Joint Modulation and Coding Method for Deep Space Link Residual Frequency Offset

Abstract

The invention provides a joint modulation coding method for deep-space link residual frequency offset. The joint modulation coding method for the deep-space link residual frequency offset is characterized by comprising the following steps, wherein a step A is that low density parity check (LDPC) coding is carried out to information bits at a transmitting terminal, and at the same time, the order of a coding sequence is changed through an intermediate conversion matrix so that the information bits are enabled to be located at positions where phase deviation is small; a step B is that Feher-patented quadrature phase shift keying (FQPSK) modulation is carried out to the coding sequence, and transmitting signals generated through the modulation are transmitted into an additive white gaussian noise (AWGN) channel; a step C is that the transmitted signals are received at a receiving terminal and demodulated by an MAP to obtain a bit-by-bit logarithmic likelihood ratio LLR, and then the obtained LLR is utilized for carrying out compensation and estimation for phase offset and frequency offset to codes; and a step D is that soft information is sent into a decoder eventually, a posteriori probability of the demodulation is used as a priori probability of decoding, and a belief propagation decoding algorithm based on the soft information is adopted to achieve a decoding process. The joint modulation coding method for the deep-space link residual frequency offset effectively assists in frequency offset compensation, and improves the frequency deviation resistant performance of a system.

Description

technical field [0001] The invention relates to a joint modulation and coding method, in particular to a joint modulation and coding method for deep space link residual frequency offset. Background technique [0002] In the process of deep space exploration, deep space communication plays a key role. Only by ensuring the normal operation of the deep space communication system can the deep space exploration mission be successful. However, deep space communication is facing challenges that ground communications and satellite communications cannot achieve. It has special difficulties, because the deep space channel has the following characteristics: long distance, long delay, channel fading characteristics, high operating frequency, available frequency bandwidth, easy link interruption, asymmetric uplink and downlink, etc. [0003] The propagation distance of deep space communication is extremely long, the signal energy attenuates with the square of the deep space detection dis...

AI Technical Summary

Problems solved by technology

However, at present, with the continuous increase of deep space detection distance, under the condition of limited hardware conditions and limited processing accuracy of deep space detectors, it is no longer the main direction of future research from the perspective of increasing antenna size and improving radio frequency. The way to transmit power is limited

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