On Reduced-Complexity Equalization Based on Ungerboeck and Forney Observation Models

This correspondence investigates the asymptotic behavior of reduced-state intersymbol interference (ISI) equalizers, based on the Ungerboeck and Forney observation models. It is shown that Ungerboeck-based equalizers can suffer from correct-path-loss (CPL) even in the noiseless regime. ISI conditions that lead to CPL are analytically derived and illustrated by examples.