Optimal Guard Distance for Maximizing Spatial-Temporal Spectrum Access Opportunity in Mobile CRNs

Cognitive radios have demonstrated its ability in improving spectrum efficiency. Along with the popularity of mobile broadband devices in future mobile communications, research for cognitive radios with mobility will be paid more and more attentions. In a mobile cognitive radio network, we derived the analytical expression for the dynamic spectrum access opportunity of secondary users in spatial and temporal dimensions. Through maximizing the spatial-temporal opportunity, we obtained the closed-form solution of the optimal guard distance, which is a key part of primary protection region against the mobile secondary users’ interference. Numerical results verified the accuracy and correctness of our theoretical analysis, and indicated that using our solution the secondary user has more spatial-temporal opportunity than the existing research result.