一种基于差分技术的CBR业务时钟自适应恢复方案

A Clock Recovery Scheme of CBR Services Basedon Differential Technique

信元在ＡＴＭ网内传送时，不可避免地产生了信元延时抖动。信元延时抖动对于基于ＡＴＭ平台的ＣＢＲ业务时钟自适应恢复有很大的负面影响［１～５］，即会造成时钟频率的抖动和漂移。这使得这种时钟恢复方案在某些场合不能应用［１，２］。本文提出了一种基于差分技术的业务时钟恢复方案，该方案可以显著地降低由于信元延时抖动而造成的业务时钟频率的抖动和漂移，同时不增加缓存的容量，即不会增加信元的总的延时。这对于提高基于ＡＴＭ平台的ＣＢＲ业务的质量有着较大的意义。

There exists Cell Delay Variation (CDV) phenomenon resulted both from the inner buffers and ATM multiplexing when ATM cells are transported over ATM, it is obvious that the CDVphenomenon is harmful to clock recovery of CBR services based on PLL technique. A different scheme is presented here, which can reduce the jitter/wander because of CDV drastically, while the buffer size needn't to be enlarged.