Cooperative Spectrum Sensing for Cognitive Radio Based on Adaptive Threshold

Cognitive radio (CR) has emerged as a promising solution to the spectrum scarcity problem, faced by all existing as well as newly proposed wireless services. In cognitive radio network (CRN) spectrum sensing plays the most important role and is considered as an integral part of CR. Among all the spectrum sensing schemes proposed in literature energy detection (ED) is commonly adopted due to its low complexity. But for low signal to noise ratio (SNR) region the performance of ED scheme deteriorates. To enhance the sensing performance of ED scheme for low SNR region, an adaptive threshold is considered in this paper. This adaptive threshold is a function of fixed (conventional) threshold and SNR of primary user (PU) signal received at CR. However the individual CR node may not give valid sensing results due to shadowing, multipath fading and hidden terminal problems of wireless communication channel. Therefore to deal with these problems we further implement the proposed approach under cooperation. In cooperative spectrum sensing (CSS) scheme, each CR will individually sense the spectrum using adaptive threshold and then transfer its decision to a central node also known as fusion center (FC). All the binary decisions received at FC are fused together and then final decision about the availability of spectrum is taken by FC. The simulation results show the better performance of adaptive threshold under cooperation than non-cooperation.