ofdm symbol synchronization position search method

Abstract

The invention discloses a method for searching for a synchronous position of an OFDM symbol, comprising: detecting a P1 symbol, detecting a correlation value according to a correlation operation result of an input signal, and obtaining a synchronous position of a P1 symbol, which is a coarse synchronous position; confirming a P1 symbol, After confirming the P1 symbol by comparing the P1 symbol to confirm the correlation peak value and the predetermined threshold TH_valid, perform a synchronization position search to obtain the precise synchronization position of the P1 symbol; decode the P1 symbol, and use the P1 symbol to confirm that the estimated integer frequency deviation is compensated for the frequency deviation of the input signal The P1 symbol is decoded, and the S1 decoding correlation peak value and the S2 decoding correlation peak value are compared with their corresponding predetermined threshold TH1 and predetermined threshold TH2 respectively to complete the capture of the P1 symbol. The method of the present invention improves the synchronization error by adopting the synchronization position search method, reduces the bit error rate of P1 symbol decoding, thereby reduces the P1 symbol capture time and the system capture time.

Description

technical field [0001] The invention relates to the field of communication, in particular to a method for searching for a synchronous position of an OFDM (orthogonal frequency division multiplexing) symbol of the second-generation European terrestrial digital television (DVB-T2). Background technique [0002] OFDM technology is widely used in modern communication systems. As the second generation digital terrestrial television standard in Europe, DVB-T2 ("Digital Video Broadcasting (DVB); Frame structure channel coding and modulation for a second generation digital terrestrial television broadcasting system (DVB-T2)," ETSI EN302755), inherited the first In the OFDM technology of the first generation standard DVB-T, the basic unit of data is called a T2 frame. like figure 1 Shown is a structure diagram of a T2 frame, and each frame includes a P1 preamble symbol, a P2 preamble symbol, and a data symbol immediately thereafter. P1 symbol synchronization of DVB-T2 system is th...

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Problems solved by technology

[0009] The above correlation peak method of P1 symbol detection can resist all kinds of serious interference and noise, but its disadvantage is that the error of the synchronization position is very large

J.G.Doblado (“Coarse time synchronization for DVB-T2,” IEEElec.letters, Vol.46, No.11, May 2010) and M.Rotoloni, (“On correlation-based synchronization for DVB-T2,” IEEE Comm.Letters, vol. .14, No.3, pp.248-250, Mar.2010) respectively proposed methods to improve the synchronization error, but in the case of severely interfered channels, especially when the two-path channel interference is 0dB, there is still a large synchronization error

[0010] On the other hand, it can be seen from the structure of the P1 symbol that the usual cyclic prefix protection technology is not used for the P1 symbol. When there is a synchronization error, the FFT starts from the wrong position, and the signal with the length of the synchronization error is all noise (non-cyclic signal )

When the synchronization error is large, too much noise makes the bit error rate of S1 and S2 decoding high

As a result, the P1 symbol capture time is extended, increasing the system capture time

[0011] How to solve the problem that the system capture time is too long when the P1 symbol synchronization time error is large is still a problem to be solved

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