Improvement on Sampling Clock Offset Estimation for Mobile OFDM Systems

Davi A. L. Castro, Cristiano M. Panazio, Cássio F. Dantas

DOI: 10.14209/sbrt.2015.172

Evento: XXXIII Simpósio Brasileiro de Telecomunicações (SBrT2015)

Keywords: OFDM Sampling Clock Offset Sampling Fre- quency Offset Time-varying Channels Doppler spread ISDB-T system

Abstract

Sampling Clock Offset (SCO) estimation is an important issue in Orthogonal Frequency-Division Multiplexing (OFDM) systems because sampling frequency mismatch between the transmitter and the receiver may severely degrade the system performance due to the loss of orthogonality between the subcarriers. SCO estimation in mobile environment is quite challenging since channel variation leads to an additional phase rotation that masks the SCO effects. However, most of the existing techniques rely on the assumption of a time-invariant channel and become considerably inaccurate in a mobile environment. In this paper, we propose an improvement to an existing pilot- aided SCO estimator aiming to provide robustness to channel variations. Performance was evaluated through simulations in a ISDB-T (Integrated Services Digital Broadcasting Terrestrial) compliant system, and the results have shown a considerable RMSE reduction for all ranges of SNR, specially for higher Doppler spread.

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