Adaptive MIMO algorithms for train-to-wayside transmissions in tunnels

In order to satisfy vital train-to-wayside transmissions for metro applications, IEEE802.11× modems are deployed along the tracks on an Ethernet network in tunnel. This paper presents possible enhancements of the PHY layer of these systems based on MIMO techniques with and without channel state information at transmitter in order to increase system performance without increasing the number of deployed access points and the transmitted power. The tunnel scenario with a masking train in the case of low and high spatial correlation is modeled thanks to the Kronecker model obtained with a 3D ray tracing tool. We consider the following MIMO schemes: spatial multiplexing, space-time block codes, max-dmin and P-OSM precoders at 5.8 GHz with a targeted Frame Error Rate equals to 3.10^-2 for a frame length of 100 bytes. The MIMO algorithms are compared in terms of achieved signal to noise ratio (SNR) versus spectral efficiency.