Distributed cooperative spectrum sensing over different fading channels in cognitive radio

Spectrum sensing is the important aspect of cognitive radio (CR). In order to use the vacant spectrum, cognitive radio user must be able to identify the presence of empty spectrum efficiently. A non-cooperative spectrum sensing faces the problem of shadowing and hidden terminal due to which the CR user fails to monitor the vacant spectrum. To solve the problem of hidden terminal and shadowing in non-cooperative spectrum sensing, cooperative spectrum sensing (CSS) is used. CSS can be divided in two categories, centralised and distributed. In this paper comparison of centralised and distributed CSS is presented and a cluster based distributed CSS is proposed to improve the performance of spectrum sensing. Mathematical formulas are derived for the different fusion rules for cluster based CSS, further the performance of centralised and distributed CSS is investigated for different fading channels. It is found that performance over Nakagami channels is better than Rayleigh and Rician fading channels.