System and method for merging clusters of wireless nodes in a wireless network

• US 8,189,494 B2
• Filed: 05/11/2009
• Issued: 05/29/2012
• Est. Priority Date: 05/23/2008
• Status: Expired due to Fees

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Budampati, Ramakrishna S., Gonia, Patrick S., Kolavennu, Soumitri N., Mahasenan, Arun V.
• Primary Examiner(s): Moore, Jr., Michael J
• Assistant Examiner(s): Tsegaye, Saba
• Application Number:
  US12/464,002
• Publication Number:
  US 20090290511A1
• Time in Patent Office: 1,114 Days
• Field of Search: 370/254, 370/256, 370/324, 370/328, 370/338, 370/350, 370/458, 370/503, 370/507, 370/508, 370/509, 455/41.2, 455/453, 455/502, 455/507, 455/518, 455/519, 455/520
• US Class Current: 370/254
• CPC Class Codes: H04J 3/0641 Change of the master or reference, e.g. take-over or failure of the master
• CPC Class Codes: H04W 56/0015 one node acting as a reference for the others
• CPC Class Codes: H04W 84/20 Master-slave selection or change arrangements

Abstract

A system includes a first cluster having multiple first wireless nodes. One first node is configured to act as a first cluster master, and other first nodes are configured to receive time synchronization information provided by the first cluster master. The system also includes a second cluster having one or more second wireless nodes. One second node is configured to act as a second cluster master, and any other second nodes configured to receive time synchronization information provided by the second cluster master. The system further includes a manager configured to merge the clusters into a combined cluster. One of the nodes is configured to act as a single cluster master for the combined cluster, and the other nodes are configured to receive time synchronization information provided by the single cluster master.

Claims

1. A system comprising:

a first cluster comprising multiple first wireless nodes, one first wireless node configured to act as a first cluster master, other first wireless nodes configured to receive time synchronization information provided by the first cluster master;

a second cluster comprising multiple second wireless nodes, one second wireless node configured to act as a second cluster master, other second wireless nodes configured to receive time synchronization information provided by the second cluster master; and

a manager configured to merge the clusters into a combined cluster, one of the wireless nodes configured to act as a single cluster master for the combined cluster, the other wireless nodes configured to receive time synchronization information provided by the single cluster master;

wherein the manager is configured to merge the clusters into the combined cluster by;

selecting a first specified wireless node in the first cluster and a second specified wireless node in the second cluster for use in merging the clusters;

altering the first cluster so that the first specified wireless node becomes the first cluster master in order to merge the clusters through the first cluster master; and

causing the first specified wireless node to become a child node of the second specified wireless node to merge the clusters, wherein the first specified wireless node is configured to at least temporarily provide time synchronization information received from the second specified wireless node to the other first wireless nodes in the combined cluster.

2. The system of claim 1, wherein the first specified wireless node is configured to receive time synchronization information from the second specified wireless node that is acting as a parent node, and wherein the second cluster master is configured to then act as the single cluster master for the combined cluster.

3. The system of claim 1, wherein the manager is configured to alter the configuration of the first cluster by:

issuing one or more commands to reverse one or more flows of time synchronization information between (i) the first wireless node currently acting as the first cluster master and (ii) the first specified wireless node that is becoming the first cluster master.

4. The system of claim 1, wherein:

the manager is configured to detect one or more wireless links between one or more first wireless nodes in the first cluster and one or more second wireless nodes in the second cluster; and

the manager is further configured to select one of the links for use in merging the clusters, the selected link associated with the first and second specified wireless nodes.

5. The system of claim 4, wherein the manager is configured to select the selected link based on cluster levels of the first and second specified wireless nodes, the cluster levels identifying hierarchical positions of the first and second specified wireless nodes within the first and second clusters, respectively.

6. The system of claim 4, wherein at least one of the wireless nodes in each cluster is configured to:

passively receive communications from one or more of the wireless nodes in the other cluster;

determine that the received communications are associated with an acceptable quality; and

report an opportunity for a cluster merge to the manager.

7. The system of claim 1, wherein the manager is configured to merge the clusters by:

causing the first wireless nodes to alter their current time to substantially match a current time of the second cluster before the first specified wireless node becomes the child node of the second specified wireless node.

8. The system of claim 7, wherein the manager is configured to cause the first wireless nodes to alter their current time by:

identifying a time difference between the current times of the first and second clusters; and

using the time difference to reset the first wireless nodes to the current time of the second cluster.

9. The system of claim 7, wherein the manager is configured to cause the first wireless nodes to alter their current time by:

identifying a time difference between the current times of the first and second clusters; and

causing the first wireless nodes to reset their current time to match the current time of the second cluster at a beginning of a frame used by the first wireless nodes.

10. The system of claim 1, wherein:

the wireless nodes in the combined cluster are arranged in a spanning tree with the single cluster master at a base of the spanning tree; and

the manager is further configured to cause a different one of the wireless nodes to act as the single cluster master in the combined cluster after the first and second clusters have been merged to at least one of;

decrease a depth of the spanning tree and select a new single cluster master utilizing more accurate clock information than that of the current single cluster master.

