Multipath resistant coherent timing error detector for DS-CDMA applications

Abstract

A new coherent timing error detector (TED) for timing/code tracking loops used inside RAKE receivers in CDMA systems is presented. In contrast to the conventional TED it is well suited for the case of multipath propagation channels. In order to accomplish this task a compensation term is introduced inside the tracking loop directly behind the conventional TED. This compensation term is calculated using the knowledge on the relative delays of all paths and their respective channel coefficients. A compensation scheme like the one described here becomes necessary whenever closely spaced paths have to be tracked. This fact makes this algorithm a favorable candidate for indoor scenarios where individual paths can be spaced even more closely than one chip. The performance of the presented scheme is assessed by means of simulation.