Blind Equalization Techniques

Abstract

AbstractA tutorial review of various approaches to single‐user blind channel equalization and estimation is presented. Multipath propagation and limited bandwidth are the two main causes of signal distortion in digital communications leading to intersymbol interference at the receiver which, in turn, may lead to high error rates in symbol detection. Traditionally, a training sequence is transmitted during the acquisition mode to enable the receiver to design an equalizer or estimate the channel. In blind channel equalization and estimation no training sequences are available or used. In this article emphasis is on linear time‐invariant channels. The relevant channel models and equalizer structures are reviewed first followed by a discussion of joint channel and symbol estimation methods, direct equalization and symbol estimation approaches without channel estimation, and channel estimation using second‐order and higher‐order statistical methods as well as non‐statistical approaches. Commercial applications of blind equalization are also briefly discussed.