An energy detection based signal detection method with multiple antennas in cognitive radio

In Cognitive Radio systems, the performance of spectrum sensing will directly affect spectrum reallocation. Energy detection (ED) method is one of the most commonly used signal sensing methods in spectrum sensing, due to its low implementation complexity. ED can achieve a good detection performance when the noise variance is known. However in most cases, the noise variance is estimated. To reduce the impact of uncertainty in noise variance, an ED based signal detection method is proposed in this paper. This method exploits multiple antennas in a simple way to obtain the decision statistic as ED does. A technique is proposed to construct the decision statistic so that it is independent of the noise variance. As a consequence, the proposed method can significantly reduce the effect of noise variance uncertainty. Theoretical formulas are derived to describe the probability of detection and the probability of false alarm, which are free of noise variance uncertainty. The simulation results show that the detection performance of the proposed method can outperform the existing ED detection methods when the number of antenna is greater than four.