Method and apparatus for automatic control of time-of-day synchronization and merging of networks

• US 8,014,378 B1
• Filed: 10/23/2003
• Issued: 09/06/2011
• Est. Priority Date: 10/23/2003
• Status: Active Grant

• Current Assignee: Harris Global Communications, Inc. (L3Harris Technologies, Inc.)
• Original Assignee: ITT Manufacturing Enterprises, Inc. (ITT, Inc.)
• Inventors: Yoon, Chang-June C. J., Walsh, Patrick R.
• Primary Examiner(s): Hu, Jinsong
• Assistant Examiner(s): Georgewill, Opiribo
• Application Number:
  US10/690,552
• Time in Patent Office: 2,875 Days
• Field of Search: 370/350, 370/238, 370/338, 370/340, 370/410, 370/234
• US Class Current: 370/350
• CPC Class Codes: H04L 67/1095 Replication or mirroring of data, e.g. scheduling or transport for data synchronisation between network nodes
• CPC Class Codes: H04W 4/00 Services specially adapted for wireless communication networks; Facilities therefor

Abstract

A method and apparatus for synchronizing time of day (TOD) information between radio nodes of a network and for detecting and merging otherwise isolated radio networks. In this manner individual isolated networks are able start when they are ready and once connectivity is detected with another network, the two networks can merge. Radio nodes within each network periodically send out TOD messages and periodically receive TOD messages issued by other nodes look to identify networks within communication range. Upon detecting another network a radio node informs a central control node that uses network detection information received from its members to determine the extent of the connectivity between the two networks and whether to merge the two networks. Network searching is optimized to limit impact on the overall network performance, resulting in little or no degradation in network performance.

Claims

1. A communication unit that transmits messages to and receives messages from neighboring communication units, the communication unit comprising:

a transmitter to transmit an outgoing message to a neighboring communication unit;

a receiver to receive an incoming message from a neighboring communication unit;

a storage unit to store communication unit connectivity information, neighboring communication unit connectivity information and merge request information; and

a processor to control said transmission of outgoing messages and reception of incoming messages, wherein said processor includes;

a synchronization module to join the communication unit to an existing communication network at power up from among a plurality of existing communication networks each with a different Time Of Day synchronization mode, and to start an isolated network with neighboring communication units in response to failure to join the communication unit to at least one of the existing communication networks;

a merge module to examine said stored communication unit connectivity information, stored neighboring communication unit connectivity information and stored merge request information to determine merge control parameters to control merger between the network containing the communication unit and operating in a first Time Of Day synchronization mode and a neighboring communication network operating in a second Time Of Day synchronization mode that is different from the first mode, wherein the network containing the communication unit includes a plurality of communication units and said neighboring communication network includes a plurality of communication nodes; and

a controller module to control merging of the communication unit with said neighboring communication network in accordance with said merge control parameters determined by said merge module to merge the network containing the communication unit with the neighboring communication network.

2. The communication unit of claim 1 wherein said transmitter transmits said outgoing message in the form of radio signals.

3. The communication unit of claim 1 wherein said receiver receives said incoming message in the form of radio signals.

4. The communication unit of claim 1 wherein said synchronization module includes:

a time synchronization module to determine the Time Of Day synchronization mode used by the communication unit.

5. The communication unit of claim 4 wherein the synchronization module further includes:

a startup module to join the communication unit to an existing communication network at power up using a user configurable primary Time Of Day synchronization mode.

6. The communication unit of claim 5 wherein the synchronization module further includes:

a Time Of Day mode module to change the Time Of Day synchronization mode of the communication unit in response to the communication unit failing to join a communication network with neighboring communication units using a previously selected Time Of Day synchronization mode and to join the communication unit to an existing communication network using the changed Time Of Day synchronization mode.

7. The communication unit of claim 1 wherein said storage unit further includes:

a connectivity module to store at least one of an identifier for a communication network to which the communication unit belongs, an identifier for a neighboring communication unit, an identifier for a communication network to which a neighboring communication unit belongs, and an identifier for a neighboring communication unit'"'"'s neighbor.

8. The communication unit of claim 1 wherein said processor further includes:

a search module to determine search parameters that control the manner in which the communication unit searches for neighboring communication units and neighboring communication network nodes;

wherein the controller module further controls transmission of outgoing messages and reception of incoming messages in a manner consistent with search parameters determined by the search module.

9. The communication unit of claim 8 wherein said search module further includes:

a transmit rate module to determine a rate at which the communication unit transmits outgoing messages containing network connectivity information.

