Blind Adaptive Channel Shortening by Unconstrained Optimization for Simplified UWB Receiver Design

Abstract

Ultra wide band (UWB) systems are baseband communication systems which use extremely narrow pulses for information transfer and occupy a huge bandwidth with very low power spectral density. Due to the large bandwidth, UWB propagation channels are highly dense in multipaths, ranging from 100 to 300 in different scenarios. These multipaths are resolvable and can be captured through a RAKE receiver. Thus UWB systems are inherently safe from inter symbol interference (ISI). On the other hand, this phenomenon makes the UWB receiver structure very complex from analysis and design point of view and involves high manufacturing costs as the RAKE must implemented with a large number of fingers. Channel shortening can help in designing a simplified and cost effective UWB receiver by reducing the number of fingers in RAKE receiver. In this paper, we present a new blind adaptive channel shortening algorithm based on unconstrained optimization to enable simple and cost effective UWB receiver design.