Robust Secrecy Rate Beamforming for Multi-cell Networks with TS-based Information and Energy Harvesting

Next-generation communication networks are positively looking towards the energy-efficient transfer of information and energy over the same wireless channel. Thus, users would be able to receive information and harvest energy. However, under the requirement of smaller base station (BS)-to-users (UEs) distances and higher received power levels, the physical layer will become more vulnerable to cyber attacks by potential multi-antenna eavesdroppers. To realize secure wireless information and power transfer, we consider transmit time-switching (TS) mode, where energy and information signal are transmitted separately in time by the BS. Such protocol is not only quite easier to implement than the receive power splitting (PS) approach but also delivers the opportunity of multi-purpose beamforming, where energy beamformers during wireless power transfer are useful in jamming the eavesdropper. In the presence of imperfect channel estimation and multi-antenna eavesdroppers, the energy and information beamformers and the transmit TS ratio are jointly optimized to maximize the worst-case user secrecy rate subject to UEs’ harvested energy thresholds and BS transmit power budget. This secrecy rate optimization problem is very complicated due many computationally challenging constraints. A new robust path-following algorithm for its computational solution is proposed, which involves one simple convex quadratic program (QP) at A. A. Nasir is with the Department of Electrical Engineering, King Fahd University of Petroleum and Minerals (KFUPM), Dhahran, Saudi Arabia (Email: [email protected]). H. D. Tuan is with the Faculty of Engineering and Information Technology, University of Technology Sydney, Broadway, NSW 2007, Australia (email: [email protected]). T. Q. Duong is with Queen’s University Belfast, Belfast BT7 1NN, UK (email: [email protected]) H. V. Poor is with the Department of Electrical Engineering, Princeton University, Princeton, NJ 08544, USA (e-mail: [email protected]). ar X iv :1 61 1. 05 99 2v 2 [ cs .I T ] 1 4 D ec 2 01 6