Study Of Key Technologies Of M-APSK Modulation And Demodulation

With the vigorous development of Chinese aerospace industry, the lack of spectrum resources and the demand of high rate data transmission for satellite TT&C remind people of using high-order modulation. Since Amplitude Phase Shift Keying(M-APSK) represents a good trade-off between M-QAM and M-PSK, with error performance close to M-QAM, and resilience to nonlinearity close to M-PSK, M-APSK represents an attractive modulation scheme for digital transmission over nonlinear satellite channels.With the background of deep space explore and high rate data transmission for satellite, the study of key technologies of modulation and demodulation is carried out based on the BLUE BOOK 131.2-1 recommended by CCSDS. The rest main contents of this article are organized as follows.The advantage of M-APSK. The union limit symbol error rate for M-APSK over nonlinear channel is given in this part. The performance of M-APSK over nonlinear channel with various input power is presented analytically. M-APSK modulation scheme is compared with M-QAM modulation scheme as two aspects considered, including performance of SER/BER and sensitivity to the nonlinearity of satellite channel.Optimal design of M-APSK constellation. Firstly, the optimal design scheme based on minimum Euclidean distance and maximization of Mutual information. Then the optimal design of amplitude phase shift keying(APSK) constellation for a new simplified demapping algorithm is proposed. The simplified demapping algorithm for M-APSK and the optimization object function has been introduced in detail. At last, the performance of constellation optimal design scheme is evaluated by simulations.Modulation recognition of M-APSK signals. The two classic traditional schemes, modulation recognition scheme based on ratio of Likelihood function and modulation recognition scheme based on Feature Extraction, are introduced briefly. Then modulation recognition of MAPSK signals using template matching is proposed in this part. The components of the algorithm have been introduced in detail, including constellation amplitude extraction, coherent accumulation, baud rate estimation, template matching module and decision module. The performance of the proposed scheme is evaluated by simulations.