Interweave Cognitive Networks with Co-Operative Sensing

This paper investigates the effects of different cooperative sensing strategies on erroneous spectrum sensing for an interweave cognitive radio network. The setup is as follows. Primary receiver nodes and secondary nodes are randomly distributed in R². We model them as two independent homogeneous Poisson point processes. Beacon (out-of-band) signals, periodically transmitted by primary receivers, indicate to the secondary nodes that spectrum is occupied. Whenever beacon detection fails, the transmissions of secondary nodes generate harmful interference. Thus, to alleviate this issue, the misdetection probability of secondary nodes must be reduced. To this end, we propose two strategies: 1) a secondary node cooperates with its closest neighbour, and 2) a secondary node cooperates with M random neighbours within a given radius. Furthermore, along with these co-operation strategies, we investigate three primary beacon detection methods for secondary nodes: 1) separately decoding each primary beacon, 2) detecting only the closest primary receiver?s beacon, and 3) detecting the aggregate beacon signal from all primary receivers. For the exponential path loss and Rayleigh fading considered, we derive the total misdetection probability for each scheme along with the resulting outage probability of a primary receiver. We finally show through numerical results that M co-operation works better for lower reception thresholds, and that for a reception threshold of -120 dBm, a 10⁴ fold decrease in the misdetection probability is achievable.