An efficient exact-least-squares fractionally spaced equalizer using intersymbol interpolation

An efficient exact least squares procedure is presented specifically for the adaptive adjustment of a fractionally spaced equalizer (FSE). Channel equalization is examined and the problems that fractional spacing creates for the use of fast exact least squares adjustment algorithms are shown. Several improvements that drastically reduce the complexity of implementation in both computation and storage requirements, including an interpolation of the known training sequence and a modification of structure, are proposed. General expressions are given for these requirements for various algorithms, and the exact results are applied to a specific example. Finally, the decision-directed operation of the FSE is discussed.