RECEIVER-BASED LINK-LAYER PROTOCOL

• US 20080181130A1
• Filed: 01/29/2007
• Published: 07/31/2008
• Est. Priority Date: 01/29/2007
• Status: Abandoned Application

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Balu, Shivashankar, Datta Chowdhury, Atish
• Application Number:
  US11/668,055
• Publication Number:
  US 20080181130A1
• Time in Patent Office: Days
• US Class Current: 370/254
• 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

In one embodiment, a system comprises a plurality of nodes. Each node comprises a transceiver to communicate with at least one of the other nodes over a communication medium. Each node has an associated logical, repeating time period, where each time period comprises a first portion in which the respective node is in a listen mode in which the respective node listens on the communication medium and a second portion in which the respective node is an inactive mode in which the respective node is operated in a low-power mode. When a sending node included in the plurality of nodes intends to transmit data via the communication medium to a destination node included in the plurality of nodes, the sending node attempts to transmit the data to the destination node via the communication medium when the destination node is in the listen mode.

Claims

1. A system comprising:

a plurality of nodes, each node comprising a transceiver to communicate with at least one of the other nodes over a communication medium;

wherein each node has an associated logical, repeating time period, wherein each time period comprises a first portion in which the respective node is in a listen mode in which the respective node listens on the communication medium and a second portion in which the respective node is an inactive mode in which the respective node is operated in a low-power mode;

wherein when a sending node included in the plurality of nodes intends to transmit data via the communication medium to a destination node included in the plurality of nodes, the sending node attempts to transmit the data to the destination node via the communication medium when the destination node is in the listen mode.

2. The system of claim 1, wherein each node comprises a respective wireless transceiver for communicating over a wireless communication medium.

3. The system of claim 2, wherein each node comprises a respective radio frequency transceiver for communicating over a radio frequency wireless communication medium.

4. The system of claim 2, wherein at least a subset of the nodes are coupled to a sensor.

5. The system of claim 1, wherein at least a subset of the nodes are battery-powered.

6. The system of claim 1, wherein the respective logical, repeating time period associated with each node varies from node to node.

7. The system of claim 1, wherein the respective logical, repeating time period associated with at least one node varies from period to period.

8. The system of claim 1, wherein for at least one node, the respective transceiver is powered off when that node is operated in the lower-power mode.

9. The system of claim 1, wherein when the sending node attempts to transmit the data to the destination node, the sending node:

checks the communication medium to determine if a first frequency is free;

if the first frequency is free, transmits a first message to the destination node via the communication medium on the first frequency;

listens for a second message on the communication medium on the first frequency;

if the sending node receives the second message from the communication medium on the first frequency within a first timeout period since transmitting the first message;

extracts information indicative of a second frequency;

checks the communication medium to determine if the second frequency is free; and

if the second frequency is free, transmits the data to the destination node via the communication medium on the second frequency.

10. The system of claim 9, wherein the sending node selectively packs at least one of control information and the data into the first message.

11. The system of claim 9, wherein the destination node selectively packs control information into the second message.

12. The system of claim 9, wherein the first message comprises a ready-to-send message and the second message comprises a clear-to-send message.

13. The system of claim 9, wherein the plurality of nodes use a priority-based random-backoff process to control access to the communication medium, wherein the sending node uses the priority-based random-backoff process and a priority associated with the data to be transmitted in order to at least one of:

check the communication medium to determine if the first frequency is free and check the communication medium to determine if the second frequency is free.

14. The system of claim 9, wherein the sending node considers the transmission of the data to be a failure if, after transmitting the data via the communication medium on the second frequency, the sending node receives a negative acknowledgement message from the destination node within a second timeout period since transmitting the data on the second frequency.

15. The system of claim 1, wherein each time period associated with each node comprises a super frame.

16. The system of claim 15, wherein when a broadcast node included in the plurality of nodes wishes to broadcast broadcast data to the other nodes, the broadcasting node:

checks the communication medium to determine if a first frequency is free; and

if the first frequency is free;

transmits a broadcast preamble for the duration of one super frame via the communication medium on the first frequency;

thereafter, transmits a start-of-broadcast frame via the communication medium on the first frequency; and

thereafter, transmits the broadcast data via the communication medium on the first frequency.

