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High-order quadrature amplitude modulation (QAM) carrier synchronization method based on coding and pilot frequency joint assistance

A coding-assisted, carrier synchronization technology, applied in multi-carrier systems, baseband system components, shaping networks in transmitters/receivers, etc., can solve the problems of long acquisition time, high complexity, and large pilot frequency requirements.

Inactive Publication Date: 2012-01-25
UNIV OF ELECTRONICS SCI & TECH OF CHINA
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  • Application Information

AI Technical Summary

Problems solved by technology

The existing acquisition and synchronization methods under extremely low spectral density require long acquisition time, high complexity, and a large number of pilots

Method used

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  • High-order quadrature amplitude modulation (QAM) carrier synchronization method based on coding and pilot frequency joint assistance
  • High-order quadrature amplitude modulation (QAM) carrier synchronization method based on coding and pilot frequency joint assistance
  • High-order quadrature amplitude modulation (QAM) carrier synchronization method based on coding and pilot frequency joint assistance

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Experimental program
Comparison scheme
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Embodiment Construction

[0068] The following is the specific implementation of the method.

[0069] 1. Channel coding

[0070] The first step is to construct an LDPC code without variable nodes with a degree of 1; the second step is to map all variable bits connected to check nodes in the LDPC code into Hadamard codes (with information bits removed).

[0071] 2. Insert pilot

[0072] Insert the pilot as shown in the figure. Put the general pilot at the beginning of the frame and half at the end of the frame.

[0073] 3. Coarse synchronization

[0074] Rough estimation of frequency and phase according to the following two formulas

[0075] Δ f ^ Coarse = 1 2 π DT s arg { Σ k = 1 N ...

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Abstract

The invention discloses a carrier synchronization method based on coding and pilot frequency joint assistance. The method comprises the steps that: first, an LDPC-Hadamard code with a short code length and low code rate is designed, an optimal pilot frequency structure is designed based on a valuation theory, a carried rough synchronization method is designed based on correlation functions and ideas, and the valuation precision can reach a Cramer-Rao bound (CRB); and then soft demodulation and decoding operation are carried out on a roughly synchronized signal, soft modulation is carried out on soft information which is output after decoding, and the fine synchronization of carrier is carried out with the soft modulation signal based on expectation maximum algorithm. Simulation shows that the high-order QAM carrier synchronization method based on coding and pilot frequency joint assistance can greatly improve the carrier synchronization accuracy and scope, reduce the decoding times of a decoder, and work in deep space, a satellite and other communication systems with low signal-to-noise ratio.

Description

technical field [0001] The invention relates to a carrier synchronization method suitable for communication systems with low signal-to-noise ratio, such as digital communication systems such as satellites and deep space. This method gives the pilot design method, and designs a coarse synchronization method that can approach the Claro-American boundary in the environment of low signal-to-noise ratio; and performs fine synchronization through the pilot frequency and the soft information output by the decoder . This method can greatly improve the estimation accuracy of synchronization parameters, and solve the synchronization problem in communication systems with low signal-to-noise ratio and large dynamic range. Background technique [0002] Synchronization of signals is an important practical issue in the design of communication systems. If the synchronization performance of a communication system is degraded, it will directly cause the performance of the entire communicati...

Claims

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Application Information

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IPC IPC(8): H04L27/34H04L25/03H04L1/00
Inventor 晏辉唐发建史治平张忠培
Owner UNIV OF ELECTRONICS SCI & TECH OF CHINA
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