Key Technology Research And Design Of Energy-efficiency Based Green Cooperative Transmission Schemes

In order to satisfy the requirements for effectiveness and reliability in wireless communication,cooperative communication has emerged as a promising technology in the fields of communication engineering in the recent years.Cooperative communication can effectively defeat channel fading and improve transmission performance in wireless communication via mutual cooperation between cooperative users in wireless network.Cooperative communication effectively improves transmission data rate and expands network coverage region.It also has great advantages such as the increasing of network throughput,the extending network life cycle and the reduction of construction costs.In addition,with the increasing of node density and network coverage,cooperative communication puts forward higher requirements to energy-efficiency.Hence,green cooperative transmission technology has become one of research hotspots in future cooperative communications.Efficient green cooperative transmission techniques in wireless sensor networks(WSN)are investigated in this dissertation.Cooperation efficiency enhancement schemes and the reduction of energy consumption in transmission process are emphasized.The purpose of this research is to explore cooperative relay technology into the application of WSN,and provide the theoretical support to the key issues such as best relay selection,outage probability analysis and energy-efficiency analysis.Specific research works are provided as below.The research background and research significance are introduced in Chapter 1.In this chapter,the structure and advantages of different relay system in cooperative communications are briefly introduced.In addition,the concept of green cooperative transmission technology,the research status of energy-efficiency in wireless network and the tradeoff between energy-efficiency and transmission reliability are introduced in this chapter.On this basis of it,this chapter illustrates the current research status of buffer-aided relaying in cooperative transmission.Energy-efficiency optimization approach for cooperative transmission in WSN is introduced in Chapter 2.The cooperative transmission model based on energy-efficiency is considered in this chapter.The relationship between energy-efficient cooperative transmission and the related factors are provided,such as transmission packet size,cooperative relays,data modulation parameters in broadcasting and forwarding phases as well as broadcasting distance between source and cooperative cluster.A cooperative transmission scheme based on the minimization of effective data transmission energy consumption per bit is proposed.Numerical results indicate that,when the total transmission distance is determined,WSN energy-efficient cooperative transmission performance can be effectively enhanced through the optimal deployment of transmission packet size and cooperative nodes.Energy-efficient buffer-aided optimal relay selection scheme with power adaptation and inter-relay interference(IRI)cancellation is investigated in Chapter 3.Considering the tradeoff between energy consumption and outage behavior in buffer-aided relay selection,the scheme regards the minimization of energy consumption as its objective,with the consideration of relay buffer state,outage probability and relay power control,in order to eliminate IRI.In the proposed scheme,source-relay and relay-destination communications can be performed within a time-slot,which mimics full-duplex(FD)relaying.The Markov chain model is implemented to analyze the evolution of relay buffer states.System steady state outage probability and achievable diversity order are derived respectively.In addition,average packet transmission delay at source and optimal relays and power reduction of the proposed scheme are also investigated.Numerical results show that the proposed scheme outperforms other relay selection schemes in terms of outage behavior with power adaptation and IRI cancellation in the same relay number and buffer size scenario.System packet latency performance and average transmit power reduction performance can be improved significantly in the same relay number scenario,which realizes the tradeoff between energy-efficiency,outage behavior and latency performance in green cooperative communications.Energy-efficient buffer-aided relaying cross-layer cooperation scheme based on queuing model is studied in the Chapter 4.This scheme considers the case that there exists a direct link between source and destination.M/M/K queuing model is implemented to analyze the steady state of buffer-aided relaying in cooperative communications.At the same time,in the case of WSN node energy constraint,the effect of source-destination channel gain to system throughput,statistical latency performance and system packet loss performance are investigated.Numerical results indicate that,the proposed scheme can effectively enhance system throughput performance and decrease system packet loss rate.In addition,the proposed scheme can effectively reduce the average transmission power,thus it effectively extends WSN network life cycle.Finally,conclusions and further work prospects are given in Chapter 5.This dissertation initially studies and explores energy-efficiency based green cooperative transmission schemes.Research achievements provide significant values for the further related works.