Performance of a Cooperative Network With an Energy Buffer-Aided Relay

In this paper, we analyze the performance of a cooperative communication network with an energy buffer-aided energy harvesting relay. We consider both fixed and adaptive-rate signalling. The relay is assumed to harvest energy from ambient sources. We consider the harvest-store-use (HSU) protocol employing best-effort or on-off policies, with both finite and infinite-size energy buffers, and analyze the outage probability and ergodic rate performance. Since it is known that using a discrete-state Markov chain to model the energy buffer is inaccurate even for moderate number of levels, we assume use of a discrete-time continuous-state space Markov chain. We do not ignore the direct channel, and assume that the direct and relayed signals are optimally combined. We compare performance of the scheme with that of harvest-use (HU) and direct (relay-less) transmission. Simulation results are presented to validate the derived analytical expressions and bring out useful insights.