译码转发系统中一种半分布式用户选择策略

Semi-Distributed User Selection Scheme in Decode-and-Forward Systems

针对译码转发系统中传统的用户选择策略复杂度过高的问题,提出一种半分布式用户选择策略(SDUS策略).该策略以最大化系统瞬时互信息量为目标,引入中继选择的判决门限,并根据此门限生成协作集,目的节点从协作集及源节点(当协作集为空集时)中选择信道质量最好的用户作为协作节点.SDUS策略不仅能够显著降低系统的运算复杂度,还能够改善系统的中断性能.仿真实验表明,当信噪比为20 dB且系统中的中继节点数为120时,SDUS策略的运算开销仅约为机会中继策略和选择协作策略的39.5%和51.1%.

A semi-distributed user selection scheme （SDUS scheme） is proposed to reduce the high complexity in conventional user selection schemes in decode-and-forward （DF） systems. A decision threshold for relay selection is introduced to maximize the instantaneous mutual information of the system. Based on the threshold, the cooperative set is generated. The destination node selects the node with the best channel quality from the cooperative set and the source （when the cooperative set is null） as the cooperative node. The SDUS scheme not only reduces the computa- tional complexity of the system significantly, but also improves the outage performance. Simulation results show that, when the signal-to-noise ratio is 20 dB and the number of relay nodes is 120, the computational cost of the SDUS scheme is just about 39.5% and 51.1% of those of the opportunistic relaying scheme and the selection cooperation scheme, respectively.