Method of communication between reduced functionality devices in an IEEE 802.15.4 network

• US 20060092896A1
• Filed: 10/19/2005
• Published: 05/04/2006
• Est. Priority Date: 10/20/2004
• Status: Active Grant

• Current Assignee: Invensys Systems Incorporated (Invensys PLC)
• Original Assignee: Ranco Incorporated of Delaware (Schneider Electric SE)
• Inventors: Mulligan, Geoff, Ehlers, Gregory A.
• Granted Patent: US 7,486,631 B2
• Time in Patent Office: Days
• US Class Current: 370/338
• CPC Class Codes: H04W 4/90 Services for handling of emergency or hazardous situations, e.g. earthquake and tsunami warning systems [ETWS]
• CPC Class Codes: H04W 72/1263 Mapping of traffic onto schedule, e.g. scheduled allocation or multiplexing of flows
• CPC Class Codes: H04W 76/10 Connection setup
• CPC Class Codes: H04W 76/50 for emergency connections
• CPC Class Codes: H04W 88/04 adapted for relaying to or from another terminal or user

Abstract

In a 802.15.4 network, each reduced functionality device (RFD) is permitted to communicate with only an assigned full function device (FFD). The present invention allows each of the RFDs to communicate with another RFD upon the RFD determining that the local FFD assigned to the RFD is inoperable or unable to communicate. Under emergency conditions, the RFD is able to communicate with a closely located RFDs such that the closely located RFDs can receive and respond to an emergency situation and/or repeat the message. To satisfy the 802.15.4 standards, communication between the RFDs is allowed only during emergency conditions and when the FFD is inoperative. A comprehensive test procedure is included to insure the integrity of the system is preserved at all times.

Claims

1. A method of enhancing communication in a communication network, the method comprising the steps of:

providing at least one full functional device (FFD) having a transceiver operable to receive and send messages using radio frequency;

providing a plurality of reduced functionality devices (RFDs) each having a transceiver operable to receive and transmit messages using radio frequency, wherein each of the RFDs is assigned to only one FFD;

activating each RFD during a predetermined activation period, wherein each RFD communicates to its assigned FFD upon initial activation;

determining whether the communication from the activated RFD to the assigned FFD has been established, wherein the activated RFD enters an orphaned state upon the failure to communicate with the assigned FFD;

continuing to operate the transceiver of the activated RFD to receive messages from either the assigned FFD or the other RFDs when the activated RFD is in the orphaned state; and

allowing the activated RFD to respond to the messages received from the other RFDs only when the activated RFD is in the orphaned state.

2. The method of claim 1 further comprising the step of preventing the activated RFD from responding to messages from the other RFDs upon the establishment of communication between the activated RFD and the assigned FFD.

3. The method of claim 1 wherein the step of allowing the activated RFD to respond to the messages received from the other RFDs includes retransmitting the message.

4. The method of claim 1 further comprising the step of repeatedly attempting to establish communication between the activated RFD and the activated FFD while the RFD is in the orphaned state, wherein the activated RFD exists the orphaned state upon establishment of communication between the activated RFD and its assigned FFD.

5. The method of claim 4 wherein the activated RFD attempts to establish communication with the assigned FFD at predetermined intervals.

6. The method of claim 1 wherein each of the RFDs is a hazardous condition detector.

7. The method of claim 1 wherein each of the RFDs is allowed to respond to remote FFDs other than the FFD assigned to the RFD.

8. The method of claim 1 wherein the communication network is operated under IEEE standard 802.15.4.

9. The method of claim 6 wherein each hazardous condition detector is battery powered.

10. The method of claim 1 further comprising the step of positioning each of the plurality of RFDs such that each RFD is in communication range of the FFD and at least one other RFD.

11. The method of claim 10 further comprising the step of initiating a test procedure at the FFD during which each RFD individually transmits a test message and the remaining plurality of RFDs confirm receipt of the test message, wherein the FFD generates an alarm when none of the other RFDs receive the test message from the RFD.

12. The method of operating a reduced functionality device (RFD) in a communication network including a plurality of RFDs assigned to a full functional device (FFD), the method comprising the steps of:

activating each of the RFDs the RFD during a predetermined activation period, wherein each RFD attempts to establish communication to the assigned FFD during the activation period;

determining whether the communication from the activated RFD to the assigned FFD has been established, wherein the activated RFD enters an orphaned state upon the failure to communicate with the FFD;

continuing to operate the transceiver of the activated RFD to receive messages from any of the plurality of other RFDs when the activated RFD is in the orphaned state; and

allowing the activated RFD to respond to messages received from any of the plurality of other RFDs when the activated RFD is in the orphaned state.

13. The method of claim 12 further comprising the step of preventing the activated RFD from responding to the messages from the plurality of RFDs upon the establishment of successful communication between the activated RFD and the assigned FFD.

14. The method of claim 12 wherein the step of allowing the activated RFD to respond to the messages received from the plurality of RFDs includes retransmitting the message.

15. The method of claim 12 further comprising the step of repeatedly attempting to establish communication between the activated RFD and the FFD while the activated RFD is in the orphaned state, wherein the activated RFD exits the orphaned state upon establishment of communication between the activated RFD and the FFD.

16. The method of claim 12 wherein each of the RFDs is a hazardous condition detector.

17. The method of claim 12 wherein the communication network is operated under IEEE standard 802.15.4.

18. A method of operating a communication network including a full functional device (FFD) having a wireless transceiver and a plurality of reduced function devices (RFDs) each having a wireless transceiver and assigned to the FFD, the method comprising the steps of:

positioning the RFDs such that each RFD is in communication range with the FFD and at least one other RFD;

activating the FFD to perform a test procedure during which the FFD causes each of the RFDs to transmit a test message and each other RFD confirms receipt of the test message to the FFD; and

activating an alarm when the test signal from any RFD is not received by any of the other RFDs.

19. The method of claim 18 wherein the communication network is operated under IEEE standard 802.15.4.

20. The method of claim 18 wherein the identity of each RFD and FFD receiving the test message from the RFD transmitting the test message is stored in the memory of the FFD conducting the test.

21. The method of claim 18 wherein the identity of each RFD and FFD receiving the test message from the RFD transmitting the test message is stored in the memory of the RFD sending the test message.

22. The method of claim 21 where the data stored in memory contains signal strength data associated with RFD and FFD reporting.

23. The method of claim 18 wherein each RFD is a hazardous condition detector including an internal battery.

24. The method of claim 18 wherein the wireless transceiver of each RFD is activated during a predetermined activation period, wherein the RFD attempts to establish communication to the FFD during the activation period;

determining whether communication has been established between the RFD and the FFD, wherein the RFD enters an orphaned state upon the failure to establish communication with the FFD;

continuing to operate the transceiver of the RFD to receive messages from either the FFD or other RFDs when the RFD is in the orphaned state; and

allowing the RFD to respond to the messages received from the other RFDs only when the RFD is in the orphaned state.