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Symmetrical-constant amplitude zero auto correlation (CAZAC)-sequence-based orthogonal frequency division multiplexing (OFDM) system synchronization method

A sequential and symmetric technology, applied in the field of OFDM system synchronization based on symmetric CAZAC sequence, can solve problems such as poor synchronization performance, and achieve the effects of eliminating secondary peaks, accurate timing synchronization, and good autocorrelation

Active Publication Date: 2014-03-26
SHANGHAI INST OF MICROSYSTEM & INFORMATION TECH CHINESE ACAD OF SCI
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Problems solved by technology

Among them, the non-data-assisted algorithm does not need to design an additional synchronization sequence, which saves system bandwidth and improves bandwidth utilization, but the synchronization performance is worse than that of the data-assisted algorithm.

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  • Symmetrical-constant amplitude zero auto correlation (CAZAC)-sequence-based orthogonal frequency division multiplexing (OFDM) system synchronization method
  • Symmetrical-constant amplitude zero auto correlation (CAZAC)-sequence-based orthogonal frequency division multiplexing (OFDM) system synchronization method
  • Symmetrical-constant amplitude zero auto correlation (CAZAC)-sequence-based orthogonal frequency division multiplexing (OFDM) system synchronization method

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Embodiment Construction

[0031] 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.

[0032] Embodiments of the present invention relate to a method for synchronizing an OFDM system based on a symmetric CAZAC sequence, such as figure 1 As shown, it specifically includes the following steps:

[0033] (1) Construct a length N in the frequency domain 1 =N / 4 CAZAC sequences, where N is the length of the synchronization sequence.

[0034] This sequence can be expressed as:

[0035] Where j is the imaginary unit...

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Abstract

The invention relates to a symmetrical-constant amplitude zero auto correlation (CAZAC)-sequence-based orthogonal frequency division multiplexing (OFDM) system synchronization method, which comprises the following steps of: constructing a CAZAC sequence with a quadruple symmetrical structure in a time domain; correspondingly multiplying the first and third parts of the CAZAC sequence by using a complex pseudo-noise (PN) sequence to obtain a synchronization sequence; correspondingly multiplying the first and fourth parts of a received signal by using a known PN sequence to obtain a timing metric function; searching for a maximum value of the timing metric function to finish timing synchronization; obtaining decimal frequency offset by utilizing a phase difference between front and rear symmetrical sequences; and obtaining integral frequency offset by utilizing the shift of the CAZAC sequence in a frequency domain. By the method, the influence, caused by the existence of the symmetrical structure and cyclic prefix of the conventional sequence, of side peaks and a peak platform on timing is eliminated, so the timing is more accuracy. A frequency offset estimate has lower standard deviation, and simultaneously, the range of the frequency offset estimate is wider and can reach the whole system bandwidth.

Description

technical field [0001] The invention relates to a synchronization method in the technical field of OFDM, in particular to an OFDM system synchronization method based on a symmetric CAZAC sequence. Background technique [0002] Since the 1980s, OFDM (orthogonal frequency division multiplexing 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. [0003] Orthogonal Frequency Division Multiplexing (OFDM) technology is a multi-carrier modulation method, which overcomes frequency selective fading of channels by reducing and eliminating the influence of intersymbol crosstalk. Its basic principle is to decompose the data stream into several sub-bit streams, so that each sub-data stream will have a much lower bit rate, and use the low-rate multi-state symbols formed by such a low bit rate to modulate the corresponding sub-carriers, A transmission system in which multiple ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04L27/26
Inventor 汪涵朱磊基施玉松张力张士柱李凤荣邢涛王营冠
Owner SHANGHAI INST OF MICROSYSTEM & INFORMATION TECH CHINESE ACAD OF SCI
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