Research On Multi-user Access Scheme Based On DCSK Chaotic Modulation

Chaos digital communication technology is one of the important research fields of modern wireless communication.The most representative chaotic system is the differential chaos shift keying(DCSK)communication system.Due to the shortcomings of low data efficiency in the DCSK system,the Permutation Index(PI)is integrated into the DCSK system and a PI-DCSK modulation scheme is proposed.However,the PI-DCSK system has defects such as waste of transmission energy and low energy efficiency.In addition,multi-user access is an important trend in modern communications.Therefore,in order to solve the above problems,this article focuses on the PI-DCSK system to research,so that the improved chaotic digital communication system can meet the low power consumption and high efficiency requirements of Ultra-Wideband(UWB)communication systems.It provides an important alternative for short-distance communication applications of the next-generation Internet of Things.This article first conducts a thorough investigation of chaotic communication technology,presents the research status of chaotic communication in detail,and introduces the basic theory of chaotic communication.It also introduces the working principles of several classical chaotic digital modulation communication systems,and introduces the theoretical formula derivation of bit error rate of the DCSK system.Secondly,in order to solve the problem of energy waste in the PI-DCSK system,we propose the M-ary differential permutation index DCSK(DPI-DCSK)system,and use a quasi-orthogonal permutation set as a multi-user access scheme.The proposed system uses the chaotic signal carrying the current M-ary symbol as the reference signal of the next symbol,so that no energy is wasted on the reference signal that does not carry information.Meanwhile,this article analyzes the energy consumption and energy efficiency of the proposed DPI-DCSK system,and derives the bit error rate(BER)expression of the system under multipath Rayleigh fading channels,and validates it through system simulation.The effects of various parameters on the BER performance of the system are shown.The results show the performance advantages of its application in UWB scenarios and multi-user access.Finally,in view of the low energy efficiency of the PI-DCSK system,the M-ary short reference permutation index DCSK(SR-PI-DCSK)system is proposed to make it suitable for multi-user access communication.The system shortens the reference chaotic signal to less than half a symbol period,thereby improving the energy efficiency and spectrum utilization of the system.This scheme further improves the data transmission rate of the short reference DCSK system by fusing the permutation index modulation technology.This article shows the superiority of the system by analyzing the data promotion rate and energy saving rate of the system.The BER theoretical expression of the system under multipath Rayleigh fading channels is deduced,and the correctness of the theoretical derivation is verified by simulation results.Compared with the traditional PI-DCSK,the results show that the system has better performance gains.