Co-operative communication with SNR weighted algorithm in cognitive radios

Nowadays wireless networks are regulated by fixed spectrum access policy. But all the fixed assigned spectrums are not utilized fully at all times. At the same time frequency spectrum need has increased drastically as the spectrum is being used for different multimedia applications with voice communication. It gives rise to a need to dynamically access the available frequency spectrum. Cognitive Radio (CR) is the intelligent technology which can sense vacant frequency spectrum i.e. the spectrum not being used by licensed users at the time when CR requires it. So sensing vacant channel is very important in CR technology. Sometimes due to fading and shadowing effects single CR user can´t detect the presence of licensed (Primary) user. Co-operative spectrum sensing helps in improving the sensing process and getting more reliable results. Here we are discussing three different co-operative spectrum sensing algorithms with energy detection for local spectrum sensing. We will discuss traditional co-operative spectrum sensing (TCSS), SNR weighted co-operative spectrum sensing (SWCSS) and selective SNR weighted co-operative spectrum sensing (SSWCSS). Simulation shows that SWCSS gives better results than TCSS and the numbers of co-operating secondary users (SU) are reduced and consumption of system resource is minimized. SSWCSS is similar to SWCSS but the number of co-operating secondary users (SU) can be reduced further.