ATM网络中电路仿真业务定时恢复的改进方法  

An Improvement Method to the Timing Recovery for ATM Circuit Emulation

作　　者：葛宁[1] 丛永华 冯重熙[1] 

机构地区：[1]清华大学电子工程系通信教研组,北京100084

出　　处：《电子学报》1998年第1期48-52,共5页Acta Electronica Sinica

摘　　要：ATM技术很好地解决了数据的透明传送问题，但定时信息在ATM网中的传递透明性由于统计复用而受到损害目前用于电路仿真业务的定时恢复方法根据是否使用公共时钟大致分为同步和异步两种模式由于SDH网的推广，同步方式已被ITU－T采用主要有SFET（SyncthenousFrequencyEncodingTechniqu）、TS（TimeStamp）和SRTS（SynchronousResidualTimeStamp）三种．由于ATM业务的多样性，它们最大都有可能引入IUI的低频抖动本文提出了一种改进方法，首次将2级量化理论应用于定时恢复，可使任何业务的定时低频抖动降低到0．02UI以下。ATM can support various services in a universal format. The transport of CBR services is an important feature of ATM, and is referred to as circnit emulation .The recovery of soaree clock hequency is one of the critical issues due to packet oriented technology. There are two classes of generic approaches to ATM timing recovery, namely, non-syncbonous methods and syncbonous methods. SFET, TS and SRTS are three main synchronous methods,among them SRTh has been accepted by ITU-T as the timing recovery standard for AALl.However it will introduce up to lUI waiting time jitter at some values of souree clock frequency. An improvement method, namely Synchronous Filtered Residual Time Stamp(SFRTh), is proposed in this paper. It is based on 2-stage Sigma-Delta quantization and reduces the waiting time jitter below 0.02UI so that it greaily improves timing quality in ATM.

关 键 词：电路仿真 定量恢复 拌动 ATM网 ISDN 

分 类 号：TN913.24[电子电信—通信与信息系统]