In-Tunnel Multi-Ray Analysis for LOS V2V Links with Multiple Antennas

This paper presents a geometric multi-ray tracing analysis for vehicle-to-vehicle (V2V) communication in tunnel environments. The objective is to investigate the performance of V2V MIMO (multiple-input multiple-output) antenna systems in the presence of multiple (specular) reflections inside a tunnel, e.g. from ground, walls and ceiling. To this purpose, we built upon our prior work where we established the V2V MIMO channel with ground reflections as an extension of the classical two-ray model. Then, in line with this vision, we increased the number of potential reflected rays to those dominating the particular tunnel's geometry. We assessed the performance of the in-tunnel V2V MIMO link assuming transmit symbols repetition and different receiver combining schemes. Analytical results for a semicircular tunnel reveals that multiple antenna systems can be useful to exploit/counteract the constructive/destructive interference patterns typically observed in tunnel-like surroundings.