle of arrival for Intra-Consist link in Open Air (Line 11) ...........................

Figure 121 :

 121 Figure 121: Path loss model for the Intra-Consist link in a non-continuous train ..........................

Figure 122 :

 122 Figure 122: Probability Density Function of Intra-Consist link in station (non-continuous train) ...

Figure 123 :

 123 Figure 123: Channel taps vs distance for Intra-Consist link (non-continuous train) in Station (Line 6) ............................................................................................................................................

Figure 124 :

 124 Figure 124: Probability Density Function of channel taps for Intra-Consist link (non-continuous train) in Station (Line 6) .......................................................................................................

Figure 125 :

 125 Figure 125: Averaged Narrowband Results for Train-to-Train link in tunnel.................................

Figure 126 :

 126 Figure 126: Path loss model for Train-to-Train link in tunnel with outdoor antennas ....................

Figure 127 :

 127 Figure 127: Averaged Narrowband Results for Train-to-Train link in station ................................

Figure 128 :

 128 Figure 128: Path loss model for Train-to-Train link in station with outdoor antennas ...................

Figure 129 :

 129 Figure 129: Averaged Narrowband Results for Train-to-Train link in open air .............................

Figure 130 :

 130 Figure 130: Path loss model for Train-to-Train link in open air with outdoor antennas .................

Figure 131 :

 131 Figure 131: Comparison of averaged Narrowband Results for Train-to-Train links: outdoor receiving antenna (upper); indoor receiving antenna (bottom) .............................................

Figure 132 :

 132 Figure 132: Probability Density Function for Train-to-Train links with outdoor receiving antenna Figure 133: Probability Density Function for Train-to-Train links with indoor receiving antenna...

Figure 134 :

 134 Figure 134: Comparison of path loss models for Train-to-Train links with outdoor antennas .......

Figure 135 :

 135 Figure 135: Photos of the measurements (a) to (d) .....................................................................

Figure 136 :Figure 137 :

 136137 Figure 136: Angular power distribution for the two positions of the receiver ................................

Figure 138 :

 138 Figure 138: Inter car configuration ..............................................................................................

Figure 139 :

 139 Figure 139: Angular power distribution at P1 with the door open and close ................................

Figure 140 :

 140 Figure 140: Angular power distribution at P2 with the door open and close ................................

Figure 141 :

 141 Figure 141: Angular power distribution at P3 with the door open and close ................................

Figure 142 :

 142 Figure 142: Sum-up of the angular power distribution for the 3 positions ....................................Figure 143 (a) and (b): illustration of the measurements configuration for penetration through the window ................................................................................................................................

Figure 144 :

 144 Figure 144: Angular power distribution for the five positions of Figure 143 (a) ............................

Figure 145 :

 145 Figure 145: Received signal level in dBm for each angle at each of the 5 positions ....................

Figure 146 :

 146 Figure 146: Evolution of received signal level for Tx-Rx distance and for each angle ..................

Figure 147 :

 147 Figure 147: (a) scheme of the measurements-(b) photography of the scenario ..........................

Figure 148 :

 148 Figure 148: Angular power distribution for (-22°, 0°, 22°) for each of the 7 positions outside the cabin as indicated on scheme Figure 147 (a) ......................................................................

Figure 149 :

 149 Figure 149: Received signal level for each position and each angle ...........................................

Figure 150 :

 150 Figure 150: Received signal level versus Tx-Rx distance for each angle (-22°, 0°, +22°) ............

Figure 151 :

 151 Figure 151: Angular power distribution for (-22°, 0°, 22°) for each of the 7 positions outside the cabin as indicated on scheme Figure 147 (a), on the centre ................................................

Figure 152 :

 152 Figure 152: Received signal level for each position and each angle (-22°, 0°, +22°) ...................

Figure 153 :

 153 Figure 153: Received signal level versus distance for each angle (-22°, 0°, +22°) ......................

Figure 154 :

 154 Figure 154: Outdoor-Outdoor measurements to simulate transmission between consist.............

Figure 155 :

 155 Figure 155: Outdoor-Outdoor measurements -Angular power distribution at the 7 positions .....

Figure 156 :

 156 Figure 156: Summary of received power level for the 7 positions and for [-22°, 0°, +22°]............

Figure 157 :

 157 Figure 157: Received power level versus the distance for [-22°, 0°, +22°] ..................................

Figure 158 :

 158 Figure 158: Transmitter on the roof of the train ...........................................................................

Figure 159 :

 159 Figure 159: Angular power distribution at the 5 positions ............................................................

Figure 160 :

 160 Figure 160: Received signal level in dBm versus angles in degree for the 5 positions ................

Figure 161 :

 161 Figure 161: Received power level versus the distance ................................................................

Figure 162 :

 162 Figure 162: Illustration of the Outdoor-to-roof scenario ...............................................................

Figure 163 :

 163 Figure 163: Illustration of measurement scenario for Roof to Roof configuration .........................

Figure 164 :

 164 Figure 164: Angular power distribution for the seven positions....................................................

Figure 165 :

 165 Figure 165: Received signal in dBm for the 3 angles (-22°, 0°, +22°) and for the 7 positions ......

Figure 166 :

 166 Figure 166: Received signal level in dBm versus Tx-RX distance for each angle (-22°, 0°, +22°)

  Railway environment ....................................................................................................... Table 2: European Standard EN50121-3-2 vs 2006 ...................................................................... Table 3: European Standard EN50121-3-2 vs 2015 ...................................................................... Table 4 Intentional EMI Sources ...................................................................................................

Figure 1 :

 1 Figure 1: Future train wireless communications

Figure 2 :

 2 Figure 2: Diffraction phenomena around car: electromagnetic simulation model (left); simulated electric field (right)It was also observed that when the base station is inside the car and the sensor nodes are under the car, coherence bandwidth 𝐵 𝑐 varies from 1.5 to 4 MHz at 2.45 GHz, and it decreases as the distance between the base station and the sensor node becomes larger. When both the base station and sensor nodes are under the car, 𝐵 𝑐 varies from 15 to 25 MHz. On the other hand, the delay spread is larger when the base station is inside the car (13.3 ns to 100 ns) than when is it under it (8.7 ns to 13.3 ns), due to the stronger multipath. Finally, the attenuation of the links, when the base station is inside the car, goes from 85 to 88 dB at 2.45 GHz, while it varies from 34 to 53 dB when it is under the car. Cross-polarization of the antennas has an influence when the LOS path prevails, and causes an attenuation increase of 10-15 dB.

Figure 3 :

 3 Figure 3: Simulated and measured power-loss results for 3-meter setup with vertical polarization at 2.45 GHz

Figure 4 :

 4 Figure 4: Different lateral cuts of tunnels

R2R

Figure 5 :Figure 6 :Figure 7 :

 567 Figure 5: Intra-vehicle (left) and inter-vehicle (right); note that the vertical gray lines depict the boundaries between rail vehicles

Figure 8 :

 8 Figure 8: Train-to-train: inside (left), roof (right)

  Traction system  Auxiliary converter  Brake system  Access doors  Heating, ventilation, and air conditioning (Cabin and passengers)  … Contract No. H2020 -636032 R2R-T2.2-D-DZR-006-18 Page 33 of 186 10/12/2016

Measurement distance 3 m. 3 GHz- 6

 36 GHz 80 dBµV/m Peak 10/12/2016 Intentional EMI sources Within this category are included the equipment on board the rolling stock which include electromagnetic radiation as part of their functionality. Radio systems, fleet management systems, passenger information systems, train-to-wayside communication systems, ticket validation systems and signalling systems are included within this category. Mainly, the technologies in use by these equipment are mobile phone networks (GSM, UMTS, LTE), Wi-Fi, RFID and radio technologies (analogue radios and TETRA).

  R2R-T2.2-D-DZR-006-18 Page 35 of 186 10/12/2016

Figure 9 :Figure 10 :Figure 11 :

 91011 Figure 9: Vehicle Example A (Tram)

Figure 12 :

 12 Figure 12: VNA-based measurement setup for static channels: VNA (left); UWB antennas (right)

Figure 13 :

 13 Figure 13: VSA-based measurement setup: transmitter (left); receiver (right)

Figure 14 :

 14 Figure 14: RUSK Channel Sounder in railway environment

Figure 15 :

 15 Figure 15: MEDAV RUSK block diagram

Figure 16 :

 16 Figure 16: Broadband multicarrier spread spectrum signal (MCSSS) magnitude in time (left) and frequency domain (right)3.3.2 DLR equipmentDLR has the following equipment at their disposal:

Figure 17 :Figure 18 :

 1718 Figure 17: Antennas on wheel and bogie for channel measurementsFor these measurements the train has been positioned in an open field in order to obtain the multipath coming from the train itself and not from reflections on surrounding objects. Omnidirectional magnetic-mount monopole antennas (Mobile Mark MGRM-UMB-1C[START_REF] Mark | Mobile Mark MGRM-UMB-1C Magnet Mount Antenna[END_REF]]) have been placed in six transmitting positions on bogie and wheels (see example in Figure17), while receiving antennas have been placed inside and under the car in order to simulate two location options for the base station (see Figure18). For each measurement, a transmitter antenna and a receiving antenna have been connected to two ports of a Vector Network Analyzer (VNA); the VNA has been configured with a bandwidth of 200 MHz, and a central frequency of 2.45 GHz for obtaining the channel response in the ISM band of 2.45 GHz (2.4-2.5 GHz). Static measurements have been done with this setup, so that the Power Delay Profile (PDP) and Coherence Bandwidth (Bc) of the different wireless links have been obtained.

