Energy Harvesting for Physical-Layer Security in OFDMA Networks

TL;DR

This paper investigates energy harvesting and secure communication in OFDMA systems using SWIPT, proposing two suboptimal algorithms to optimize power splitting and subcarrier allocation for enhanced security and energy efficiency.

Contribution

It introduces two novel suboptimal algorithms for joint subcarrier and power splitting optimization in secure SWIPT OFDMA networks, addressing NP-hardness.

Findings

Proposed algorithms outperform conventional methods.

Iterative algorithm approaches the upper bound.

Step-wise algorithm balances performance and complexity.

Abstract

In this paper, we study the simultaneous wireless information and power transfer (SWIPT) in downlink multiuser orthogonal frequency-division multiple access (OFDMA) systems, where each user applies power splitting scheme to coordinate the energy harvesting and secrecy information decoding processes. Assuming equal power allocation across subcarriers, we formulate the problem to maximize the aggregate harvested power of all users while satisfying secrecy rate requirement of individual user by joint subcarrier allocation and optimal power splitting ratio selection. Due to the NP-hardness of the problem, we propose two suboptimal algorithms to solve the problem in the dual domain. The first one is an iterative algorithm that optimizes subcarrier allocation and power splitting in an alternating way. The second algorithm is based on a two-step approach that solves the subcarrier allocation and power splitting sequentially. The numerical results show that the proposed methods outperform conventional methods. It is also shown that the iterative algorithm performs close to the upper bound and the step-wise algorithm provides good tradeoffs between performance and complexity.