Abstract

This paper investigates the outage probability of a vehicle-to-vehicle (V2V) multiple antenna communication link with respect to the density of antennas. The objective is to study the trade-off between complexity (number of antennas) and link performance considering explicit ground reflections. The antennas are assumed to be located at regularly distributed positions across the surface of contiguous vehicles. Under the assumption of symbol repetition across Tx antennas, we also focus on well-known mechanisms such as maximum-ratio and equal-gain combining (MRC and EGC, respectively). The objective is to minimize the outage probability of the V2V link with deterministic and stochastic channel components (i.e., Rice-distributed), where the line-of-sight (LOS) is affected by ground reflections (as an extension of the two-ray model). This scenario is more realistic for V2V applications due to the proximity of the antennas to the ground. The outage probability is averaged over a range of inter-vehicle distances with respect to the free-space loss solution. The results show that performance is improved even for a relatively small number of antennas, and that a point is reached beyond which improvement becomes differential. This suggests an optimum trade-off between outage probability and complexity can be reached over a range of inter-vehicle distances.