Outage performance of SWIPT-enabled two-way relay networks

Abstract

This paper investigates the outage performance of simultaneous wireless information and power transfer (SWIPT) in two-way relay channels, where two sources exchange their information via an energy harvesting (EH) relay with digital network coding (NC) employed. The relay harvests energy from the received radio-frequency (RF) signals transmitted from the two sources and then use it to forward the received signals. For such a system, we study the power splitting-based two-way relay (PS-TWR) transmission strategy and analytically derive an explicit expression of the system outage probability. In order to explore the system outage performance limit, we formulate an optimization problem to minimize the system outage probability by jointly optimizing the power splitting ratio and the time assignment ratio. Since the problem is non-convex and have no known solution method, we present a genetic algorithm (GA) to solve it. Numerical results demonstrate our theoretical analysis and show that the power splitting ratio and the time assignment ratio greatly affect the system outage performance. Moreover, it is also shown that for the SWIPT-enabled two-way relay system, the relay node should be deployed closer to the source with better channel quality and when it is positioned on the middle point between the two sources, the system gets the worst outage performance, which is very different from traditional non-SWIPT two-way relay systems.