中继未知任何信道信息条件下中继选择的研究

由于信道情况差的中继对协作贡献小，且消耗额外的能量，基于某种标准选择出一个或者多个好的中继参加协作，可以提高协同通信系统性能，所以中继选择是协同通信系统的研究热点。针对一个发送端、接收端及每个中继都配置单根天线的无线中继网络，在假设发送方不知道信道信息而接收方已知全部信道信息前提下，本文提出了中继未知任何信道信息时的中继选择方案。首先提出基于信噪比最大的单中继选择方案，推导了单中继选择的成对错误概率表达式；其次提出基于中继排序方法的多中继选择方案，推导了选择2个中继的成对错误概率的下界；最后给出了仿真结果。理论与仿真结果都表明，中继未知任何信道信息的情况下，选择2个中继参加协作的系统错误概率却高于单中继选择。 

Relay Selection Schemes and Their Performance Analysis in Wireless Relay Networks

Those relays in deep fading are actually not helpful in the cooperation, and indeed they consume extra energy. Selecting one or multiple relays to forward signals based on a certain criteria can improve performance of a cooperative communication system. Therefore, relay selection in the cooperative communication system has gain increasing attention. In this paper, assume that a transmitter has no channel information and a receiver has complete information of channels in a wireless relay network with a single antenna in the transmitter, in the receiver, in the relays, respectively. Under an assumption that each relay has no any channel information, a single relay selection scheme which can maximize the signal-to-noise ratio and a multiple relay selection scheme based on relay ordering method are proposed in this paper. Furthermore, the pair-wise error probabilities of single relay selection and multiple relay selection when two relays are selected for relaying are calculated respectively. Then, the simulation results are given. Both the theory and the simulation results show that the error probability of selecting two relays is higher than one of the single relay selection.