Figure 19 :

 19 Figure 19: Access Point locations

Figure 20 :Figure 21 :

 2021 Figure 20: Sensor node locations under the car

Figure 22 :

 22 Figure 22: Sensor node locations inside the car

Figure 23 :

 23 Figure 23: Principle of channel soundingIn a practical measurement setup as depicted in Figure23, the channel sounder transmitter generates a wide-band signal. The bandwidth of the transmit signal is limited by the sampling frequency 𝑓 s = 1 𝑇 s

Figure 24 :

 24 Figure 24: Waveform generation at transmitter side

Figure 25 :Figure 26 :

 2526 Figure 25: Radiation pattern of Mobile Mark MGRM-UMB-1C antenna at 2.45 GHz

50 Figure 28 :

 5028 Figure 28: Small scale fading extraction

Figure 29 :

 29 Figure 29: Small scale envelope distribution

Figure 30 :

 30 Figure 30: Averaged power delay profile

Figure 31 :

 31 Figure 31: Spatial autocovariance

Figure 32 :

 32 Figure 32: Temporal power variations

Figure 33 :

 33 Figure 33: Doppler spectrum

Figure 35 :Figure 36 :

 3536 Figure 35: Flow traffic of two trains

Figure 37 :Figure 38 :

 3738 Figure 37: Opposing traffic of two trains

Figure 39 :

 39 Figure 39: One train pass a second train

  in the middle of the consist

Figure 40 :Figure 41 :

 4041 Figure 40: Consist-to-Consist (Bombardier)

4. 1 . 4 ScheduleDay 1 :Day 3 :Day 4 :

 14134 One train -Inter-Vehicle measurementsDifferent antennas (directional and omnidirectional) should be mounted in different positions (see Figure41) on the train. coupled) -> Opposing -> Opposing -> Flow (catch up, escape) Two trains -Directional antennas The antennas will be mounted inside the train at the train driver cabin. This is only possible, if the radio characteristics of the front window are known. Therefore, a datasheet or measurements (TRI provides a window, DLR measure the radio characteristics) are necessary. coupled) -> Opposing -> Flow (catch up, escape) Two trains Additional measurements, e.g. to repeat some scenarios from previous days or modified scenarios based on lessons learnt. R2R-T2.2-T-DZR-006-18 Page 63 of 186 10/12/2016

Antennas 2 Figure 43 : 3 R2RFigure 44 :Figure 45 :

 24334445 Figure 43: Omni-directional (red marked) antenna on train 28, coach 3

Figure 46 :

 46 Figure 46: Vehicle-to-Vehicle setup

Figure 47 :

 47 Figure 47: Train-to-Train with omni-directional antennas

Figure 48 :

 48 Figure 48: Train-to-Train with directional antennas

  Figure 50: Frecciarossa ETR 500

Figure 51 :

 51 Figure 51 : Channel Sounder

Figure 52 :

 52 Figure 52: Mobile Mark MGRM-WHF Wideband Monopole Antenna b) At the other end, a 12-monopole array will be used (Figure 53).

Figure 53 :

 53 Figure 53: Monopole Array antenna

Figure 54 :

 54 Figure 54: Inter-Consist measurements

Figure 55 :

 55 Figure 55: Train-to-Train Measurements

Figure 58 :Figure 59 :Figure 60 :

 585960 Figure 58: Photos of the mmw measurement setup -VµBIQ

Figure 61 :

 61 Figure 61: Characteristics of the mmw antenna

Figure 62 :

 62 Figure 62: Real and imaginary part of the chirp signal

Table 24 :

 24 Characteristics of the scope set up

Figure 63 :Figure 64 :

 6364 Figure 63: Back-to-Back measurement setup without RF module

Figure 65 :

 65 Figure 65: (a) waveguide attenuator (b) attenuation loss measurement

Figure 66 :

 66 Figure 66: mmw measurement setup

Figure 68

 68 Figure 68: Intra-Consist links

R2R

Figure 70 :

 70 Figure 70: Measurement setup for inter-vehicle measurements

Figure 71 :Figure 72 :

 7172 Figure 71: Measurement setup for inside ITS-G5 measurements

Figure 73 : 5 . 1 . 3

 73513 Figure 73: Measurement setup for outside ITS-G5 measurements 5.1.3 Night 3

Figure 74 :

 74 Figure 74: Measurement setup for T2T omni-directional measurements

Figure 76 :

 76 Figure 76: Measured metro lines and stations Both wideband and narrowband measurements were carried out. Wideband measurements were done using a channel sounder with the following configuration: Transmitter Power (dBm) 30 Carrier Frequency (MHz) 2600 Bandwidth (MHz) 80 Modulation Pulses Demodulation Logarithmic Detector

Figure 79 :Figure 80 :

 7980 Figure 79: Intra-consist measurement setup

Figure 82 :

 82 Figure 82: Path loss measurement

Figure 83 :

 83 Figure 83: Train-to-train measurement setup

Figure 86 :

 86 Figure 86: View of the train for measurements in Valenciennes Following measurement scenarios were performed:  Intra-Vehicle Communication  Inter Car Scenario  Penetration through the train window  Outdoor to Driver's room  Outdoor to Driver (Centre)  Outdoor to Outdoor (O2O)  Train to Infrastructure  Outdoor to Roof

Figure 87 :

 87 Figure87 :The time-variant impulse response and its frequency-domain equivalents[START_REF] Unterhuber | A Survey of Channel Measurements and Models for Current and Future Railway Communication Systems[END_REF]

Figure 88 :Figure 89 :

 8889 Figure 88 shows the normalized PDP for the two measured link distances of 3 m and 29 m for a slow and fast manoeuvre during the first night. The probability density functions (PDF) of the PDP is presented in Figure 89 (a) and (b) for 3 m and in Figure 89 (c) and (d) for 29 m. All four figures show the strong LOS behaviour of the link, visible with the highest concentration at delay τ = 0 sec. The shift to -3 dB for the fast and -5 dB of the slow measurements is caused by the varying antenna characteristics.

Figure 90 :

 90 Figure 90 : Tapped delay line model

Figure 91

 91 Figure 91 (a), tap one is Rician distributed with a k-factor of 17.44 dB. Tap two to thirteen are nearly similar and fit to two Rayleigh distributions as shown in

Figure 92

 92 Figure 92: 29 m measurement, distribution fitting for different taps

Figure 93

 93 Figure93shows the narrowband results for a tunnel in Line 10. Instantaneous and averaged data are presented for antennas placed on the roof of the train (Outdoor antenna); the reception of one antenna inside the train is also presented for comparison (Indoor antenna).

Figure 93 :

 93 Figure 93: Narrowband Results for Inter-Consist link in Tunnel (Line 10)

Figure 94 :

 94 Figure 94: Glass characterization: losses (blue graph); phase deviation (yellow graph)

  for a tunnel in Line 11, with outdoor antennas in both cases. It can be observed the main influence of the first tap (i.e. the LOS component). The corresponding Probability Density Functions (PDFs) for each tap are displayed in Figure96and Figure 98, respectively. R2R-T2.2-T-DZR-006-18 Page 122 of 186 10/12/2016 Station Narrowband results for a station in Line 10 are shown in Figure 99.

Figure 99 :

 99 Figure 99: Narrowband Results for Inter-Consist link in Station (Line 10) Regarding wideband results, the evolution of the taps and their PDFs are shown in Figure 100 and Figure 101 respectively, for a station in Line 10. Results are also presented for a station in Line 11 in Figure 102 and Figure 103, and for Line 6 in Figure 104 and Figure 105.

