Analysis of spectrum utilization of cognitive radio networks in Nakagami fading channels

This paper addresses the spectrum utilization due to cognitive radio (CR) access in terms of the secondary users' network capacity in Nakagami fading channels. A new mathematical model is developed for the secondary network capacity when both accessing and sensing channels undergo Nakagami-m fading with none-integer fading parameters. Exact and approximate analytical expressions for the capacity are derived. Some simplified special cases are also investigated such as the integer-fading parameter. The numerical evaluation of channel capacity is presented for different channel sensing and accessing methods under different fading scenarios. The effects of detection and accessing channels' parameters on the capacity are also explored. It is found that a good sensing system with high secondary user signal-to-noise ratio, accessing the licensed band maximizes the spectrum utilization. To maximize the spectrum utilization a proper sensing scheme is required given that an acceptable QoS of primary users is maintained.