Modeling and Optimization of Wireless Channel in High-Speed Railway Terrain

Abstract

The high-speed railway (HSR) wireless channel models based on field measurements have poor universality and low modeling accuracy due to the limitations of the experimental methods and the terrain conditions. To overcome this problem, this paper considers the wireless channels in various HSR scenarios (such as tunnels, mountains, viaducts, cuttings and plains) as the research objects and establishes a novel finite-state Markov chain (FSMC) optimization simulation model based on the signal-to-noise ratio (SNR) threshold, the channel states and the state transition probability matrix, by using the nonuniform space division SNR quantization strategy (hereinafter referred to as Strategy 1) and the equal-area space division SNR quantization strategy (hereinafter referred to as Strategy 2). The SNR curves that are obtained via simulation closely fit the experimental results; therefore, the proposed simulation model can accurately characterize the channel state in a variety of HSR scenarios. Furthermore, the simulation results demonstrate that in the tunnel scenario, Strategy 1 realizes a smaller mean square error (MSE) and a higher modeling accuracy than Strategy 2. The MSE values of the two strategies are similar in the plain scenario. Strategy 2 realizes a smaller MSE and a higher modeling accuracy in the mountain, viaduct and cutting scenarios.