Abstract
In this paper, a recently proposed sensing scheme for cognitive radio systems based on an estimate of the differential entropy is extended to achieve reliable sensing performance in the presence of severe fading by cooperation among J active receivers. The cooperating users being equipped with multiple antennas send their individual sensing decisions to a fusion center which in turn applies different combining techniques for the final joint decision. To assess the performance of the proposed algorithm, we consider a wireless channel with Nakagami-m fading. It turns out that the extended sensing approach leads to a substantial improvement as compared to the non-cooperative case in corresponding fading channels. The performance of the proposed algorithm is studied for different fading levels and the kth nearest neighbor differential entropy estimator in combination with maximum-ratio combining is identified as a scheme which shows a good error performance and can be applied in a variety of fading characteristics.