Robust train-to-wayside video communications in tunnels using H.264 error-resilient video encoding combined with multiple antenna systems

Abstract

With the development of driverless metro systems, the demand for high data rate train-to-wayside wireless transmission is increasing drastically in order to satisfy operational needs such as maintenance, video surveillance of the inside of the trains and passenger information. Thus, the association of new transmission techniques such as new video coding techniques, multi antennas at transmission and reception sides and recent precoders provides technically and economically efficient solutions to improve existing systems. This paper presents and evaluates two novel strategies to enhance train-to-wayside wireless video transmissions in tunnels using realistic channel models obtained with ray tracing previously experimentally validated. Multiple Description Coding (MDC) or Region Of Interest (ROI) coding, using the new Flexible Macroblock Ordering (FMO) technique, is combined with appropriate Multiple Input Multiple Output (MIMO) schemes, namely, spatial multiplexing (SM), orthogonal spatial multiplexing (OSM) and precoded orthogonal spatial multiplexing (P-OSM) depending if full channel state information at transmitter side (CSI-T) is available or not. For each strategy, both video encoding process and MIMO algorithm are combined in an efficient way to provide the best video quality at the receiver with no increase of the number of radio access points along the infrastructure.