A communication failure and repair mechanism with adjustable transmission rates for PU packets in CRNs

As one key technology of future radio communication networks, cognitive radio networks (CRNs) can effectively handle the shortage of network resources. Two classes of users exist in traditional CRNs, namely, primary users (PUs) with higher priority and secondary users (SUs) with cognitive ability. In CRNs, during the communication process, packets need to travel through various servers, such as switches and routers, and these devices may fail at any time. We consider this type of problem to be a communication failure. The occurrence of communication failures trigger system repairs, which make the system return to regular work. In this paper, we present a communication failure and repair mechanism with adjustable transmission rates for PU packets in CRNs. We assume that PU packets can maintain low-speed transmission during the system failure state and resume high-speed transmission after the failure is repaired. We establish a three-dimensional Markov chain (3DMC) and build a queueing model based on discrete time. Through numerical experiments, we analyze some indicators' impact on the system capability. In addition, compared with the traditional communication failure and repair mechanism, our proposed mechanism can reduce the blocking rate while considerably increasing the throughput of data packets.