三个主用户信道，到达率λ1，服务率μ1。全被主用户占满时，再有主用户进入会形成阻塞block1；三个次级用户信道，到达率λ2，服务率μ2。全被次级用户占满时，再有次级用户进入会形成阻塞block2；主用户拥有优先权，但只能使用自己的信道；次级用户在感知主用户信道空闲时，可以占用。但有主用户进入时必须让出，导致掉线drop。-Three primary user channel, the arrival rate λ1, service rate μ1. When all were filled primary user, and the user enters the Lord will create blockages block1　three secondary user channel, the arrival rate λ2, service rate μ2. When all were filled secondary user, then the user has to enter a secondary form blocking block2　primary user has priority, but only uses its own channel　a secondary user detects that the primary user channel is idle, can occupy. But the primary user must be allowed to enter the time, resulting in dropped calls drop.