A Wide Range Code-Assisted Carrier Synchronization Method

Abstract

The invention relates to a wide-range code auxiliary carrier synchronization achieving method. By means of the method, code auxiliary carrier synchronization is divided into a rough synchronization part and a fine synchronization part. The wide-range code auxiliary carrier synchronization achieving method includes: firstly using a maximization evaluation function as a rule, limiting carrier shifting within a certain range through a two-dimensional search window algorithm, and choosing a precise estimation algorithm with large parameter estimation range and low complexity to achieve carrier recovery accurately. The wide-range code auxiliary carrier synchronization achieving method has the advantages of being capable of remarkably improving synchronization range, having high estimation accuracy, and being capable of effectively achieving carrier synchronization and obtaining decoding capability approaching ideal synchronization.

Description

technical field [0001] The invention belongs to the technical field of demodulation and synchronization in communication, and in particular relates to a method for implementing wide-range code-assisted carrier synchronization. Background technique [0002] In the wireless communication system, the modulated data sequence is transmitted through various types of channels. Due to the influence of factors such as the instability of the transmitting and receiving oscillator frequency, oscillator drift, and mismatching of the transmitting and receiving filters, the received signal is inevitably introduced. carrier deviation. During coherent demodulation, the receiver must use various carrier synchronization methods to estimate the value of the carrier deviation as accurately and quickly as possible, and generate a coherent carrier with the same frequency and phase as the modulated carrier at the transmitting end, so as to restore the same frequency as the transmitting end. Modula...

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Problems solved by technology

[0004] In order to effectively achieve demodulation synchronization in a low SNR environment, it is usually necessary to use LDPC codes with large code length and low code rate. The code-assisted synchronization method can make full use of the coding information of a large number of symbols and has high estimation accuracy. However, it shows the problem of small parameter estimation range. This is because the large frequency offset and phase offset will greatly reduce the signal power input to the decoder, resulting in unreliable decoding of soft information, which in turn makes the synchronizer and decoder Both cannot converge, especially the large residual frequency offset will lead to serious deterioration of LDPC decoding performance

Secondly, the code-assisted synchronization method needs to use the soft information output by the LDPC decoder to iteratively update the estimated value of the synchronization parameters, and the LDPC code usually uses the logarithmic domain Belief Propagation (BP) principle to realize iterative decoding, and the frequency estimation usually uses The maximum search of the method introduces a high amount of calculation, and under the condition of low signal-to-noise ratio, more iterations are required to make the decoder and synchronizer converge

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