| Cognitive Radio (CR) technology, as one of the key to the problem that wireless spectrum resource is shrinking with the low utilization at the same time, is an important project deserved to research. And research on spectrum sensing is also significant, which is the foundation and premise of CR technology.After analysing the existing spectrum sensing schemes, this dissertation focuses on cooperated spectrum sensing and multi-channel spectrum sensing to improve the feasibility of spectrum sensing scheme and reduce the complexity of CR systems, and gain some achievements.First of all, a novel reliability prediction algorithm based on Artificial Neural Network (ANN) is proposed to make use of messages from cognitive users with different sensing performance, which can provide valid prediction of cognitive users’sensing reliability based on a few of history sensing data. Combining this algorithm and the weighted data fusion, a cooperated spectrum sensing scheme for single channel is designed to help the fusion center to make the final decision about the primary user signal.Secondly, considering the sensing reliability and sensing capability limits of different cognitive users, an allocation scheme for spectrum to be sensed based on the communication requirements and sensing reliability is designed to allocate different number of spectrum bands to different cognitive users reasonably and guarantee that each spectrum band will be sensed by more than one cognitive users. Finally, a energy detection algorithm based on Basis Expansion Model (BEM) and a multi-channel spectrum sensing scheme based on Compressed Sample (CS) is designed after analysing the effects of Carrier Aggregation (CA) to spectrum sensing. The novel energy detection algorithm can estimate the energy of the spectrum band with less sample information, and the scheme for multi-channel spectrum sensing can acqiure the energy of the whole wideband spectrum by detecting less spectrum bands. |
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