Parasitic time synchronization for a centralized communications guardian

• US 7,729,254 B2
• Filed: 11/19/2004
• Issued: 06/01/2010
• Est. Priority Date: 11/19/2003
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Driscoll, Kevin R., Hall, Brendan
• Primary Examiner(s): Yao; Kwang B
• Assistant Examiner(s): NGUYEN, ANH NGOC M
• Application Number:
  US10/993,221
• Publication Number:
  US 20050128950A1
• Time in Patent Office: 2,020 Days
• Field of Search: 370/235, 370/229, 370/230, 370/236, 370/336, 370/442, 370/400, 370/498
• US Class Current: 370/235
• CPC Class Codes: H04L 12/422 Synchronisation for ring networks Time Division Multiplex ring networks, e.g. SDH/SONET H04J3/085
• CPC Class Codes: H04L 12/44 Star or tree networks

Abstract

A parasitic time synchronization network is provided including a plurality of nodes, one or more hubs, each hub having communication links with the plurality of nodes and one or more guardians. Each node is adapted to transmit and receive data and communicate with every other node through the one or more hubs. The communication links between any one hub and the plurality of nodes defines a communication channel. Each guardian is associated with one communication channel. Each node is assigned a time slot in which it is permitted to transmit data through an associated hub of the one or more hubs. A guardian of an associated channel blocks propagation of data transmissions between the plurality of nodes through the associated hub allows only data transmissions from one of the plurality of nodes, wherein the guardian periodically receives a cluster of beacons generated by a plurality of the plurality of nodes.

Claims

1. A parasitic time synchronization network, the network comprising:

a plurality of nodes, wherein each node is adapted to transmit and receive data;

one or more hubs, each hub having communication links with the plurality of nodes;

wherein each node is adapted to communicate with every other node through the one or more hubs;

wherein the communication links between any one hub and the plurality of nodes defines a communication channel; and

one or more guardians, wherein each guardian is associated with one communication channel;

wherein each node is assigned a time slot in which it is permitted to transmit data through an associated hub of the one or more hubs;

wherein a guardian of an associated channel blocks propagation of data transmissions between the plurality of nodes through the associated hub and allows only data transmissions from one of the plurality of nodes;

wherein the guardian periodically receives a cluster of beacons generated by a plurality of the plurality of nodes;

wherein the guardian is further adapted to observe receipt of a first beacon,

wherein when the guardian observes receipt of an nth beacon within a predefined time interval t then the guardian concludes that the first beacon, the nth beacon, and any beacons received between the first and nth beacons comprise a cluster of beacons indicating the beginning of a time slot, wherein n is greater than or equal to two.

2. The network of claim 1, wherein the guardian is adapted to know when the beginning of a time slot occurs by observing the cluster of beacons.

3. The network of claim 2, wherein the guardian is adapted to distinguish between the cluster of beacons and one or more outlier beacons generated by one or more degraded nodes.

4. The network of claim 1, wherein the network is a TDMA network and the time slot is a TDMA slot.

5. The network of claim 1, wherein the network is a TTP/C protocol network and the beacons are action time signals.

6. The network of claim 1, wherein each guardian is located within an associated hub.

7. The network of claim 6, wherein each node transmits beacons and data on the same communication link.

8. The network of claim 1, wherein upon identifying the cluster of beacons indicating the beginning of a time slot, and after a predefined time delay, the guardian opens a transmission window, wherein the transmission window allows the propagation of data transmissions from one of the plurality of nodes.

9. The network of claim 8, wherein the one of the plurality of nodes allowed to propagate data transmission is the node authorized to transmit by the network protocol.

10. The network of claim 9, wherein the guardian increments TDMA schedule position based on the receipt of the cluster of beacons.

11. The network of claim 8, wherein the one of the plurality of nodes allowed to propagate data transmission is determined by priority based arbitration.

12. The network of claim 11, wherein the guardian starts the timing of a priority arbitration window based on the receipt of the cluster of beacons.

13. The network of claim 8, wherein the one of the plurality of nodes allowed to propagate data transmission is determined by a voting mechanism for transmission schedule enforcement.

14. The network of claim 8, wherein the predefined time delay begins on the receipt of the nth beacon of the cluster of beacons.

15. The network of claim 1, wherein the guardian periodically receiving the cluster of beacons generated by the plurality of the plurality of nodes define an independent time basis for the guardian to implement other network processes.

16. The network of claim 1, wherein the guardian periodically receiving the cluster of beacons generated by the plurality of the plurality of nodes define an independent time basis for the guardian to guard against system faults.

17. The network of claim 1, wherein the guardian detects the operating mode of the network by periodically receiving the cluster of beacons generated by the plurality of the plurality of nodes.

