中文摘要：

研究了基于放大转发（AF）的协作传输系统的中断概率性能。考虑了源节点到目的节点的直通链路，建立了适用于中继随机分布的非对称和对称信道下协作传输系统的数学模型，给出了协作传输系统节点信道和位置多种状况下接收端的瞬时信噪比的概率密度函数表达式，针对不同的状况给出了系统中断概率的精确表达式，并对于各中继信道具有不同信道状态参数的情形，提出了系统中断概率的一种近似表达式。

英文摘要：

The paper investigated the outage probability of cooperative communication systems with amplify-and-forward （AF） relays. Firstly, the mathematical model of all the relay nodes randomly distributed within a certain region was presented with both asymmetric and symmetry channels being considered, and the probability density function expression of instantaneous receiver SNR was derived by using the method of moment generating function （MGF）. Secondly, based on the mathematical model, an exact outage probability formulation was derived for a multi-cluster head AF cooperative communications system under different channels conditions. Finally, an approximate outage probability formula was derived based on the conditions that all the relay channels have different state parameters.