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Iterative demodulation method of turbo code for satellite communication under high dynamic and extremely low SNR

A technology of satellite communication and demodulation method, which is applied in the field of satellite communication, can solve the problems of large delay in demodulation and decoding, and high complexity of satellite communication reception and demodulation, so as to reduce complexity, enhance the ability to tolerate high dynamics, and have good adaptability Effect

Inactive Publication Date: 2019-11-15
ARMY ENG UNIV OF PLA
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Problems solved by technology

[0007] In short, the problems existing in the existing technology are: the reception and demodulation complexity of satellite communication is high under the condition of high dynamic and extremely low signal-to-noise ratio, and the delay of demodulation and decoding is relatively large

Method used

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  • Iterative demodulation method of turbo code for satellite communication under high dynamic and extremely low SNR
  • Iterative demodulation method of turbo code for satellite communication under high dynamic and extremely low SNR
  • Iterative demodulation method of turbo code for satellite communication under high dynamic and extremely low SNR

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Embodiment Construction

[0035] Such as figure 1 As shown, the high dynamic extremely low signal-to-noise ratio satellite communication Turbo code iterative demodulation method of the present invention comprises the following steps:

[0036] (10) Receive signal down-conversion: convert the receive bandpass signal into a baseband signal through quadrature down-conversion;

[0037] (20) Elimination of large frequency offset of the signal: After the baseband signal is segmented into Fourier transform and accumulated, it is added to the Fourier transform shift of the matched filter response function to obtain the likelihood function; by searching the likelihood function The peak value obtains a rough estimate of the frequency offset, and uses the estimate to compensate the carrier frequency offset of the received bandpass signal;

[0038] Such as figure 2 As shown, the (20) signal large frequency offset elimination step includes:

[0039] (21) Segmented Fourier transform of the baseband signal: the le...

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Abstract

The invention discloses a satellite communication Turbo code iterative demodulation method with high dynamic and an extremely low signal-to-noise ratio. The method includes the following steps: (10) converting a received bandpass signal into a baseband signal; (20) acquiring a rough estimation value of frequency offset, and performing carrier frequency offset compensation by using the estimation value; (30) performing matched filtering on the signal subjected to carrier frequency offset compensation; (40) estimating timing frequency offset, and performing timing frequency offset correction onthe filtered signal; (50) preestimating frequency offset, and compensating the signal; (60) performing precision estimation on the frequency offset and phase offset, and compensating the signal subjected to preestimated compensation; (70) performing precision estimation on residual timing frequency offset and timing deviation after carrier offset compensation, and outputting a decoding decision result; and (80) introducing a frequency offset counter to subsequent coded packets, and improving an EM algorithm to complete Doppler frequency offset change tracking. The Turbo code iterative demodulation method disclosed by the invention is low in complexity, high in efficiency and good in adaptability.

Description

technical field [0001] The invention belongs to the technical field of satellite communication, in particular to a turbo code iterative demodulation method for satellite communication under high dynamic and extremely low signal-to-noise ratio with high efficiency and good adaptability. Background technique [0002] The wide application of advanced coding technologies represented by Turbo codes and LDPC codes in the satellite mobile communication and navigation industries enables communication systems to work under conditions of very low signal-to-noise ratio. But its excellent performance is based on correct demodulation. Even a small frequency offset will cause a sharp drop in bit error performance at the receiving end, so obtaining accurate synchronization information is essential for normal communication. [0003] At the same time, in order to fully obtain the high coding gain brought by the channel code and make the system transmit in a manner close to the Shannon limit...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04L27/22H04B7/185H04L27/00H04L27/26
Inventor 杨杰朱宏鹏李广侠李志强王闯蔡君
Owner ARMY ENG UNIV OF PLA
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