Blind Timing and Frequency Offset Estimation in OFDM based Communication System

Abstract

We consider blind synchronization in OFDM based communication systems. For synchronization without relying on preamble symbol, we use the first data symbol in which the first half is identical to the second half in the time domain. The proposed scheme estimates the timing offset and a fractional part of the frequency offset, based on both the first data symbol and its cyclic prefix (CP) in time domain and then, finds a integer part of the frequency offset with virtual carriers in frequency domain. Compared to Schmidl's method which performs very well even at low signal to noise ratio (SNR) with a preamble, the accuracy of the proposed timing and frequency offset estimator is definitely acceptable and the timing metric has a peak only at the correct position while has a plateau due to CP in the conventional scheme. The performance of the proposed method is shown analytically in AWGN channel and by simulation in frequency selective channel