Optimization Design Of M-ary Differential Chaos Shift Keying Based On Cooperative Communication Systems

In recent years,chaotic digital communication systems become a popular research topic in the wireless communication scenarios.As an excellent type of chaotic digital communication systems,differential chaos shift keying(DCSK)communication systems combine both spread-spectrum and modulation features,and thus possess strong anti-multipath-fading capability.At present,there exist many academic investigations related to the analysis of DCSK communication systems.However,in order to meet the requirements of modern mobile communication systems and the key performance indicators of high rate transmission in fifth-generation mobile networks,more and more researchers have moved on to investigating the cooperative-diversity-aided DCSK communication systems.Accordingly,based on the excellent characteristics of chaotic signals,the thesis proposes two kinds of DCSK cooperative communication techniques to improve the transmission rate and reduce the bit error rate(BER).The detailed design schemes are illustrated as follows:1)Utilizing the initial sensitivity and cross-correlation characteristics of chaotic signals,we propose an optimized M-ary DCSK cooperative communication system,referred to as chaotic code division multiple access M-ary DCSK(CCDMA-M-DCSK)cooperative communication system.First,the basic principle of the CCDMA-M-DCSK cooperative communication system is introduced in detail.Then,the theoretical expressions in terms of the BER and the throughput are derived for the CCDMA-M-DCSK cooperative communication system over multipath Rayleigh fading channels,and their correctness is verified by some simulations.In addition,with an aim to further demonstrate the superiorities of the CCDMA-M-DCSK cooperative communication system.There make a detailed comparsion with the traditional counterparts.The results prove that the proposed CCDMA-M-DCSK cooperative communication system not only can improve the information transmission rate,but also can reduce the BER performance of the system.2)Exploiting the multi-resolution(MR)technology,which can be used to provide diverse Quality-of-Service(Qo S)for different bits,an improved relay transmission strategy for the multi-resolution M-DCSK(MR-M-DCSK)cooperative system is proposed.First of all,we introduce the basic principles of two kinds of relay transmission strategy,i.e.,the improved relay transmission strategy and the traditional counterpart,and make some performance discussions for the above two strategies in the MR-M-DCSK cooperative system.Moreover,in order to further illustrate that the MR-M-DCSK cooperative communication system with the use of the improved relay transmission strategy can achieve outstanding performance,such system is utilized to make a performance comparison with the traditional counterparts,e.g.,the MR-M-DCSK cooperative communication system and the MR-M-DCSK communication system.Simulation results show that the proposed MR-M-DCSK cooperative communication system can achieve lower BER performance.