Outage Performance Analysis in Relay-Assisted Inter-Vehicular Communications over Double-Rayleigh Fading Channels

This paper studies the inter-vehicular communication (IVC) system where a vehicle transmits information to another vehicle assisted by an access point (AP), which may be mounted along a street or on a rooftop. The paper first presents the double-Rayleigh fading vehicle-to-vehicle (V2V) channel model and the amplify-and-forward (AF) relaying system. And then the optimal power allocation (OPA) solutions are derived through maximizing source-to-destination channel capacity. Based on mathematic analysis, the closed-form expression on outage probability is concluded finally. Simulation results show that the OPA scheme improves the average throughput by about 2 dB at low to high SNR (signal-to-noise ratio) and has no less than 2 dB gains on outage probability at medium to high SNR over equal power allocation (EPA) method. They also manifest that the theoretical analysis on average outage probability coincides very well with the Monte Carlo numerical calculations. The diversity order can be achieved as large as 2.7 dB in the relay-assisted IVC system when the relay approaches to the source and under EPA solution.