Research On Performance Optimization Algorithm Of Wireless Energy-carrying Cooperative Communication System

By utilizing the mutual collaboration among nodes in the networks,the cooperative technology can resist different scale fading during communication efficiently,and thus it has recently become a hot topic in wireless communications.Due to the scarcity of resources,communication systems in some special environments cannot supply power to network nodes.Therefore,the energy-constrained nodes need to harvest energy from the environment and use the harvested energy to cooperatively forward information to destination,which is defined as simultaneous wireless information and power transmission(SWIPT).The relaying techniques in the cooperative communication systems with SWIPT is researched on this thesis.It focuses on the relay energy harvesting protocol and relay selection strategy,aiming at improving the system throughput and outage performance.The research contents are as follows.In the single-relay cooperative communication system with SWIPT under RF interference,this thesis discretizes the energy harvesting and information transmission process of relay,and proposes three relay working modes: energy harvesting,information buffering and information forwarding.Combining energy diversity and opportunity energy harvesting,it proposes an EDOEH protocol,and a heuristic algorithm on relay mode selection,which enables the relay node to select an appropriate working mode according to the channel capacity and the SNR threshold value.Simulation results show that the heuristic algorithm based on ED-OEH protocol can effectively improve system throughput.For the multi-relay cooperative communication system with SWIPT,this thesis proposes a relay selection scheme combining the selection priority of buffer state and SNRs of links,and the selection priority can effectively reduce the outage probability by increasing the number of available transmission links.By modeling the transfer process of the buffer queue status of the relay cluster with Markov chain,it derives the system outage probability based on the change of the buffer queue status in the relay cluster.The numerical analysis results verify that the proposed relay selection can effectively reduce the outage probability.