Another Look in the Analysis of Cooperative Spectrum Sensing over Nakagami- $m$ Fading Channels

Modeling and analysis of cooperative spectrum sensing is an important aspect in cognitive radio systems. In this paper, the problem of energy detection (ED) of an unknown signal over Nakagami-m fading is revisited. Specifically, an analytical expression for the local probability of detection is derived, while using the approach of ED at the individual secondary user (SU), a new fusion rule, based on the likelihood ratio test, is presented. The channels between the primary user to the SUs and from the SUs to the fusion center are considered to be independent Nakagami-m. The proposed fusion rule uses the channel statistics, instead of the instantaneous channel state information. Closedform solutions for the system-level probability of detection and probability of false alarm are also derived. The usefulness of factor graph and sum-product algorithm models for computing likelihoods is discussed to highlight its advantage, in terms of computational cost. The performance of the proposed schemes has been evaluated both by analysis and simulations. The results show that the proposed rules perform well over a wide range of the signal-to-noise ratio.