A Cramer-Rao Bound for Semi-Blind Channel Estimation in Redundant Block Transmission Systems

A Cramér-Rao bound (CRB) for semi-blind channel estimators in redundant block transmission systems is derived. The derived CRB is valid for any system adopting a full-rank linear redundant precoder, including the popular cyclicprefixed orthogonal frequency-division multiplexing system. Simple forms of CRBs for multiple complex parameters, either unconstrained or constrained by a holomorphic function, are also derived, which facilitate the CRB derivation of the problem of interest. The derived CRB is a lower bound on the variance of any unbiased semi-blind channel estimator, and can serve as a tractable performance metric for system design. Index Terms Cramér-Rao bound (CRB), semi-blind channel estimation, block transmission systems, complex parameters, constrained parameters.