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Turbo method used for OFDM frequency synchronization

A frequency synchronization and frequency offset technology, applied in the field of OFDM frequency synchronization, can solve the problems of poor performance, small range, small estimation range, etc., and achieve the effect of strong practical value, improved performance, and improved accuracy

Inactive Publication Date: 2006-04-05
UNIV OF ELECTRONICS SCI & TECH OF CHINA
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Problems solved by technology

There are advantages and disadvantages for choosing a large or small differential distance d: if the differential distance d is selected to be large, the advantage is that the accuracy of frequency deviation estimation is high, but the disadvantage is that the range of frequency deviation estimation is small; if the differential distance d If d is smaller, the advantage is that the range of frequency offset estimation is large, but the disadvantage is that the accuracy of frequency offset estimation is low, see the literature Tufvesson, F.; Edfors, O.; Faulkner, M.; "Timeand fiequency synchronization fbr OFDM using PN-sequence preambles," Vehicular Technology Conference, 1999. VTC 1999-Fall. IEEE VTS 50th, Volume: 4, 1999, Page(s): 2203-2207 vol.4
[0010] The conventional OFDM frequency synchronization method only estimates the frequency offset once, so it can only choose a fixed differential distance d, so it must have the above-mentioned shortcomings of small estimation range or low estimation accuracy, resulting in poor performance

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  • Turbo method used for OFDM frequency synchronization
  • Turbo method used for OFDM frequency synchronization
  • Turbo method used for OFDM frequency synchronization

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[0046] The implementation steps of this patent under a specific OFDM configuration are given below. It should be noted that the parameters in the following examples do not affect the generality of this patent.

[0047] Assuming that the OFDM useful symbol length is N=4096, and ρ=1, it means that the transmitted data is completely a training sequence signal. It is known that the m-sequence with a sequence selection period of 127 is denoted as m[i]i∈[0, 126], then the number of repetitions of the m-sequence that can be contained in the training sequence (that is, the number contained in one OFDM symbol) It is 4096 / 127=32. Then the transmitting end repeats the m-sequence 33 times and puts it into one OFDM symbol (the last m-sequence will be truncated) and transmits it. The receiving end first obtains time synchronization, that is, finds the starting point of the OFDM symbol, and the OFDM useful data is recorded as d[i] i∈[0, 4095]; at the same time, it also finds the starting p...

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Abstract

At sending end, repearing a known sequence for multiple times continuously constitutes a training sequence. Emission data are constituted by weighted addition in point to point between the said training sequence and OFDM original data in the same number of points. Multiple times of evaluation of frequency shift are obtained by calculating difference correlation from received data in different difference intervals for multiple times. After each evaluation, compensation of frequency shift is carried out for the data, and after compensation, calculation of frequency shift is carried out for data again. Thus, the abobve operations are repeated circularly, till evaluated frequency shift is less than a threshold. The method possesses advantages of evaluating frequency shift in wide range and high accuracy.

Description

technical field [0001] The invention belongs to the field of wireless communication or wired communication, and particularly relates to a method for OFDM frequency synchronization. Background technique [0002] OFDM has attracted more and more attention due to its high data transmission rate, strong anti-multipath interference ability, and high spectrum efficiency. It has been successfully used in wired and wireless communications. Such as: ADSL (Asymmetric Digital Subscriber Line), Wireless LAN, DAB (Digital Audio Broadcasting), DVB, EEE802.11a and HyperLAN / 2. In the IEEE802.16 currently being formulated, OFDM technology is also involved in a large number. OFDM, a new modulation technology, can also be used in a new generation of mobile communication systems. The use of OFDM technology will greatly improve the transmission data rate and spectral efficiency of the new generation of mobile communication systems, and has a good ability to resist multipath, co-channel interf...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04J11/00H04L27/32H04L7/00H03M13/23
Inventor 严春林唐友喜房家奕李少谦
Owner UNIV OF ELECTRONICS SCI & TECH OF CHINA
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