Improved Idle Channel Utilization in Distributed Multi-Channel Cognitive Radio Systems

In the absence of a control channel, the idle channel utilization (ICU) is dictated by both the spectrum sensing strategy and the packet access protocol in a distributed cognitive radio (CR) network. In this paper, we investigate a distributed multi-channel random access CR network under imperfect spectrum sensing, where each secondary user (SU) randomly selects a fixed number of channels for sensing and transmits on arbitrary detected idle channels. Based on this model, we first develop a slotted opportunistic access aloha protocol for multiuser random access. Then, the distribution of the successful packet transmissions is derived, according to which we obtain the expression of the average ICU. Finally, the analytical results are validated by substantial simulations. We show that their impacts on ICU by adjusting the number of the sensed channels and packet transmission probability, along with the distance from SUs to primary users.