On the Estimation of Sampling Clock Frequency Offset in Single and Multiple Carrier Systems

The aim of this correspondence is to report in a closed-form expression a lower bound on the performance of sampling clock frequency offset (SFO) estimators for both single carrier and multi-carrier linearly modulated signals. This benchmark is expressed in terms of the so-called modified CramerRao bound (MCRB), which is shown to coincide asymptotically asymptotically (large sample) with the Cramer-Rao bound (CRB) for scalar parameter estimation. Comparison of the MCRB with the performance of existing SFO estimators gives rise to several challenging research problems: design of efficient SFO estimators and development of a framework to assess correctly the performance of the second-order feedback SFO estimators with respect to the MCRB.