Frequency offset estimation method based on reference sequence

A reference sequence and frequency offset estimation technology, which is applied in the field of frequency offset estimation based on reference sequences, can solve the problems of restricting the application range of algorithms, CP multipath signal pollution, narrow frequency offset tracking range, etc. Narrow, expanded frequency offset estimation range, strong practicability

Inactive Publication Date: 2012-05-30
SHANGHAI RES CENT FOR WIRELESS COMM
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AI Technical Summary

Problems solved by technology

[0005] In the existing methods for estimating fractional frequency offset, although the frequency offset tracking range of the CP-based method is the entire fractional frequency offset distribution range, the estimation accuracy of the CP is vulnerable to the multipath signal pollution of the previous OFDM symbol. is not high; and the existing estimation method based on the reference sequence, because the reference sequence is not necessarily on the adjacent OFDM symbols, resulting in a very narrow frequency offset tracking range, which cannot satisfy the fractional frequency offset estimation range of one-half The requirement of subcarrier spacing restricts the application range of the algorithm
Therefore, the traditional method of estimating frequency offset by reference sequence has obvious deficiencies

Method used

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  • Frequency offset estimation method based on reference sequence
  • Frequency offset estimation method based on reference sequence
  • Frequency offset estimation method based on reference sequence

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Embodiment 1

[0021] This embodiment provides a frequency offset estimation method based on a reference sequence, the flow of the method is as follows figure 1 shown, including:

[0022] (1) The receiving end receives the time-domain OFDM signal sent by the sending device, and then performs processing such as removing CP and FFT on the OFDM signal to obtain a frequency-domain signal;

[0023] (2) Extract the data of the reference sequence position from the frequency domain signal, and obtain the frequency domain reference sequence Y corresponding to the uth OFDM symbol containing the reference sequence in the time dimension u (k), u={p, q, m, n}, and the sampling interval L of adjacent OFDM subcarriers in the time dimension p，q and L m，n , L p，q for Y p (k) and Y q (k) The number of time interval samples, L m，n for Y m (k) and Y n (k) time interval sampling number;

[0024] (3) Obtain the known pilot sequence X according to the parameter configuration u (k), u={p, q, m, n};

[00...

Embodiment 2

[0030] This embodiment provides an application of the reference sequence-based frequency offset estimation method of the present invention in a specific OFDM system.

[0031] The OFDM system is an LTE system, and its system configuration is:

[0032] In the LTE system, each resource block occupies a frequency subcarriers, occupying time OFDM symbols, extended CP (that is, a resource block contains 6 OFDM symbols), the CP length is 1 / 4 of the FFT size, that is, the symbol CPs are all long CPs at this time; under the normal CP (That is, one subframe includes 7 OFDM symbols), at this time, the first symbol CP is a long CP, and the remaining 6 symbols CP are short CPs. The subcarrier spacing Δf of the LTE / LTE-A system c =15kHz, the time length of OFDM symbol (excluding CP) is 66.67μs. In the case of normal CP in the LTE / LTE-A system, the CP is divided into long CP and short CP. The duration of the long CP is 5.21 μs, and the duration of the short CP is 4.69 μs. In the ti...

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Abstract

The invention discloses a frequency offset estimation method based on a reference sequence. The method comprises the following steps: (1) acquiring two pairs of reference sequences with time interval difference from an OFDM signal received by a receiving end; (2) according to a configuration parameter of an OFDM system, acquiring two pairs of local pilot frequency sequences corresponding to the two pairs of reference sequences; (3) through carrying out difference product on each pair of reference sequence and a corresponding local pilot frequency sequence, obtaining phase information of each pair of reference sequence; (4) carrying out conjugate multiplying on phase information of the two pairs of reference sequences to obtain new phase information; (5) according to new phase information, carrying out frequency offset estimation to obtain a frequency offset estimated value. The method is suitable for frequency tracking of the OFDM system based on the reference sequence, a problem of a narrow frequency offset tracking scope of a traditional method is solved, when a frequency offset estimation scope is enlarged, excellent estimation performance can be ensured simultaneously, algorithm complexity is low, and practicality is strong.

Description

technical field [0001] The invention belongs to the technical field of communication, and relates to a frequency offset estimation method based on a reference sequence. Background technique [0002] Frequency Division Multiplexing (Orthogonal Frequency Division Multiplexing, OFDM) technology has become a key technology in 3G and 4G wireless communication systems, and is a multi-carrier communication technology that can effectively combat inter-symbol interference. Different from the traditional frequency division multiplexing transmission method, the subcarriers of the OFDM system are orthogonal to each other, and the frequency spectrum of each subcarrier partially overlaps, so that the frequency domain can be utilized to a greater extent. OFDM technology has been successfully applied in symmetrical digital loop (Asymmetric Digital Subscriber Line, ADSL), wireless local loop (wireless Local Loop, WLL), digital audio broadcasting (Digital Audio Broadcasting, DAV), wireless lo...

Claims

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Application Information

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IPC IPC(8): H04L27/26
Inventor 贾国庆熊勇杨秀梅朱磊雷舒培
Owner SHANGHAI RES CENT FOR WIRELESS COMM
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