Multicast MIMO enhancement for V2X over LTE

Motivated by recent interest in vehicle-to-vehicle/ infrastructure/pedestrian (V2X) communication over the fourth generation of the Long-Term Evolution (LTE) cellular standard, we study the efficiency of the Multimedia Broadcast Multicast Services (MBMS), a key enabler for V2X communication, which currently employs only single antenna transmission. We show that by utilizing more transmit antennas at the base station - which are already used for point-to-point communications - and simple space-time coding (STC) techniques, a significant boost in performance can be achieved. To this end, we evaluate the performance of different transmission strategies along with the information theoretic optimal performance. For a fast Rayleigh fading channel, we show that a gain of 1 bit/sec/Hz is achieved for a signal-to-noise ratio of 10dB, and higher gains for higher signalto- noise-ratios for for an outage probability of 0.01. Moreover, we demonstrate that Alamouti STC is near optimum for typical signal-to-noise ratios. However, for more antennas, due to the inherent loss of multiplexing of orthogonal STC schemes, non-orthogonal STC schemes with higher multiplexing need to be considered.