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.