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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 co-operative 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. Co-operative 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 …