Carrier Synchronization Method Based on Time Domain Correlation and Coding Assistance

Abstract

The invention discloses a time-domain correlation and coding aiding based carrier synchronization method which achieves carrier synchronization by the aid of time-domain correlation functions of pilot frequency and output soft information of an iterative decoder of a coding system. Firstly, a pilot frequency and data add-drop frame structure is adopted, namely the pilot frequency is equally divided into two sections to be inserted into an initial position and a middle position of a data block; secondly, rough carrier estimation is performed by the aid of the time-domain correlation function of the pilot frequency, and a received signal is compensated by the aid of a rough estimation value; and finally, fine carrier estimation is performed by the aid of the time-domain correlation functions of the pilot frequency and the Turbo decoding soft information, and a fine estimation value is utilized for compensating the received signal to achieve effective carrier synchronization. The method includes the specific steps of baseband complex signal receiving, rough estimation, signal correction, soft demodulation, data demultiplexing, Turbo decoding expansion, hard decision, decoding termination condition, data multiplexing, and modulation and fine estimation. The method overcomes the defects of the prior art, and carrier frequency estimation accuracy is improved while operation complexity is lowered.

Description

technical field [0001] The invention belongs to the technical field of wireless communication, and further relates to a carrier synchronization method based on time domain correlation and coding assistance in the technical field of channel coding. The present invention can be used in the fields of military communication, satellite communication, remote measurement communication, etc., by means of the time domain correlation function of the soft information output by the iterative decoder in the pilot frequency and coding system to realize carrier synchronization and ensure the reliability of communication. Background technique [0002] Whether short-burst communication can be effectively carried out under the condition of low signal-to-noise ratio / very low signal-to-noise ratio, carrier synchronization is the primary problem that needs to be solved all the time. Especially like Turbo codes and LDPC codes working under the condition of low signal-to-noise ratio, the decoding ...

AI Technical Summary

Problems solved by technology

The simulation results show that the two algorithms are effective for phase jitter within 10° and small frequency deviation (ΔfT s ≤7×10 -4 ), the estimation performance of the 22-bit pilot sequence can reach the Cramereau boundary, but when the frequency offset exceeds the frequency estimation range, that is, ΔfT s >7×10 -4 When , since the pilot sequence is very short, the frequency estimation accuracy of the ML algorithm is very low, and the residual frequency offset after coarse synchronization is still relatively large. Still unable to improve the reliability of soft information

Therefore, in order to improve the anti-frequency offset performance of the algorithm, the length of the pilot can only be increased

At the same time, they use the maximum likelihood search algorithm of the pilot sequence for rough estimation, and the maximum likelihood search algorithm for the pilot and decoding soft information for fine estimation, and the fine estimation process of the ML-ISDD algorithm requires the decoding soft information For non-linear changes, the ML-ITDD algorithm fine estimation needs to judge and re-encode the decoded soft information, which increases the complexity of the system to a certain extent

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