Wireless Energy Harvesting Cooperative Communications with Direct Link and Energy Accumulation

TL;DR

This paper proposes an incremental relay protocol for a wireless energy harvesting cooperative network with a direct link, demonstrating improved outage performance through energy accumulation and opportunistic cooperation.

Contribution

It introduces the IATF protocol that optimizes relay cooperation based on energy availability, with a Markov chain model for battery behavior and outage probability analysis.

Findings

IATF outperforms direct transmission in outage probability.

Energy accumulation enhances relay cooperation efficiency.

Theoretical results are validated by numerical simulations.

Abstract

This paper investigates a wireless energy harvesting cooperative network (WEHCN) consisting of a source, a decode-and-forward (DF) relay and a destination. We consider the relay as an energy harvesting (EH) node equipped with EH circuit and a rechargeable battery. Moreover, the direct link between source and destination is assumed to exist. The relay can thus harvest and accumulate energy from radio-frequency signals ejected by the source and assist its information transmission opportunistically. We develop an incremental accumulate-then-forward (IATF) relaying protocol for the considered WEHCN. In the IATF protocol, the source sends its information to destination via the direct link and requests the relay to cooperate only when it is necessary such that the relay has more chances to accumulate the harvested energy. By modeling the charging/discharging behaviors of the relay battery as a finite-state Markov chain, we derive a closed-form expression for the outage probability of the proposed IATF. Numerical results validate our theoretical analysis and show that the IATF scheme can significantly outperform the direct transmission scheme without cooperation.