Patent ID: 8908543

Claim:
A method of operating a User Terminal (UT) in a Cognitive Radio (CR) wireless communication system, the method comprising: determining whether a signal of a licensed system is detected in at least one frequency band used by the CR wireless communication system, wherein the licensed system is a system that has priority of the at least one frequency band; when the signal of the licensed system is detected, determining, by a controller, a per-subcarrier Transmit (Tx) power according to a water filling mechanism in such a manner that a sum rate is maximized without exceeding a current maximum Tx power; upon receiving a binary message requesting to regulate the maximum Tx power from a Base Station (BS), determining, by the controller, a Penalty Factor (PF) based on at least one of the current maximum Tx power, the per-subcarrier Tx power, a per-subcarrier data rate, a minimum required data rate, and a threshold coefficient for a maximum allowed data rate; and regulating a new maximum Tx power by multiplying the PF by the current maximum Tx power.