METHOD AND APPARATUS FOR WIRELESS COMMUNICATION IN A MESH NETWORK WITH NODE ACTIVITY MONITORING

• US 20080040509A1
• Filed: 07/12/2007
• Published: 02/14/2008
• Est. Priority Date: 07/17/2003
• Status: Abandoned Application

• Current Assignee: Sensicast Systems
• Original Assignee: Sensicast Systems
• Inventors: Berry, Victor, Werb, Jay, Weiss, Howard, Lamb, C.
• Application Number:
  US11/776,858
• Publication Number:
  US 20080040509A1
• Time in Patent Office: Days
• US Class Current: 709/242
• CPC Class Codes: H04L 2209/805 Lightweight hardware, e.g. radio-frequency identification [RFID] or sensor
• CPC Class Codes: H04L 5/0037 Inter-user or inter-terminal allocation
• CPC Class Codes: H04L 9/0825 using asymmetric-key encryption or public key infrastructure [PKI], e.g. key signature or public key certificates
• CPC Class Codes: H04L 9/083 involving central third party, e.g. key distribution center [KDC] or trusted third party [TTP]
• CPC Class Codes: H04L 9/16 the keys or algorithms being changed during operation
• CPC Class Codes: H04L 9/3247 involving digital signatures
• CPC Class Codes: H04W 12/069 using certificates or pre-shared keys
• CPC Class Codes: H04W 24/02 Arrangements for optimising operational condition
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 52/0219 where the power saving management affects multiple terminals
• CPC Class Codes: H04W 8/005 Discovery of network devices, e.g. terminals
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A method and apparatus for communication in a wireless sensor network. In one embodiment, one or more routers in a network may be available for communication with one or more star nodes at a randomized time and/or frequency. A connectivity assessment, which may be performed at several different frequencies and/or times, may be performed to evaluate the quality of communications between devices in the network. Primary and secondary communication relationships may be formed between devices to provide for system redundancy. Node activity may be monitored, e.g., based on heartbeats sent from a node, to help ensure that nodes remain active. One or more proxies may be maintained where each proxy includes a status of one or more devices in the network, e.g., one or more star nodes or routers. Proxies may be used to handle information requests and/or status change requests, e.g., a proxy may be requested to change a communication relationship between devices in the network and may generate command signals to cause the corresponding devices to make the change.

Claims

1. A wireless mesh network comprising:

a plurality of star nodes constructed and arranged to transmit and receive wireless signals; and

a plurality of routers each constructed and arranged to transmit and receive wireless signals for communication with at least one star node, and constructed and arranged to transmit and receive wireless signals for communication with at least one other device in the wireless sensor network;

wherein at least one router maintains a list of star nodes and/or routers that have communicated with the at least one router and an indication of a time that the at least one router last received a communication from the star node and/or router.

2. The network of claim 1, wherein the at least one router determines that a star node or router has lost connectivity based on a failure of the at least one router to receive a communication from the star node or router within a timeout interval.

3. The network of claim 1, further comprising a host computer, and wherein the at least one router sends an exception report to the host computer upon determining that a star node or router has lost connectivity.

4. The network of claim 3, wherein the host computer determines that at least one star node or router has maintained connectivity based on the absence of an exception report related to the at least one star node or router.

5. The network of claim 3, wherein the host computer determines that at least one star node or router has not been tampered with based on the absence of an exception report related to the at least one star node or router.

6. The network of claim 1, wherein at least one star node or router on the list sends a heartbeat message to the router that is not sent from the router to another device in the network, the heartbeat message indicating that the star node or router is functioning and is able to communicate with the router.

7. The network of claim 2, wherein lost connectivity of a star node or router causes an adjustment in use of network resources, including communication bandwidth.

8. A wireless mesh network comprising:

a plurality of star nodes constructed and arranged to transmit and receive wireless signals; and

a plurality of routers each constructed and arranged to transmit and receive wireless signals for communication with at least one star node, and constructed and arranged to transmit and receive wireless signals for communication with at least one other device in the wireless sensor network;

wherein at least one star node or router periodically sends a heartbeat message to a parent router, where the heartbeat message indicates that the at least one star node or router is functioning and is able to communicate with the parent router.

9. The network of claim 8, wherein the parent router sends an acknowledgement to the star node or router indicating receipt of the heartbeat message.

10. The network of claim 9, wherein the acknowledgement includes time synchronization information used by the star node or router to synchronize its clock with a clock of the parent router.

11. The network of claim 8, wherein the acknowledgement includes information regarding a store-and-forward message to be send to the star node or router.

12. The network of claim 8, wherein the star node or router stores information regarding past communication with the parent router that indicates a communication quality.

13. The network of claim 12, wherein the information regarding past communication is accumulated on a per-frequency basis.

14. The network of claim 12, wherein the star node or router preferentially uses frequencies that have better communication quality for communications with a parent router.

15. The network of claim 8, wherein the star node or router listens for a scheduled beacon sent from the parent router.

16. The network of claim 8, wherein the at least one star node or router sends a second heartbeat message on an alternate frequency if the heartbeat message is not acknowledged by the parent router.

17. The network of claim 8, wherein the at least one star node or router shortens a time interval between sending of successive heartbeat messages if the heartbeat message is not acknowledged by the router.

18. The network of claim 8, further comprising a host computer, and wherein the at least one star node or router sends a heartbeat message to the host computer via another router if the parent router does not acknowledge the heartbeat message.

19. The network of claim 9, wherein the heartbeat sent from the at least one star node or router received by the parent router is not propagated from the parent router.

20. The network of claim 9, wherein the at least one star node or router functions as a parent node to another device in the network and receives heartbeat messages from the other device.