10. The communication unit of claim 9 wherein the transmit rate module determines the transmit rate based upon a user configurable reference transmit rate value and a percentage of network size parameter value for the communication network to which the communication unit belongs.

11. The communication unit of claim 10 wherein the transmit rate is proportional to the percentage of network size parameter value.

12. The communication unit of claim 8 wherein said search module further includes:

a scan window module to determine a scan window interval during which the communication unit receives incoming network connectivity messages; and

a scan window delay module to determine a delay between scan window intervals.

15. The communication unit of claim 1 wherein said merge module further includes:

a merge priority module to determine a merge priority for each neighboring communication network in response to the communication unit controlling said merging, wherein the merge priority controls the priority in which the communication unit allows the communication network to which the communication unit belongs to merge with neighboring communication networks.

16. The communication unit of claim 15 wherein the merge priority module determines the merge priority for a neighboring communication network based upon a comparison of a number of active communication units in the neighboring communication network with a number of total communication units in the neighboring communication network.

17. The communication unit of claim 16 wherein the merge priority is proportional to a quotient of the number of active communication units and the number of total communication units for each respective neighboring network.

13. In a communication network having a plurality of communication units, a communication unit that transmits messages to and receives messages from neighboring communication units, the communication unit comprising:

a transmitter to transmit an outgoing message to a neighboring communication unit;

a receiver to receive an incoming message from a neighboring communication unit;

a storage unit to store communication unit connectivity information, neighboring communication unit connectivity information and merge request information; and

a processor to control said transmission of outgoing messages and reception of incoming messages, wherein said processor includes;

a merge module to examine said stored communication unit connectivity information, stored neighboring communication unit connectivity information and stored merge request information to determine merge control parameters to control merger between the communication unit operating in a first Time Of Day synchronization mode and a neighboring communication network operating in a second Time Of Day synchronization mode that is different from the first mode;

a controller module to control merging of the communication unit with said neighboring communication network in accordance with said merge control parameters determined by said merge module; and

a search module to determine search parameters that control the manner in which the communication unit searches for neighboring communication units and neighboring communication network nodes, wherein said search module includes;

a scan window module to determine a scan window interval during which the communication unit receives incoming network connectivity messages, wherein the scan window module determines the scan window interval based upon a user configurable reference scan window value and a percentage of network size parameter value for the communication network to which the communication unit belongs; and

a scan window delay module to determine a delay between scan window intervals;

wherein the controller module further controls transmission of outgoing messages and reception of incoming messages in a manner consistent with search parameters determined by the search module.

14. The communication unit of claim 13 wherein the scan window interval is inversely proportional to the percentage of network size parameter value.

18. A method for establishing communication between a plurality of communication units comprising:

(a) joining a communication unit to an existing communication network at power up from among a plurality of existing communication networks each with a different Time Of Day synchronization mode, and starting an isolated network with neighboring communication units in response to failure to join the communication unit to at least one of the existing communication networks;

(b) storing communication unit connectivity information, neighboring communication unit connectivity information and merge request information within the communication unit;

(c) examining said stored communication unit connectivity information, stored neighboring communication unit connectivity information and stored merge request information to determine merge control parameters to control merger between the network containing the communication unit and operating in a first Time Of Day synchronization mode and a neighboring communication network operating in a second Time Of Day synchronization mode that is different from the first mode, wherein the network containing the communication unit includes a plurality of communication units and said neighboring communication network includes a plurality of communication nodes; and

(d) controlling merging of the network containing the communication unit with the neighboring communication network in accordance with said merge control parameters.

19. The method of claim 18, wherein communications are in the form of radio signals.

20. The method of claim 18, wherein step (a) further includes:

(a.1) determining the Time Of Day synchronization mode used by the communication unit.

21. The method of claim 20, wherein step (a.1) further includes:

(a.1.1) joining the communication unit to an existing communication network using a user configurable primary Time Of Day synchronization mode.

22. The method of claim 21, wherein step (a.1) further includes:

(a.1.2) changing the Time Of Day synchronization mode of the communication unit in response to the communication unit failing to join a communication network with neighboring communication units using a previously selected Time Of Day synchronization mode; and

(a.1.3) joining the communication unit to an existing communication network using the changed Time Of Day synchronization mode.

23. The method of claim 18, wherein step (b) further includes:

(b.1) storing at least one of an identifier for a communication network to which the communication unit belongs, an identifier for a neighboring communication unit, an identifier for a communication network to which a neighboring communication unit belongs, and an identifier for a neighboring communication unit'"'"'s neighbor.

