On the robustness of the fractionally-spaced constant modulus criterion to channel order undermodeling

Abstract

This paper studies the constant modulus (CM) criterion specifically for the case where the time span of the fractionally-spaced equalizer (FSE) is less than that of the channel. Hence, there necessarily exists an error in the equalized signal. Results for the binary case (Part I) are extended to multi-level signalling. This analysis is connected with the previous work of Fijalkow et al. on misadjustment of a CM receiver to suggest a finite interval of acceptable FSE length which shows that a longer FSE may not be better than a shorter FSE - in some cases, matching the FSE length to that of the channel may not reduce the MSE to a prescribed threshold, while a shorter FSE may be successful in achieving this threshold. Show more