Grid based cooperative spectrum sensing in cognitive networks under correlated shadowing

Correlated shadowing can have significant effects on the performance of cooperative spectrum sensing. In this paper, we investigate a grid based cooperative spectrum sensing in cognitive networks under correlated shadowing. We study three types of grids: equilateral triangular, square and hexagonal grids, where the sensing users are deployed at the intersections of the polygons. The collaboration is formed as a location testing problem with Gaussian noise, where the shadow fading is modeled as a multivariate Gaussian process with two dimensional exponential correlation model. We have evaluated the results regards to the number of collaborating users combined with the separation distance of two adjacent users. It is found that the three layouts yield the same detection performance as that of experiencing independent shadowing when the separation distance exceeds approximately 6 times the decorrelation distance in urban areas.