Robust transmissions in wireless powered multi-relay networks with chance interference constraint

Abstract

In this paper, we consider a wireless powered multi-relay network in which a multi-antenna hybrid access point underlaying a cellular system transmits information to distant receivers. Multiple relays capable of energy harvesting are deployed in the network to assist the information transmission. The hybrid access point can wirelessly supply energy to the relays, achieving multi-user gains from signal and energy cooperation. We propose a joint optimization for signal beamforming of the hybrid access point as well as wireless energy harvesting and collaborative beamforming strategies of the relays. The objective is to maximize network throughput subject to probabilistic interference constraints at the cellular user equipment. We formulate the throughput maximization with both the time-switching and power-splitting schemes, which impose very different couplings between the operating parameters for wireless power and information transfer. Although the optimization problems are inherently non-convex, they share similar structural properties that can be leveraged for efficient algorithm design. In particular, by exploiting monotonicity in the throughput, we maximize it iteratively via customized polyblock approximation with reduced complexity. The numerical results show that the proposed algorithms can achieve close to optimal performance in terms of the energy efficiency and throughput.Ministry of Education (MOE)The work of Shimin Gong was supported in part by the National Natural Science Foundation of China (NSFC) under Grant 61601449, 61503368, 61602462, Shenzhen Basic Research Program under Grant JCYJ20151117161854942, and Shenzhen Talent Peacock Plan Program under Grant KQTD2015071715073798. The work of Lin Gao was supported by NSFC under Grant 61771162. The work of Dusit Niyato was supported in part by Singapore MOE Tier 1 under Grant 2017-T1-002- 007 RG122/17, MOE Tier 2 under Grant MOE2014-T2-2-015 ARC4/15, and NRF2015-NRF-ISF001-2277. The associate editor coordinating the review of this paper and approving it for publication was E. Basar. (Corresponding author: Shimin Gong.