Power Control of Spectrum-Sharing in Fading Environment With Partial Channel State Information

This paper addresses the spectrum-sharing for wireless communication where a cognitive or secondary user shares a spectrum with an existing primary user (and interferes with it). We propose two lower bounds, for the primary user mean rate, depending on the channel state information available for the secondary-user power control and the type of constraint for spectrum access. Several power control policies are investigated and the achieved primary-user mean rates are compared with these lower bounds. Specially, assuming all pairs of transmitter-receiver are achieving real-time delay-sensitive applications, we propose a novel secondary-user power control policy to ensure for both users, at a given occurrence, predefined minimum instantaneous rates. This power control uses only the secondary-user direct links gains estimations (secondary-to-secondary link and secondary-to-primary link).