Blind estimation of symbol timing and carrier frequency offset in wireless OFDM systems

Authors

Helmut Bölcskei

Reference

IEEE Transactions on Communications, Vol. 49, No. 6, pp. 988-999, June 2001.

Abstract

Orthogonal frequency division multiplexing (OFDM) systems are highly sensitive to synchronization errors. In this paper, we introduce an algorithm for the blind estimation of symbol timing and carrier frequency offset in wireless OFDM systems. The proposed estimator is an extension of the Gini-Giannakis estimator [1] for single-carrier systems. It exploits the cyclostationarity of OFDM signals and relies on second-order statistics only. Our method can be applied to pulse shaping OFDM systems with arbitrary time-frequency guard regions, OFDM based on offset QAM, and biorthogonal frequency division multiplexing (BFDM) systems. We furthermore propose the use of different subcarrier transmit powers (subcarrier weighting) and periodic transmitter precoding to achieve a carrier frequency acquisition range of the entire bandwidth of the OFDM signal, and a symbol timing acquisition range of arbitrary length. Finally, we provide simulation results demonstrating the performance of the new estimator.

Keywords

OFDM, pulse shaping, synchronization, symbol timing, carrier frequency offset, blind estimation

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