Multiple access-inspired cooperative spectrum sensing for cognitive radio

The first challenge of cognitive radio is spectrum sensing. Cooperative spectrum sensing (CSS) has the advantage of better accuracy over non-cooperative schemes. One of the critical problems in CSS is the delay between sensing and decision. Wideband spectrum sensing forms another challenge due to its complexity and large dynamic range requirements. To solve these problems, we propose new cooperative spectrum sensing techniques inspired by multiple access methods: Time-division (TD), frequency-division (FD), staggered frequency-division (SFD), frequency-hopping (FH), irregular subband (IS), and staggered irregular subband (SIS) cooperative spectrum sensing. Cooperative users are first divided into groups. In TD-CSS, those groups in turn detect the presence of primary users to reduce delay. To tackle the difficulties of wideband spectrum sensing, FD-CSS assigns different groups to different spectrum bands. SFD-CSS can solve time delay and wideband spectrum sensing issues at the same time by making each group sequentially detect different frequency in different order. FH-CSS performs better than FD-CSS if the channel information is unknown. Finally, asymmetric band access concepts can be applied to CSS to allow different groups focus on frequency bands with irregular subband bandwidth using IS-CSS or SIS-CSS.(1).