Blind channel and carrier frequency offset estimation using periodic modulation precoders

Recent results have shown that blind channel estimators, which are resilien t to the location of channel zeros, color of additive stationary noise, and channel order overestimation errors, can be developed for communication sy stems equipped with transmitter-induced cyclostationarity precoders, The pr esent paper extends these blind estimation approaches to the more general p roblem 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 est imating, in closed-form, the unknown channel, regardless of the channel spe ctral nulls, It is shown that compensating for the carrier frequency offset introduces no penalty in the asymptotic performance of the subspace channe l estimator. Simulations are presented to corroborate the performance of th e proposed algorithms.