METHOD AND APPARATUS FOR WIRELESS COMMUNICATION IN A MESH NETWORK USING CONNECTIVITY ASSESSMENT AT MULTIPLE FREQUENCIES

• US 20080036589A1
• Filed: 07/12/2007
• Published: 02/14/2008
• Est. Priority Date: 07/17/2003
• Status: Active Grant

• Current Assignee: Honeywell International SARL (Honeywell International Inc.), Yokogawa USA, Inc. (Yokogawa Electric Corporation)
• Original Assignee: Sensicast Systems
• Inventors: Berry, Victor, Werb, Jay, Weiss, Howard, Lamb, C.
• Granted Patent: US 7,675,863 B2
• Time in Patent Office: Days
• US Class Current: 340/539.22
• 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. 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 sensor 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 at least one router performs a connectivity assessment for a plurality of different frequencies that indicates a measure of a quality of wireless communication between the at least one star node or the at least one router and at least one other device in the network at each respective frequency, the connectivity assessment being used to determine a communication relationship between the at least one star node or at least one router and the at least one other device.

2. The network of claim 1, wherein a primary parent/child communication relationship is established between the at least one star node or the at least one router and a first available device with which the at least one star node or at least one router has a highest quality of communication amongst available devices based on the connectivity assessment.

3. The network of claim 2, wherein a secondary parent/child communication relationship is established between the at least one star node or the at least one router and a second available device with which the at least one star node or at least one router has a second highest quality of communication amongst available devices based on the connectivity assessment.

4. The network of claim 1, wherein the at least one star node or at least one router performs the connectivity assessment and reports the results of the connectivity assessment based on a wireless signal sent to the at least one star node or at least one router.

5. The network of claim 1, wherein the communication relationship includes a primary parent/child relationship between the at least one star node or at least one router and a first device, and a secondary parent/child relationship between the at least one star node or at least one router and a second device, and

wherein the at least one star node or at least one router changes the primary or secondary parent/child relationship to be established with another device based on a command signal.

6. The network of claim 1, wherein at least one router changes its status from router to star node in the network based on a command signal.

7. The network of claim 1, wherein the connectivity assessment is performed based on one-way communication between the at least one star node or at least one router and the at least one other device.

8. The network of claim 1, wherein the connectivity assessment is performed based on two-way communication between the at least one star node or at least one router and the at least one other device.

9. The network of claim 1, wherein the connectivity assessment is performed based on a probabilistic analysis of communication between the at least one star node or at least one router and the at least one other device.

10. The network of claim 1, wherein the connectivity assessment involves communication link quality metrics.

11. The network of claim 10, wherein the communication link quality metrics include received signal strength and/or correlation quality.

12. The network of claim 1, wherein the connectivity assessment involves use of thresholds for correlating communication link quality metrics with reduced connectivity experience.

13. The network of claim 1, wherein the connectivity assessment involves accounting of a proportion of scheduled communication packets that are received and/or acknowledged.

14. The network of claim 13, wherein the communication packets are received and acknowledged by the at least one other device.