On the performance of roadside unit-assisted energy harvesting full-duplex amplify-and-forward vehicle-to-vehicle relay systems

Abstract

This paper considers the performance of a full-duplex (FD) vehicle-to-vehicle (V2V) relay system where the relay uses amplify-and-forward (AF) protocol and harvests the energy from the radio frequency (RF) signals transmitted by source. Unlike previous reports, we investigate the case that both relay and destination are moving vehicles. Therefore, the channel between source and relay is Rayleigh fading while the channel between relay and destination is cascade (double) Raleigh fading. In addition, both fixed and variable gains are used at the FD relay. Based on mathematical analysis, we successfully derive the exact closed-form expressions of the outage probability (OP) and symbol error probability (SEP) to evaluate the system performance. Monte-Carlo simulations are exploited to demonstrate the correctness of all derived mathematical expressions. Numerical results clearly indicate that the OP and SEP performance of the considered energy harvesting (EH)-FD-V2V relay system with variable gain is much better than that with fixed gain. Moreover, the OP and SEP performance are strongly impacted by residual self-interference (RSI) due to the incomplete noise cancellation during the FD transmission. Besides the RSI, the OP and SEP performance is greatly reduced because of the cascade Rayleigh fading. We also observe that there is an optimal EH time duration to minimize the OP and SEP and this optimal value is different for fixed and variable gains. Therefore, from the transmission power of source and the type of gains used at FD relay, we can choose a suitable time EH time duration to get the best system performance.