A low complexity sign ML detector for symbol and frequency synchronization of OFDM systems

Frame and frequency synchronization for guard-interval-based orthogonal frequency multiplexing (OFDM) systems require a correlator to correlate the last Ng samples of the received OFDM symbol with their copies ahead. The straightforward implementation of this correlator results in high hardware complexity and high power consumption to perform Ng complex additions for each correlator output. In this paper, only the sign bits of correlator results are used to estimate the frame and the frequency offset, and for the sake of reducing complexity and power consumption, we also present other two methods. The Wallace-Tree adder and shift registers can be replaced by an up/down accumulator and dual port memory respectively. Simulation results show that it can work properly over both AWGN and multipath fading channels, with very low hardware complexity and low power consumption.