Carrier phase correcting method for QAM modulation

A carrier phase, 1.16-QAM technology, applied in multi-carrier systems, shaping networks in transmitters/receivers, baseband system components, etc., to achieve wire-speed processing, accurate and fast phase estimation, and reduce dependencies

Active Publication Date: 2011-05-11
WUHAN POST & TELECOMM RES INST CO LTD
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Problems solved by technology

[0006] The technical problem to be solved by the present invention is how to redu...

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  • Carrier phase correcting method for QAM modulation
  • Carrier phase correcting method for QAM modulation
  • Carrier phase correcting method for QAM modulation

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Embodiment Construction

[0027] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0028] Similar to other digital modulation methods, the QAM transmit signal set and the corresponding receive signal set can be conveniently represented by a constellation diagram, and each constellation point on the constellation diagram corresponds to a signal in a respective signal set, such as image 3 , Figure 4 As shown, in the 16-QAM transmitted signal set and the corresponding received signal set constellation diagram, the constellation points of the 16 signals are distributed in a rectangular array, in which the four constellation points D1, D2, D3, and D4 located in the center define is class4, the four constellation points A1, A2, A3, A4 located in the outermost periphery are defined as class1, and the remaining eight constellation points B1, B2, B3, B4 and C1, C2, C3, C4 are respectively located in the four corners of two squares...

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Abstract

The invention discloses a carrier phase correcting method based on QAM modulation, which comprises the steps of: forming a signal set S1 after taking the biquadrate of all signals S0j in a received signal set S0, calculating a correcting angle of theta1-phi of the received signal corresponding to each point on the class1 in the S1, correcting the S1 signal so as to acquire an S2, calculating to obtain the minimum value of a real field of the received signal which is subjected to biquadrate extraction and corresponds to each point on the class 1, setting the minimum value as a selected threshold value limit, dividing the signals in the S2 into I, II and III three areas on the basis of the condition as follows: Rcostheta is less than limit, Rcostheta is more than limit and Rsintheta is morethan 0, Rcostheta is more than limit and Rsintheta is less than 0, performing the maximum likelihood fit on each received signal in the I, II and III areas according to three angles of phi, 4*atan(1/3) and -4*atan(1/3), calculating a second correcting angle beta, and correcting the angles of (theta1-phi+beta) of all the received signals in the signal set S0. In the method provided by the invention, the biquadrate operation and the correcting operation need not be performed twice, so the operand is greatly reduced, the dependence on hardware is reduced and the digital circuit linear-speed treatment is convenient to perform.

Description

technical field [0001] The invention relates to QAM modulation and demodulation technology, in particular to a carrier phase correction method for data at a receiving end when a 16-QAM modulation mode is adopted. Background technique [0002] QAM (Quadrature Amplitude Modulation) quadrature amplitude modulation is a modulation method of digital signals. During the modulation process, the amplitude and phase of the carrier signal are used to represent different digital bit codes at the same time, and the multi-ary system is combined with the quadrature carrier technology. Up, and further improve the utilization rate of the frequency band. [0003] Carrier phase recovery is a technical difficulty in coherent optical communication. Since the optical phase-locked loop is not practical at present, it is relatively feasible to compensate by digital processing. The phase estimation (PE phase estimation) algorithm has been studied more in recent years. Its main purpose is to relax ...

Claims

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Application Information

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IPC IPC(8): H04L27/36H04L25/03
Inventor 刘武贺志学杨铸
Owner WUHAN POST & TELECOMM RES INST CO LTD
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