24. The method of claim 18, wherein step (c) further includes:

(c.1) determining search parameters that control the manner in which the communication unit searches for neighboring communication units and neighboring communication network nodes; and

(c.2) controlling transmission of outgoing messages and reception of incoming messages in a manner consistent with said determined search parameters.

25. The method of claim 24, wherein step (c.1) further includes:

(c.1.1) determining a rate at which the communication unit transmits outgoing messages containing network connectivity information.

26. The method of claim 25, wherein said transmit rate is based upon a user configurable reference transmit rate value and a percentage of network size parameter value for the communication network to which the communication unit belongs.

27. The method of claim 26, wherein the transmit rate is proportional to the percentage of network size parameter value.

28. The method of claim 24, wherein step (c.1) further includes:

(c.1.1) determining a scan window interval during which the communication unit receives incoming network connectivity messages; and

(c.1.2) determining a delay between scan window intervals.

31. The method of claim 18, wherein step (c) further includes:

(c.1) determining a merge priority for each neighboring communication network in response to the communication unit controlling said merging, wherein the merge priority controls the priority in which the communication unit allows the communication network to which the communication unit belongs to merge with neighboring communication networks.

32. The method of claim 31, wherein the merge priority for a neighboring communication network is based upon a comparison of a number of active communication units in the neighboring communication network with a number of total communication units in the neighboring communication network.

33. The method of claim 32, wherein the merge priority is proportional to a quotient of the number of active communication units and the number of total communication units for each respective neighboring network.

29. In a communication network having a plurality of communication units that transmit messages to and receive messages from neighboring communication units, a method for establishing communication between the plurality of communication units comprising:

(a) storing communication unit connectivity information, neighboring communication unit connectivity information and merge request information within a communication unit;

(b) examining said stored communication unit connectivity information, stored neighboring communication unit connectivity information and stored merge request information to determine merge control parameters to control merger between the communication unit operating in a first Time Of Day synchronization mode and a neighboring communication network operating in a second Time Of Day synchronization mode that is different from the first mode, wherein step (b) further includes;

(b.1) determining search parameters that control the manner in which the communication unit searches for neighboring communication units and neighboring communication network nodes, wherein step (b.1) further includes;

(b.1.1) determining a scan window interval during which the communication unit receives incoming network connectivity messages, wherein the scan window interval is determined based upon a user configurable reference scan window value and a percentage of network size parameter value for the communication network to which the communication unit belongs; and

(b.1.2) determining a delay between scan window intervals; and

(b.2) controlling transmission of outgoing messages and reception of incoming messages in a manner consistent with said determined search parameters; and

(c) controlling merging of the communication unit with a neighboring communication network in accordance with said merge control parameters.

30. The method of claim 29 wherein the scan window interval is inversely proportional to the percentage of network size parameter value.

34. A communication network comprising:

a plurality of communication units each having connectivity with a plurality of neighboring communication units that belong to the same communication network operating in a first Time Of Day synchronization mode, wherein each communication unit includes a synchronization module to join that communication unit to an existing communication network at power up from among a plurality of existing communication networks each with a different Time Of Day synchronization mode, and to start an isolated network with neighboring communication units in response to failure to join that communication unit to at least one of the existing communication networks;

wherein one of said communication units is designated a control node that is delegated authority for controlling merges between the communication network to which the control node belongs and operating in the first Time Of Day synchronization mode and a selected neighboring communication network operating in a second Time Of Day synchronization mode that is different from the first mode, wherein the selected neighboring communication network includes a plurality of communication units, and wherein the control node includes;

a connectivity information storage module to store connectivity information related to connectivity between a plurality of communication units within said network and a plurality of neighboring communication units that belong to neighboring communication networks;

a merge module to examine the stored connectivity information and to set merge control parameters that control whether a merge is initiated between the communication network operating in the first Time Of Day synchronization mode to which the control node belongs and the selected neighboring communication network operating in the second Time Of Day synchronization mode; and

a controller module to control network merging in a manner consistent with merge parameters determined by the merge module.

35. The network of claim 34 wherein said each communication unit transmits messages in the form of radio signals.

36. The network of claim 34 wherein said merge module further includes:

a merge priority module to determine a merge priority parameter for a neighboring communication network that determines a priority in which the communication network to which the control node belongs allows merges with neighboring communication networks.

37. The network of claim 36 wherein the merge priority module determines the merge priority for a neighboring communication network based upon a comparison of a count of active communication units within a neighboring communication network with a count of all communication units within a neighboring communication network.

38. The network of claim 37 wherein the merge priority is proportional to a quotient of the count of active communication units and the count of all communication units for each respective neighboring network.