A Novel Symbol Timing Synchronization Scheme for OFDM Systems Based on Variational Pseudo-Noise Preamble

摘要

The symbol timing synchronization inaccuracy can bring about phase offset (FO), inter-symbol interference (ISI) and inter-channel interference (ICI). To overcome these shortcomings as much as possible, in this paper, a novel symbol timing synchronizer is proposed for orthogonal frequency division multiplexing (OFDM) systems based on the properties of PN sequences. By utilizing four identical blocks with inverted signs of the latter two blocks and two different PN sequences with the same period as weighted factors to ensure that the metric function has impulse-like shape at correct timing position without any burst side-peaks. It is demonstrated by the computer simulations that the proposed scheme achieves accurate timing offset estimation with smaller error mean (EM) and standard deviation (SD) compared with the existing method under flat-fading channels. When it is subjected to frequency-selective fading channels, in spite of some unsatisfactory results when Fast Fourier Transform (FFT) window size is small, the performance is relatively better than others with the increases of FFT window size referring to 3GPP LTE specifications.