Synchronization system for all optical slotted ring dynamic networks

• US 6,738,582 B1
• Filed: 07/23/2002
• Issued: 05/18/2004
• Est. Priority Date: 03/26/2002
• Status: Expired due to Fees

• Current Assignee: Matisse Networks
• Original Assignee: Martisse Networks
• Inventors: Shachar, Shlomo, Moshe, Oren
• Primary Examiner(s): NEGASH, KINFE MICHAEL
• Application Number:
  US10/200,141
• Time in Patent Office: 665 Days
• Field of Search: 398/98, 398/59, 398/154-155, 398/196, 398/206, 398/202, 375/327, 375/329, 375/340
• US Class Current: 398/98
• CPC Class Codes: H04J 14/0227 Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
• CPC Class Codes: H04J 14/0232 for downstream transmission
• CPC Class Codes: H04J 14/0246 using one wavelength per ONU
• CPC Class Codes: H04J 14/0283 WDM ring architectures
• CPC Class Codes: H04J 14/08 Time-division multiplex systems
• CPC Class Codes: H04J 3/0626 plesiochronous multiplexing systems, e.g. plesiochronous digital hierarchy [PDH], jitter attenuators
• CPC Class Codes: H04J 3/0638 Clock or time synchronisation among nodes; Internode synchronisation synchronization for ring networks H04L12/422; data switching networks with synchronous transmission H04L12/43
• CPC Class Codes: H04J 3/0652 Synchronisation among time division multiple access [TDMA] nodes, e.g. time triggered protocol [TTP] bus network with centralized control in which slots are of a TDMA packet structure H04L12/4035
• CPC Class Codes: H04L 12/43 with synchronous transmission, e.g. time division multiplex [TDM], slotted rings
• CPC Class Codes: H04Q 11/0066 Provisions for optical burst or packet networks
• CPC Class Codes: H04Q 2011/0033 using time division switching
• CPC Class Codes: H04Q 2011/0092 Ring

Abstract

A method for communicating data over a network having a plurality of nodes thereupon is discussed. A time slot clock signal is transmitted from one node of the plurality of nodes to other nodes of the plurality of nodes. After each of the other nodes of the plurality of nodes receives the time slot clock signal, the time slot clock signal is recalculated to achieve an integer number of slots on the network. The recalculated time slot clock signal is transmitted from the one node of the plurality of nodes to the other nodes of the plurality of nodes.

Claims

1. A method of communicating data over a network having a plurality of nodes thereupon, said method comprising the steps of:

transmitting a time slot clock signal from one node of said plurality of nodes to other nodes of said plurality of nodes;

waiting for a return signal from at least one of said other nodes of said plurality of nodes;

recalculating the time slot clock signal to achieve an integer number of slots on the network based on said return signal; and

transmitting the recalculated time slot clock signal from the one node of said plurality of nodes to the other nodes of said plurality of nodes.

2. A method as recited in claim 1, wherein said network comprises an optical fiber ring network and said step of transmitting a time slot clock signal comprises transmitting a time slot clock signal from the one node to the other nodes of said optical fiber ring network.

3. A method as recited in claim 2, wherein said step of waiting for the return signal from at least one of said other nodes of said plurality of nodes comprises waiting for a last of said other nodes of said optical fiber ring network to send the return signal to the one node of said optical fiber ring network.

4. A method as recited in claim 1, wherein said method is performed periodically to maintain the integer number of slots on the network.

5. A method as recited in claim 2, wherein the step of recalculating the time slot signal to achieve an integer number of slots on the network comprises at least one step of:

changing a duration of the time slot used in the time slot clock signal; and

changing the optical length of the optical fiber ring network.

6. A method as recited in claim 5, wherein the step of changing the optical length is used to make a rough adjustment to achieve the integer number of slots and the step of changing the duration of the time slot is used to make a fine adjustment to achieve the integer number of slots.

7. A method as recited in claim 5, wherein the step of changing the optical length of the optical fiber ring network comprises adjusting an optical delay line.

8. A method as recited in claim 1, wherein said step of transmitting a time slot clock signal comprises transmitting a system bit clock signal that includes the time slot clock signal contained therein.

9. A method as recited in claim 1, further comprising the step of transmitting a packet from a particular node of said plurality of nodes to another node of said plurality of nodes within one of said integer number of slots on the network.

10. A method as recited in claim 9, wherein the step of transmitting a packet further comprises inserting a guard time before and after the packet within said one of said integer number of slots.

11. A method as recited in claim 9, wherein said packet comprises a preamble, a barker and a packet payload, where the barker is used by a receiver of said another node of said plurality of nodes to extract the packet payload.

12. A method as recited in claim 2, wherein the step of waiting for the return signal from at least one of said other nodes of said plurality of nodes comprises waiting for the time slot clock signal to pass through a coupler connected with each of said other nodes of said plurality of nodes and to arrive back at said one node.

13. A method as recited in claim 2, wherein the step of waiting for the return signal from at least one of said other nodes of said plurality of nodes comprises waiting for the time slot clock signal to be received and retransmitted by each of said other nodes of said plurality of nodes and arrive back at said one node.

