| Satellite communication system can quickly achieve a wide range of coverage.The integration of space and earth information network requires that the satellite communication system can meet the needs of massive user access.Sparse code multiple access can provide strong technical support for satellite communication in fully and effectively utilizing limited spectrum resources.Through the reasonable codebook design,SCMA system can improve the user access,improve the anti fading ability of the system.In addition,this paper deeply studies the characteristics of SCMA system suitable for satellite communication proposes a design scheme of SCMA codebook with low PAPR,and designs a receiver synchronization scheme suitable for SCMA system according to the characteristics of SCMA codebook.The main work of this paper is as follows:1.The existing SCMA codebook design methods are deeply studied.A low PAPR codebook design method is proposed,which can reduce the PAPR of superimposed signals by reducing the mapping points on each complex dimension of the parent constellation.The simulation and performance comparison between the codebook design method and the existing methods are carried out.2.The characteristics of SCMA system are analyzed in detail,and the models of transmitter and receiver are described in detail The results show that the performance of existing multiuser detection algorithm is sensitive to timing deviation and carrier frequency difference.3.The synchronization technology of SCMA system for satellite communication system is deeply stu.died.The algorithm transmits external information between demodulation and decoding of transmission data to achieve fast and accurate timing estimation and improve the performance of demodulation and decoding.This paper designs a two-stage frequency difference estimation algorithm based on rough acquisition and fine correction to expand the range of frequency difference estimation and improve the accuracy of frequency difference estimation. |
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