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Frequency deviation estimating method in QAM (quadrature amplitude modulation) communication system

A communication system and offset estimation technology, which is applied in the field of frequency offset estimation under the quadrature amplitude modulation (QAM) mode, and can solve problems such as unfavorable engineering implementation and loss of signal accuracy.

Active Publication Date: 2012-06-13
安徽省菲特科技股份有限公司 +1
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Problems solved by technology

The existing frequency offset estimation technology performs complex processing such as arctangent operation on the result of multiplying the received symbol and the corresponding hard-judgment conjugate, which is not conducive to engineering implementation, and at the same time, the accuracy of the signal will be lost

Method used

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  • Frequency deviation estimating method in QAM (quadrature amplitude modulation) communication system
  • Frequency deviation estimating method in QAM (quadrature amplitude modulation) communication system
  • Frequency deviation estimating method in QAM (quadrature amplitude modulation) communication system

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Embodiment Construction

[0044] see figure 1, in the present embodiment, at first carry out frame header detection, what frame header adopts is by four 11-bit long Barker codes, two 7-bit long Barker codes and two 3-bit long Barker codes according to (1 1 1-1-1 -1 1-1-1 1-1), (1 1 1-1-1-1 1-1-1 1-1), (1 1 1-1-1 1-1), (1 1-1 ), (1 1 1-1-1-1 1-1-1 1-1), (1 1 1-1-1-1 1-1-1 1-1), (1 1 1-1-1 1-1), (1 1-1) are concatenated to form a 64-bit frame header, in which the values ​​of the first 32 bits and the last 32 bits are the same; after the frame header is detected, the preliminary frequency offset estimation and detailed frequency estimation are carried out synchronously. Partial;

[0045] The method of preliminarily estimating the frequency offset is as follows:

[0046] Step 1: Assume that the Barker code of the original frame header is x 1 , x 2 ,...,x 32 , x 1 , x 2 ,...,x 32 , assuming that the frequency offset of the system is Δf and the phase offset of the system is The symbol rate of the ...

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Abstract

The invention discloses a frequency deviation estimating method in the QAM (quadrature amplitude modulation). The frequency deviation estimating method is characterized by including steps of carrying out frame synchronization by means of relative detection and picking up frame header codes; pairwise corrugating and multiplying the frame header codes with the interval 32 for rough frequency deviation estimation,; then corrugating and multiplying two adjacent frame header codes in pairwise for fine frequency deviation estimation; and combining the rough frequency deviation estimation and the fine frequency deviation estimation to obtain accurate frequency deviation estimation. By the aid of the frequency deviation estimating method, high-order QAM modulation accuracy and frequency deviation estimating accuracy on the condition of low signal to noise ratio in the QAM communication system are effectively increased, and the frequency deviation estimating range is broadened.

Description

technical field [0001] The invention relates to the field of wireless communication, in particular to a frequency offset estimation method in a quadrature amplitude modulation (QAM) mode. technical background [0002] In order to further increase the transmission rate of the wireless communication system, high-order modulation is widely used in the communication system. The constellation diagram of the high-order quadrature amplitude modulation QAM signal is relatively dense and distributed on multiple circles with different radii. When there is a frequency offset, there is a tendency of confusion between adjacent constellation points in the constellation diagram. When the frequency offset is large, it will cause a large number of demodulation errors, which will seriously deteriorate the link performance. Therefore, when there is a frequency offset in the modulated signal, it is very necessary to obtain the frequency offset value of the signal to perform frequency compensat...

Claims

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Application Information

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IPC IPC(8): H04L25/03H04L25/02H04L27/34
Inventor 吴端陶洪刘洋赵科
Owner 安徽省菲特科技股份有限公司
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