Optimizing Energy Harvesting Decode-and-Forward Relays With Decoding Energy Costs and Energy Storage

Yanxin Yao,Mehul Motani,Zhengwei Ni,Wanqiu Hu

doi:10.1109/access.2021.3092882

Abstract

Energy harvesting (EH) relay communication systems with decoding energy costs in multiple block cases have not been widely studied. This paper investigates the relay network with a decode-and-forward relay powered by EH. Unlike other works, we consider the relay with energy decoding costs which harvests random energy from both a dedicated transmitter and other ambient radio-frequency (RF) sources. The EH relay adopts a harvest-receive-forward time-switching architecture. We optimize the time fractions of the three phases and the reception rate at the relay to maximize the offline throughput for single and multiple block cases under two EH scenarios. The multi-block optimization problem constitutes a complex non-convex problem, which we decouple into a single block problem with two auxiliary variables determined by an outer optimization problem. The original problem is finally solved at the cost of linear optimization after series of tricks. Several conclusions are derived: (i) energy storage is necessary (unnecessary) when the relay harvests energy from the transmitter (ambient RF sources), (ii) the optimal reception rate remains unchanged, while the optimal time fractions vary with the energy harvested from ambient RF sources leading to different average throughput. We give numerical simulations to verify our theoretical analysis.

Highlights

Practical communication systems with energy harvesting (EH) capabilities are expected to become ubiquitous with the rapid development of Internet of Things (IoT) networks
We investigate the offline throughput performance of a relay network with a transmitter, an EH decodeand-forward (EH-DF) relay and a receiver without a direct link.The energy required for decoding information, which is a major source of energy consumption at a relay with DF technique [48], [49], has not been well studied for EH relays, especially for the multi-block case at the relay
In this paper, we considered maximizing the offline throughput of a network with an EH-DF relay, which can harvest energy from the dedicated transmitter and from other ambient RF sources considering decoding energy costs, which is not a well-studied topic

Summary

Introduction

Practical communication systems with energy harvesting (EH) capabilities are expected to become ubiquitous with the rapid development of Internet of Things (IoT) networks. An EH device can act as a Road Side Unit (RSU), which helps to relay information of vehicles to faraway stations or other nearby vehicles [7]. Another application example is in the fog computing scenario; an EH device can act as a relay, which can help other devices to forward information to the network edge (e.g. IoT gateway). It is important to study optimal energy utilization and communication mechanisms to improve system performance. In these studies, various objectives, such as maximization of throughput [8], energy

Objectives

Results

Discussion

Conclusion