Clock regeneration for optical communications

• US 8,437,641 B2
• Filed: 10/21/2009
• Issued: 05/07/2013
• Est. Priority Date: 10/21/2008
• Status: Active Grant

• Current Assignee: Bay Microsystems, Inc. (Vcinity, Inc.)
• Original Assignee: Bay Microsystems, Inc. (Vcinity, Inc.)
• Inventors: Lee, Barry Tsai Lung, Chang, Chu-Jyh, Ono, Goichoro
• Primary Examiner(s): SINGH, DALZID E
• Application Number:
  US12/603,501
• Publication Number:
  US 20100098432A1
• Time in Patent Office: 1,294 Days
• Field of Search: 398/154, 398/155, 370/503, 370/518
• US Class Current: 398/155
• CPC Class Codes: H04B 10/299 Signal waveform processing, e.g. reshaping or retiming
• CPC Class Codes: H04J 3/07 using pulse stuffing for systems with different or fluctuating information rates or bit rates
• CPC Class Codes: H04J 3/1652 Optical Transport Network [OTN]

Abstract

A system and method for regenerating a client clock signal for use in optical communications is disclosed. The system and method involves using a carrier clock signal and a client clock signal to calculate quantities of data that are received and transmitted at an edge node and then adjusting a clock source in response to the difference between the calculated quantities of received and transmitted data.

Claims

1. A system for regenerating a client clock signal for use in optical communications, the system comprising:

a clock signal generator configured to generate a client clock signal; and

a clock processor configured to receive the client clock signal and a carrier clock signal, the clock processor having;

a carrier-side quantizer configured to calculate a carrier-side data quantity in response to the carrier clock signal;

a client-side quantizer configured to calculate a client-side data quantity in response to the client clock; and

a frequency command controller configured to generate a frequency command in response to the difference between the carrier-side data quantity and the client-side data quantity;

wherein the clock signal generator is adjusted in response to the frequency command.

2. The system of claim 1 wherein the carrier-side quantizer is configured to equate an interval of the carrier clock signal with a data quantity.

3. The method of claim 1 wherein the carrier-side quantizer is configured to count a number of clock intervals of the carrier clock signal and to multiply the equated data quantity by the counted number of intervals of the carrier clock signal.

4. The system of claim 1 wherein the client-side quantizer is configured to equate an interval of the client clock signal with a data quantity.

5. The method of claim 1 wherein the client-side quantizer is configured to count a number of clock intervals of the client clock signal and to multiply the equated data quantity by the counted number of intervals of the client clock signal.

6. The system of claim 1 wherein:

the carrier-side quantizer is configured to equate an interval of the carrier clock signal with a data quantity, to count a number of clock intervals of the carrier clock signal, and to multiply the equated data quantity by the counted number of intervals of the carrier clock signal; and

the client-side quantizer is configured to equate an interval of the client clock signal with a data quantity, to count a number of clock intervals of the client clock signal, and to multiply the equated data quantity by the counted number of intervals of the client clock signal.

7. The system of claim 1 wherein the carrier-side quantizer comprises a carrier-side data convertor configured to convert the carrier-side clock signal to an equivalent data quantity and a carrier-side accumulator configured to accumulate the equivalent data quantity over a pre-established interval to generate the carrier-side data quantity.

8. The system of claim 1 wherein the carrier-side quantizer further comprises a carrier-side clock information interpreter configured to adjust the carrier-side data quantity in response to carrier clock information that is encoded in a carrier-side protocol data unit.

9. The system of claim 1 wherein the client-side quantizer comprises a client-side data convertor configured to convert the client-side clock signal to an equivalent data quantity and a client-side accumulator configured to accumulate the equivalent data quantity over a pre-established interval to generate the client-side data quantity.

10. The system of claim 1 further comprising an adder configured to find the difference between the client-side data quantity and the carrier-side data quantity.

11. A method for regenerating a client clock signal for use in optical communications, the method comprising:

at a clock processor;

generating a client clock signal;

calculating a quantity of data that is received at a carrier interface, wherein the calculation is made in response to a carrier clock signal;

calculating a quantity of data that is received at a client interface, wherein the calculation is made in response to the client clock signal; and

adjusting the frequency of the client clock signal in response to the difference between the quantity of data that is received at the carrier interface and the quantity of data that is received at the client interface;

wherein calculating the quantity of data that is received at the carrier interface further comprises counting a number of clock intervals of the carrier clock signal and multiplying the equated data quantity by the counted number of intervals of the carrier clock signal.

12. The method of claim 11 wherein calculating the quantity of data that is received at the carrier interface comprises equating an interval of the carrier clock signal with a data quantity.

13. The method of claim 11 wherein calculating the quantity of data that is received at the client interface comprises equating an interval of the client clock signal with a data quantity.

14. The method of claim 11 wherein calculating the quantity of data that is received at the client interface further comprises counting a number of clock intervals of the client clock signal and multiplying the equated data quantity by the counted number of intervals of the client clock signal.

15. A method for regenerating a client clock signal for use in optical communications, the method comprising:

at a clock processor;

generating a client clock signal;

calculating a quantity of data that is received at a carrier interface, wherein the calculation is made in response to a carrier clock signal;

calculating a quantity of data that is received at a client interface, wherein the calculation is made in response to the client clock signal; and

adjusting the frequency of the client clock signal in response to the difference between the quantity of data that is received at the carrier interface and the quantity of data that is received at the client interface;

wherein calculating the quantity of data that is received at the client interface further comprises counting a number of clock intervals of the client clock signal and multiplying the equated data quantity by the counted number of intervals of the client clock signal.

16. The method of claim 15 wherein calculating the quantity of data that is received at the carrier interface comprises equating an interval of the carrier clock signal with a data quantity.

17. The method of claim 15 wherein calculating the quantity of data that is received at the carrier interface further comprises counting a number of clock intervals of the carrier clock signal and multiplying the equated data quantity by the counted number of intervals of the carrier clock signal.

18. The method of claim 15 wherein calculating the quantity of data that is received at the client interface comprises equating an interval of the client clock signal with a data quantity.