BER Performance Analysis and Optimization for Energy Harvesting Two-way Relay Networks

This paper investigates the sum-bit error rate (BER) performance of amplify-and-forward (AF) energy harvesting two-way relay networks (TWRNs), where two source nodes communicate with each other through a self-sustaining wireless relay node using time switching-based relaying (TSR) protocol. Two physical layer network coding (PNC) schemes are considered, namely two-time-slot and three-time-slot PNC, denoted by 2-PNC and 3-PNC, respectively. We derive analytical expressions for the sum-BER of these two schemes and propose to appropriately time share between modulation schemes of different dimensions according to the energy harvesting time fraction in order to normalize the spectral efficiency. Simulation and numerical experiments are performed to verify our analysis. It is observed that 3-PNC outperforms 2-PNC in terms of sum-BER when the energy harvesting time fraction is small. However, this fraction can be optimized such that the 2-PNC scheme achieves better overall sum-BER performance.