A full-duplex SWIPT system with self-energy recycling to minimize energy consumption

Hyunjong Na,Chungyong Lee

doi:10.1186/s13638-018-1249-4

Abstract

In simultaneous wireless information and power transfer system (SWIPT), additional resource allocation for power transfer degrades system performance. Therefore, how to allocate power and time to data transmission and energy transfer is very important for the performance of time switching-based SWTPT system. In this paper, we propose a time switching-based full-duplex SWIPT system combined with self-energy recycling since self-interference harvesting is more efficient than simultaneous data transmission if the magnitude of self-interference is sufficiently large. Proposed system has additional self-energy recycling phases compared to the conventional time switching-based full-duplex SWIPT system. Considering the limitation of maximum transmission power, proposed system is optimized transmission time as well as power. For the validity of the proposed system, we show the bi-convexity of proposed system and propose an iterative algorithm for optimization of proposed system. In simulations, we compare proposed system with the half-duplex system without simultaneous data transmission phase and the full-duplex system without self-energy recycling phase. Simulation results show proposed system consume less energy than the conventional systems.

Highlights

In recent years, simultaneous wireless information and power transfer (SWIPT) schemes are attracting in terms of enabling to carry information and energy simultaneously [1]
The self-energy recycling (S-ER) scheme was proposed in point-to-point (P2P) full duplex (FD) system where power splitting (PS)-based energy harvesting (EH) is used at user equipment (UE) [9]
5 Conclusions In this paper, we propose the time switching (TS)-based FD SWIPT system in D2D communication system to minimize total energy consumption where S-ER is implemented at both users

Summary

Introduction

Simultaneous wireless information and power transfer (SWIPT) schemes are attracting in terms of enabling to carry information and energy simultaneously [1]. The source transfers the energy to relay, and relay harvests SI as well as the signal from the source node in the second phase. Ding et al proposed the beamforming scheme of multiple-input multiple-output (MIMO) relay for rate maximization where relay harvests SI in the second phase [14]. The short lifetime of IoT devices due to small size battery is a critical problem In this environment, the device equipped with a large battery, such as a smartphone, can transfer energy-to-energy-deficient devices to prolong communication time. We propose a TS-based FD SWIPT system for D2D communication to prolong the lifetime by minimizing energy consumption under the target rate constraint. The entire time in the conventional TS-based FD SWIPT system consists of two phases if one user does not have enough energy to transmit data. In contrast to the alternative convex search (ACS) technique which can obtain a local minimum, the proposed scheme can obtain a better solution close to global optimum

System model and optimization problem formulation

Optimal power allocation with fixed τ

Iterative scheme based on line search method

Simulation results

Findings

Conclusions