On the Capacity of Underlay Cognitive Radio Networks Over Shadowed Multipath Fading Channels

Cognitive radio is of great interest for current and future wireless communications. In this paper, the capacity of underlay cognitive radio networks is studied where closed-form expressions for both the ergodic capacity and the outage capacity of the secondary user (SU) are derived. The obtained results reveal new details on the joint effect of multipath fading and shadowing on the capacity of the SU where the increase of the ergodic capacity and degradation of the outage capacity due to heavy shadowing are demonstrated and quantified. Furthermore, the analytical results are verified by Monte-Carlo simulations for different fading scenarios.