Research On Multiple User Chaos Shift Keying Technology Based On DCSK

Chaotic digital modulation is a widely used chaotic communication technology.Differential Chaos Shift Keying(DCSK)and Correlation Delay Shift Keying(CDSK)are two typical systems in Chaotic Shift Keying.Chaotic signals are selected as carriers in the DCSK system,and the spectrum expansion can be realized while adopting the information bit modulation.But the transmission rate of the system is relatively low.Then reference signal and the information bearing signals are superimposed by an adder for transmission in the CDSK system.Although the transmission rate is improved,more interference parts are introduced at the same time.At present,the multiple user DCSK communication system is a research hotspot,which can be satisfied with the pursuit of high speed for communication,but has the problem of poor bit error performance.In order to improve the bit error performance of multiple user systems and further raise the data rate,several different improved systems are proposed.The formula of this thesis are derived by using Gaussian Approximation(GA)and verified by Monte Carlo simulation.The main research work of this thesis is carried out from the following three aspects:1.Aiming at the problem that the bit error performance of the traditional multiple user DCSK system is not ideal,a Time Reverse Multiple User(TR-MU)DCSK communication system is studied.The system uses multiple delay times to form multiple information time slots.In each information time slot,two carrier signals are formed by using time inversion technology to modulate user information,and then the two information bearing signals are superimposed by an adder for transmission.The bit error rate of the system under the Rayleigh fading channel is derived.And the correctness of the theoretical derivation is verified by Monte Carlo simulation.Simulation results show that the system has better bit error performance than traditional multiple user systems.2.In order to further reduce the bit error rate of multiple user DCSK systems,a Short Reference Orthogonal Multiple User(SR-OMU)DCSK communication system is studied.One reference time slot and multiple information time slots to transmit signals are used in the system.The length of the signal in the reference time slot is reduced,and multiple information time slots are formed by different delay times.At the same time,two data bit information is transmitted by using the Hilbert transform orthogonality in each information time slot without introducing interference between users.The bit error rate of the system under the Rayleigh fading channel is analyzed and the experimental simulation is performed.The results show that the bit error performance of the traditional multiple user system are effectively improved.3.In order to further improve the transmission rate of traditional multiple user DCSK systems,a Multiple Input Single Output Multiple User Orthogonal High Efficiency(MISO-MU-OHE)DCSK communication system is studied.Multiple information signals share a reference signal to transmit information is used in the system.In the information time slot,orthogonal chaotic generator and Walsh codes are used to form multiple orthogonal carriers to carry multiple user information bits.Then the multiple information bearing signals are superimposed by an adder and transmitted in an information time slot.At the same time,MISO technology is applied to the system.The bit error rate of the system under the Rayleigh fading channel is obtained,and the superiority of the system is verified by simulation.