Secrecy energy efficiency optimization in heterogeneous networks with simultaneous wireless information and power transfer

摘要

In this paper, we investigate the secrecy energy efficiency (SEE) optimization for a heterogeneous network with simultaneous wireless information and power transfer, where multiple femtocell base stations (FBSs) are deployed under the coverage of one macrocell base station (MBS). Meanwhile, the MBS serves multiple macrocell users (MUs) in the presence of a malicious multiple-antenna eavesdropper (Eve) while each FBS serves a pair of information receiver (IR) and energy receiver (ER), where the ER with multiple antennas acts as a potential Eve to wiretap the information transmitted to IR in the same femtocell. Then, to promote the secrecy performance, artificial noise (AN) is injected into the downlink transmit signal at the MBS and FBSs. Furthermore, with the aim of achieving green and secure communications in 5G, the problem of maximizing average SEE performance of the whole network is reformulated while considering cross-tier multi-cell transmit beamforming (TBF) design. To obtain the optimal design, we resort to the successive convex approximation (SCA) and semi-definite relaxation (SDR) techniques to reformulate this nonconvex max-min fractional program problem into a series of solvable forms. Subsequently, an iterative algorithm is proposed to arrive at provably convergent design. Finally, simulation results validate the effectiveness and security of the proposed AN-aided TBF design. (c) 2019 Elsevier B.V. All rights reserved.