Method and apparatus for time synchronization in a communication system
US6449291B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 24, 1998 |
| Grant date | Sep 10, 2002 |
| Priority date | — |
| Expiry date | Nov 24, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L47/28
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for time synchronization in a communications system such as a system including cable modems is provided. The synchronization method comprises the steps of receiving a first timestamp from a headend unit with the cable modem, and generating a first cable modem time reference with the cable modem in response to the receipt of the first timestamp. The cable modem then receives a second timestamp from the headend unit and generates a second cable modem time reference in response to the receipt of the second timestamp. A headend difference time comprising the difference of the first and second timestamps is then generated as is a cable modem difference time comprising the difference of the first and second cable modem time references. A clock error time that comprises the difference of the headend difference time and the cable modem difference time is then generated as well as a correction factor in response to the clock error time. The local clock of the cable modem is then synchronized with the master clock of the headend unit through the adjusting of the output of the local clock output in response to the correction factor. The correction factor in one instance…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.