Dissertation
Dissertation > Industrial Technology > Radio electronics, telecommunications technology > Communicate > Data communication > Data transmission technology

Study on Synchronization Techniques for OFDM System

Author WangZuoFang
Tutor LiBingBing
School Xi'an University of Electronic Science and Technology
Course Communication and Information System
Keywords Orthogonal frequency division multiplexing (OFDM) Symbol timing Carrier frequency offset estimation DVB-T/H
CLC TN919.3
Type Master's thesis
Year 2007
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The development, characteristics and key techniques of OFDM system are briefly introduced.Different symbol timing synchronization and frequency offset estimation algorithms are discussed in detail, based on the introduction of OFDM essential principles, channel modes and the analysis of synchronization error affection. As for OFDM system without assistant data, symbol timing and carrier frequency offset estimation are discussed, two improved symbol timing algorithms are proposed, namely sign maximum likelihood energy rate (SMLER) and ML energy rate (MLER), and a new frequency offset estimatiom joint algorithm is proposed, this algorithm obtained fractional frequency offset estimation by ML algorithm and obtained integral frequency offset estimation according to the virtual carriers position offset. As for OFDM system with assistant pilot symbols, symbol timing and carrier frequency offset estimation are also discussed. To increase the symbol synchronization precision of a common training sequence, zero cyclic prefix (ZCP) is adopted changing the flat synchronization correlation peak to sharp correlation peak. A new frequency domain training sequence construction model is also proposed and time domain sequence in any needed periods can be obtained by the model. Finally a new synchronization algorithm is proposed by combining ZCP with the construction mode. As for OFDM system with assistant pilot sub-carriers, mainly DVB-T and DVB-H systems, a fixed length unitary peak (FLUP) algorithm is proposed to accomplish mode and guard period identification, and an integrated synchronization algorithm is proposed for DVB-T and DVB-H systems. In addition, all the proposed new algorithms are compared with the original algorithms by simulations.

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