Accumulate then Forward: An Opportunistic Relaying Protocol for Wireless-Powered Cooperative Communications

TL;DR

This paper proposes an accumulate-then-forward opportunistic relaying protocol for wireless-powered cooperative networks, leveraging energy harvesting and battery modeling to improve communication reliability over direct transmission.

Contribution

It introduces the ATF protocol that fully incorporates energy harvesting dynamics and derives an exact outage probability using Markov chain modeling.

Findings

ATF outperforms direct transmission in outage probability.

Optimizing relay energy consumption enhances performance.

Closed-form outage probability expression is derived.

Abstract

This paper investigates a wireless-powered cooperative communication network consisting of a source, a destination and a multi-antenna decode-and-forward relay. We consider the relay as a wireless-powered node that has no external power supply; but it is equipped with an energy harvesting (EH) unit and a rechargeable battery such that it can harvest and accumulate energy from radio-frequency signals broadcast by the source. By fully incorporating the EH feature of the relay, we develop an opportunistic relaying protocol, termed accumulate-then-forward (ATF), for the considered WPCCN. We then adopt the discrete Markov chain to model the dynamic charging and discharging behaviors of the relay battery. Based on this, we derive a closed-form expression for the exact outage probability of the proposed ATF protocol. Numerical results show that the ATF scheme can outperform the direct transmission one, especially when the amount of energy consumed by relay for information forwarding is optimized.