Optimal power allocation method and outage probability analysis in AP-assisted inter-vehicular communications

This paper studies the relay-assisted inter-vehicular communications (IVCs) with double Rayleigh fading vehicle-to-vehicle links. The OPA (optimal power allocation) solution is derived through maximizing source-to-destination channel capacity assuming amplify-and-forward relaying. The outage performance is discussed and the lower bound on outage probability at medium to high SNR (signal-to-noise ratio) is presented. Simulation results manifest that the ergodic capacity can be improved by about 2 dB at low SNR through OPA method over EPA (equal power allocation) solution, whereas the outage probability decreases more than 2 dB at high SNR compared to EPA. They also show that the lower bound on average outage probability approximates to the exact calculation result at medium to high SNR in the relay-assisted IVC system.