11. An apparatus comprising:

an interface configured to receive information identifying a link between first and second clusters of wireless nodes in a wireless network, the first cluster comprising a first wireless node configured to act as a first cluster master and provide time synchronization information for other first wireless nodes in the first cluster, the second cluster comprising a second wireless node configured to act as a second cluster master and provide time synchronization information for other second wireless nodes in the second cluster; and

a processing unit configured to merge the clusters into a combined cluster, wherein one of the wireless nodes in the combined cluster is configured to act as a single cluster master for the combined cluster and to provide time synchronization information for the other wireless nodes in the combined cluster;

wherein the processing unit is configured to merge the clusters by;

selecting a first specified wireless node in the first cluster and a second specified wireless node in the second cluster for use in merging the clusters;

altering the first cluster so that the first specified wireless node becomes the first cluster master in order to merge the clusters through the first cluster master; and

causing the first specified wireless node to become a child node of the second specified wireless node to merge the clusters such that the first specified wireless node at least temporarily provides time synchronization information received from the second specified wireless node to the other first wireless nodes in the combined cluster.

12. The apparatus of claim 11, wherein the processing unit is configured to cause the first specified wireless node to become the child node and receive time synchronization information from the second specified wireless node that is acting as a parent node, and wherein the second cluster master is configured to then act as the single cluster master for the combined cluster.

13. The apparatus of claim 11, wherein the processing unit is configured to alter the configuration of the first cluster by:

issuing one or more commands to reverse one or more flows of time synchronization information between (i) the first wireless node currently acting as the first cluster master and (ii) the first specified wireless node that is becoming the first cluster master.

14. The apparatus of claim 11, wherein the processing unit is configured to merge the clusters by:

causing the first wireless nodes in the first cluster to alter their current time to substantially match a current time of the second cluster before the first specified wireless node becomes the child node of the second specified wireless node.

15. The apparatus of claim 11, wherein:

the wireless nodes in the combined cluster are arranged as a spanning tree with the single cluster master at a base of the spanning tree; and

the processing unit is further configured to cause a different one of the wireless nodes to act as the single cluster master in the combined cluster after the first and second clusters have been merged to at least one of;

decrease a depth of the spanning tree and select a new single cluster master utilizing more accurate clock information than that of the current single cluster master.

16. A method comprising:

providing time synchronization information from a first wireless node acting as a first cluster master to other first wireless nodes in a first cluster;

providing time synchronization information from a second wireless node acting as a second cluster master to other second wireless nodes in a second cluster;

merging the wireless nodes in the first and second clusters into a combined cluster; and

providing time synchronization information from one of the wireless nodes acting as a single cluster master to the other wireless nodes in the combined cluster;

wherein merging the wireless nodes in the first and second clusters comprises;

selecting a first specified wireless node in the first cluster and a second specified wireless node in the second cluster for use in merging the clusters;

altering the first cluster so that the first specified wireless node becomes the first cluster master in order to merge the clusters through the first cluster master; and

causing the first specified wireless node to become a child node of the second specified wireless node to merge the clusters, wherein the first specified wireless node is configured to at least temporarily provide time synchronization information received from the second specified wireless node to the other first wireless nodes in the combined cluster.

17. The method of claim 16, wherein the first specified wireless node becomes the child node and receives time synchronization information from the second specified wireless node that is acting as a parent node, and wherein the second cluster master then acts as the single cluster master for the combined cluster.

18. The method of claim 16, wherein merging the wireless nodes into the combined cluster further comprises:

causing the first wireless nodes in the first cluster to alter their current time to substantially match a current time of the second cluster before the first specified wireless node becomes the child node of the second specified wireless node.

19. The method of claim 16, wherein altering the configuration of the first cluster comprises:

issuing one or more commands to reverse one or more flows of time synchronization information between (i) the first wireless node currently acting as the first cluster master and (ii) the first specified wireless node that is becoming the first cluster master.

20. The method of claim 16, wherein:

the wireless nodes in the combined cluster are arranged as a spanning tree with the single cluster master at a base of the spanning tree; and

further comprising causing a different one of the wireless nodes to act as the single cluster master in the combined cluster after the first and second clusters have been merged to at least one of;

decrease a depth of the spanning tree and select a new single cluster master utilizing more accurate clock information than that of the current single cluster master.

21. A non-transitory tangible computer readable medium embodying a computer program, the computer program comprising:

computer readable program code for receiving information identifying a link between first and second clusters of wireless nodes in a wireless network, the first cluster comprising a first wireless node configured to act as a first cluster master and provide time synchronization information for other first wireless nodes in the first cluster, the second cluster comprising a second wireless node configured to act as a second cluster master and provide time synchronization information for other second wireless nodes in the second cluster; and

computer readable program code for merging the clusters into a combined cluster, wherein one of the wireless nodes in the combined cluster is configured to act as a single cluster master for the combined cluster and to provide time synchronization information for the other wireless nodes in the combined cluster;

wherein the computer readable program code for merging the clusters comprises;

computer readable program code for selecting a first specified wireless node in the first cluster and a second specified wireless node in the second cluster for use in merging the clusters;

computer readable program code for altering the first cluster so that the first specified wireless node becomes the first cluster master in order to merge the clusters through the first cluster master; and

computer readable program code for causing the first specified wireless node to become a child node of the second specified wireless node to merge the clusters such that the first specified wireless node at least temporarily provides time synchronization information received from the second specified wireless node to the other first wireless nodes in the combined cluster.