Block Markov superposition transmission for high-speed railway wireless communication systems

The focus of this paper is coded orthogonal frequency division multiplexing (OFDM) system for high-speed railway wireless communication based on block Markov superposition transmission (BMST). The effect of Doppler spreading destroys the orthogonality among subcarriers, resulting in intercarrier interference (ICI) in the OFDM systems. In order to mitigate the ICI and get the soft information easily, we present a simple soft output algorithm based on zero forcing (ZF) equalization, and the soft information is given to the soft-in soft-out (SISO) demapper. We combine the OFDM system with BMST code, which can be easily designed for any given code rate with a predictable performance lower bound. Based on the iterative sliding-window decoding algorithm, BMST scheme outperforms the convolutional code (CC) scheme in the OFDM system for quadrature phase-shift keying (QPSK) and 16-quadrature amplitude modulation (QAM). Numerical results show that the BMST-OFDM system performs well over doubly selective channels.