Research And Implementation Of Dynamic Spectrum Sensing And Access In Cognitive Communication

In recent years,with the rapid development of wireless communication technologies,the number of wireless communication devices and handheld mobile devices has gradually increased.How to improve the spectrum utilization of natural spectrum resources has become an increasingly important issue.Firstly,this paper discusses the development status from two aspects of spectrum sensing and access strategy.According to the detection signal bandwidth,the advantages and disadvantages of different spectrum sensing algorithms are described from the two levels of narrowband spectrum sensing and wideband spectrum sensing.The commonly used access strategy methods are introduced,which leads to the research focus of this paper,the research on spectrum sensing and access transmission waveform design of secondary users in cognitive communication.In the end,the paper designs a secondary user cognitive communication scenario using software radio equipment,and verifies the feasibility and correctness of the perception algorithm and transmission waveform design.This paper analyzes the performance of different spectrum sensing algorithms from different levels of comparison.Firstly,the energy spectrum sensing and matching filtering perception in narrowband spectrum sensing are compared.The energy spectrum sensing does not require the prior knowledge of the primary user,and the computational complexity is low.The simulation results show that the algorithm has good perception under high SNR.Then,in the wideband spectrum sensing,according to the spectrum pool theory,the hierarchical spectrum clustering algorithm is proposed to divide the spectrum pool,and compared with the K-means clustering algorithm and the C-means clustering algorithm.From the comparative analysis of simulation results,the performance of hierarchical spectrum clustering algorithm is better than K-means clustering algorithm and C-means clustering algorithm,and the accuracy and the perception can still be maintained 98% under the condition of multiple sub-channel feature,it is more than 10% higher than the other two algorithms.Due to the problem that wideband compressed sensing is difficult to achieve,this paper studies the wideband spectrum sensing technology based on the Sub-Nyquist sampling,which can effectively detect the main user while reducing the sampling rate,and obtain the signal noise through the simulation results.When the signal to noise ratio is 17 dB,the accuracy of the perceived result is over 95%,the accuracy is over 90%,and the sensing performance is excellent.Then the method of spectrum modulation and spectrum coding framework to generate multi-carrier waveform is analyzed.The feasibility and correctness of generating multi-carrier waveform through the framework are verified by theoretical derivation and simulation.The simulation results show that the discontinuity is Gaussian white noise channel,subcarrier orthogonal frequency division multiplexing has a lower bit error rate when compared to continuous subcarrier orthogonal frequency division multiplexing,and is suitable for secondary users to transmit in cognitive communication.Finally,this paper aims at the communication scenarios of secondary users in cognitive wireless communication,applied energy spectrum sensing algorithms and designed transmission waveforms and built a demonstration experiment of secondary users by using general software radio equipment,demonstrating and verifying the perception,access and communication of secondary users in cognitive communication.Multiple experiments and using the received information to verify the reliability of the transmission system,the probability of success can reach more than 95%.