Research On Energy-efficiency Based Buffer-aided Relay Selection Scheme In SWIPT Network

In recent years,with the ever-expanding industry scale of information and communication technology(ICT),the popularization of intelligent mobile terminals,and the surge in data traffic demand as well as ubiquitous wireless access services,energy consumption of smart mobile devices has been greatly increasing.Smart mobile devices are generally powered by batteries with limited power.However,battery storage has not increased significantly over the past few decades.It has become bottleneck in network life.In order to achieve low energy consumption of equipment and prolong network life cycle,simultaneous wireless information and power transfer(SWIPT)technology has emerged.SWIPT can significantly expand channel capacity and extend signal coverage.It has great potential in the aspects of cost reduction,guarantee network life cycle,and system throughput improvement.Aiming at the problem of energy constraint buffer-aided relay selection iin SWIPT,energy-efficiency priority based buffer-aided relay selection scheme in SWIPT is investigated.It aims to theoretically explore the application of relay selection in SWIPT.Meanwhile,a relay-aided infonmation and power transfer protocol based on time switching(TS)structure and the corresponding SWIPT relay receiver structure are designed.The work carried out by the thesis is arranged in the following five chapters.The research history and research value of SWIPT are introduced in Chapter 1.The concept of energy-efficient green wireless network and the current research status of SWIPT network are briefly introduced.At the same time,the research progress of buffer-aided relaying in cooperative transmission is briefly described.The basic principles of SWIPT are introduced in Chapter 2.The key transmission technologies such as buffer-aided relaying and energy harvesting that improves SWIPT system reliability are briefly introduced.On this basis,the current research status of SWIPT network energy harvesting and tradeoff between information transmission and energy harvesting is expounded.Energy-efficiency based buffer-aided relay selection scheme in SWIPT is investigated in Chapter 3.Aiming at the problem of buffer-aided relay selection in SWIPT with energy constraint,energy-efficiency priority based buffer-aided relay selection scheme in SWIPT is investigated.The proposed scheme considers many factors to influence optimal receive/transmit relay selection.Those factors include:relay operation mode,relay link channel state information(CSI),buffer state,buffer size as well as the harvested energy.Moreover,SWIPT system energy efficiency is studied in the proposed scheme.In the constraint of energy harvesting and information transmission spectral efficiency,an appropriate mathematical model is constructed to perform energy efficiency priority based buffer-aided optimal receive/transmit relay selection in SWIPT.Numerical results show that,the proposed scheme effectively reduces SWIPT outage probability and achieves the tradeoff between energy efficiency and outage performance in buffer-aided relaying SWIPT.A relay-aided information and power transfer protocol based on time switching structure in SWIPT is studied in the Chapter 4.Aiming at the low energy consumption of equipment and the long life cycle of network environment,wireless information and energy simultaneous transmission technology has emerged as one of the novel green transmission technologies in wireless communication.Green simultaneous wireless information and power transfer(SWIPT)network is taken as the research background,SWIPT relays that provided with energy harvesting are introduced in this thesis.Time switching(TS)based relay-aided information and power transfer scenario and mathematical model are presented.A relay-aided information and power transfer protocol based on TS structure and the corresponding SWIPT relay receiver structure are designed.Outage performance(OP)and energy-efficiency(EE)performance are analyzed,and the effect of TS factor to OP and EE performance are presented respectively.Numerical results show that,in order to guarantee OP and EE performance in SWIPT,the source should transmit signals with optimum power.The tradeoff between information transmission and energy harvesting in SWIPT can be achieved consequently.Finally,the summary of the thesis and the prospect of future work are given in Chapter 5.This thesis makes a preliminary research and design on the key technology of energy-efficiency priority based buffer-aided relay selection scheme in SWIPT.Some preliminary results have been achieved,which have certain guiding value for further in-depth research.