Research On Relay Cooperative Communication Based On Energy Harvesting Technology

With the development of the fifth generation mobile communication,intelligent terminal and the internet of things,miniature smart personal device and the explosion of communication traffic volume bring new challenges for the communication energy supply.Therefore,the future wireless communication systems can adopt “opening up the source and regulating the flow”.On the one hand,we must consider energy consumption problem,on the other hand,we have to find new way of energy supply.Cooperative communication can solve the problem of energy consumption and energy harvesting can provide energy source,combing the two together can satisfy the demand of wireless communication device on the energy in the future.The research of combing cooperative communication and energy harvesting has just started at home and abroad and exists many problems,therefore we combine energy harvesting,especially wireless power transfer and simultaneous wireless information and power transfer,with cooperative communication in this article,establish many models which are consistent with the actual scenes.The focus of this paper is to explore the application of energy harvesting and transmission technology on the basis of cooperative communication.This paper advocates the capacity analysis of an amplify-and-forward(AF)cooperative communication system model in multi-relay multiuser networks.In contrast to conventional cooperative networks,relays in the considered network have no embedded energy supply.They need to rely on the energy harvested from the signals broadcasted by the source for their cooperative information transmission.Based on this structure,a two-step selection scheme is proposed considering both channel state information(CSI)and battery status of relays.Assuming each relay has finite or infinite energy storage for accumulating the energy harvested from the source signal,we use the infinite or finite Markov chain to capture the evolution of relay batteries and certain simplified assumptions to reduce computational complexity of the Markov chain analysis.The approximate closed-form expressions for the average capacity of the proposed scheme are derived.All theoretical results are validated by numerical simulations.Finally,based on this three-node reference model,we propose a harvest-then-cooperate(HTC)protocol,in which the source and relay harvest energy from the AP in the downlink and work cooperatively in the uplink for the source's information transmission.Considering a delay-limited transmission mode,the approximate closed-form expression for the average throughput of the proposed protocol is derived over Rayleigh fading channels.