A SURVEY ON DECISION FEEDBACK EQUALIZERS

Abstract

Wireless channels seldom fulfill the conditions needed for distortion-less transmission. Practical wireless channels suffer from the effect of a non-flat magnitude response and a non-linear phase response that leads for distortions in the received signals. Moreover effects such as small scale fading, large scale fading and Doppler shifts lead to dis similarity between the transmitted and received signals. Wireless channels not showing the ideal impulse response leads to the reception of multiple copies of the transmitted signal at the receiver thereby resulting in Inter Symbol Interference (ISI). A cumulative and cascading effect of the above mentioned reasons results in the degraded performance of digital communication systems. To circumvent these detrimental effects, several equalizer designs have been proposed. This paper focuses on the design aspects of equalizers with an inclination towards decision feedback equalizers, due to their efficiency in nullifying the detrimental effects of practical wireless channels.