Figure 100 :Figure 101 :Figure 102 :Figure 103 :Figure 104 :Figure 105 :

 100101102103104105 Figure 100: Channel taps vs distance for Inter-Consist link in Station (Line 10)

Figure 106 :

 106 Figure 106: Narrowband Results for Inter-Consist link in Open Air (Line 10)

Figure 109 :

 109 Figure 109: Probability Density Function with External Antennas

Figure 110 :

 110 Figure 110: Probability Density Function with External and Internal AntennaTable 33: Statistical parameters for external-to-internal link Parameter Value PDF Rayleigh Standard deviation Station 2.64 Tunnel 1.62 Open Air 1.79

Figure 111 :

 111 Figure 111: Power Delay Profile (PDP) for Inter-Consist link in Line 10

Figure 112 :

 112 Figure 112: Power Delay Profile (PDP) for Inter-Consist link in Line 11

Figure 113 :

 113 Figure 113: Power Delay Profile (PDP) for Inter-Consist link in Line 6

Figure 114 :

 114 Figure 114: PDP vs angle of arrival for Intra-Consist link in Tunnel (Line 11)

Figure 115 :

 115 Figure 115: PDP vs angle of arrival for Intra-Consist link in Station (Line 11)

Figure 116 :

 116 Figure 116: Path loss model for the Intra-Consist link (continuous train) In order to represent this path loss evolution, a two-slope model has been chosen due to the different nature of the received signal near and far from the transmitter: 𝐴(𝑑𝐵) = { 55.8 𝑖𝑓 𝑑 < 6 31.6 • log(𝑑(𝑚)) + 31.2 𝑖𝑓 𝑑 ≥ 6 (20)

Figure 117 :Table 43 :

 11743 Figure 117: Probability Density Function of Intra-Consist link in station (continuous train) Table 43: Statistical parameters of Intra-Consist link in station (continuous train) Parameter Value PDF Rician Standard deviation 0.54 K (dB) 1.55

Figure 118 :Figure 119 :Figure 120

 118119120 Figure 118: Impact of people movement on Intra-Consist link (continuous train)

Figure 120 :

 120 Figure 120: PDP vs angle of arrival for Intra-Consist link in Open Air (Line 11) Environments Comparison RMS spread and Mean Delay values have been extracted from the wideband measurements in Line 11, as well as the statistical distributions of the different taps (Table45 and Table 46)

Figure 121 :

 121 Figure 121: Path loss model for the Intra-Consist link in a non-continuous train The equation for the path loss model is the following one: 𝐴(𝑑𝐵) = 22.37 • log(𝑑(𝑚)) + 40.5 (21)

Figure 122 :Table 47 :Figure 123 : 6 )Figure 124 :

 122471236124 Figure 122: Probability Density Function of Intra-Consist link in station (non-continuous train)Table 47: Statistical parameters of Intra-Consist link in station (non-continuous train) Parameter Value PDF Rician Standard deviation 0.63 K (dB) 0.96

Figure 125 :

 125 Figure 125: Averaged Narrowband Results for Train-to-Train link in tunnel

Figure 126 :

 126 Figure 126: Path loss model for Train-to-Train link in tunnel with outdoor antennas

Figure 127 :Figure 128 :

 127128 Figure 127: Averaged Narrowband Results for Train-to-Train link in station

Figure 129 :

 129 Figure 129: Averaged Narrowband Results for Train-to-Train link in open air

Figure 131 :

 131 Figure 131: Comparison of averaged Narrowband Results for Train-to-Train links: outdoor receiving antenna (upper); indoor receiving antenna (bottom)

Figure 132 :Figure 133 :Finally,

 132133 Figure 132: Probability Density Function for Train-to-Train links with outdoor receiving antennaTable 51: Statistical parameters for Train-to-Train links with outdoor receiving antenna Parameter Value PDF Rician Standard deviation Station 0.36 Tunnel 0.29 Open Air 0.26 K (dB) Station 10.83 Tunnel 12.92 Open Air 13.79

Figure 134 :

 134 Figure 134: Comparison of path loss models for Train-to-Train links with outdoor antennas These path loss models follow this expression: 𝐴 (𝑑𝐵) = 10𝑛 𝑙𝑜𝑔 (𝑑(𝑚)) + 𝑃 0 (25)

  This scenario consists of measuring the wireless link between different elements inside a single vehicle. These will be Line-Of-Sight (LOS) links, mostly affected by the internal structure of the vehicle. As shown in Figure135(a), two typical positions are selected. The azimuth angles at the Rx antenna were swept in 22° steps from 0 to 360°, while the Tx antenna is fixed with the opening to the corridor shown in Figure135 (b).

Figure 135 :

 135 Figure 135: Photos of the measurements (a) to (d) (a): scheme of the scenarios, (b): view of the TX and Rx position on first floor. (c): view of Tx and Rx position on 2 nd floor. (d): view of the stairs

Figure 136 :Figure 137 :

 136137 Figure 136: Angular power distribution for the two positions of the receiver

Figure 138 :Figure 139 :Figure 141 :

 138139141 Figure 138: Inter car configuration Figure 139 to Figure 141 illustrate the angular power distribution at the three different positions when the door is open or close.

Figure 142 :

 142 Figure 142: Sum-up of the angular power distribution for the 3 positions

Figure 143 Angular power distribution at position 1 Angular power distribution at position 2 Angular power distribution at position 3 Angular power distribution at position 4 Angular power distribution at position 5 Figure 144 :

 14312345144 Figure 143 (a) and (b): illustration of the measurements configuration for penetration through the window

Figure 146 :

 146 Figure 146: Evolution of received signal level for Tx-Rx distance and for each angle

  Figure 147 (b). The receiver takes several positions outside the cabin (cf. scheme on Figure147 (a)). Both the Tx and the Rx antenna height are 2.6 m. 7 Rx locations are measured with a location spacing of 3 m. The distance from location to the side-line of the trail is 0.4 m. The distance between the first location to the Tx is set to be 5 m. The Rx antenna is swept between [-22°, +22°] since the vibration of the train during the trip won't be more that this range. Here, 0° corresponds to the facing direction to the Tx.

Figure 147 :Angular power distribution at position 1 Angular power distribution at position 2 ContractAngular power distribution at position 3 Angular power distribution at position 4 Angular power distribution at position 5 Angular power distribution at position 6 Angular power distribution at position 7 Figure 148 :Figure 149 :

 1471234567148149 Figure 147: (a) scheme of the measurements-(b) photography of the scenario The following Figure 148 (a) to (f) illustrate the angular power distribution for each of the position of the transmitter (-22°, 0°, +22°).

Figure 150 :

 150 Figure 150: Received signal level versus Tx-Rx distance for each angle (-22°, 0°, +22°)

  a). Similarly, both the Tx and the Rx antenna height are 2.6 m. 7 Rx locations are measured with a location spacing of 3 m. The distance between the first location to the Tx is set to be 5 m. The Rx antenna is swept between [-22°, +22°] since the vibration of the train during the trip will not be more than this range. Figure 151 illustrates the different received power values for the seven positions. Figure 152 is a summary of Figure 151. The mean delay and RMS delay for each position and each angle is given in Table

Contractdistribution at position 4 Angular power distribution at position 5 Angular power distribution at position 6 Angular power distribution at position 7 Figure 151 :Figure 152 :

 4567151152 Figure 151: Angular power distribution for (-22°, 0°, 22°) for each of the 7 positions outside the cabin as indicated on scheme Figure 147 (a), on the centre

Figure 153 :

 153 Figure 153: Received signal level versus distance for each angle (-22°, 0°, +22°)

Angular power distribution at position 5 Angular power distribution at position 6 Angular power distribution at position 7 Figure 155 :

 567155 Figure 155: Outdoor-Outdoor measurements -Angular power distribution at the 7 positions

Figure 157 :

 157 Figure 157: Received power level versus the distance for [-22°, 0°, +22°]

Figure 158 :Angular power distribution at position 1 Angular power distribution at position 2 Angular power distribution at position 3 Angular power distribution at position 4 Angular power distribution at position 5 Figure 159 :

 15812345159 Figure 158: Transmitter on the roof of the train

Figure 161 :

 161 Figure 161: Received power level versus the distance for [0°, 22°, 44°,66°,88°,110°,132°,154°,176°,198°,220°,242°,264°,286°,308°,330°,352°]

Figure 162 :

 162 Figure 162: Illustration of the Outdoor-to-roof scenario

  (b). The receiver is situated on the ground and takes different positions as shown on the scheme given in Figure 163 (a). Both the Tx R2R-T2.2-T-DZR-006-18 Page 174 of 186 10/12/2016 and the Rx antenna height are 4.5 m. The azimuth angles at the Rx antenna were swept in 22 0 steps from 0 0 to 360 0 , while the Tx antenna is fixed on the roof the train. All the location and surrounding information is given in detail in the Figure 163 (a).

