| High throughput and low interference are important design standards for wireless communication systems.Network Coding(NC)is widely used in wireless communication,by reducing the time slot for information exchange between users.Differential chaos shift keying(DCSK)modulation technology is selected as a candidate for network coding scheme because of its superior performance such as antimultipath fading,no carrier synchronization,etc..However,the low data transmission rate and poor performance of DCSK have led to a decrease in throughput and poor performance of the network coded based on DCSK transmission systems,which cannot meet people's increasing requirements for high throughput and high performance.Therefore,this paper combines the M-ary differential chaos shift keying modulation and network coding,and proposes a network coding transmission system based on Mary transmission differential chaos shift keying modulation.The main innovations are summarized as follows:(1)Aiming at the problem of poor throughput and performance of the original network coding transmission system based on DCSK modulation,a direct network coding transmission systems based on M-DCSK modulation(DNC-MDCSK)is proposed.The theoretical bit error rate(BER)and throughput of the DNC-MDCSK transmission system are derived,and their correctness is proved by simulation.Finally,the advantages of the DNC-MDCSK transmission system in terms of the BER performance,throughput,complexity,and cost of the system are verified through simulation.(2)In order to reduce the influence of noise on the Multilevel code shifted differential chaos shift keying modulation system,a multilevel code shifted differential chaos shift keying system with reference diversity(MCS-DCSK-RD)is proposed.At the transmitter,multiple Walsh code sequences are used to transmit the reference signal and its duplicated versions(referred to herein as "reference diversity")to reduce the noise of the signal,and to derive the optimal reference diversity number based on the derived theoretical BER performance.Then the correctness of the theoretical derivation and the superiority of the system are verified by simulation.In addition,this article further optimizes the proposed system to reduce the noise in the received signal(NRR)by weighting average of the received signal.(3)The network coding transmission system needs to pass through the channels multiple times,and the noise interferes with the system greatly.A direct network coding transmission system based on MCS-DCSK-RD modulation(DNC-MCSDCSK-RD)is proposed.Use the strong noise reduction ability of the MCS-DCSK-RD modulation scheme and its further optimization scheme to improve the performance of the system.The performance and throughput of the proposed system are deduced theoretically,and the correctness of the theoretical deduction and the advantages of the system are verified through simulation. |
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