The Research Of Optimal Relay Selection Algorithm For Full Rate Two-path Cooperative Communication Network

With people’s increasing diverse needs on wireless multimedia, the next generation of wireless communication networks’ development must in the trend of more reliable information transfer performance and higher information transfer rate. Therefore, in the face of increasingly tense status of spectrum resource, without sacrificing the extra bandwidth of multiple antenna system becomes one of research hotspots of many scholars. However, volume, energy restriction and other physical conditions of the mobile user terminal has greatly restricted the full application of multiple antenna system.In order to overcome these shortcomings, the cooperative wireless communications system came into being as a multiple antenna technology development.Cooperative wireless communications system takes advantage of multiple single-antenna nodes’ mutual cooperation in the wireless network to form a virtual antenna array, so that it can obtain the cooperative diversity, effectively resist the channel fading, improve the overall link reliability and effectively increase the system throughput. However, there are multiple potential partner nodes exist in the system, choosing one node or nodes’ collection to cooperative forwarding, or dose it need to cooperate when the direct link have good performance from source to destination, or after fixing the node, what kind of ways we should choose to deal with the message that from the source at the relay side, all these problems are related to the whole communication system transmission performance.This thesis made a detailed comparison among amplify-and-forward scheme, decode-and-forward scheme and coded cooperation; analyzed cooperative diversity technology and relay selection technology; and then discussed the opportunistic relay selection algorithm which based on instantaneous channel information and an improved opportunistic relay selection algorithm with a confirmation and backoff mechanism. Secondly, it describes a full-rate wireless cooperative relay transmission scheme. Through the combination of linear complex pre-coding technique and cyclic delay diversity technique, the simulation shows that the scheme can not only obtain the full diversity gain and improve cooperative transmission process of channel’s fading resistance ability, but also obviously reduce the detection complexity. Finally, this thesis proposed an optimal relay selection algorithm for full rate two-path wireless cooperative communication system. Through the combination of above full-rate wireless cooperative relay transmission scheme, by appropriate improvement, this thesis based on the lowest symbol error rate and backoff mechanism to achieve optimal double relay selection simultaneously in this transmission scheme. The simulation result shows that the error performance can be improved effectively by using the selected double nodes in the system, which can realize symbol error rate minimum.