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Synchronous method of large search range OFDM system carrier based on statistical uniform

A search range and statistical averaging technology, applied in the direction of multi-frequency code system, etc., can solve the problem that the maximum likelihood estimation cannot be guaranteed

Inactive Publication Date: 2006-09-20
BEIJING INSTITUTE OF TECHNOLOGYGY
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Problems solved by technology

And when the transmission channel is not AWGN, (8) can not guarantee the maximum likelihood estimation

Method used

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  • Synchronous method of large search range OFDM system carrier based on statistical uniform
  • Synchronous method of large search range OFDM system carrier based on statistical uniform
  • Synchronous method of large search range OFDM system carrier based on statistical uniform

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Embodiment Construction

[0071] The present invention will be further described below in conjunction with the drawings and embodiments.

[0072] The noise performance of the improved blind synchronization method of carrier frequency based on cyclic prefix can be realized by analyzing the received signal r(k). According to the system model defined above, within the OFDM bandwidth, the received signal r(k) is actually the superposition of the transmitted signal s(k) and the noise signal n(k), namely:

[0073] r(k)=s(k)+n(k) (20)

[0074] Note that the above signals can actually be regarded as a set of random complex number sequences, assuming that the variances of the real and imaginary parts of s(k) and n(k) are:

[0075] Var [ Re ( s 2 ( k ) ) ] = Var [ Im ...

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Abstract

Because data symbol is independent identically distributed random data symbol, if the sub-carrier is big enough, the phase difference to the number K sub-carrier caused by carrier shift and differential modulation is a random phase evenly distributed on (-pi,pi). If the value choice interval of carrier sequence number is supposed to be (-W,-W+1,...,-1,0,1,...,W-1,W), the carrier shift can be estimated by making a statistical average for all carriers. In order to improve estimation accuracy of theta z, a process for averaging multi continuing OFDM data symbols can be adopted.

Description

Technical field [0001] The invention relates to the field of digital communication and radar. Background technique [0002] In the digital terrestrial television broadcasting system based on OFDM transmission technology, because the signal uses orthogonal multi-carrier modulation technology, it is more sensitive to time and phase synchronization issues, especially the synchronization requirements of carrier frequency and phase. The carrier system is also more stringent. [0003] If the carrier frequency at both ends of the transceiver is desynchronized, in addition to causing certain attenuation and phase distortion of the direct wave signal, it will also cause mutual interference between sub-carriers, thereby destroying the orthogonality between sub-carriers in the OFDM system. Failure to take strict synchronization measures will have a serious impact on the performance of the entire system. [0004] Refer to as figure 1 In the OFDM system shown, an OFDM symbol block output by ...

Claims

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Application Information

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IPC IPC(8): H04L27/26
Inventor 陶然张颖辉陈恩庆王越
Owner BEIJING INSTITUTE OF TECHNOLOGYGY
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