合作通信(又称合作分集)技术是一种新的空间分集技术。该技术通过用户之间共享天线构成虚拟天线阵列。对比于传统的多天线系统(MIMO),并不要求用户终端配备多根天线,大大降低了用户终端的设计复杂度和成本。合作通信协议的设计一直是该领域的热点问题,本文重点讨论合作用户的选择方案。首先简要介绍两种常见的合作用户选择方案:对称和非对称合作方案。其次,从中断概率、SNR增益、分集和复用折中、位置偏差影响等多方面对这两种合作用户选择方案进行了详细的分析和比较。最后根据分析和比较的结果,讨论这两种方案各自的应用场合。 Cooperative communications (also known as cooperative diversity) technology is a new space diversity technology. This technology constitutes a virtual antenna array by sharing antennas between users. Compared with the traditional multi-antenna system (MIMO), the user terminal is not required to be equipped with multiple antennas, which greatly reduces the design complexity and cost of the user terminal. The design of cooperative communication protocol has always been a hot issue in this field. This article focuses on the options of cooperative users. First, we briefly introduce two common collaborative user options: Symmetric and asymmetric cooperation. Secondly, we analyze and compare the two cooperative user selection schemes in detail from many aspects, such as interrupt probability, SNR gain, diversity and multiplicative compromise, and position error impact. Finally, based on the results of analysis and comparison, we discuss the respective applications of these two solutions.