| The carrier frequency offset (CFO) estimation plays a crucial role in establishing a reliable wireless link. Most of the existing training signal designs for CFO estimation overlooked the consistency of the estimation. The consistent CFO estimation gives a reliable estimate regardless of the channel impulse response
as long as the snap-shot received SNR is sufficiently high. Although the probability of inconsistent estimate is low, the price for the link failure due to the inconsistent training signal can be immeasurable in emergency and disaster situations, military applications, and communication for space-shuttle or flight control stations.
Consistency in CFO estimation was first addressed in [1] for the null tones based blind estimation method. Recently, [2] considered consistency in a pilot-tone based estimation method. However, the pilot tones in [2] do not guarantee the estimation consistency. Very recently in [4], we have presented several consistent pilot designs.
An important but unaddressed problem that this paper will address is "which consistent pilot design will give better CFO estimation performance?". We have observed that estimation performances of consistent pilots can be significantly different at moderate to low SNR, mainly due to the different statistics of outliers which cause large CFO estimation errors resulting in link failures. An explanation is that some consistent pilots may have estimation metric trajectory with sidelobe peaks comparable to the mainlobe peak for some channel responses yielding less robust performance at low SNR. Hence, both robust and consistent pilot designs are crucial for emergency-related or other critical communication systems. In this paper, we will present pilot designs which are consistent and robust even at low SNR. Furthermore, we will introduce new and more general pilot designs with consistency over an arbitrary estimation range.
References:
[1] X. Ma, C. Tepedelenlioglu, G. B. Giannakis, and S. Barbarossa, IEEE Journal Select. Areas Commun., pp. 2504-2515, Dec. 2001.
[2] J. Lei and T-S. Ng, IEEE Trans. Wireless Commun., pp. 588-599, Mar. 2004.
[3] M. Morelli and U. Mengali, IEEE Trans. Commun., Sept. 2000, pp. 1580-1589.
[4] H. Minn, Y. Li, N. Al-Dhahir, and R. Calderbank, "Pilot Designs for Consistent Frequency Offset Estimation in OFDM Systems," accepted in IEEE ICC'06, June 2006. |
| Hlaing Minn received his B.E. degree in Electronics from Yangon Institute of Technology, Yangon, Myanmar, in 1995, M.Eng. degree in Telecommunications from Asian Institute of Technology (AIT), Bangkok, Thailand, in 1997 and Ph.D. degree in Electrical Engineering from the University of Victoria, Victoria, Canada, in 2001.
He was with the Telecommunications Program in AIT as a laboratory supervisor during 1998. He was a research assistant from 1999 to 2001 and a post-doctoral research fellow during 2002 in the Department of Electrical and Computer Engineering at the University of Victoria. Since September 2002, he has been with the Erik Jonsson School of Engineering and Computer Science, the University of Texas at Dallas, USA, as an assistant professor. His research interests include wireless communications, cognitive signal designs and algorithms, cross-layer designs, joint and iterative signal processing algorithms, cooperative systems, estimation, detection, synchronization, channel estimation in MIMO OFDM/OFDMA/OFCDM/MB-OFDM/UWB systems. He is an Editor for the IEEE Transactions on Communications. |