User Selection for Cooperative Spectrum Sensing in Mobile Heterogeneous Cognitive Radios

Cooperative spectrum sensing is a key technique for cognitive radio networks, in which cooperative user selection is vital to reduce overhead and ensure high detection performance. In this paper we proposed a hybrid user selection scheme, which takes into consideration of user mobility and heterogeneity. Mobility, which increases the spatial diversity, affects the user stability and correlation. The characteristics which users with different number of antennas reflect is called heterogeneity. Heterogeneity affects the user's detection capability. The scheme ensures the optimal users to provide a high cooperative spectrum sensing performance based on the user's own constraint in mobile heterogeneous cognitive radio. The simulation and analysis results show that the user selection is tradeoff between diversity gain and sensing reliability. Spatial diversity improves the spectrum sensing performance under sensing reliability, while mobility degrades the detection performance when the users step out of the primary protected region (PPR). If the users are always inside the PPR, we select the users whose characteristics are as follows: their speeds are as fast as possible, correlation among them is as small as possible, and their detection capability is as great as possible. Therefore, the proposed scheme is suitable both in the static and mobile cognitive radios.