Power allocation under service-outage constraints for spectrum-sharing cognitive radio networks

A power allocation strategy is proposed for spectrum-sharing channels, in which two users share the spectrum band with one of them having a primary access to the band. The secondary user can utilize the spectrum as long as it complies with the service requirements of the primary user. Specifically, the latter allows the former to utilize the channel as long as its rate degradation as a results of the secondary user transmission is limited to a certain threshold with a predefined probability. The secondary and primary users employ truncated channel inversion with fixed rate (TIFR) transmission policy. We obtain the power allocation and capacity of the secondary user's link under joint secondary transmit power constraint and service-outage constraint imposed by the primary user. Numerical simulations are conducted to corroborate our theoretical results.