A synchronization scheme for OFDM systems using the super-imposed perfect sequences

In this paper, a bandwidth efficient synchronization scheme for joint timing and frequency estimation is investigated for orthogonal frequency division multiplexing (OFDM) systems. The investigated architecture super-imposes a transparent generalized chirp-like (GCL) sequence [1] onto the frequency domain data symbols. In contrast to the existing synchronization schemes, the super-imposed architecture does not require dedicate bandwidth for transmitting pilot sequences and is robust to the multi-path channels. In this paper, both the timing offset and the carrier frequency offset (CFO) estimators are derived by using the maximum likelihood (ML) criterion. The power ratio of the GCL sequence is determined by minimizing the system bit error rate (BER) using simulation experiments. Simulation results demonstrate that the proposed scheme substantially outperforms the traditional schemes in many respects.