| OFDM is short for Orthogonal Freuqency Division MultiPlexing,an FDM modulation technique forr transmittinglagre amounts of digital data over a radio wave.OFDM wokrs by splitting the radio singal int multiple orthogonal smaller sub-singals that are then transmitted simultaneously at dieffernt frequencies to the rerceiver.It can effectively combats the multiply path effect,eliminates the intenal symbol interferences,defeats the freuqeney selectively loss,reduces the amount of crosstalk in singal transmission and it has high channel efficiency.DAB,DVB,802.llWLAN,802.16 and WIMAX technologies use OFDM.on Augest 18th 2006,a Chinese standard was publicized with a numeric symbol GB20600-2006 and was named as"Framling Structure,Channel Coding and Modulation for Digital Television Terrestrial Broadcasting System".Its multiple carriers systems use TDS-OFDM as it's key technology.Snychronization is a key problem in all telecommunication systems and it plays a more important role in OFDM system because OFDM is a multi-carrier system. This paper first studied synchronous OFDM technology programmes, including the European DVB-T and the original integration programmes synchronization system structure, and the combination of DVB-T standard and TDS-OFDM standard features, from symbols, carrier, three simultaneous sampling Analysis of various aspects of simultaneous performance of the system, the traditional TDS-OFDM system in the remaining synchronization deviation tracking algorithm in the high complexity, the power of PN sequences related to the weakness of computing, based on frequency domain Pilot (DVB-T ) Of the carrier synchronization on the basis of a modification of the use of frequency transmission parameters information (TPS) for synchronization of the carrier deviation ways to avoid over-related operations, the carrier frequency offset against the PN sequence of the related impact of quantitative analysis of the carrier frequency offset Sliding frame synchronization algorithm related to the impact, no auxiliary function based on the crude carrier synchronization algorithm to improve on the basis of a D-Space as a carrier for rough estimate simultaneously so as to achieve rapid synchronization carrier rough estimates and compensation, based on the PN sequence to meet the relevant The symbol synchronization, and then use the TPS based on the sampling frequency offset synchronization algorithm joint carrier synchronous sampling.Through the papers over the last synchronization algorithm for simultaneous real and the whole structure and simulation to prove that this method of simultaneous performance, and done a summary and outlook. |
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