Abstract: In view of Amplify-and-Forward（AF） protocol in relaying communication, a dual-hop cognitive cooperative communication system is proposed based on best relay selection strategy. The spectrum sharing environment consists of one Secondary User（SU） source, K（SU）relays, one（SU） destination and one Primary User（PU） receiver. Also, the outage performance of the cognitive cooperative communication system is analysed over non-identical Rayleigh fading channels and an exact closed-form expression for the outage probability is derived at the same time. Finally, the correctness of the proposed analysis is corroborated via Monte Carlo simulations. The theoretical analysis and simulation results show that the proposed analytical method reduces the outage probability and improves the ergodic capacity. Thus the performance of the system is effectively improved.

Key words: cognitive cooperative communication, amplify-and-forward, relay selection, outage probability, Raleigh fading

摘要： 针对中继通信中的放大转发协议，提出了一个基于最佳中继选择方案的双跳认知协作通信系统。该系统的频谱共享环境由一个主接收用户，一个次级信源，[K]个次级中继和一个次级信宿组成。并在独立非同一分布的瑞利衰落环境下对该认知协作通信系统的中断性能进行了分析，推导出了中断概率的准确闭合表达式。利用蒙特卡罗仿真实验证实了分析结果的正确性。理论分析和仿真结果都表明，分析所运用的方法降低了系统的中断概率，提高了遍历容量，从而有效地改善了系统的性能。

关键词: 认知协作通信, 放大转发, 中继选择, 中断概率, 瑞利衰落