Adaptive clock recovery in asynchronous transfer mode networks
US6400683B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 29, 1999 |
| Grant date | Jun 4, 2002 |
| Priority date | — |
| Expiry date | Apr 29, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2012/5681
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
In a data communication network, a system clock rate can be inferred at a receiver by measuring the data rate during successive periods. This information is used to adjust or adapt a receiver output clock to the inferred system clock. To adapt a receiver buffer output clock frequency to the buffer input clock frequency, the level of the buffer is periodically monitored. If the fill level is greater than an upper threshold, the output clock frequency is incremented. If the fill level is less than a lower threshold, the output clock frequency is decremented. A count is maintained of the number of successive adjustment operations performed while the fill level is outside the range bounded by the thresholds. When the fill level returns to the bounded range, a number of reverse frequency adjustments are performed. The number of reverse frequency adjustments are less than the number of earlier opposite frequency adjustments, preferably by a factor of two. The reverse corrections converge the output clock frequency toward the input clock frequency, reducing oscillations.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.