earticle

영어

In a cognitive radio network (CRN), a preempted secondary user (SU) is placed in a call level queue to wait for accessing another free channel. If the availability of channels is transparent to SUs, packets will be generated during their waiting time and the performance of the CRN will be influenced by which way to handle these packets. This paper mainly analyzes the performance of a CRN adopting discarding or buffering policy, Here, an analytical model is developed to derive the formulas for both call level performance measures (i.e., call blocking probability) and packet level performance measures (i.e., packet delay, packet loss ratio and throughput) for SUs. Numerical results show that theoretical models are consistent with simulation results. The major observations include (i) the performances of a CRN degrade as the primary user (PU) or SU call arrival rate increases. (ii) Under discarding policy, the call blocking probability and packet delay are smaller than adopting buffering policy, while the packet delay and throughput are greater. (iii) Adopting different policies cause a smaller effect on call blocking probability and throughput than on packet loss ratio and packet delay.