A more practical spectrum sensing technique in cognitive radio networks

Conventional spectrum sensing techniques using multiple antennas has two weak points to develop further in practice. The first point is the requirement of channel state information (CSI) to combine signal from each antenna. The second point is the assumption of exact values of the signal and noise variance to perform spectrum sensing. In practice, it is not easy and requires time to obtain CSI due to the low level of the primary user signal. In addition, the exact values of the signal and noise variance are also impractical to know. In this paper, we develop a spectrum sensing technique which does not require CSI as well as exact information of the signal and noise variance. The primary user signal and noise are assumed as independent and identical distribution, complex Gaussian random variable. The performance of the proposed system is compared to one method without requiring CSI that had been developed and one traditional method using Equal Gain Combining (EGC) scheme. Index terms: spectrum sensing, multiple antennas, energy detector, cognitive radio, diversity combining schemes.