Outage analysis of vehicle-roadside relay-vehicle beamforming in cooperative communications

In this paper, we study the time-average outage performance of vehicle-roadside relay-vehicle (VRV) decode-and-forward (DF) beamforming under Rayleigh flat fading channels. Maximal ratio combining (MRC) and transmit beamforming (TBF) are widely accepted ones, which maximize the signal-to-noise ratio (SNR) at the receiver when channel state information is available. With these schemes, there are four possible implementational combinations : MRC-MRC, MRC-TBF, TBF-MRC and TBF-TBF, respectively. We provide a cumulative distribution function (CDF) of end-to-end SNR for the respective cases with an assumption of an equal number of diversity branches for each hop, which is used to obtain the time-average outage performance. With numerical investigative the time-average outage is shown as a function of the distance between relays. We also compare the time-average outage performance of the four combinations.