Multi-Objective Optimization for Full-Duplex SWIPT Systems

Meng Li,Huici Wu,Xiaofeng Tao,Na Li

doi:10.1109/access.2020.2973323

Abstract

This paper studies a multi-objective optimization (MOO) problem in full-duplex (FD) networks with simultaneous wireless information and power transfer (SWIPT). In the considered networks, an FD base station (BS) communicates with multiple half-duplex (HD) uplink (UL) and downlink (DL) users simultaneously. The energy receivers (ERs) harvest energy from the ambient radio frequency (RF) signals and may act as potential eavesdroppers. Specifically, there exists two conflicting yet important system design objectives, i.e., secrecy energy efficiency (SEE) maximization and energy harvesting efficiency (EHE) maximization. An MOO design based on the weighted Tchebycheff approach is proposed to investigate the tradeoff between these two design objectives. The proposed design takes into account the quality-of-service (QoS) guarantees of secrecy rate and energy harvesting (EH) under the imperfect channel state information (CSI) of ERs. The formulated MOO problem is solved with a two-layer optimization algorithm, where the modified Dinkelbach method is applied to deal with the generalized fractional programming (FP) in the outer layer problem and semidefinite relaxation (SDR), successive convex approximation (SCA) as well as S-procedure methods are applied to transfer the inner layer problem into a convex iterative program. Moreover, we propose a suboptimal solution to the formulated problem and analyze the computational complexities. Finally, numerical results are provided to demonstrate the effectiveness of the proposed algorithms and reveal a tradeoff region between SEE and EHE.

Highlights

With the exponential growth of ubiquitous Internet of Things (IoT) devices, supplying adequate energy to sustain the self-sustainability of IoT devices has become one of the most important challenges
To facilitate energy harvesting (EH), energy receivers (ERs) are usually deployed more closer to the transmitter than information receivers (IRs), so ERs have better channels than IRs and can eavesdrop the information sent to IRs
Motivated by the above issues, in this paper we focus on studying the relationship between secure information transfer (SIT) and wireless energy transfer (WET) in FD simultaneous wireless information and power transfer (SWIPT) systems from energy efficiency (EE) perspective

Summary

Introduction

With the exponential growth of ubiquitous Internet of Things (IoT) devices, supplying adequate energy to sustain the self-sustainability of IoT devices has become one of the most important challenges. Since RF signals can carry both information and energy, many researches have been carried out in simultaneous wireless information and power transfer (SWIPT) [1]–[8]. Allowing simultaneous wireless information transfer (WIT) and WET gives rise to information security. To facilitate energy harvesting (EH), energy receivers (ERs) are usually deployed more closer to the transmitter than information receivers (IRs), so ERs have better channels than IRs and can eavesdrop the information sent to IRs. On the other hand, the transmitter amplify the power of RF signals to satisfy the WET requirement, which leads to the leakage of information transmission. In addition to fulfilling the EH requirements of ERs, it is necessary to guarantee communication security in the presence of possible eavesdropping by any of all ERs [9]–[11]. Note that the above works mainly focus on the half-duplex (HD) systems with SWIPT which generally results in low spectrum utilization

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Conclusion