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Carrier synchronization method of MPSK system based on maximum likelihood estimation

A technology of maximum likelihood estimation and carrier synchronization, applied in transmission systems, digital transmission systems, modulated carrier systems, etc., it can solve the problems of limited frequency offset range, insufficient estimation accuracy, and large amount of computation, and achieve a wide frequency offset estimation range. , the amount of calculation is small, the effect of good estimation performance

Inactive Publication Date: 2010-01-13
BEIJING INSTITUTE OF TECHNOLOGYGY
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Problems solved by technology

[0022] However, these estimation methods are either too computationally intensive, or the estimation accuracy is not high enough, are not suitable for low signal-to-noise ratio situations, or have a limited frequency offset range, and are not suitable for engineering implementation.

Method used

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  • Carrier synchronization method of MPSK system based on maximum likelihood estimation
  • Carrier synchronization method of MPSK system based on maximum likelihood estimation
  • Carrier synchronization method of MPSK system based on maximum likelihood estimation

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Embodiment

[0123] Assuming a BPSK modulation system, the symbol rate is f s =1 / T s =1MBaud, the maximum frequency deviation is f max = 20kHz. For burst mode, the frame header length is L 0 =128; For continuous mode, assume that the data length used to estimate the frequency offset and phase offset is also K=L 0 = 128. The specific implementation steps of carrier synchronization are as follows:

[0124] Step 1: Remove the baseband signal r after down-conversion k The modulation information in, get a single carrier signal h which is only polluted by additive noise k .

[0125] For burst communication mode, the frame header is known to the receiver, and the local frame header of the receiver is BPSK mapped as s k , K=0,1,...,L0-1, the frame header signal after removing the modulation information is

[0126] h k = r k s k * , k = 0,1 , . . . , L 0 - 1 - - - ( 30 )

[0127] For continuous communication mode, the data is unknown to...

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Abstract

The invention discloses a carrier synchronization method of an MPSK system based on maximum likelihood estimation, belonging to the technical field of the modulation and the demodulation of digital communication and comprising the following steps: firstly, eliminating the modulation information of a receiving signal to obtain a single carrier only polluted by noises; then, utilizing a fast search algorithm based on dichotomy to obtain maximum likelihood estimation values of frequency deviation and phase deviation; and then, compensating an original receiving signal by the maximum likelihood estimation values to complete carrier synchronization and demodulation, wherein the estimation and compensation method needs to be continuously used for tracking the carrier synchronization in the demodulation process. A simulation result shows that the carrier synchronization method has very good property approximated to the Cramer-Rao lower bound, very little calculation amount and very wide frequency deviation estimation range and is a practical carrier synchronization method.

Description

Technical field [0001] The invention relates to a carrier synchronization method of an M level phase shift keying (MPSK) system, and belongs to the technical field of modulation and demodulation in digital communication. Background technique [0002] In satellite communication, deep space communication and various wireless communication systems, MPSK signal modulation is one of the most commonly used modulation methods because of its constant envelope and high power efficiency. Due to the adoption of various advanced channel coding, the communication system has good performance under low signal-to-noise ratio, but it also puts forward higher requirements for MPSK system, that is, it can work reliably under low signal-to-noise ratio. Among them, the most critical problem to be solved is the carrier synchronization problem. [0003] The communication system includes two transmission modes: burst communication and continuous communication. The data of burst communication is composed...

Claims

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Application Information

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IPC IPC(8): H04L27/227
Inventor 卜祥元刘策伦安建平王爱华
Owner BEIJING INSTITUTE OF TECHNOLOGYGY
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