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OFDM (Orthogonal Frequency Division Multiplexing) time synchronization algorithm based on conjugate symmetric sequence

A conjugate symmetry and time synchronization technology, applied in the field of OFDM, can solve the problems of OFDM frequency deviation, affecting OFDM time synchronization, peak-to-average ratio, etc.

Inactive Publication Date: 2011-09-14
SHANGHAI INST OF MICROSYSTEM & INFORMATION TECH CHINESE ACAD OF SCI
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Problems solved by technology

However, OFDM has the problems of being easily affected by frequency deviation and the peak-to-average ratio is too high, which seriously affects the time synchronization of OFDM.

Method used

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  • OFDM (Orthogonal Frequency Division Multiplexing) time synchronization algorithm based on conjugate symmetric sequence
  • OFDM (Orthogonal Frequency Division Multiplexing) time synchronization algorithm based on conjugate symmetric sequence
  • OFDM (Orthogonal Frequency Division Multiplexing) time synchronization algorithm based on conjugate symmetric sequence

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Embodiment 1

[0044] Such as figure 1 Shown, the OFDM time synchronization algorithm based on the conjugate symmetric sequence of the present invention comprises the following steps:

[0045]1) Construct a sequence with conjugate symmetry in the time domain, the sequence length is N, satisfying

[0046] x(n)=conj(x(N-n)), n=1, ..., N / 2-1(1)

[0047] Where conj represents the conjugate operation;

[0048] Transmitting the OFDM signal with the sequence leader of the conjugate symmetry property through the transmitter;

[0049] 2) For the signal received by the receiver, the calculation of the timing measurement function is carried out:

[0050] timing metric function M ( d ) = | P ( d ) | 2 ( R ( ...

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Abstract

The invention relates to an OFDM (Orthogonal Frequency Division Multiplexing) time synchronization algorithm based on a conjugate symmetric sequence. The OFDM time synchronization algorithm comprises the steps of constructing a sequence with conjugate symmetry; carrying out symmetric related calculation at a receiving end by using the conjugate symmetry of the sequence so as to obtain a related peak value of a timing measurement function; and determining a beginning position of an OFDM signal by using the position of the related peak value so as to finish time synchronization. By using the invention, the adverse effect on the time synchronization, caused by a cyclic prefix and the conjugate symmetry of the sequence, is overcome, and higher timing accuracy is obtained; and the OFDM time synchronization algorithm based on the conjugate symmetric sequence, provided by the invention, can be effectively used for the time synchronization of the OFDM system under a multipath channel.

Description

technical field [0001] The invention belongs to the technical field of OFDM, in particular to an OFDM system time synchronization algorithm based on a conjugate symmetric 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 low-rate symbols...

Claims

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Application Information

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IPC IPC(8): H04L27/26
Inventor 汪涵朱磊基施玉松张力张士柱
Owner SHANGHAI INST OF MICROSYSTEM & INFORMATION TECH CHINESE ACAD OF SCI
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