18. The network of claim 1, further comprising:

one or more electronic devices in communication with the plurality of nodes, wherein the electronic devices include one or more of sensors, processors, actuators, controllers, and input devices.

19. A network, comprising:

one or more hubs;

a plurality of nodes, wherein each node is adapted to communicate with every other node through the one or more hubs;

a synchronization function enabled within network, including;

a central guardian; and

a plurality of clusters of beacons transmitted to the central guardian by a plurality of the plurality of nodes, wherein based on receipt of one of the plurality of clusters of beacons the central guardian opens a transmission window for one of the plurality of nodes and allows data transmissions from the one of the plurality of nodes to propagate to other nodes and blocks any transmissions from the others node during the transmission window;

wherein the central guardian distinguishes between the one of the plurality of clusters of beacons and the one or more outlier beacons by observing receipt of a first beacon, and when the guardian observes receipt of an nth beacon within a predefined time interval t, then the guardian concludes that the first beacon, the nth beacon, and any beacons received between the first and nth beacons comprise one cluster of beacons, wherein n is greater than or equal to two.

20. The network of claim 19, wherein the central guardian is adapted to distinguish between each of the plurality of clusters of beacons and one or more outlier beacons.

21. The network of claim 20, wherein upon identifying one cluster of beacons, and after a predefined time delay, the guardian opens a transmission window, wherein the transmission window allows the propagation of data transmissions from one of the plurality of nodes.

22. The network of claim 21, wherein the transmission window allows the propagation of data transmissions from one of the plurality of nodes only when the one of the plurality of nodes is transmitting during its assigned TDMA slot.

23. The network of claim 22, wherein the central guardian increments TDMA schedule position based on the receipt of the one cluster of beacons.

24. The network of claim 21, wherein the one of the plurality of nodes allowed to propagate data transmission is determined by priority based arbitration.

25. The network of claim 24, wherein the guardian starts the timing of a priority arbitration window based on the receipt of the one cluster of beacons.

26. The network of claim 21, wherein the one of the plurality of nodes allowed to propagate data transmission is determined by a voting mechanism for transmission schedule enforcement.

27. The network of claim 26, wherein the predefined time delay begins on the receipt of the nth beacon of the one cluster of beacons.

28. The network of claim 19, wherein the network is a TDMA protocol network and the time slot is a TDMA slot.

29. The network of claim 28, wherein the network is a TTP/C protocol network and the beacons are action time signals.

30. The network of claim 19, wherein the guardian periodically receiving the cluster of beacons generated by the plurality of the plurality of nodes define an independent time basis for the guardian.

31. A method for synchronizing a centralized guardian in a hub with a plurality of nodes of a network, the method comprising:

observing, with the centralized guardian, receipt of a first beacon;

observing, with the centralized guardian, receipt of an nth beacon within a predefined time interval t, wherein n is greater than or equal to two;

concluding, with the centralized guardian, that the first beacon, the nth beacon and any beacons observed between the first and nth beacon comprises a cluster of beacons; and

when the receipt of the nth beacon occurs within the predefined time interval t, defining, with the centralized guardian, the receipt of the nth beacon as the beginning of a time slot.

32. The method of claim 31, further comprising:

waiting a delay period after the beginning of the time slot; and

opening a transmission window for one node of the plurality of nodes.

33. A parasitic time synchronization network, comprising:

means for synchronizing a centralized guardian with a plurality of nodes of a network;

means for observing receipt of a first beacon;

means for observing receipt of an nth beacon within a predefined time interval t, wherein n is greater than or equal to two;

means for concluding that the first beacon, the nth beacon and any beacons observed between the first and nth beacon comprises a cluster of beacons; and

when the receipt of the nth beacon occurs within the predefined time interval t, defining the receipt the nth beacon as the beginning of a time slot.

34. The network of claim 33, further comprising:

means for waiting a delay period after the beginning of the time slot; and

means for opening a transmission window for one node of the plurality of nodes.

35. A computer-readable medium having computer-executable instructions for performing a method of synchronizing a centralized guardian with a plurality of nodes of a network, the method comprising:

observing receipt of a first beacon;

observing receipt of an nth beacon within a predefined time interval t, wherein n is greater than or equal to two;

concluding that the first beacon, the nth beacon and any beacons observed between the first and nth beacon comprises a cluster of beacons; and

when the receipt of the nth beacon occurs within the predefined time interval t, defining the receipt of the nth beacon as the beginning of a time slot.

36. The method of claim 35, further comprising:

waiting a delay period after the beginning of the time slot; and

opening a transmission window for one node of the plurality of nodes.