Abstract: This paper investigates the outage probability for Amplify-and-Forward（AF） and Decode-and-Forward（DF） in single relay system in detail. The frequency selective Rayleigh fading channel and Nakagami-m channel are studied, respectively. The Probability Density Function（PDF） and Cumulative Distribution Function（CDF） of signal to noise ratio are solved in relay system. According to the CDF, the closed form solution under the giving data rate acquirement can be obtained. The simulation results show that the theoretical results are tight approximate the simulation results, and demonstrate the procession of the analysis.

Key words: outage probability, decode-and-forward, amplify-and-forward, Rayleigh channel, Nakagami-m channel

摘要： 针对无线通信系统的两种典型信道—频率选择性的多径Rayleigh衰落信道和Nakagami-m信道，中继方式为解码-转发（DF）和放大-转发（AF）的单中继系统的中断概率问题进行详细且深入的研究。分别计算AF方式和DF方式中继系统信噪比的概率密度函数（PDF）和累积分布函数（CDF），利用CDF可得在给定的系统数据速率要求的前提下相应的中断概率的闭式解。对该中继系统的中断概率模型进行仿真。仿真分析显示，闭合表达式与数值仿真结果吻合良好。

关键词: 中断概率, 解码-转发, 放大-转发, 瑞利信道, 纳卡伽米信道