Figure 164

 164 Figure164gives the angular power values for 3 angles (-22°, 0°, +22°) for each transmitter position in green (Figure163 (a)). Figure165summarises the results regarding the received signal level in dBm for each angle and each position. Table69and Table70give the mean value for the delay and table give the RMS delay for each position and each angle.

Figure 163 :Angular power distribution for position 1 Angular power distribution for position 2 Angular power distribution for position 3 Angular power distribution for position 4 Angular power distribution for position 5 Angular power distribution for position 6 Angular power distribution for position 7 Figure 164 :Figure 165 :

 1631234567164165 Figure 163: Illustration of measurement scenario for Roof to Roof configuration

Figure 166 :

 166 Figure 166: Received signal level in dBm versus Tx-RX distance for each angle (-22°, 0°, +22°)

Table

Table 5 :

 5 Overview of measurement equipment .............................................................................

Table 6 :

 6 Railway environment .......................................................................................................

Table 7 :

 7 Combination of possible environments (finally selected ones are marked red) ................

Table 8 :

 8 Combination of tracks and manoeuvre ............................................................................

Table 9 :

 9 Priorities for different scenarios .......................................................................................

Table 10 :

 10

Time table for all four days ............................................................................................ Table 11: Basic data .....................................................................................................................

Table 12: Manoeuvres day 1 ......................................................................................................... Table 13: Manoeuvres Day 2 ........................................................................................................ Table 14: Manoeuvres Day

3 ........................................................................................................ Table 15: Manoeuvres Day 4 ........................................................................................................ Table 16: Features of Channel Sounder ....................................................................................... Table 17: Measurement plan ........................................................................................................ Table 18: Inter-Consist measurement environments ..................................................................... Table 19: Train-to-Train measurement environments .................................................................... Table 20: Intra-Consist measurement environments ..................................................................... Table 21: Intra-Consist measurement environments ..................................................................... Table 22: VµBIQ development system at 60 GHz with 2 GHz bandwidth ...................................... Table 23: Characteristics of the recording system ......................................................................... Table 24: Characteristics of the scope set up ................................................................................ Table 25: Channel sounder's parameters ...................................................................................... Table 26: Summary of metro measurements .............................................................................. Table 27: Path loss calculation results ........................................................................................

Table 28 :

 28 Tap fitting parameters 3 m ...........................................................................................

Table 29 :

 29 Tap fitting parameters 29 m .........................................................................................

Table 30 :

 30 Glass characterization results .....................................................................................

Table 31 :

 31 Average attenuation in different environments.............................................................

Table 32 :

 32

Statistical parameters of external link .......................................................................... Table 33: Statistical parameters for external-to-internal link ........................................................ Table 34: Multipath components for Inter-Consist link in Line 10 ................................................. Table 35: RMS spread and Mean Delay for Inter-Consist link in Line 10 ..................................... Contract No. H2020 -636032 R2R-T2.2-D-DZR-006-18 Page 17 of 186 10/12/2016 Table 36: Statistical parameters of channel taps for Inter-Consist link in Line 10 ........................

Table 37 :

 37

Multipath components for Inter-Consist link in Line 11 .................................................

Table 38 :

 38

RMS spread and Mean Delay for Inter-Consist link in Line 11 .....................................

Table 39 :

 39

Statistical parameters of channel taps for Inter-Consist link in Line 11 ........................

Table 40 :

 40

Multipath components for Inter-Consist link in Line 6 ...................................................

Table 41 :

 41 RMS spread and Mean Delay for Inter-Consist link in Line 6 .......................................

Table 42 :

 42 Statistical parameters of channel taps for Inter-Consist link in Line 6 ..........................

Table 43 :

 43 Statistical parameters of Intra-Consist link in station (continuous train) .......................

Table 44 :

 44 Statistical parameters of Intra-Consist link (continuous train) with people movement ..

Table 45 :

 45 RMS spread and Mean Delay for Intra-Consist link (continuous train) in Line 11 .........

Table 46 :

 46

Multipath components for Intra-Consist link (continuous train) in Line 11 ....................

Table 47: Statistical parameters of Intra-Consist link in station (non-continuous train) ................

Table 48 :

 48 RMS spread and Mean Delay for Intra-Consist link (non-continuous train) in Line 6....

Table 49 :

 49

Statistical parameters of channel taps for Intra-Consist link (non-continuous train) in Line 6 ..........................................................................................................................................

Table 50: Multipath components for Intra-Consist link (non-continuous train) in Line 6 ............... Table 51: Statistical parameters for Train-to-Train links with outdoor receiving antenna ............. Table 52: Statistical

parameters for Train-to-Train links with indoor receiving antenna ............... Table 53: Path loss model parameters ........................................................................................ Table 54: Characteristics of the measurements .......................................................................... Table 55: Mean delay (ns) versus angle position ........................................................................ Table 56: RMS delay (ns) versus angle position ......................................................................... Table 57: Mean delay (ns) versus angle position ........................................................................ Table 58: RMS delay (ns) versus angle position ......................................................................... Table 59: Mean delay (ns) versus angle position ........................................................................ Table 60: RMS delay (ns) versus angle position ......................................................................... Table 61: Mean delay (ns) versus angle position ........................................................................ Table 62: RMS delay (ns) versus angle position ......................................................................... Table 63: Mean delay (ns) versus angle position ........................................................................

Table 64 :

 64 RMS delay (ns) versus angle position .........................................................................

Table 65 :

 65 Mean delay (ns) versus angle position ........................................................................

Table 66 :

 66 RMS delay (ns) versus angle position .........................................................................

Table 67 :

 67 Mean delay (ns) versus angle position ........................................................................

Table 68 :

 68

RMS delay (ns) versus angle position ......................................................................... Table 69: Mean delay (ns) versus angle position ........................................................................ Table 70: RMS delay (ns) versus angle position .........................................................................

Table 1 : Railway environment

 1

		Urban
	Area	Sub-Urban
		Rural
	Special	Curves
	scenarios	Tunnels
		Bridge / Viaduct
		Cuttings
		Cross Bridge
		Noise Barrier
		Catenary
	Obstacles	Signalling System
		Roof
		Building
		Vegetation (tree)
		Open field

Table 2 : European Standard EN50121-3-2 vs 2006 EN 50121-3-2:2006

 2

	Frequency	Limit	Ref. standard
	30 MHz -230 MHz	40 dBµV/m QP	EN 55011	These limits are defined for a
				measurement distance of
				10 m. The limits are increased
	230 MHz -1 GHz	47 dBµV/m QP	EN 55011	by 10 dB for a measurement
				distance of 3 m.

Table 3 : European Standard EN50121-3-2 vs 2015 EN 50121-3-2:2015

 3

	Frequency	Limit	Ref. standard
	30 MHz -230 MHz	40 dBµV/m QP	Measurement instrumentation
			defined in Clause 4of
			EN55016-1-1:2010.
			Measuring antennas defined
			in 4.4 of: EN 55016-1-4:2010.
	230 MHz -1 GHz	47 dBµV/m QP	Measuring site described in Clause 5 of EN 55016-1-	Measurement distance 10 m.
			4:2010.
			Measurement method
			defined in 7.2 of EN 55016-3-
			2:2010.
	1 GHz -3 GHz	76 dBµV/m Peak 56 dBµV/m Avg	Measurement instrumentation defined in Clause 5 and 6 of EN55016-1-1:2010.
			Measuring antennas defined
			in 4.5of: EN 55016-1-4:2010.
			Measuring site described in
			Clause 8 of EN 55016-1-
			4:2010.
			Measurement method
			defined in 7.3 of EN 55016-3-
			2:2010.

