Clock reconstruction for time division multiplexed traffic transported over asynchronous ethernet networks
US7289538B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 14, 2002 |
| Grant date | Oct 30, 2007 |
| Priority date | — |
| Expiry date | Jun 17, 2025 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04J3/0632
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A clock reconstruction mechanism for synchronous TDM communications traffic transported over asynchronous networks such as Ethernet networks. The invention is applicable to edge switches in Metropolitan Area Networks (MANs) that transport legacy TDM traffic using a Circuit Emulation Services (CES) module whereby TDM traffic is encapsulated and transported across the Ethernet network where it is de-encapsulated and clocked out to the destination. The mechanism encapsulates the input TDM data stream into Ethernet packets and inserts a network timestamp within the packet. At the destination CES, a local timestamp is generated for each received packet as it is received. The network timestamp is extracted and input along with the local timestamp to a Digital Time Locked Loop (DTLL) which is operative to accurately reconstruct the original transmit TDM clock. The filter in the DTLL performs a Least Squares Regression (LSR) algorithm and Infinite Impulse Response (IIR) filter algorithm to generate a clock control signal for adjusting the clock generated.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.