A spectrum reuse scheme based on region division for secondary users in cognitive radio networks

This paper analyzes a spectrum reuse scheme based on region division for secondary users in cognitive radio networks with outage constraint of the primary user. The secondary users can reuse the spectrum by sharing the primary user´s uplink (UL) frequency resources in the system. With the help of the stochastic geometry, the secondary user reusing the frequency spectrum can be modeled as the probability that the SINR of the primary user is below an appropriate threshold. In order to solve the constraint of the probability which appears as a transcendental equation, Lambert W function is introduced and the closed-form solution of the region division in the whole cell is obtained when the primary user location is determined. In the simulation, the relationships between system capacity and key parameters including the primary user location, the density and output power of secondary user are analyzed in detail. The results prove the effectiveness of the proposed frequency reuse scheme of the secondary users.