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Method for synchronizing orthogonal frequency division multiplexing (OFDM) system time domain through utilizing constant amplitude zero auto correlation (CAZAC) sequence

A time domain synchronization and sequence technology, applied in the field of time domain synchronization of OFDM systems, can solve the problems of increasing time and system implementation complexity, and achieve the effects of reducing implementation complexity, improving speed, and accurate timing synchronization.

Active Publication Date: 2013-02-13
SHANGHAI INST OF MICROSYSTEM & INFORMATION TECH CHINESE ACAD OF SCI
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Problems solved by technology

Most of the current synchronization algorithms complete the integer frequency offset estimation in the frequency domain. However, the fast Fourier transform operation will significantly increase the time required for synchronization and the complexity of the system implementation. Synchronization Algorithm in Time Domain

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  • Method for synchronizing orthogonal frequency division multiplexing (OFDM) system time domain through utilizing constant amplitude zero auto correlation (CAZAC) sequence
  • Method for synchronizing orthogonal frequency division multiplexing (OFDM) system time domain through utilizing constant amplitude zero auto correlation (CAZAC) sequence
  • Method for synchronizing orthogonal frequency division multiplexing (OFDM) system time domain through utilizing constant amplitude zero auto correlation (CAZAC) sequence

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[0028] Below in conjunction with specific embodiment, further illustrate the present invention. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the teachings of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

[0029] Embodiments of the present invention relate to a method for time domain synchronization of an OFDM system using a CAZAC sequence, such as figure 1 shown, including the following steps:

[0030] (1) Construct a CAZAC sequence of length N, where N is the length of an OFDM symbol, which can be expressed as:

[0031] Among them, j is the imaginary unit, r=N-1, k=0,1,...,N-1;

[0032] Then add a cyclic prefix and a cycli...

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Abstract

The invention relates to a method for synchronizing an orthogonal frequency division multiplexing (OFDM) system time domain through utilizing the constant amplitude zero auto correlation (CAZAC) sequence. The method comprises the following steps that: the CAZAC sequence is utilized to construct a training sequence with repeated front and rear structures in the time domain; a weighting sequence which is as long as the training sequence is constructed; the weighting sequence is multiplied by the original training sequence so as to obtain a new training sequence; at a receiving end, the pseudo-noise (PN) sequence part of the known weighting sequence is correspondingly multiplied by a part which is weighted by the PN sequence and is in the received training sequence for summation, so that a timing metric function is obtained, and the symbol timing synchronization is completed through searching the maximum value; a decimal frequency deviation estimation is obtained through calculation; and an integral frequency deviation judgment function is constructed, and the integral frequency deviation estimation is completed in the time domain. With the adoption of the method, the influences of a symmetrical sequence structure, auxiliary peaks which are caused by cyclic prefix and a peak platform in the conventional synchronizing method are eliminated, so that the timing synchronizing accuracy is high.

Description

technical field [0001] The invention relates to a synchronization method in the technical field of OFDM, in particular to an OFDM system time domain synchronization method using a CAZAC sequence. Background technique [0002] Orthogonal Frequency-Division Multiplexing (OFDM) technology has not only been widely used in the field of broadcast digital audio and video, but also has become a part of the wireless local area network standard and is the key to the fourth generation of mobile communication technology. OFDM technology is a multi-carrier modulation method. By serial-to-parallel conversion of high-rate data streams, the duration of data symbols on each subcarrier is relatively increased, thereby effectively reducing the inter-symbol frequency caused by the time dispersion of the wireless channel. interference. There is orthogonality among the subcarriers of the OFDM system, which allows the subchannel spectrum to overlap with each other. Therefore, compared with the c...

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Application Information

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IPC IPC(8): H04L27/26H04L25/03
Inventor 张力汪涵高丹王营冠
Owner SHANGHAI INST OF MICROSYSTEM & INFORMATION TECH CHINESE ACAD OF SCI
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