Least-squares channel equalization performance versus equalization delay

Linear channel equalization has been a successful way to combat intersymbol interference (ISI) introduced by physical communication channels at high enough symbol rates. We consider the performance of least-squares equalizers in the single-input/multi-output (SIMO) channel context when the true channel is composed of an mth-order significant part and tails of "small" leading and/or trailing terms. Using a perturbation analysis approach, we show that if the diversity of the significant part is sufficiently large with respect to the size of the tails, then the lth-order least-squares equalizers, with l/spl ges/m-1, perform well for all the delays corresponding to the significant part. On the other hand, the performance of the equalizers for the delays corresponding to the tails may be poor.