... 1/μp,which is the same as the PU’s service time. Therefore, the total rate of a PU leaving the system only dependson Np(t). This implies that the number of PUs in the system is independent of the SUs’ ... Np(t)=iis the number of PUs in the system,Ns(t)=jis the number of SUs in the system, Ns(t)=k is the number of SUs in service. Here, we use (i, j, k)asthenotationofastate in the model.2.1 ... Pnonprei,j,k. The mean waiting time of PU refers to the averageextra time that the PU spends on waiting d ue to the introduction of the NP mechanism in the CRN.4. Simulation results and discussionIn the...