Multiuser Sensing for Opportunistic Spectrum Access in Cognitive Radio Networks

Sensing is the important task for cognitive radio (CR) users to confirm that the existing spectrum is unoccupied by primary users (PUs). CR users perform spectrum
sensing and detect primary users (PUs) signal even when they are transmitting data packet. During this sensing period, secondary users (SUs) are seeking spectrum availability, and access them when it is unoccupied by PUs. In this paper, we investigate multiple CR users with limited sensing capability seeking the spectrum opportunity with the interference constraint to PU. We implement Partially Observable Markov Decision Process (POMDP)framework, in which spectrum opportunities follow Markov Discrete Process (MDP). In this scenario, multiple CR users compete to sense spectrum opportunities and exploit multiuser diversity to allocate spectrum opportunities among CR user. If SUs have packet to send, they will select the channel to sense according to the Greedy approach, else SUs will not participate on channel sensing and turn to sleep mode. Random algorithm where multiple CR user randomly sense channel is used as comparison. Packet arrival rate is considered as well to observe the throughput performance as function of user number. Numerical results show that Greedy sensing outperforms random sensing strategy. Subsequently, number of user and packet arrival rate can affect the throughput performance
of SUs as well.