Table 4 Intentional EMI Sources

 4

	EQUIPMENT	TECHNOLOGY	FREQUENCY	EMISSION POWER
		GSMR	Tx Range: 876 to 915 MHz Rx Range: 921 to 960 MHz	8 W
	ERTMS		Power transmission frequency: 27.095 MHz ± 5 kHz (acc.	Magnetic flux between antenna and balise
		Eurobalise	UNISIG SUBSET-036)	7.7 nVs < Φ < 300 nVs (acc.
			Data transmission frequency: FC=4.234 MHz ± 175 kHz	UNISIG SUBSET-036 -section
				5.2.2.6)
		GSMR	Tx Range: 876 to 915 MHz Rx Range: 921 to 960 MHz	8 W
	RADIO
		Analogue radios. According to country.	Tx Range: 456.95 MHz to 458.65 MHz Rx Range: 466.95 MHz to 468.65 MHz	HF power output: 8 W -10 W
		TETRA	Emergency systems: 380-385 MHz, 390-395 MHz Civil systems: 410-470 MHz, 870-921 MHz	10 W
	Fault	GPRS	GPRS: 900 + 1800 MHz for Spain. There can be different values for other countries.	2 W
	Management System	3G	3G: 900 + 2100 MHz for Spain. However differences for other countries.	1 W
	PIS Passenger	GPRS	GPRS: 900 MHz + 1800 MHz for Spain. There can be different values for other countries.	2 W

2-T-DZR-006-17 Page 36 of 186 10/12/2016

Table 5 : Overview of measurement equipment

 5

	equipment	frequency	BW	nb
	spectrum analyser PXA 9020	20 Hz to 8.4 GHz	160 MHz	1
	spectrum analyser MXA 9020	20 Hz to 8.4 GHz	160 MHz	1
	Generator R&S	300 kHz to 6.4 GHz	18 MHz	2
	Generator Anritsu 68397C	20 MHz to 67 GHz	~20MHz	1
	VNA HP 8720 D	50MHz to 20 GHz		1
	VNA HP 8753S	200 Khz to 6 GHz		1
	Tektronix Scope TDS6124	12 GHz	40 Gs	1
	Tektronix AWG 7102		10 GS/s	2

Table 6 : Railway environment

 6

		Urban
	Area	Sub-Urban
		Rural
		Curves
	Special Scenarios	Tunnels
		Bridge / Viaduct
		Cuttings
		Cross Bridge
		Noise Barrier
	Obstacles	Catenary Signalling System
		Roof
		Building
		Vegetation (tree)
		Open field
	High density	Railway Station
		Shunting Yard

R2R-T2.2-T-DZR-006-18 Page 56 of 186 10/12/2016

Table 7 : Combination of possible environments (finally selected ones are marked red)

 7

		Curve Bridge	Noise	Buildings Vegetation Roof Catenary	Signaling	Open
				Barrier					System	field
	Urban	x	x	x	x	x		x	x
	Sub-Urban	x	x	x	x	x		x	x
	Rural	x	x		x	x		x	x	x
	Tunnel	x						x	x
	Viaduct	x	x	x	x			x	x	x
	Cutting	x	x			x		x	x
	Railway Station	x			x	x	x	x	x
	Shunting Yard	x			x	x	x	x	x

Table 8 : Combination of tracks and manoeuvre

 8

	# Tracks Flow Contra Flow Overtake Opposing Traffic Pass (v2=0) Coupling
	1	x	x				x
	Two 2	x	x	x	x	x	x
	3+	x	x	x	x	x	x

Table 9 : Priorities for different scenarios

 9

			Train End	Vehicle	Vehicle	Train Front
		Urban	Sub-Urban	Rural	Tunnel	Railway station
		Noise-Barrier Buildings	Vegetation	Open field	Buildings Roof
	Flow	2	2		3	4	1
	Opposing	2	2		3	4	1
	Pass	2			3		4	1	1
	Inter-Vehicle	2				4	3	1	1
		1… highest 2… mid-high 3… mid-low 4… low priority
	This results in a tight measurement schedule for 4 days (nights).

.8 Detailed Schedule for Measurements

	4.1
								. A documentation video would be
	useful	for	final	reporting	and	promotion.	This	video	can	be	found	in:
	https://www.youtube.com/watch?v=ndzAO-PuNTY&t=48s.
						Page 70 of 186					10/12/2016

Table 10 : Time table for all four days

 10

	Time	Location	Description
	21:00 -24:00	Depot in Naples	Loading of measurement equipment
			into trains, set-up of equipment,
			calibration of transmitter and receiver
	0:00 -5:00	Railway track between	Channel measurements
		Naples and Rome
	5:00 -7:00	Depot in Naples	Second calibration of transmitter and
			receiver, unloading of measurement
			equipment

Table 11 : Basic data

 11

	Distance Rome -Naples		220 km
	Travelling time at maximum speed	67 min
	Acceleration (moderate)		0.5 m/s 2
	Acceleration (fast)		1 m/s 2
	Distance and time to reach a speed of 300 km/h with moderate acceleration:
	𝑑 𝑎𝑐,1 =	𝑣 2 2𝑎	≈ 7 𝑘𝑚
	𝑇 ac,1 ≈ 3 min
	The distance to reach a speed of 30 km/h is, again with moderate acceleration,
	𝑑 ac,2 =	𝑣 2 2𝑎	≈ 70 m
	𝑇 ac,2 ≈ 17 s

R2R-T2.2-T-DZR-006-18 Page 71 of 186 10/12/2016 Day 1

One train, the transmitter and receiver are located in the same train but in different cars.

Table 12 : Manoeuvres day 1

 12

		Velocity	Duration	Description
	1	v1 = 50 km/h 4 h	Travel with constant speed from Naples in direction
				to Rome till PK 36, covers all possible scenarios
	2	Maximum	45 min	Travel back to depot at maximum allowed speed
	Day 2, 3 and 4

Two trains, the transmitter and receiver are located in different trains. The measurements are done on  Day 2 with directional antennas,  Day 3 + 4 with omni-directional antennas,

Table 13 : Manoeuvres Day 2

 13

	Velocity	Duration	Surrounding Description
	v1 = 50 km/h	2h 40 min	Urban,	Passing, same direction, slow
	v2 = 40, …, 60 km/h		sub-urban, tunnels, open field,	Train 1 drives at constant speed, while train 2 slowly catches up train 1 until same height, then train 2 slows down until it is 7 km behind train 1
			forest	This manoeuvre is repeated several times till PK 75
	v1 = 300 km/h	20 min	Forest	Counter-direction, fast
	v2 = -300 km/h			Train 1 stops at PK 75, Train 2 at PK 36, Train 2 changes direction and then both trains accelerate
				to max speed, crossing at ~ PK 61
	v1 = 270 km/h	35 min		Passing, same direction, fast
	v2 = 240, …, 300 km/h			Train 1 changes direction at PK 36, accelerates to max speed, Train 2 starts at PK 61 and accelerates to 250 km/h
	v1 = 30 km/h	25 min	Urban,	Counter-direction, slow
	v2 = -30 km/h		sub-urban	Train 2 stops at PK 215 and changes direction, Train 1 stops at PK 203, both trains accelerate to
				30 km/h, crossing at ~ PK 209

Table 14 : Manoeuvres Day 3

 14

	Velocity	Duration	Surrounding Description
	v1 = 50 km/h	2h	Urban,	Passing, same direction, slow
	v2 = 40, …, 60 km/h		sub-urban, tunnels, open field,	Train 1 drives at constant speed, while train 2 slowly overtakes train 1 until 5 km, then train 2 slows down until it is 5 km behind train 1
			forest	This manoeuvre is repeated several times till PK 75
	v1 = 300 km/h	8 min	Forest	Counter-direction, fast
	v2 = -300 km/h			Train 1 stops at PK 75, Train 2 at PK 36, Train 2 changes direction and then both trains accelerate
				to max speed, crossing at ~ PK 61
	v1 = 270 km/h	40 min		Passing, same direction, fast
	v2 = 240, …, 300 km/h			Train 1 changes direction at PK 36, accelerates to max speed, Train 2 starts at PK 61 and accelerates to 250 km/h

Table 15 : Manoeuvres Day 4

 15

	Velocity	Duration	Surrounding Description
	v1 = 50 km/h	2h	Urban,	Passing, same direction, slow
	v2 = 40, …, 60 km/h		sub-urban, tunnels, open field,	Train 1 drives at constant speed, while train 2 slowly overtakes train 1 until 5 km, then train 2 slows down until it is 5 km behind train 1
			forest	This manoeuvre is repeated several times till PK 75
	v1 = 270 km/h	40 min		Passing, same direction, fast
	v2 = 240, …, 300 km/h			Train 1 changes direction at PK 36, accelerates to max speed, Train 2 starts at PK 61 and accelerates to 250 km/h
	v1 = 30 km/h	21 min	Urban,	Counter-direction, slow
	v2 = -30 km/h		sub-urban	Train 2 stops at PK 215 and changes direction, Train 1 stops at PK 203, both trains accelerate to
				30 km/h, crossing at ~ PK 209

Table 16 : Features of Channel Sounder

 16

		Transmitter
	Frequency range	500-6010 (4 bands)	MHz
	Output power	42	dBm
	IF bandwidth	1/10/30/100	MHz
	Modulation	Pulse/external	10 ns/ LTE
		Receiver
	Frequency range	400-7000 (4 bands)	MHz
	IF dual conversion	860/160	MHz
	Noise figure	3	dB
	IF bandwidth	5/10/20/100	MHz
	Demodulation	Logarithmic detector	/LTE
	Dynamic range	90	dB
	For the channel sounder, the following configuration will be used in the measurements:

 Frequency: 5.2 GHz  Bandwidth: 100 MHz  Output power: 42 dBm

Table 20 : Intra-Consist measurement environments Type of Environment Number of Locations per Environment Tunnel (wide) -Straight 3 Tunnel (narrow) -Straight 3

 20

	Station (pit-shaped)	3
	Open Air	3

.3 COMPLEMENTARY MEASUREMENT CAMPAIGN: 60 GHZ FOR T2T COMMUNICATIONS 4.3.1 Motivation for the 60 GHz channel measurement

  Millimeter-wave (mmw) radio technology is considered to be suitable for such short-coverage radio links with high data-rate due to high propagation loss and large available bandwidth. ITU-R recommends four carrier frequencies around 60 GHz including 58.32 GHz, 60.48 GHz, 62.64 GHz and 64.80 GHz with a bandwidth of 2.16 GHz, which promotes the corresponding standardization like IEEE 802.15.3c and IEEE 802.11ad aiming at high data-rate within short ranges. Besides, mmw technology regarded as one of 5G potential candidates has attracted plenty of interest from both academic and industrial sectors. It is certainly worthwhile to explore the radio channel properties at 60 GHz for the metro and high-speed train environments, which fits for both application requirements and industrial interests.