17. The system of claim 1, wherein when the destination node is in the listen mode for a respective logical period, the destination node:

when the first portion of the respective logical period has elapsed, causes the destination node to enter the inactive mode;

listens on the communication medium on a first frequency for a ready-to-send message;

when a ready-to-send message is received;

selects a second frequency from a set of predetermined frequencies;

checks the communication medium to determine if the selected second frequency is free;

if the selected second frequency is free;

transmits a clear-to-send message on the first frequency, wherein the clear-to-send message includes information indicative of the selected second frequency;

listens for transmission of the data via the communication medium on the second frequency; and

if the destination node receives the data on the communication medium on the second frequency within a predetermined timeout period since transmitting the clear-to-send message, verifies integrity of the data received by the destination node.

18. The system of claim 17, wherein when the destination node is in the listen mode for a respective logical period, the destination node:

listens on the communication medium on the first frequency for a broadcast preamble;

when the destination node receives the broadcast preamble;

if the destination node receives a start-of-broadcast frame within one instance of the logical, repeating time period associated with the destination node;

receives the broadcast data on the communication medium on the first frequency; and

verifies the integrity of the received broadcast data.

19. A method of communicating between a sending node and a receiving node over a communication medium, the method comprising:

during a first portion of each of successive, repeating logical time periods associated with the receiving node, operating the receiving node in a listen mode in which the receiving node listens on the communication medium;

during a second portion of each of the successive, repeating logical time periods, operating the receiving node in an inactive mode in which the receiving node is operated in a low-power mode; and

attempting to transmit data on the communication medium from the sending node to the receiving when the receiving node is operating in the listen mode.

20. The method of claim 19, wherein attempting to transmit data on the communication medium from the sending node to the receiving node when the receiving node is operating in the listen mode comprises:

checking the communication medium to determine if a first frequency is free;

if the first frequency is free, transmitting a first message from the sending node to the receiving node via the communication medium on the first frequency;

listening at the sending node for a second message on the communication medium on the first frequency; and

if the sending node receives the second message within a first timeout period since transmitting the first message;

extracting from the first message, at the sending node, information indicative of a second frequency;

checking the communication medium, at the sending node, to determine if the second frequency is free; and

if the second frequency is free, transmitting the data from the sending node to the receiving node via the communication medium on the second frequency.

21. The method of claim 20, further comprising selectively packing, at the sending node, at least one of:

control information and the data into the first message.

22. The method of claim 20, further comprising selectively packing, at the receiving node, control information into the second message.

23. The method of claim 20, wherein the sending node and receiving node are included in a plurality of nodes, wherein each of the plurality of nodes use a priority-based random-backoff process to control access to the communication medium, wherein the sending node uses the priority-based random-backoff process and a priority associated with the data to be transmitted in order to at least one of:

check if the first frequency is free and check if the second frequency is free.

24. The method of claim 20, considering the transmission of the data to be a failure if, after transmitting the data on the second frequency, the sending node receives a negative acknowledgement message from the receiving node within a second timeout period since transmitting the data on the second frequency.

25. The method of claim 19, wherein each time period associated with each node comprises a super frame.

26. The method of claim 25, further comprising broadcasting broadcast data from the sending node on the communication medium by:

checking the communication medium, at the sending node, to determine if a first frequency is free; and

if the first frequency is free;

transmitting, from the sending node, a broadcast preamble for the duration of one super frame via the communication medium on the first frequency;

thereafter, transmitting, from the sending node, a start-of-broadcast frame via the communication medium on the first frequency; and

thereafter, transmitting, from the sending node, the broadcast data via the communication medium on the first frequency.

