Research On Performance Of Cognitive User Dynamic Spectrum Access Method

With the development of technologies in the field of communications and the rapid advancement of wireless communication services,the demand for spectrum resources has gradually increased.In order to solve the increasingly problem of the scarcity of spectrum resources,Cognitive Radio(CR)technology came into being.CR can utilize the"spectral holes"that occur in the business process,providing the possibility of"secondary utilization"of the spectrum and effectively improving the spectrum utilization.For various complex cognitive radio network environment,Dynamic Spectrum Access(DSA)technology can effectively allocate resources for cognitive network systems,improve system load capacity and access efficiency,and thus balance network load.Therefore,further research on dynamic spectrum access methods has long-term significance and prospects for the development of wireless communication services.Firstly,this paper introduces and analyzes the research status and key technologies of cognitive radio,and summarizes the advantages and disadvantages of existing access technologies,and provides a theoretical foundation for the establishment and research of the following models.Secondly,a dynamic spectrum access strategy based on dual-channel sensing is proposed for the multi-user and multi-channel spectrum access model.The strategy reduces the contention of cognitive users for the channel through the dynamic allocation of spectrum channels.Considering the suddenness of the user access in the actual environment,the POMDP model is used to model the user access mechanism.The number of the perceptual access channels is adaptively allocated according to the number of access users,which reduces contention among users and collision interference to authorized channels.Then,the comprehensive analysis considers the complexity of the network model and the flexibility of the dynamic spectrum access technology.The Overlay/Underlay hybrid access mode is adopted instead of the original single Overlay access mode.Based on the above model,a hybrid dynamic spectrum access strategy is proposed.The cognitive user adopts the Underlay access mode shared transmission at a lower transmission rate by setting the probability threshold to reduce the perception of the channel with lower credibility.This strategy can effectively improve the access efficiency of cognitive users based on the compromise between throughput and system performance.Finally,the simulation analysis shows that the proposed two dynamic spectrum access strategies can effectively reduce the collision probability and improve the network service quality.In summary,the dynamic spectrum access method studied in this paper can improve the performance of cognitive radio networks,and has important significance for the research of complex wireless communication environments in the future.