| In wireless network communications,how to optimize the utilization of spectrum resources is the core problem of networks.In order to ensure the correctness of the result of frequency assignment to each equipment,it is need to evaluate the signal quality after frequency assignment,for avoiding the interferences between each subnet device and selecting suitable modulation mode according to the signal quality situation.In this paper,based on the field strength prediction of diffraction model to calculate the electromagnetic wave attenuation,using heuristic algorithm in the fixed frequency system,and using heuristic algorithm combined with improved frequency hopping sequence in the frequency hopping system to complete the frequency assignment respectively.Then the compressed sensing algorithm is used to collect a small number of signal point data to evaluate the signal quality and ensure the rationality of the frequency assignment scheme.First of all,using the ITU-R P.526 proposal to predict regional attenuation of electromagnetic wave,by compared with the measured data,it is proved that the results are close,so it can be used in actual forecast model instead of the measured data.Considering the characteristics that compressed sensing algorithm can collect a small number of data to reconstruct the original signal,the simulation of signal quality reconstruction is used by compressed sensing algorithm,and it proves the correctness of this scheme.Secondly,for the fixed frequency system frequency assignment problem,considering the deficiency of the heuristic algorithm that only evolving in population space(genetic algorithm and particle swarm optimization algorithm,etc.),combining it with the cultural algorithm of two-layer evolution model,a culture particle swarm algorithm is proposed for frequency assignment,and the simulation proves that this method has better performance.After that,the signal quality assessment is performed on the equipment after the frequency assignment,and the results show that the frequency assignment is good.Finally,considering the synchronous and asynchronous networking in the frequency hopping system,the simulated annealing algorithm is used for the initial frequency assignment combined the constraint conditions between subnet and subnet firstly.Then an improved frequency hopping sequence based on chaotic sequence is proposed,after the wide interval processing,it is combined with the initial distribution results to complete the final frequency hopping network.Then the signal quality evaluation of the frequency hopping system is completed by the performance of the frequency hopping sequence and the compressed sensing. |
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