Symbol timing recovery in digital subscriber loops in the presence of residual echo and impulsive noise

Abstract

In this paper, a general analysis is presented for the jitter performance of a common type of Symbol Timing Recovery (STR) system employed in a Digital Subscriber Loop (DSL) transceiver with adaptive echo cancellation for high-speed digital communications typical of evolving Integrated Service Digital Networks (ISDN's). Exact analytical expressions for the mean and variance of the timing wave and for the r.m.s. phase jitter are derived as a function of the system parameters representing a particular DSL and its noise environment, including such effects as residual-echo and Impulsive Noise (IN). Numerical results, obtained for an experimental study of a 144 kbits/s SDL timing recovery system, show that the presence of these disturbing signals can substantially degrade the STR performance. >