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

A technique of statistical averaging and carrier synchronization, applied in multi-frequency code systems and other directions, and can solve problems such as the inability to guarantee maximum likelihood estimation

Inactive Publication Date: 2007-12-12
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

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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 accompanying drawings and embodiments.

[0072] The noise performance of the improved cyclic prefix based carrier frequency blind synchronization method 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 fields of digital communication and radar. Background technique [0002] In the digital terrestrial television broadcasting system based on OFDM transmission technology, since the signal adopts mutually orthogonal multi-carrier modulation technology, it is more sensitive to the problem of time and phase synchronization, especially for the synchronization requirements of carrier frequency and phase. Carrier systems are also more stringent than carrier systems. [0003] If the carrier frequencies at both ends of the transceiver are out of sync, in addition to causing certain attenuation and phase distortion to the direct wave signal, it will also cause mutual interference between subcarriers, thus destroying the orthogonality between subcarriers in the OFDM system. If the receiving end Failure to take strict synchronization measures will have a serious impact on the performance of the entire system. [0004] Referring to th...

Claims

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Application Information

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Patent Type & Authority Patents(China)
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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