Application Of Chaos Theory In Wireless Communication

Wireless communication is a communication way to exchange information in free space,Wireless channel,exchanging in time,space and frequency,limited frequency band,complex environmental noise,serious multipath effect and Doppler frequency.shift,which makes the wireless communication greally affected by environment,Due to chaotic system is sensitive to iinitial value and generates a large number of non periodic,continuous broadband spectrum,noise like and renewable chaotic signals,it is suitable for communication applications.But the chaos in wireless communication application is still susceptible to noise and multipath effects,the application of chaotic system in wireless communication is facing serious challenges.This paper presents a new type of chaotic wireless communication system The system is based on chaotic theory,and includes chaotic signal transmitter and receiver,multipath channel receiver design.In the wireless communication system,the inter-symbol interference(ISI)caused by the multipath propagation deteriorates the receiver's performance,which leads to the error of information extraction,and reduces the overall performance of the system.In this paper,a new algorithm based on chaotic matched filter is proposed,The algorithm presents a theoretical optimal receiver.The ISI caused by multipath can completely eliminate when the optimal receiver is used.And then the sub optimal receiver is presented using in the actual channel.The two receiver judge receive signals through setting reasonable threshold.And then the theoretical BERs of two receiver are studied.The simulation results show it can effectively remove the ISI,reduce the BERs and improve the communication efficiency by using the sub optimal receiver.However,in the actual wireless channel,the parameters of the channel model are unknown,and it is necessary to estimate the parameters of the channel.Based on the sparsity of the wireless multipath channel,this paper proposes a compressed sensing(CS)algorithm to estimate the multipath parameters of the chaotic system.Firstly,making the channel sparsity under the complete dictionary domain.Secondly,matching chaotic signals with the corresponding variables in the CS algorithm,and the sampling matching pursuit algorithm(CoSaMP)is used to estimate the parameters of the wireless channel.The simulation results compared with the traditional Least Square(LS)algorithm show that the CS algorithm is more accurate for the estimation the parameters of the wireless channel.The CS algorithm is applied to the proposed communication system.The simulation results show that the system can work normally even under unknown channel.