Research On Relay Selection Of Wireless Cooperative Communication

With the rapid development of wireless communication technology in the past twodecades, the requirements for transfer rate and quality of communication are also rising,however, multipath effects has restricted the development of communication technology.MIMO technology can effectively suppress the multipath fading to improve the capacityof the communication system. The characteristics of wireless network mobile terminalwhich is small size and power constant limit the application of MIMO technique. Eachother of the single antenna can be shared between multiple users in wireless network inorder to achieve a virtual MIMO system, which constitute a cooperative communicationsystem. Cooperative communication technologies can improve the performance ofcommunication systems by using some means, such as reducing the outage probability,increasing system capacity, increasing the data transfer rate of the system, increasing thequality of service and so on. Cooperative communication technology is the current focus.First, the thesis introduces the diversity techniques, at the same time expounds andcompares the classification and receives merging technique. The key points are MIMOtechnology of spatial diversity and cooperative diversity technology.Secondly, this paper discuses the existing the relay select strategies of cooperativecommunication technology, summarize their advantages and disadvantages. Then basedon the opportunistic relaying propose a suboptimal relay selection algorithm. In thisalgorithm not all relay nodes keep listening mode, and don’t need estimate the link of allrelay to keep the same performance.Finally, this paper discusses the relay transmission scheme, first takes consider ofthe fixed coordination strategy, adaptive coordination strategy and other aspects ofcooperation strategy, analyzes the advantages and disadvantages of these strategies. Thispaper propose a dynamic amplify decode forwarding (DADF) scheme based on theamplify and forward (AF) or decode and forward (DF). Under the binary-input additivewhite Gaussian noise channel, each relay is decided to use either AF or decode andforward DF according to the instantaneous signal to noise ratio conditions between the source and the relay. This scheme taking advantages of AF and DF protocols. Numericalresults of the channel capacity and the bit error rate indicate that this strategy notablyimproves system performance.