A Mini-Slot Sensing with Selective Coordinator in Cognitive Radio System

In this paper, a mini-slot sensing with selective coordinator in cognitive radio is investigated. In traditional sensing, a whole sensing duration is only used to sense one channel. In proposed mini-slot sensing, a sensing duration is divided into many mini-slots and each mini-slot can be used to sense one channel independently, then data from all slots are been sent to a coordinator for final decisions. A proof is put up to demonstrate that mini-slot sensing has a better performance than the traditional sensing. In this research, the ability of different secondary users sensing different channels are not equal. Based on this assumption, we prove that in mini-slot sensing, not all slots do benefits to CR system. Slots can be divided to two groups: contributor (slots which improve system performance) and destroyer (slots which decrease the performance). A selective coordinator is proposed to assist mini-slot sensing which receive data from all slots and reject the destroyers in making final decisions. Based on the analysis above, an optimization problem is formulated to find the optimal assignment for slots to channels. A Greedy based two stage assignment method is proposed as the sub-optimal solution. Simulation results show that our proposed method has a better performance than traditional methods.