This paper considers queueing models for cognitive radio networks that account for the sensing time of secondary users (SUs). In cognitive radio networks, secondary users are allowed to opportunistically use idle channels originally allocated to primary users (PUs). To this end, SUs must sense the state of the channels before transmission. After sensing, if an idle channel is available, the SU can start transmission immediately; otherwise, the SU must carry out another channel sensing. In this paper, we study two retrial queueing models with an unlimited number of sensing SUs, where PUs have preemptive priority over SUs. The two models differ in whether or not an arriving PU can interrupt a SU transmission also in case there are still idle channels available. We show that both models have the same stability condition and that the model without interruptions in case of available idle channels has a slightly lower number of sensing SUs than the model with interruptions.

本文考虑了认知无线电网络的排队模型，该模型考虑了辅助用户（SU）的感知时间。在认知无线电网络中，允许次要用户机会性地使用最初分配给主要用户（PU）的空闲信道。为此，SU必须在传输之前检测通道的状态。感知到空闲信道可用后，SU可以立即开始传输。否则，SU必须执行另一次信道感测。在本文中，我们研究了具有无限数量的感应SU的两个重试排队模型，其中PU具有优先于SU的优先级。两种模型的不同之处在于，即使在仍有空闲信道可用的情况下，到达的PU是否也可以中断SU传输。