THE EFFECT OF TIMING JITTER ON THE PERFORMANCE OF A DISCRETE MULTITONE SYSTEM

The transmission of high-speed data over severely band-limited channel s may be accomplished through the use of discrete multitone (DMT) modu lation, a modulation technique that has been proposed for a number of new applications, While the performance of a DMT system has been analy zed by a number of authors, these analyses ignore the effect of timing jitter on system performance. Timing jitter becomes an increasingly i mportant concern as higher data rates are supported and larger constel lations are allowed on the DMT subchannels. Hence, in this paper, we a ssume that synchronization is maintained by using a digital phase-lock ed loop to track a pilot carrier, Given this model, we derive error ra te expressions for an uncoded DMT system operating in the presence of timing jitter, and we derive an expression for the interchannel distor tion that results from a varying timing offset across the DMT symbol. In addition, we investigate the performance of trellis-coded DMT modul ation in the presence of timing jitter, Practical examples from the as ymmetric digital subscriber line (ADSL) service are used to illustrate various results.