Secondary users (SUs) can detect the states of primary users (PUs) and access the idle spectrum in an opportunistic way in cognitive radio networks (CRNs). With the spread of wireless communication devices, the mobility of both PUs and SUs is ubiquitous. To obtain more accurate spectrum sensing data, SUs must be located within the transmission range of PUs. With the unknown mobility, it is difficult to guarantee the efficiency of spectrum sensing. Focused on this issue, we propose a new scheme, called Particle Swarm Optimization (PSO) -based agent cooperative spectrum sensing (PSOA) in this paper. In this scheme, we deploy multiple mobile agents spreading over the network, to cooperate in spectrum sensing instead of SUs. All agents will move according to the latest global optimal agents of the corresponding target PUs with the fitness function calculated by modified PSO. With the optimal movement, the distribution of agents can guarantee that most PUs are within the detection coverage of PSOA. The evaluation results show that our scheme can save over 80% of sensing time and over 80% of energy consumption (affected by the agents' number and max velocity) than the active searching scheme. PSOA also guarantees the sensing probability of 80% and higher in our simulation.
With the existing Cognitive Radio Networks development, we present a sub-spectrum sensing scheme based on reputation which takes advantage in energy consumption, security and fairness from spectrum sensing, data fusion and spectrum allocation by classifying users and spectrum bands reasonably. The analysis shows that the sub-spectrum sensing scheme can save energy and defense SSDF attacks effectively.
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