Enhanced Multiband Multiuser Cooperative Spectrum Sensing for Distributed CRNs

Multi-band cooperative spectrum sensing (CSS) can provide opportunistic spectrum access to secondary users (SUs) in cognitive radio networks (CRNs). In multi-band CSS, the sensing task is divided among SUs based on their capability, residual energy, channel conditions, etc. However, SUs' scheduling to sense a subset of channels in distributed CRNs is challenging mainly because of the lack of a central entity and the changing conditions due to new SUs entering the network. To address these challenges, we propose a two-stage multi-band multi-user CSS (M2CSS) scheme to assign a subset of channels to SUs for spectrum sensing. We first formulate an optimization problem to choose a leader for each channel. We then formulate an optimization problem to select cooperative SUs for each channel such that SUs with similar sensing information for the same channel are not selected. Further, we propose an enhanced M2CSS (EM2CSS) scheme to allow new SUs to participate in the sensing process. We formulate an optimization problem to assign multiple channels to joining SUs. We then distribute the sensing assignments among existing and joining SUs to minimize sensing energy consumption. Extensive simulation results show the efficacy of the proposed schemes when compared to existing schemes.