This paper presents the performance of double threshold energy detection in cooperative cognitive networks over Nakagami-m fading channel. Square Law Combining (SLC) diversity technique helps in detection at cognitive center for different values of shape factor M and this algorithm is examined by placing multiple relays between Primary user (PU) and Secondary user (SU). Performance of the network has been analyzed for amplify and forward relaying scheme as irrespective of their location and distance from the primary users and cognitive center. The simulated results are shown for detection probability (P d ), collision probability (P c ) and unavailable probability (P n ) .
Keywords-primaryusers; secondary user;cognitive center;square law combing ; double threshold energy detection; amplify and forward.I.