		4
			36.02 m
		17.4 m
		1	2
		T	R
				2.8 m
	T	RUSK TX Unit	Intra-Consist Link
	R	RUSK RX Unit
	n Transmitter Antenna	RF Cable TX	2.42 m
	m Receiver Antenna	RF Cable RX

Table 22 : VµBIQ development system at 60 GHz with 2 GHz bandwidth equipment frequency BW Number of equipement

 22

	Vbiq Mmw RF module	64.5 GHz	Up to 1.2 GHz	1
	Tektronix Scope TDS6124 C	12 GHz	40 Gs	1

Table 23 : Characteristics of the recording system

 23

	10 div per measurement	1 µs/div
	Sample rate	5 GHz
	Number of continuous chirps	7

Table 25 : Channel sounder's parameters Carrier frequency

 25 Tunable between[START_REF] Schmidt | UWB propagation channels within an aircraft and an office building environment[END_REF][START_REF] García | Channel Model for Train to Train Communication using the 400 Mhz Band[END_REF] GHz

	Bandwidth	368 MHz
	Transmitting power	16 dBm
	antenna info	integrated antenna with 7.5 dBi antenna gain, opening angle is in order of 60 degrees
	Delay resolution	About 3 ns
	Maximum delay span	2.8 microsec
	Maximum Doppler shift span	In the order of 1-3 kHz
	Maximum MIMO antenna element	2×2

2-T-DZR-006-18 Page 87 of 186 10/12/2016

Table 27 : Path loss calculation results

 27

			Mux 1	Mux 2
	PTx	dBm	37
	Lcable	dB	5.5
	GTx	dBi	8
	GRx	dBi	8	8
	Lcable	dB	17.8	4.3
	r	m	3	29
	f	GHz	5.2
	c	m/s	3*10 8
	k		2
	FSPL	dB	-56.31	-76.02
	PRx	dBm	-26.6	-32.8

  the fitting parameters for the 3 m link are listed. The normalized power out of the PDP is given for all tabs; the worst case (3m slow speed) is used. Caused by the short link distance, only the first tap, including the LOS link, needs to be modelled different to the rest of the taps. As shown in

	10	-34.42					0.9
	11	-33.44					1
	12	-34.96
	13	-36.03					0.9
	Tap	Norm. Power	Fading	k-factor	Rician	Rayleigh
	#	dB	distribution	dB			
	1	-5.15	Rice	17.44	1	0.095 -
	2	-16.08
	3	--19-63
	4	-21.93
	5	-26.47	Rayleigh	-	-	-	0.9
	6	-28.14
	7	-29.67
	8	-31.93
	9	-33.08					1
							10/12/2016

Table 28 : Tap fitting parameters 3 m

 28

	Tap	Norm. Power	Fading	k-factor	Rician	Rayleigh
	#	dB	distribution	dB			
		-5.15 Rice	17.44	1 0.095	-
		-16.08
		--19-63
		-21.93
		-26.47	Rayleigh	-	-	-	0.9
		-28.14
		-29.67
		-31.93
		-33.08					1
		-34.42					0.9
		-33.44					1
		-34.96
		-36.03					0.9

Table 29 : Tap fitting parameters 29 m

 29

	Tap	Norm.	Fading	k-factor	Rician		Rayleigh
		Power	distribution
	#	dB		dB			
	1	-6.00 Rice	10.97	1	0.2	-
	2	-12.61					1
	3	-15.65
	4	-18.36					1.19
	5	-19.80
	6 7	-20.41 -22.06	Rayleigh	-	-	-
	8	-23.61
	9	-25.48					1.25
	10	-26.36
	11	-27.44
	12	-28.15
	13	-28.94

Table 30 : Glass characterization results Frequency (GHz) Attenuation (dB) Phase (degrees) 1.6 1.9 -54.4

 30

	2.3	1.8	-80.9
	3	4.4	-105

Table 31

 31 summarizes the attenuation of the different scenarios, obtained from narrowband measurements.

Table 31 : Average attenuation in different environments Average attenuation with external antennas (dB) Average attenuation with external and internal antenna (dB)

 31

	External to internal
	difference
	(dB)

Table 32 : Statistical parameters of external link

 32

	PDF		Rice
		K (dB)	Standard Deviation
	Station	0.15	0.96
	Tunnel	9.61	0.41
	Open Air	16.41	0.20

Table 34 : Multipath components for Inter-Consist link in Line 10

 34 RMS spread and Mean Delay values have also been extracted from wideband measurements in Line 10, as well as the statistical distributions of the different taps (see Table35 and Table 36).

	Number of	Delay (ns)		Attenuation (dB)
	TAP		Station	Tunnel	Open Air
	1: ray LoS	0	0	0	0
	2	12.5	13.7	12.8	12.8
	3	25	19.9	18.9	18.8
	4	37.5	11.9	11.3	11.3
	5	50	12.7	13.1	12.0
	6	62.5	15.1	14.5	14.5
	7	75	12.7	12.1	12.1
	8	87.5	17.1	16.2	16.2

Table 35 : RMS spread and Mean Delay for Inter-Consist link in Line 10

 35

		RMS delay spread (ns)	Mean delay (ns)
	Tunnel	62.43	36.04
	Station	61.24	31.10
	Open Air	61.59	34.56

Table 36 : Statistical parameters of channel taps for Inter-Consist link in Line 10

 36

	Number	Station		Tunnel	Open Air
	of TAP	K(dB)	Standard	K(dB)	Standard	K(dB)	Standard
			deviation		deviation		deviation
	1: ray	12.06	0.11	12.33	0.12	9.99	0.21
	LoS
	2	10.44	0.15	12.10	0.11	10.47	0.17
	3	7.83	0.25	10.87	0.16	10.39	0.20
	4	13.53	0.09	14.45	0.07	13.07	0.10
	5	13.52	0.08	14.63	0.06	9.18	0.23
	6	11.65	0.12	12.97	0.11	11.37	0.14
	7	16.19	0.04	15.62	0.05	12.75	0.10
	8	14.10	0.07	15.74	0.05	12.87	0.10

Table 37 : Multipath components for Inter-Consist link in Line 11 Number of TAP Delay (ns) Attenuation (dB) Station Tunnel 1: ray LoS

 37

		0	0	0
	2	12.5	16.11	14.96
	3	25	22.81	21.16
	4	37.5	11.57	11.80
	5	50	14.78	13.81
	6	62.5	16.27	14.74
	7	75	12.78	12.14
	8	87.5	18.01	17.20

Table 38 : RMS spread and Mean Delay for Inter-Consist link in Line 11

 38

		RMS spread (ns)	Mean delay (ns)
	Tunnel	42.44	15.35
	Station	40.00	18.50

Table 39 : Statistical parameters of channel taps for Inter-Consist link in Line 11

 39

	Number of		Station		Tunnel
	TAP	K(dB)	Standard deviation	K(dB)	Standard deviation
	1: ray LoS	11.42	0.12	8.51	0.23
	2	10.77	0.16	7.57	0.26
	3	7.90	0.32	6.40	0.34
	4	8.20	0.23	7.75	0.29
	5	9.21	0.18	6.98	0.31
	6	11.09	0.14	9.83	0.18
	7	14.50	0.07	10.71	0.15
	8	13.18	0.08	11.91	0.12

Table 40 : Multipath components for Inter-Consist link in Line 6

 40

	Number of TAP	Delay (ns)	Attenuation (dB)
			Station
	1: ray LoS	0	0
	2	12.5	12.53
	3	25	21.01
	4	37.5	9.24
	5	50	8.40
	6	62.5	15.32
	7	75	15.25
	8	87.5	17.17

