提出了一种基于主用户最佳中继选择的两阶段式协作传输协议.认知网络中包含1对主用户和K对二级用户,K对二级用户之间相互竞争主用户所拥有的频谱资源,在满足二级用户服务质量条件下,主用户选取1个二级发射作为其中继来转发信号.中继选择准则是使主用户获得最大的信号与干扰和噪声比.充当中继的二级发射在辅助译码转发主用户信号的同时,也给相应的二级接收传送所需信号.理论分析了主用户的中断性能,仿真结果验证了所提出的协作传输协议的有效性,即该传输策略在提高主用户服务质量的同时,也为二级用户提供使用授权频谱的机会.此外,也说明了随着二级用户个数的增加,主用户的中断性能有所提升. This paper proposes a two-phase cooperative transmission protocol based on the best user choice of the primary user.The cognitive network contains one pair of primary users and two K users, and the K pairs of secondary users compete with one another Spectrum resources, to meet the second-level user service quality conditions, the main user to select a second-level transmission as its relay to forward the signal. The relay selection criteria is to enable the main user access to the largest signal to interference and noise ratio. The secondary transmitter also transmits the required signals to the corresponding secondary transmitters while aiding the decoding of the primary user signals and the theoretical analysis of the interrupt performance of the primary user. The simulation results verify the validity of the proposed cooperative transmission protocol, that is, This transport strategy not only improves the quality of primary user’s service, but also provides secondary users with the opportunity to use the licensed spectrum.In addition, it also shows that as the number of secondary users increases, the interruption performance of the primary user is improved.