JOINT BEAMFORMING AND POWER SPLITTING DESIGN FOR TWO WAY AF RELAY NETWORKS WITH ENERGY HARVESTING

Jun Shao, Jinxin Zhu
2020 Progress In Electromagnetics Research Letters  
In this paper, we focus on the beamforming design in a two way amplify-and-forward relay network with energy harvesting, in which a three-node system consisting of two transmitters and one relay is considered. Specifically, we investigate the joint beamforming and power splitting scheme to obtain the maximum weighted sum rate. The formulated problem is non-convex and challenging. We equivalently transform it into a more tractable problem via successive convex approximation and constrained
more » ... e-convex procedure. Then, an iterative algorithm is proposed. Numerical results demonstrate the superiority of the proposed method, as well as the effect of dynamic power splitting in improving the sum rate of relay network. INTRODUCTION Energy harvesting (EH) is considered as one of the effective approaches for improving the energy efficiency (EE) and prolonging the lifetime of wireless networks, since EH-enabled nodes can harvest energy from either radio-frequency (RF) signals or ambient energy sources such as solar panel and wind turbine, which enables them to operate continuously [1]. On the other hand, the recently development in metamaterial has promoted the implement of EH [2] [3] [4] [5] . Specifically, in [2], the authors investigated an extremely-broad band metamaterial absorber for solar energy harvesting based on a star-shaped resonator. In [3], the authors investigated the implementation of a perfect metamaterial absorber into multi-functional sensor applications. Recently, in [4] , the authors investigated mass-energy equivalence which appears in left-handed metamaterials, while in [5], the authors investigated the enhancement of image quality by using metamaterial inspired energy harvester. Currently, there are two promising EH methods in wireless networks, termed as wireless-power communication network (WPCN) and simultaneous wireless information and power transfer (SWIPT), respectively [6] . The main difference between WPCN and SWIPT is that wireless power and information are transmitted in individual and common slot, while power splitting (PS) is a widely used method in SWIPT to coordinate information decoding (ID) and EH simultaneously [7] . Since relay is commonly an energy-constrained node in cooperative networks, it is critical to require ambient energy supply for supporting cooperative communication. An important application scenario for SWIPT lies in the energy-constrained relay networks, in which the relay node harvests energy from the RF signals transmitted by the source and then uses the harvested energy to forward the received signal [8] [9] [10] [11] . Specifically, in [8], the authors proposed an EH relay scheme based on time switching (TS) relaying protocol. In [9], the authors proposed a secure beamforming in amplify-and-forward (AF) EH relay networks, with PS and TS schemes, respectively. In [10], the authors proposed an energy-efficient and secure beamforming for self-sustainable EH relay networks. Recently, in [11] , the authors proposed a precoding design of multiple-input-multiple-output (MIMO) AF relay system with SWIPT.
doi:10.2528/pierl19122301 fatcat:bsrhgeidijevtibagvizwiaebi