Low-complexity joint synchronization of symbol timing and carrier frequency for OFDM systems

Timing synchronization for guard-interval-based (GIB) orthogonal frequency multiplexing (OFDM) systems requires a correlator to correlate the last N_g (length of the guard interval) samples of the received OFDM symbol with their copies ahead. The straightforward implementation of this correlator results in the need to perform N_g complex additions for each correlator output. In this paper, we present an improved synchronization algorithm for the coarse joint estimation of symbol timing and carrier frequency offset. With the proposed algorithm, the coarse estimator can be implemented with extremely low hardware complexity by replacing the conventional correlator with a l-order low pass filter. Only one complex addition is needed for each output. The probability for frequency offset estimation error is analyzed for ideal channel. Simulation results show that it works reliably over both AWGN and multipath fading channels.