A cooperative spectrum sensing scheme based on task assignment algorithm for cognitive radio networks

In cognitive radio networks, dynamic spectrum access allows an unlicensed (secondary) user to use the frequency bands that are statically allocated to licensed (primary) users under condition of causing no harm to the primary transmission. For the process of the dynamic spectrum access to succeed, spectrum sensing becomes of great importance for the secondary user (SU) to capture the under-utilized frequency bands. This process must be as fast as possible to enable efficient spectrum utilization by the SU. In order to decrease the sensing time especially for wide band spectrum while keeping acceptable sensing accuracy, it is recommended to distribute this sensing task across the SUs in a way that leads to reduction of the probability of misdetection and the probability of false alarm. This work presents a channel assignment scheme for cooperative spectrum sensing in cognitive radio networks. Based on the individual - statistically calculated- probability of error of each SU over all channels, the algorithm assigns the best k adjacent channels for each SU to decrease the probability of misdetection and the probability of false alarm. It is shown by MATLAB simulations that the presented scheme is able to reach acceptable sensing probability of error in terms of reduced sensing delay when compared to full spectrum sensing where all nodes cooperate to sense all channels (no assignment takes place). Additionally, It is shown that the overall energy consumption of the cognitive radio network is reduced resulting in better network lifetime.