Research On Performance Optimization In Wireless Energy Harvesting Communication System

With the continuous development of wireless network, wireless communication has become an indispensable part of people's life. As a new energy providing technology, wireless energy harvesting technique could provide the node with continuous energy supply to a certain extent. Thus it could ensure the stability of the communication topology, attracting a lot of attention from both academic and industry. This paper aims to study the wireless cooperative transmission with radio frequency (RF) energy harvesting to improve the performance of the system, and the performance analysis and resource allocation algorithm in this system are provided. The main work is as follows:First, we study the optimal relay location in wireless relay system with RF energy harvesting. The relay utilizes power-splitting protocol to harvest energy from the received signal and utilizes the harvested energy to forward information.Without loss of generality, it is assumed that the relay has a certain amount of initial energy. The outage probability is derived and then the closed form of the optimal amount of harvested energy and best relay location are achieved analytically in order to minimize the outage probability. Simulation results verify the correctness of the derivation and show that the energy harvesting relay system with optimal harvested energy and relay location can achieve better outage performance than the relay system without energy harvesting.Second, the research proposes an energy incentive cooperation scheme,where the node uses energy as a reward to request cooperation from neighboring nodes to improve the achievable sum-rate of the system. We first study time division multiple access scenario and give the optimal time and power allocation under energy constraints, peak power constraints and the minimum rate constraints when channel state information (CSI) is perfectly known at transmitter.We then extend this work to the statistical CSI scenario and also give the optimal resource allocation scheme. Besides, the work has been extended to the non-orthogonal multiple access (NOMA) scenario to give the optimal resource allocation when time-splitting or power-splitting receiver is utilized. Simulation results verify that the energy-incentive cooperation transmission has a better performance and the NOMA technique would result in a higher rate compared with TDM scheme. The proposed energy-incentive cooperation scheme would have a wide application because of its simplicity and high performance gain.