Mohamed Kassab

LTE Based Communication System for Urban Guided-Transport: A QoS Performance Study

The control and management of new urban guided-transport systems such as tramways and subways are based on several IT services with heterogeneous data communication requirements. These applications are known as CBTC (Communication Based Train Control systems) and CCTV (Closed Circuit TeleVision). In order to support existing as well as emerging applications over a unique communication infrastructure, it is mandatory to be able to ensure efficient QoS management that meets the requirements of CBTC and CCTV services especially the critical ones. This paper presents an evaluation of QoS provisioning in LTE (Long Term Evolution) based communication system for urban guided-transport. The evaluation is made through simulations with the well known event driven simulator OPNET. We propose a mapping of the typical applications CBTC and CCTV to standardized 3GPP QCIs (QoS Class Identifiers) that serve as a basis for the LTE class-based QoS. After discussion of the obtained results, we provide recommendations to enhance the communication performances experienced by these applications.

Ensuring Long-Term Data Integrity: ETCS Data Integrity Requirements Can Be Fulfilled Even under Unfavorable Conditions with the Proper LTE Mechanisms

The European Train Control System (ETCS) is the leading signaling system for train command and control. In the future, ETCS may be delivered over long-term evolution (LTE) networks. Thus, LTE performance offered to ETCS must be analyzed and confronted with the railway safety requirements. It is especially important to ensure the integrity of the ETCS data, i.e., to protect ETCS data against loss and corruption. In this article, various retransmission mechanisms are considered for providing end-to-end ETCS data integrity in LTE. These mechanisms are validated in simulations, which model worst-case conditions regarding train locations, traffic load, and base-station density. The simulation results show that ETCS data integrity requirements can be fulfilled even under these unfavorable conditions with the proper LTE mechanisms.

Multi-technology vehicular cooperative system based on software defined radio (SDR)

Within the scope of the European policy for Intelligent Transport Systems (ITS), the PLATA-PROTON project proposes a multi-technology cooperative Advanced Driver Assistance System (ADAS), based on the integration of Software-Defined Radio (SDR) devices in vehicles. With the choice of significant road-safety related scenarios, V2V and V2I communications have been both implemented and simulated. This paper proposes an overview of the Software-Defined Radio (SDR) platform development and the performance evaluation based on network simulation, performed within this project.

Generating Test Scenarios Based on Real-World Traces for ERTMS Telecommunication Subsystem Evaluation

The European Rail Traffic Management System (ERTMS) allows increasing the utilization of the track by using a wireless mobile technology, the GSM-R, for dynamic signaling and control of the trains. However, the GSM-R will become the bottleneck regarding the performance of the ERTMS due to the increase of both the trains’ traffic, and the resources needed by all the applications that contribute to safety in rail transportation and to satisfaction of the users. In this context, it is necessary to develop the tools that will allow evaluating the impact on the GSM-R of the scenarios that could occur, but that are costly or difficult to test on real tracks. In this paper, we propose an approach that consists in using real-world traces of trains moving on ERTMS lines to build specific scenarios for evaluating the ERTMS telecommunication subsystem. In this way, we are able to guarantee that these evaluations are very realistic due to the fact that the train moves following the functional specification of ERTMS. Moreover, our approach is particularly interesting for the future of ERTMS since the same scenarios can be used to evaluate other prospective wireless mobile technologies that could replace the GSM-R, such as LTE.

Modelling Communication Based Train Control System for Dependability Analysis of the LTE Communication Network in Train Control Application

The Communication Based Train Control (CBTC) systems today has generated immense interest in transport domain because of its ability to enhance safety and improve operational effectiveness. The current communication solutions for urban guided transport system that is based on the Wireless local area network (WLAN) becomes obsolete with a number of shortcomings in term of capacity and capability. Hence, the Long Term Evolution (LTE) is considered as a new solution for railway communication technology. Before widely deploying this new solution in railway industry, it must be evaluated and tested to ensure the desired performance level for CBTC system according to the railway safety standards. Therefore, it is necessary to propose a model of CBTC system that allows to consider the behaviours of the LTE communication network in real time. In this paper, we propose to use Petri nets for modelling CBTC system based on a LTE architecture. Using this model, preliminary dependability analysis for the data communication system based on the LTE technology is then performed.