Table 41 : RMS spread and Mean Delay for Inter-Consist link in Line 6

 41

		RMS spread (ns)	Mean delay (ns)
	Station	34.11	16.80

Table 42 : Statistical parameters of channel taps for Inter-Consist link in Line 6

 42

	Number	Station
	of TAP	K(dB)	Standard Deviation
	1: ray	10.70	0.17
	LoS
	2	10.91	0.18
	3	7.79	0.23
	4	12.30	0.11
	5	8.32	0.21
	6	11.46	0.13
	7	9.71	0.17
	8	12.36	0.12
	6.2

.3 Intra-consist Model (Continuous Train)

Table 45 : RMS spread and Mean Delay for Intra-Consist link (continuous train) in Line 11 Parameter RMS delay spread (ns) Mean delay (ns)

 45

	Station	66.56	58.9
	Tunnel	66.9	53.5
	Open Area	64.4	51.4

Table 46 : Multipath components for Intra-Consist link (continuous train) in Line 11

 46

	Number of	Delay (ns)		Attenuation (dB)
	TAP		Station	Tunnel	Open area
	1: ray LoS	0	0	0	0
	2	12.5	5.6	7	4.8
	3	25	5.2	7.2	5.8
	4	37.5	7.1	11.3	8.3
	5	50	12.7	13.1	15.0
	6	62.5	15.1	16.5	15.5
	7	75	17.2	17.1	17.1
	8	87.5	18	18.2	18.6

Table 50

 50

. 10/12/2016

Table 48 : RMS spread and Mean Delay for Intra-Consist link (non-continuous train) in Line 6 RMS spread (ns) Mean delay (ns)

 48

	Station	75.78	46.03

Table 49 : Statistical parameters of channel taps for Intra-Consist link (non-continuous train) in Line 6

 49

	Number of TAP
		K(dB)	Standard Deviation
	1: ray LoS	8.27	0.96
	2	8.45	0.43
	3	10.97	0.40
	4	11.18	0.64
	5	10.12	0.21
	6	11.92	0.35
	7	12.68	0.47
	8	12.64	0.25

Table 50 : Multipath components for Intra-Consist link (non-continuous train) in Line 6

 50

	Number of TAP	Delay (ns) Attenuation (dB)
			Station
	1: ray LoS	0	0
	2	12.5	2.1
	3	25	5.2
	4	37.5	2.3
	5	50	8.1
	6	62.5	9.1
	7	75	11.2
	8	87.5	12.2

Table 53 : Path loss model parameters

 53

	Environment	n	P0
	Tunnel	1.45	54.8
	Station	1.64	47.8
	Open Air	1.51	59.9

Table 54 : Characteristics of the measurements

 54

		Cabin Zone 1
	Length (m)	2.89
	Width (m)	2.15
	Tx/Rx height (m)	1
		Cabin Zone2
	Rx to right-side wall (m)	0.4
	Rx to the back of the wall (m)	0.8
	Tx/Rx height (m)	1

Table 55 : Mean delay (ns) versus angle position

 55

	Degree	0	22	44	66	88	110	132	154	176	198	220	242	264	286	308	330	352
	Upstai r	4.2	4.1	15.6	26.0	22.0	21.8	26.0	24.8	54.2	21.8	16.1	16.7	14.9	10.9	21.4	13.2	4.1
	Downstai r	40.4	8.2	66.7	45.3	123.0	173.5	195.3	183.4	218.1	36.7	87.9	167.7	230.0	277.2	138.4	22.1	7.9

Table 56 : RMS delay (ns) versus angle position

 56

	Degree	0	22	44	66	88	110	132	154	176	198	220	242	264	286	308	330	352
	Upstai r	1.3	1.2	13.6	13.2	8.0	9.1	11.0	9.4	155.9	12.8	5.3	6.0	6.9	5.3	14.8	12.2	1.3
	Downstai r	195.6	7.7	255.7	167.8	325.9	323.6	378.1	311.8	438.9	13.9	258.8	300.5	444.5	505.7	337.6	5.1	8.2

Table 57 and

 57 Table 58 summarize the values of Mean delay and RMS delay in ns for different angle positions. 10/12/2016

Table 57 : Mean delay (ns) versus angle position

 57

	Degree	0	22	44	66	88	110	132	154	176	198	220	242	264	286	308	330	352
	P1	31,4	192,9	18,4	21,3	8,3	11,4	11,4	22,1	21,7	29,9	9,8	98,4	302,8	22,1	26,8	30,7	202,9
	P1 door cl ose	15,3	7,6	7,6	8,1	59,5	249,7	23,2	246,5	34,9	132,7	16,9	581,2	636,2	499,7	490,0	313,8	289,3
	P2	7,7	7,6	8,9	29,1	25,3	27,5	16,4	27,8	33,5	21,8	12,2	21,3	20,3	20,5	114,0	8,1	7,5
	P2 door cl ose	8,8	16,3	36,4	627,4	652,8	660,2	651,7	607,9	52,2	407,2	21,5	652,4	493,9	551,3	379,5	11,4	9,0
	P3	1061,3	894,6 1073,0	754,4	744,0	459,0	133,1	257,3	110,6	74,1	63,9	76,9	374,1	655,5	634,3	326,3	611,3
	P3 door cl ose	11,7	11,3	12,2	21,8	20,0	350,3	631,3	301,2	25,4	30,9	604,3	648,4	651,1	613,0	20,4	162,7	11,2

Table 58 : RMS delay (ns) versus angle position

 58

	Degree	0	22	44	66	88	110	132	154	176	198	220	242	264	286	308	330	352
	P1	1.4	398.9	52.0	127.0	5.8	7.6	4.8	11.9	6.3	11.1	7.1	303.7	517.1	10.5	10.8	16.4	414.4
	P1 door cl ose	12.6	1.1	1.6	1.2	145.8	320.9	74.8	422.4	51.9	343.7	6.6	427.4	403.7	431.4	452.3	473.9	453.5
	P2	1.4	1.0	2.7	20.1	7.0	7.8	5.6	11.7	6.5	12.0	1.2	11.2	12.2	10.9	328.2	1.8	1.3
	P2 door cl ose	1.2	10.2	132.2	402.6	402.1	394.8	402.7	428.8	132.9	450.3	8.9	399.1	448.3	448.4	440.4	6.7	1.5
	P3	525.0	611.7	517.3	650.8	654.9	622.3	386.9	511.2	317.4	241.2	255.1	287.0	591.8	662.2	661.1	565.0	655.3
	P3 door cl ose	6.6	4.3	3.5	23.4	13.8	412.8	405.2	395.7	2.5	8.4	410.7	395.6	396.4	408.8	7.5	324.6	6.3

Table 60 : RMS delay (ns) versus angle position

 60

	Degree	0	22	44	66	88	110	132	154	176	198	220	242	264	286	308	330	352
	P1	1.3	1.1	1.1	101.7	3.9	3.2	1.5	1.0	8.7	1.3	0.9	1.2	7.0	1.2	0.8	0.8	1.3
	P2	6.6	3.2	0.8	5.7	12.3	13.3	1.0	1.1	1.3	8.7	18.2	8.5	1.7	14.4	8.7	4.6	8.7
	P3	2.9	3.1	1.0	1.3	1.5	3.2	4.3	1.4	1.0	1.6	1.5	1.4	8.7	21.9	6.1	2.5	2.3
	P4	4.9	1.3	0.9	1.3	1.5	1.5	1.5	8.8	2.3	2.1	1.5	29.0	18.7	21.1	389.8	39.4	6.2
	P5	456.3	14.9	10.0	1.2	9.5	2.6	7.9	62.1	449.5	9.0	15.3	22.0	165.1	421.4	265.6	470.7	400.0

R2R-T2.2-T-DZR-006-18 Page 159 of 186 10/12/2016

Table 61 : Mean delay (ns) versus angle position

 61

	Degree	-22	0	22
	P1	8,6	8,5	8,4
	P2	7,6	8,2	7,7
	P3	15,8	7,7	7,7
	P4	9,7	7,6	7,7
	P5	501,6	8,4	8,0
	P6	555,9	7,1	7,3
	P7	467,8	8,4	16,5

Table 62 : RMS delay (ns) versus angle position

 62 The Table62and Table63show that the RMS delay and the Mean delay at large Tx-Rx distance (Position P5, P6 and P7) are much larger at the angle of -22°, which means large reflections from surrounds are incident at these setups.

