OFDM-based symbol synchronization position searching method

Abstract

The invention discloses an OFDM-based symbol synchronization position searching method. The method comprises the steps that P1 symbol detection is performed, wherein correlation values are detected according to correlation operation results of an input signal, so that the synchronization position of P1 symbols is obtained, and the synchronization position is a coarse synchronization position; P1 symbol confirming is performed, wherein correlation peak values and a predetermined threshold TH_valid are confirmed by comparing the P1 symbols, and after the P1 symbols are confirmed, synchronization position search is performed, so that the accurate synchronization position of the P1 symbols is obtained; P1 symbol decoding is performed, wherein integer frequency deviations estimated by the P1 symbols are used for performing compensation on input signal frequency deviations and then performing P1 symbol decoding, S1 decoding correlation peak values are compared with the corresponding predetermined threshold TH1, and S2 decoding correlation peak values are compared with the corresponding predetermined threshold TH2, so that P1 symbol capturing is completed. According to the symbol synchronization position searching method, synchronization errors are reduced, the error rate of P1 symbol decoding is lowered, and therefore P1 symbol capturing time and system capturing time are shortened.

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 Based on OFDM technology of the first generation standard DVB-T, the basic unit of data is called 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 the first st...

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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,” IEE Elec.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 severe interference channels, especially when the two-path channel interference is 0dB, it still has a large 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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