LTE Micro-cell Deployment for High-Density Railway Areas

Long Term Evolution (LTE) is a serious candidate for the future releases of the European Rail Traffic Management System (ERTMS). LTE offers more capacity and supports new communication-based applications and services for railways. Nevertheless, even with this technology, the classical macro-cell radio deployments reach overload, especially in high-density areas, such as major train stations. In this paper, an LTE micro-cell deployment is investigated in high-density railway areas. Copenhagen Main Station is considered as a realistic deployment study case, with a set of relevant railway communication-based applications. The micro-cell deployment is compared with a classical macro-cell deployment in terms of transmission performance. Simulation results show a capacity improvement in the micro-cell deployment and its positive impact on critical (safety) and non-critical applications.

IEEE 802.11a performance for infrastructure-to-train communications in an underground tunnel

The deployment of wireless technologies for public transport may imply several constraints due to specific environment, such as tunnels. In this paper, we evaluate the performance of IEEE 802.11a based networks deployed for infrastructure-to-train communications in underground tunnels. The signal attenuation specific to the tunnel propagation is taken into account. We propose an optimization of the handover detection mechanism to minimize the connectivity loss when the train moves between Access Points. We propose a performance evaluation based on OPNET simulator.

Analytical approach for evaluating LTE communication errors in train control application

The current communication solutions train control application that is based on WLAN or GSM-R becomes obsolete with a number of shortcomings in term of capacity and capability. Hence, deploying a new dependability vehicular communication is recommended. In this context, the Long Term Evolution (LTE) technology is considered as a new solution for railway communication because of its ability to support multi-service traffic (voice, video, data). Before widely deploying this new solution in railway industry, it must be evaluated and tested to ensure the desired performance level for train control system (TCS) according to the railway safety standards. In order to overcome the high time execution and low accuracy of statistical evaluation for small probabilities, the analytical treatment is a a complementary approach to the simulation approach. Therefore, it is necessary to propose a new analytical approach for analysing and evaluating the communication error types of the LTE based TCS. It is also the goal of this paper. The results presented in the framework of this paper are prerequisites for the dependability analysis of the advanced TCS based on the LTE technology in further works.

Evaluating TCMS Train-to-Ground Communication Performances Based on the LTE Technology and Discreet Event Simulations

This paper focuses on performance evaluation of the Train to Ground traffic exchanges used to ensure safety and monitoring train functionalities carried by the Train Control Management System (TCMS). In the framework of the European project Safe4Rail from the Shift2Rail program, we try to use LTE (Long Term Evolution) network as an alternative communication technology, instead of GSM-R (Global System for Mobile communications-Railway) because of some capacity and capability limits. First step, a pure simulation is used to evaluate the network load for a high-speed scenario, when the LTE network is shared between the train and different passengers. The simulation is based on the discrete-events network simulator Riverbed Modeler. Next, second step focusses on a co-simulation testbed, to evaluate performances with real traffic based on Hardware-In-The-Loop and OpenAirInterface modules. Preliminary simulation and co-simulation results show that LTE provides good performance for the TCMS traffic exchange in terms of packet delay and data integrity.

TOWARD A COMMON PLATFORM FOR SIMULATION-BASED EVALUATION OF BOTH FUNCTIONAL AND TELECOMMUNICATION SUB-SYSTEMS OF THE ERTMS

The deployment of the European Rail Traffic Management System (ERTMS) in Europe will be mandatory on the major corridors, but this process will be long and expensive. Industry needs faster roll-out and a reduction in cost in order to obtain the certification and authorization to put equipment into service. New lab-testing tools for European Train Control System (ETCS) validation based on automatic testing could accelerate the process. In this work, we propose a co-simulation platform relaying on two existing tools: the ERTMS simulator that implements only the functional sub-system (ETCS) of ERTMS; and the OPNET simulator that allows modeling the whole telecommunication subsystem (GSM-R) from the Physical layer to higher layers, including the Euroradio interface. We describe a co-simulation protocol that determines how the results obtained from each simulator are reused as input in the other in order to take into account the impact of the functioning of one subsystem on the other. In this way, the problems related to radio propagation impairments, network load and electromagnetic interferences can be taken into account in ERTMS evaluation. Furthermore, some actors of the railway industry think about moving towards emerging technologies like LTE (4G Long Term Evolution). This platform will also allow evaluation of prospective technologies in the framework of ERTMS scenarios before costly real-world implementation.© 2012 ASME