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 th-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 th-order least-squares equalizers, with 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.