Integrating Physics-Based Wireless Propagation Models and Network Protocol Design for Train Communication Systems

Physics-based wireless propagation modeling and network protocol design have evolved over decades as orthogonal areas in communication systems research. This fragmented approach does not exploit available efficiencies when planning and deploying communication systems. In an attempt to integrate the two areas, we harness the understanding of the underlying physics of electromagnetic propagation to enhance the robustness of network protocol design by deriving physics-based network-level performance metrics. We use ray-tracing and parabolic equation models of 2.4 GHz propagation along tunnel and open-air sections of London Underground to evaluate the performance of a communications-based train control system. For comparison, we consider existing path loss models for tunnel environments and investigate whether they can provide sufficient accuracy to be used for network protocol design. We show that physics-based models lead to reliable predictions at the network level, similar in fidelity to using measured data and unlike using simplified channel models of the path loss exponent type.