A flexible technique for source clock recovery of real-time services in ATM networks

Abstract

This paper addresses source clock recovery in ATM networks for real-time services which require a timing relation between source and destination. A detailed jitter analysis is performed for the synchronous methods, from which a simple design approach is suggested for the clock recovery system. A new timing information transport protocol is proposed for constant bit rate and variable bit rate real-time services, leading to a unified ATM adaptation layer for both types of services. The method presented is called generic synchronous technique (GST) and exhibits the following properties: (a) good control on its parameters to satisfy jitter objectives; (b) decoupling between timing and service information; (c) efficient coding leading to reduced overhead; (d) good transmission error immunity and (e) simple implementation. As a case study, it is shown that GST provides adequate clock recovery for MPEG video signals, in the most stringent case when the reconstructed system clock is used to derive a chrominance sub-carrier for use in composite video.