27. The method of claim 19, wherein when the receiving node is operating in the listen mode for a respective current logical period:

causing the destination node to enter the inactive mode when the first portion of the respective current logical period has elapsed;

listening on the communication medium on a first frequency for a ready-to-send message;

when a ready-to-send message is received at the receiving node;

selecting a second frequency from a set of predetermined frequencies;

checking the communication medium to determine if the selected second frequency is free;

if the selected second frequency is free;

transmitting a clear-to-send message from the receiving node via the communication medium on the first frequency, wherein the clear-to-send message includes information indicative of the selected second frequency;

listening at the receiving node for transmission of the data on the communication medium on the second frequency; and

if the receiving node receives the data on the communication medium on the second frequency within a predetermined timeout period since transmitting the clear-to-send message, verifying integrity of the data received by the receiving node.

28. A first node comprising:

a transceiver to communicate over a communication medium;

wherein, during a first portion of each of successive, super frames associated with the first node, the first node is operated in a listen mode in which the first node listens on the communication medium; and

wherein, during a second portion of each of the super frames, the first node is operated in an inactive mode in which the first node is operated in a low-power mode.

29. The first node of claim 28, wherein the transceiver is operable to communicate with a second node over the communication medium, wherein the second node attempts to transmit data on the communication medium to the first when the first node is operating in the listen mode.

30. The first node of claim 29, wherein, during a first portion of each of successive, super frames associated with the second node, the second node is operated in a listen mode in which the second node listens on the communication medium;

wherein, during a second portion of each of the super frames associated with the second node, the second node is operated in an inactive mode in which the second node is operated in a low-power mode;

wherein the first node attempts to transmit data on the communication medium to the second node when the second node is operating in the listen mode.

31. The first node of claim 28, further comprising a programmable processor to execute a protocol stack, wherein the protocol stack comprises a link layer that is operable to cause the first node to operate in the listen mode during the first portion of each super frame and to operate in the inactive mode during the second portion of each super frame.

32. The first node of claim 31, wherein the protocol stack further comprises a network layer that defines at least one of a priority and deadline for the data.

33. The first node of claim 28, wherein the transceiver comprises a wireless transceiver for communicating over a wireless communication medium.

34. The first node of claim 33, wherein the wireless transceiver comprises a radio frequency wireless transceiver for communicating over radio frequency wireless communication medium.

35. The first node of claim 28, further comprising a sensor interface to couple a sensor to the first node.

36. The first node of claim 28, further comprising a battery to power at least the transceiver.

37. The first node of claim 28, wherein the transceiver is powered off when the first node is operated in the lower-power mode.

38. Software comprising program instructions embodied on a storage medium, wherein the program instructions are operable to cause a programmable processor of a first node to:

operate the first node in a listen mode in which the first node listens on a communication medium during a first portion of each of successive, repeating logical time periods associated with the first node; and

operate the first node in an inactive mode in which the first node is operated in a low-power mode during a second portion of each of the successive, repeating logical time periods.

39. The software of claim 38, wherein the first node communicates with a second node over the communication medium, wherein the second node attempts to transmit data on the communication medium to the first when the first node is operating in the listen mode.

40. The software of claim 39, wherein, during a first portion of each of repeating logical time periods associated with the second node, the second node is operated in a listen mode in which the second node listens on the communication medium;

wherein, during a second portion of each of the successive, repeating logical time periods associated with the second node, the second node is operated in an inactive mode in which the second node is operated in a low-power mode; and

wherein the software is operable to cause the programmable to cause the first node to attempt to transmit data on the communication medium to the second when the second node is operating in the listen mode.

41. The software of claim 38, wherein the software comprises a protocol stack, wherein the protocol stack comprises a link layer that is operable to cause the first node to operate in the listen mode during the first portion of each of the successive, repeating logical time periods and to operate in the inactive mode during the second portion of each of the successive, repeating logical time periods.

42. The node of claim 41, wherein the protocol stack further comprises a network layer that defines at least one of a priority and deadline for the data.

43. A first node comprising:

a transceiver means for communicating over a communication medium;

means for operating the first node in a listen mode in which the first node listens on a communication medium during a first portion of each of successive, repeating logical time periods associated with the first node; and

means for operating the first node in an inactive mode in which the first node is operated in a low-power mode during a second portion of each of the successive, repeating logical time periods.