Research On Methods Of Spectrum Recommendation And Spectrum Prediction For Cognitive Radio

Spectrum resources is the foundation for wireless communication industry to survive and develop,however,study found that current spectrum efficiency is very low,in order to solve the problem of low utilization of radio spectrum resources,thus put forward the concept of cognitive radio.The cornerstone technology of cognitive radio is spectrum sensing technology,which can effectively improve the utilization of spectrum resources.Typically,there are a large number of authorized frequency bands in cognitive radio system,and as a secondary user with limited perception that it couldn't perceive all the channels.Therefore,a key question that secondary users faced is how to select a channel in a wide range of channels to sense.With the proposed model of spectrum recommendation and spectrum prediction joint process,we can effectively improve the utilization of spectrum resources This thesis focuses on the study of spectrum recommendation methods and spectrum prediction methods in cognitive radio,and the main work of this thesis is as follows:(1)The background,purpose,significance and status of cognitive radio technology are described,the basic theory of cognitive radio is analyzed in detail,in order to solve time delay caused by spectrum allocation process,a new idea for the secondary users to use the spectrum is presented,and base on this new idea a model of spectrum recommendation and spectrum prediction joint process is proposed.(2)The theory of collaborative filtering technology is described,principles of user based collaborative filtering algorithm and item based collaborative filtering algorithm and challenges they faced are analyzed in detail,on this basis,an improved collaborative filtering based spectrum recommendation algorithm is proposed,then simulation experiments are performed,simulation results show that the improved collaborative filtering based spectrum recommendation algorithm can effectively reduce the collision probability and interference caused by secondary users to primary users.(3)The theory of spectrum prediction techniques is described,the 1-NN prediction,m-out-of-n hard merger rules and HMM prediction these three typical spectrum prediction algorithms are analyzed in detail,on the basis,single SU prediction,multi-SU collaborative prediction and joint prediction based on modified HMM are proposed,simulation experiments are performed,simulation results show that improved prediction algorithms can effectively reduce the probability of false alarm,improve the detection probability and reduce response time extension,improve the communication efficiency of secondary users.