On the periodic scheduling of spectrum sensing for cognitive radio

OFDM-based cognitive radio (CR) can use a set of channels in the spectrum pool and catch the appeared spectrum opportunity on each channel. Not only the performance of the spectrum sensing algorithm, but also the length of the sensing period can affect how much the spectrum opportunity can be utilized by the CR. In order to achieve the maximum efiiciency of spectrum opportunity utilization, a nonlinear optimization problem on the determination of sensing period is formulated with the constraint of the interference with the licensed users. As far as the spectrum sensing performance of the CR is concerned, the time length of sensing determines the receiver operation character (ROC) of the spectrum sensor, and it plays a key part in the optimization of sensing period. The optimization problem is solved with the help of the penalty method. Analysis suggests that with the optimum sensing period calculated by the proposed method, the CR can guarantee the limited interference with the primary user, and achieve higher efiiciency of spectrum opportunity utilization under the condition of better ROC at the same time.