Title :
Pilot Designs for Consistent Frequency-Offset Estimation in OFDM Systems
Author :
Li, Yinghui ; Minn, Hlaing ; Al-Dhahir, Naofal ; Calderbank, A. Robert
Author_Institution :
Dept. of Electr. Eng., Texas Univ., Richardson, TX
fDate :
5/1/2007 12:00:00 AM
Abstract :
This paper presents pilot designs for consistent frequency-offset estimation of orthogonal frequency-division multiplexing systems in frequency-selective fading channels. We describe two design approaches, namely, consistency in the probabilistic sense and absolute consistency. Existing preambles and pilot designs in the literature do not guarantee the absolute consistency. We derive general criteria for both approaches, present sufficient conditions on the pilot structures over the maximum carrier frequency offset (CFO) estimation range (half of the sampling rate), and derive simple pilot designs satisfying these conditions. We also extend the sufficient conditions to any arbitrary but fixed CFO estimation range, and present some generalized design patterns. Furthermore, the CFO estimation performances of distinct consistent pilot designs can be quite different at moderate or low signal-to-noise ratio (SNR) due to different statistics of outliers which also yields a link failure. We develop efficient pilot-design criteria that provide both consistency and robustness against outliers at moderate-to-low SNR. Our consistent pilot designs facilitate flexible and economical implementation, while our robust pilot designs enable wireless links with less outage and better resilience
Keywords :
OFDM modulation; fading channels; frequency estimation; matrix algebra; radio links; OFDM systems; SNR; consistent frequency-offset estimation; frequency-selective fading channels; maximum carrier frequency offset estimation; orthogonal frequency-division multiplexing systems; signal-to-noise ratio; wireless links; Frequency division multiplexing; Frequency estimation; Frequency-selective fading channels; OFDM; Robustness; Sampling methods; Signal design; Signal to noise ratio; Sufficient conditions; Yield estimation; Bose–Chaudhuri–Hocquengem (BCH) code; consistency; cyclic-difference set; frequency offset; m-sequence; maximum-likelihood (ML) estimation; orthogonal frequency-division multiplexing (OFDM); outlier; pilot design; robustness;
Journal_Title :
Communications, IEEE Transactions on
DOI :
10.1109/TCOMM.2007.896105