A Low-Complexity ML Estimator for Carrier and Sampling Frequency Offsets in OFDM Systems

This letter considers the joint acquisition of the carrier frequency offset (CFO) and sampling frequency offset (SFO) in OFDM systems using two long training symbols in the preamble. Conventional maximum-likelihood (ML) methods require a two-dimensional exhaustive search. To overcome this problem, a low-complexity closed-form ML estimator is proposed. It is shown that the CFO can be solved in closed-form. Then we develop an approximate ML estimation algorithm for the SFO by taking the second-order Taylor series expansion. Simulation results show that the proposed algorithm achieves almost the same performance as existing ML methods, but no exhaustive search is needed.

[1]  Vinod Subramaniam,et al.  Digital video broadcasting (DVB); framing structure, channel coding and modulation for digital terr , 2001 .

[2]  S. Werner Joint Sampling Clock Offset and Channel Estimation for OFDM Signals: Cramer-Rao Bound and Algorithms. IEEE Transactions on Signal Processing. 54 (5), 1875–1885. Giannakis, Georgios B. 1996. Blind Equalization of Time-Varying Channels: A Deterministic Multichannel Approach. Proceedings of IEEE Signal , 2004 .

[3]  Marco Moretti,et al.  Estimation of residual carrier and sampling frequency offsets in OFDM-SDMA uplink transmissions , 2010, IEEE Transactions on Wireless Communications.

[4]  Oomke Weikert Joint estimation of Carrier and Sampling Frequency Offset, phase noise, IQ Offset and MIMO channel for LTE Advanced UL MIMO , 2013, 2013 IEEE 14th Workshop on Signal Processing Advances in Wireless Communications (SPAWC).

[5]  Sailes K. Sengijpta Fundamentals of Statistical Signal Processing: Estimation Theory , 1995 .

[6]  H. Meyr,et al.  Optimum Receiver Design for OFDM-Based Broadband Transmission — Part II : A Case Study , 2001 .

[7]  Jong-Ho Lee,et al.  Joint Maximum Likelihood Estimation of Carrier and Sampling Frequency Offsets for OFDM Systems , 2010, IEEE Transactions on Broadcasting.

[8]  A. M. Abdullah,et al.  Wireless lan medium access control (mac) and physical layer (phy) specifications , 1997 .

[9]  Walid Hachem,et al.  Joint sampling clock offset and channel estimation for OFDM signals: Crame/spl acute/r-Rao bound and algorithms , 2006, IEEE Transactions on Signal Processing.

[10]  Sofiène Affes,et al.  Joint Carrier and Sampling Frequency Offset Estimation Based on Harmonic Retrieval , 2006, IEEE Vehicular Technology Conference.

[11]  Tho Le-Ngoc,et al.  RLS-Based Joint Estimation and Tracking of Channel Response, Sampling, and Carrier Frequency Offsets for OFDM , 2009, IEEE Transactions on Broadcasting.

[12]  Tho Le-Ngoc,et al.  Joint Channel Estimation and Synchronization for MIMO–OFDM in the Presence of Carrier and Sampling Frequency Offsets , 2009, IEEE Transactions on Vehicular Technology.

[13]  Heinrich Meyr,et al.  Optimum receiver design for OFDM-based broadband transmission .II. A case study , 2001, IEEE Trans. Commun..

[14]  Christian Oberli ML-based Tracking Algorithms for MIMO-OFDM , 2007, IEEE Transactions on Wireless Communications.

[15]  Young-Hwan You,et al.  Pilot-Assisted Fine Frequency Synchronization for OFDM-Based DVB Receivers , 2009, IEEE Transactions on Broadcasting.