Recent results have shown that blind channel estimators, which are resilient to the location of channel zeros, color of additive stationary noise, and channel order overestimation errors, can be developed for communication systems equipped with transmitter-induced cyclostationarity precoders. The present paper extends these blind estimation approaches to the more general problem of estimating the unknown intersymbol interference (ISI) and carrier frequency offset/Doppler effects using such precoders. An all-digital open-loop carrier frequency offset estimator is developed, and its asymptotic (large sample) performance is analyzed and compared to the Cramer-Rao bound (CRB). A subspace-based channel identification approach is proposed for estimating, in closed-form, the unknown channel, regardless of the channel spectral nulls. It is shown that compensating for the carrier frequency offset introduces no penalty in the asymptotic performance of the subspace channel estimator. Simulations are presented to corroborate the performance of the proposed algorithms.
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Manuscript received January 8, 1999; revised April 20, 2000. This work was supported by the Office of Naval Research under Grant N00014-93-1-0485. The associate editor coordinating the review of this paper and approving it for publication was Dr. Alle-Jan van der Veen. E. Serpedin is with the Department of Electrical Engineering, Texas A&M University, College Station, TX 77843 USA. A. Chevreuil and P. Loubaton are with the Laboratoire Systèmes de Communication, Université de Marne-la-Vallée, Marne-la-Vallée, France. G. B. Giannakis is with the Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455 USA (e-mail: email@example.com). Publisher Item Identifier S 1053-587X(00)05969-9.