14. A method as recited in claim 13, wherein signal data is added or dropped from the time slot clock signal when the time slot clock signal is received and retransmitted by each of said other nodes.

15. A method as recited in claim 1, wherein said one node of said plurality of nodes is a master node that transmits and maintains a system bit clock using a broadcast wavelength.

16. A communications node for communicating data over a network having a plurality of nodes thereupon, comprising:

means for transmitting a time slot clock signal from one node of said plurality of nodes to other nodes of said plurality of nodes;

means for waiting for the return signal from at least one of said other nodes of said plurality of nodes;

means for recalculating the time slot clock signal to achieve an integer number of slots on the network based on said return signal; and

means for transmitting the recalculated time slot clock signal from the one node of said plurality of nodes to the other nodes of said plurality of nodes.

17. A communications node as recited in claim 16, wherein said network comprises an optical fiber ring network and said means for transmitting a time slot clock signal comprises means for transmitting a time slot clock signal from the one node to the other nodes of said optical fiber ring network.

18. A communications node as recited in claim 17, wherein said means waiting for the return signal from at least one of said other nodes of said plurality of nodes comprises means for waiting for a last of said other nodes of said optical fiber ring network to send the return signal to the one node of said optical fiber ring network.

19. A communications node as recited in claim 16, wherein the communications node is configured to periodically maintain the integer number of slots on the network.

20. A communications node as recited in claim 17, wherein the means for recalculating the time slot signal to achieve an integer number of slots on the network comprises at least one step of:

means for changing a duration of the time slot used in the time slot clock signal; and

means for changing the optical length of the optical fiber ring network.

21. A communications node as recited in claim 20, wherein the means for changing the optical length is configured to make a rough adjustment to achieve the integer number of slots and the means for changing the duration of the time slot is configured to make a fine adjustment to achieve the integer number of slots.

22. A communications node as recited in claim 20, wherein the means for changing the optical length of the optical fiber ring network comprises means for adjusting an optical delay line.

23. A communications node as recited in claim 16, wherein said means for transmitting a time slot clock signal comprises means for transmitting a system bit clock signal that includes the time slot clock signal contained therein.

24. A communications node as recited in claim 20, further comprising means for transmitting a packet from a particular node of said plurality of nodes to another node of said plurality of nodes within one of said integer number of slots on the network.

25. A communications node as recited in claim 24, wherein the means for transmitting a packet further comprises means for inserting a guard time before and after the packet within said one of said integer number of slots.

26. A communications node as recited in claim 24, wherein said packet comprises a preamble, a barker and a packet payload, where the barker is used by a receiver of said another node of said plurality of nodes to extract the packet payload.

27. A communications node as recited in claim 17, wherein the means for waiting for the return signal from at least one of said other nodes of said plurality of nodes comprises means for waiting for the time slot clock signal to pass through a coupler connected with each of said other nodes of said plurality of nodes and to arrive back at said one node.

28. A communications node as recited in claim 17, wherein the means for waiting for the return signal from at least one of said other nodes of said plurality of nodes comprises means for waiting for the time slot clock signal to be received and retransmitted by each of said other nodes of said plurality of nodes and arrive back at said one node.

29. A communications node as recited in claim 28, wherein signal data is added or dropped from the time slot clock signal when the time slot clock signal is received and retransmitted by each of said other nodes.

30. A communications node as recited in claim 16, wherein said one node of said plurality of nodes is a master node that transmits and maintains a system bit clock using a broadcast wavelength.

31. A communications node for an optical fiber network, said communications node comprising:

a fixed wavelength receiver for receiving optical data;

a tunable wavelength transmitter for transmitting optical data to destination nodes at a plurality of destination wavelengths; and

a media access controller which determines a slot clock based on a system clock signal received by the fixed wavelength receiver time slots;

wherein the tunable wavelength transmitter uses the slot clock to determine a slot in which the optical data is to be transmitted.

32. A communications node as recited in claim 31, wherein said fixed wavelength receiver comprises a burst mode receiver.

33. A communications node as recited in claim 32, wherein said burst mode receiver comprises a phase shifter to provide a phase-shifted system clock.

34. A communications node as recited in claim 31, wherein said fixed wavelength receiver comprises at least two direct digital synthesizers receiving the same control signal from a controller, used to shift the phase of the receiving optical data.

35. A communications node as recited in claim 34, wherein said fixed wavelength receiver is capable of creating a phase controlled high bitrate clock.

36. A communications node as recited in claim 31, wherein said fixed wavelength receiver comprises a phase-lock-loop.

37. A burst mode receiver for optical data comprising:

a phase shifter, receiving a system clock and producing a phase-shifted clock;

a controller in communication with and controlling the phase shifter; and

a sample unit, receiving a phase-shifted clock and producing sampled data.

38. A burst mode receiver as recited in claim 37, wherein said phase shifter comprises at least two direct digital synthesizers receiving a control signal from a second controller, used to shift a phase of the received optical data.

39. A burst mode receiver as recited in claim 38, wherein said burst mode receiver is capable of creating a phase controlled high bitrate clock.

40. A burst mode receiver as recited in claim 38, wherein said phase shifter is configured to shift a phase of a received signal when said at least two direct digital synthesizers receive a changed control word from said second controller.