	Degree	-22	0	22
	P1	1.1	1.0	1.0
	P2	1.4	1.3	1.2
	P3	60.6	0.8	1.1
	P4	19.8	1.3	1.1
	P5	431.4	1.1	1.1
	P6	424.2	1.1	1.0
	P7	451.5	1.2	14.2

R2R-T2.2-T-DZR-006-18 Page 163 of 186 10/12/2016

Table 63 : Mean delay (ns) versus angle position

 63

	Degree	-22	0	22
	P1	6.6	6.8	6.8
	P2	7.0	6.9	6.9
	P3	7.1	7.1	6.5
	P4	7.3	7.1	7.1
	P5	410.9	7.7	7.8
	P6	402.6	8.0	7.6
	P7	297.8	7.8	7.8

Table 64 : RMS delay (ns) versus angle position

 64

	Degree	-22	0	22
	P1	0.9	1.0	1.3
	P2	1.3	1.6	0.9
	P3	1.7	1.3	1.5
	P4	1.2	1.1	0.8
	P5	451.7	0.9	0.8
	P6	470.3	1.0	0.9
	P7	424.5	1.3	1.5

Table 65 : Mean delay (ns) versus angle position

 65

	Degree	-22	0	22
	P1	7.8	7.9	7.9
	P2	7.9	8.1	7.9
	P3	8.5	8.5	8.3
	P4	9.2	9.4	8.9
	P5	7.2	7.1	7.1
	P6	8.6	8.2	8.1
	P7	8.3	8.3	8.7

Table 66 : RMS delay (ns) versus angle position

 66

	Degree	-22	0	22
	P1	1.2	1.2	1.1
	P2	1.0	1.1	1.4
	P3	0.8	1.2	1.3
	P4	1.2	1.3	0.7
	P5	0.8	1.3	1.3
	P6	1.5	1.0	0.7
	P7	1.4	1.0	1.4

Table 68 : RMS delay (ns) versus angle position

 68 Table67and Table68show that the RMS delay and the Mean delay turn out to be large if the angles are different from the LOS directions. It can also be found that at P4 location (NLOS), the mean delay and RMS delay are much larger than the rest of positons, which proves that close metallic surrounding can greatly change the radio propagation in the 60 GHz band. In addition, large reflections are found in this factory.

	Degree	0	22	44	66	88	110	132	154	176	198	220	242	264	286	308	330	352
	P1	1.3	1.2	10.0	147.5	416.6	455.1	168.4	265.3	27.1	117.1	104.8	24.3	65.8	137.0	0.8	9.7	1.1
	P2	1.0	0.8	12.6	374.2	229.6	346.6	203.7	1.7	20.1	39.5	98.2	288.3	277.3	310.6	1.0	27.4	246.2
	P3	1.1	5.9	6.3	398.9	378.2	164.4	125.3	69.4	0.8	1.3	54.5	404.2	314.0	1.2	1.1	1.0	1.4
	P4	463.4	397.8	395.2	395.2	392.7	251.2	31.4	92.6	90.3	62.4	75.2	100.7	272.3	313.4	280.1	469.1	560.7
	P5	94.6	87.9	173.8	402.6	390.6	90.7	78.9	90.1	97.5	100.9	221.2	19.4	17.8	1.6	0.9	1.1	0.9

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Table 69 and

 69 Table 70 give the mean value for the delay and table give the RMS delay for each position and each angle.

Table 69 : Mean delay (ns) versus angle position

 69

	Degree	-22	0	22
	P1	8.4	8.5	8.5
	P2	7.1	7.2	7.0
	P3	7.1	7.3	7.4
	P4	8.1	8.4	8.4
	P5	6.8	6.7	7.1
	P6	8.2	8.4	8.1
	P7	8.5	8.7	8.6

Table 70 : RMS delay (ns) versus angle position

 70

	Degree	-22	0	22
	P1	1.0	1.4	1.1
	P2	1.0	1.0	1.1
	P3	1.0	1.0	1.3
	P4	1.2	1.4	1.3
	P5	1.0	1.1	1.4
	P6	1.0	1.0	1.2
	P7	1.3	1.2	1.5

10/12/2016

. This project started in May 2015 and it is supported by the Horizon 2020 program of the European Commission. Roll2Rail is one of the lighthouse projects of Shift2Rail and will contribute to Innovation Program 1. At the end of the project all the results will be further developed, leading to demonstration in real vehicles or relevant environments in Shift2Rail.

 10/12/2016This antenna array allows measuring the delay profile for different directions. This way the angle of arrival of each path can be found, and the Doppler spectrum that fits best can be estimated (e.g. Jakes, flat, asymmetrical Jakes, etc).

Once the antennas are placed on the train, the train will be moved to different environments (tunnels, stations, open air), and 20-30 different delay profiles will be measured in each environment moving the train at approximately 1 km/h. Each of these delay profiles will consist of 12 measurements taken with the antenna array. On the other hand, in order to check the consistency of the results, for each type of environment the measurements will be repeated in 3 different locations of the same kind.

Measurement Schedule

The measurement plan is summarized in Table 17, and detailed in the next sections. The measurements will be divided in an afternoon shift (15h to 20h) and a night shift (1h to 6h), where the measurements will be done in mainline from 2h to 5h.

Additionally, during the measurement campaign audio-visual material will be generated, pictures and videos. A final video has been released and it is public in the following link: https://www.youtube.com/watch?v=spSeptrzbQg&t=1s. R2R-T2.

MEASUREMENTS IN THE FIELD

This chapter reports the actual carried out measurements and deviations from the planned measurements for the high speed line in Section 5.1, for urban/Metro line in Section 5.2, and for the 60 GHz mmWave radio technology on regional trains in Section 5.

Night 4

During the afternoon of the fourth day, monopole antennas were placed in a Series 5000 train (non-continuous train) at Laguna depot (Figure 85). At night, the train was moved into Line 6, and narrowband and wideband measurements were taken at Laguna station, including path loss measurements inside the train. In both Figure 145 and Figure 146, the received signal level is higher at the direction that the RX is pointing to the TX. Strong reflections are found at the angle between [210°, 230°] degrees due to the surroundings.

Summary

The following Table 59 and Table 60 summarize the values of Mean delay and RMS delay in ns for different angle positions. This deliverable describes the motivation and methods for the characterization of the railway environment for radio transmission. An overview of existing measurements and channel models in the railway domain is given and the gaps for a detailed characterization of the radio environment are identified. Since channel measurements require a considerable technical effort and experience, the methodology for channel sounding is described in some detail. The measurements preparations are described in detail in Chapter 4. For the HSR measurements the RUSK DLR Channel Sounder was used, dynamic wideband (120 MHz) measurements at 5.2 GHz were performed. In the METRO environment a pulse-based Channel Sounder was used and static as well as dynamic measurements with wideband (80 MHz) and narrowband settings at 2.6 GHz were performed. Table 27 gives an overview of the different settings and measurements. The use of a narrower bandwidth compared to the HSR RUSK measurements means that the obtained characterization has lower temporal accuracy for multipath characterization (12.5 ns vs 8.33 ns). The mmWave measurements were performed with IFSTTAR's 60 GHz Channel Sounder. Static wideband measurements at 60 GHz were performed in a production hall.

A strong effort both in terms of equipment as well as trained staff is required to execute measurement campaigns. Chapter 5 describes the actual three different measurement campaigns carried out in the field. These include measurements with one or two trains for the high-speed line and the urban/metro measurements in the operational environment as well as stationary measurements in a depot for the 60 GHz measurements and a regional train. A HSR or Metro is not a laboratory, therefore difficulties like the need of extra-long cables, railway certified equipment (antennas, etc.), or the transport and installation of fragile measurement equipment occur. A common problem is the power supply; these vehicles are not designed to support measurement equipment that is energy consuming and sensitive to power interference (EMC). In addition, mobility support and real-time data recording are always challenges for the channel measurements. For outdoor scenarios such as virtual coupling, it is challenging to perform measurements with vehicle vibrations and weather changes, which are quite sensitive in the mmWave Bands.

Further measurements are needed for investigations on ultra-reliable, MIMO and mmWave wireless communications for railways. These may include additional measurement data for different scenarios and environments, trains and carrier frequencies as well as different applications next to wireless TCMS.

Chapter 6 reports the post processing and analysis of the channel measurements. For the high speed line measurements, the large scale and small scale fading parameters are estimated in Section 6.1 for the inter-vehicle channel measurements and the parameters for a tapped delay line channel model are provided. Similar, Section 6.2 provides the large scale and small scale fading parameters for a Metro channel model for inter-consist, intra-consist, and train-to-train scenarios as well as parameters for a tapped delay line channel model for the first two scenarios. Finally, Section 6.3 analyses and estimates parameters for a regional train at 60 GHz carrier frequency for various measurements scenarios ranging from intra-vehicle to outdoor-to-roof.