Performance Analysis of Train Communication Systems

Gheth, W. A. M (2021) Performance Analysis of Train Communication Systems. Doctoral thesis (PhD), Manchester Metropolitan University.

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Abstract

Trains are considered as a highly efficient transport mode which generate significant challenges in terms of their communication systems. For improved safety, to cope with the expected rapid increase in traffic, and to meet customer demands, an enhanced and reliable communication system is required for high-speed trains (HSRs). Mobile phone and laptop users would like to make use of the non-negligible time that they spend commuting but current HSR communication systems have a foreseeable end to their lifetime and a reliable, efficient, and fast communication replacement system has become essential. Encouraged by the use of existing power line networks for communication purposes, this research investigates the possibility of developing a train communication system based on the use of overhead line equipment (OLE). The ABCD transfer line model is developed to represent the transfer function of the OLE channel and is evaluated using computer simulations. The simulations of the OLE system used are based on orthogonal frequency division multiplexing as the chosen modulation scheme. Within the train, for the provision of broadband services, developing a reliable communication system which is a combination of power line communication and optical wireless communication services using visible light communication (VLC) is considered. Mathematical methods were developed for these networks to assess the overall capacities and outage probabilities of the hybrid systems. Derivation of such analytical expressions offered opportunities to investigate the impact of several system parameters on the performance of the system. To assess the possibility of improving the performance of the proposed integrated systems, their performance in the presence of different relaying protocols has been comprehensively analyzed in terms of capacity and outage probability. This thesis studied the outage probability and energy per bit consumption performance of different relaying protocols over the VLC channel. Accurate analytical expressions for the overall outage probability and energyper-bit consumption of the proposed system configurations, including the single-hop and multi-hop approaches were derived. It was found that the transfer function of the OLE channel can be represented by the two-port network model. It was also revealed that transmission over OLE is negatively affected by the speed of the train, frequency, and length of the OLE link. In train, relay-based communication systems can provide reliable connectivity to the end-user. However, choosing an optimal system configuration can enhance system performance. It was also shown that increasing relay numbers on the network contributes to the total power consumption of the system.