Joint Temporal and Spatial Spectrum Sharing in Cognitive Radio Networks: A Region-based Approach with Cooperative Spectrum Sensing

Efficient spectrum utilization is of great importance in cognitive networks, however current spectrum sharing techniques in the temporal or spatial domains all have deficiencies. In this paper, we propose a joint spatial and temporal spectrum sharing scheme based on the concept of regions. We define four regions, namely a primary exclusive region (PER), a temporal spectrum sharing region (T-SSR), a joint spectrum sharing region (J-SSR), and a spatial spectrum sharing region (S-SSR). T-SSR and J-SSR are proposed to utilize temporal spectrum holes which have not previously been exploited. Cooperative spectrum sensing is employed to expand the J-SSR, which is beneficial for system design. Closed-form bounds for the four regions are obtained, and conditions on T-SSR existence and the presence of a transition zone between the JSSR and S-SSR are determined. Both analytical and simulation results are presented which show how the key factors, including primary user interference constraints, spectrum sensing factors, and secondary user coverage constraints, influence these bounds. This has great practical value in improving spectrum efficiency in cognitive networks.