Research On Spectrum Sensing Technology In Cognitive Underwater Communication

With the growth of underwater communication needs, the development of underwateracoustic communication attracts more and more attention. The progress of the study ofunderwater communications is driven by the development of land-based communicationstechnologies to some extent. However, because of the special nature of the underwaterenvironment, the available communication bandwidth underwater acoustic channel is verylimited, and the two underwater spectrum allocation methods are based on a fixed allocationof class-based and competitive class and each has certain limitations. Fixed spectrumallocation will inevitably result in the problem of spectrum resource constraints and lowchannel utilization. Competitive allocation would give rise to multiple users competing forthe same channels, resulting in conflict and collision data. Therefore, reasonable spectrumresources allocation underwater and improving spectral efficiency have become the keyproblems to improving the performance of underwater acoustic communication.As a revolutionary intelligent spectrum sharing technology, Cognitive radio occursmainly in the traditional static spectrum allocation policy part of the spectrum resourceconstraints and the inherent contradictions of a portion of the spectrum utilization is not high.Users in a cognitive network, by sensing the spectrum which has been assigned to theauthorized users but unoccupied,which is alled spectrum holes, can significantly improvespectrum utilization. If this spectrum-sharing technologies are applied to underwater acousticcommunications.It will be able to improve the spectrum utilization of underwater acousticcommunication and solve the problem of underwater acoustic communication channelnarrowband to a certain extent. It is helpful to thedevelopment of underwater acousticcommunication system significance.This paper first analyzes the research background, a brief introduction to the underwateracoustic communication and cognitive radio technology, and then study the maincharacteristics of the underwater acoustic channel. Then It respectively introduce thespectrum sensing model, local spectrum detection algorithm, cooperative spectrum detectionalgorithm to introduce spectrum detection technology in detail. After the analysis andcomparison of different spectrum detection algorithms, then it focuses on simulation analysisof the energy detection and cooperative detection algorithm based on energy detection.However, the detection performance of traditional cooperative detection algorithm is notgood enough. And the additional overhead is relatively large. This paper presents a dualthreshold based on the weighted fusion cooperative detection algorithm. The algorithm can reduce the cooperation cost and improve the detection performance. At last it is simulated inRayleigh fading channel. The results show that the algorithm can be applied to cognitiveunderwater acoustic communication.