Joint symbol, frame, and carrier synchronization for Eureka 147 DAB system

We present a joint symbol, frame, and carrier synchronization method for an OFDM signal in this paper. Symbol timing is determined first by detecting an abrupt phase change in the autocorrelation of the last quarter (e.g. Eureka 147 DAB) useful symbol and its cyclic extension in the guard interval. Frequency offset of fractional carrier spacing can be estimated from the phase angle of this autocorrelation. Coarse frame synchronization or null symbol detection can also be achieved through this information. Frequency offset of integral carrier spacing and finer frame synchronizations are determined by convolution of a received phase reference symbol and several locally generated but frequency shifted phase reference symbols. Our simulation results show that this symbol timing estimation method is less sensitive to multipath fading and the frequency offset estimation is more accurate in mobile radio channels. We also show that the algorithm is robust in both AWGN and two-path fading channels for SNR down to about 8 dB