Research On Spectrum Sensing And Prediction Based On Hidden Markov Model In The Cognitive Radio

In recent years,with the rapid development of wireless radio technology and the explosive growth of mobile data service,fixed spectrum allocation scheme has been unable to meet the needs of radio communication in today's world.However,the study shows that the utilization rate of authorized spectrum is very low in the whole global,and cognitive radio can interact with electromagnetic environment adaptively to detect spectrum hole,and bring to transform frequency point dynamically and to adjust transmission parameters into effect,this feature has been extensive research in improving the utilization rate of spectral.Spectrum sensing is the primar task of cognitive radio systems,spectrum perception can reduce the probability of collision between primary and secondary users on microscopic view quickly and accurately,improve the communication quality and the throughput of the system.And it can improve the utilization rate of idle spectrum on the macroscopical view effectively.This dissertation will discuss how cognitive users can capture spectrum hole quickly and accurately.In order to achieving spectrum perception quickly and accurately and covering the shortage of the trust of local spectrum perception,this dissertation firstly proposes an adaptive cooperative spectrum prediction scheme based on discrete hidden Markov model,which gives the corresponding weight according to the trust of local spectrum perception,The next time of channel state is predicted by data fusion.The simulation results show that this method has higher accuracy in spectrum prediction.Due to discrete hidden markov model can only deal with discrete observation sequences,information distortion occurs when processing numerical continuous observation sequences.In addition,in order to make full use of history information of spectrum perception,and improve the accuracy and timeliness of spectrum perception,the dissertation introduce the continuous hidden markov model into collaborative spectrum perception.It is proved that the energy value of the authorized user satisfies the different Gaussian distribution under different channel states,Therefore,the two different states of the channel are determined by pattern recognition.The simulation results show that spectrum sensing scheme based on continuous hidden markov model has higher spectrum sensing performance by pattern recognition.