Systems and methods of selective scanning for ad-hoc networks

• US 9,307,507 B2
• Filed: 03/15/2013
• Issued: 04/05/2016
• Est. Priority Date: 11/30/2012
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Zhou, Yan, Cherian, George, Abraham, Santosh Paul
• Primary Examiner(s): Orgad, Edan
• Assistant Examiner(s): Maglo, Emmanuel
• Application Number:
  US13/836,178
• Publication Number:
  US 20140153444A1
• Time in Patent Office: 1,117 Days
• Field of Search: 370/256
• US Class Current: 1/1
• CPC Class Codes: H04L 45/28 using route fault recovery
• CPC Class Codes: H04W 40/005 Routing actions in the presence of nodes in sleep or doze mode
• CPC Class Codes: H04W 40/12 based on transmission quality or channel quality
• CPC Class Codes: H04W 40/20 based on geographic position or location
• CPC Class Codes: H04W 40/22 using selective relaying for reaching a BTS [Base Transceiver Station] or an access point
• CPC Class Codes: H04W 40/246 Connectivity information discovery
• CPC Class Codes: H04W 56/0015 one node acting as a reference for the others
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks
• CPC Class Codes: H04W 84/20 Master-slave selection or change arrangements
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Methods, devices, and computer program products for selective scanning of ad-hoc networks are described herein. In one aspect, a method includes receiving a message identifying a number of times the message has been forwarded. The method further includes selectively scanning for other ad-hoc networks based on the identified number. In one aspect, a root device for an ad-hoc network is responsible for generating synchronization messages for nodes of the ad-hoc network. The synchronization message includes a count of the number of times the synchronization message has been forwarded. When the hop count reaches a limit, the synchronization message is no longer retransmitted or forwarded by receiving nodes. Nodes receiving this message may recognize they are positioned near the edge of the ad-hoc network. In at least one embodiment, these nodes may selectively scan for other ad-hoc networks based on the hop count reaching or exceeding a predetermined threshold.

Claims

1. A method of wireless communication by a leaf device in a first ad-hoc communications network, comprising:

determining a discovery interval and a paging interval for the first ad-hoc communications network;

receiving, by a device, a message from the first ad-hoc communications network identifying a number of times the message has been forwarded;

remaining awake and processing messages outside the discovery interval and paging interval in response to the number of times the message has been forwarded exceeding a threshold, wherein processing messages outside the discovery window and paging interval comprises;

scanning, by the device, for other ad-hoc networks, and joining a second ad-hoc network based on the scanning; and

entering a sleep state outside the discovery interval and the paging interval in response to the number of times the message has been forwarded being below the threshold.

2. The method of claim 1, further comprising incrementing the number of times the received message has been forwarded and forwarding the received message if the identified number is less than a maximum number of hops.

3. The method of claim 1, further comprising not forwarding the message if the identified number is greater than or equal to a maximum number of hops.

4. The method of claim 1, further comprising joining a second ad-hoc network based on the selective scanning.

5. The method of claim 1, wherein the device is a leaf device of the ad-hoc network if the identified number of times is greater than or equal to a maximum number of hops.

6. The method of claim 1, wherein the received message comprises a synchronization message transmitted by a root device.

7. The method device of claim 1, wherein whether to selectively scan is further based on configuration data.

8. The method of claim 1, wherein selectively scanning for other ad-hoc networks comprises receiving messages outside an availability window for the ad-hoc communications network.

9. The method of claim 1, wherein the selective scanning is based on a remaining battery life of the device.

10. The method of claim 8, wherein selectively scanning for other ad-hoc networks further comprises determining if a particular discovery packet or other message received outside the availability window matches a criteria defined by configuration data.

11. A leaf device for wireless communication in a first ad-hoc communications network, comprising:

a processor configured to determine a discovery interval and a paging interval for the first ad-hoc communications network;

a receiver configured to receive a message from the ad-hoc communications network identifying a number of times the message has been forwarded, and

wherein the processor is further configured to;

remain awake and process messages outside the discovery interval and paging interval in response to the number of times the message has been forwarded exceeding a threshold, wherein processing messages outside the discovery window and paging interval comprises;

scanning for other ad-hoc networks in response to the identified number being greater than or equal to a maximum number of hops, and joining a second ad-hoc network based on the scanning; and

entering a sleep state outside the discovery interval and the paging interval in response to the number of times the message has been forwarded being below the threshold.

12. The device of claim 11, wherein the processor is further configured to:

increment the number of times the received message has been forwarded and forward the received message if the identified number is less than a maximum number of hops.

13. The device of claim 11, wherein the processor is further configured to not forward the message if the identified number is greater than or equal to a maximum number of hops.

14. The device of claim 11, wherein the processor is further configured to join a second ad-hoc network based on the selective scanning.

15. The device of claim 11, wherein the device is a leaf device of the ad-hoc network if the identified number of times is greater than or equal to a maximum number of hops.

16. The device of claim 11, wherein the received message comprises a synchronization message transmitted by a root device.

17. The device of claim 11, wherein whether to selectively scan is further based on configuration data.

18. The device of claim 11, wherein the processor is further configured to selectively scan for other ad-hoc networks by receiving messages outside an availability window for the ad-hoc communications network.

19. The device of claim 11, wherein the selective scanning is based on a remaining battery life of the device.

20. The device of claim 18, wherein the processor is further configured to selectively scan by determining if a particular discovery packet or other message received outside the availability window includes matches a criteria defined by configuration data.

21. A leaf device for wireless communication in an ad-hoc communications network, comprising:

means for determining a discovery interval and a paging interval for the first ad-hoc communications network;

means for receiving a message from the ad-hoc communications network identifying a number of times the message has been forwarded;

means for remaining awake and processing messages outside the discovery interval and paging interval in response to the number of times the message has been forwarded exceeding a threshold, wherein processing messages outside the discovery window and paging interval comprises;

means for scanning, by the device, for other ad-hoc networks, and joining a second ad-hoc network based on the scanning; and

means for entering a sleep state outside the discovery interval and the paging interval in response to the number of times the message has been forwarded being below the threshold.

22. The device of claim 21, further comprising means for incrementing the number of times the received message has been forwarded and forwarding the received message if the identified number is less than a maximum number of hops.

23. The device of claim 21, further comprising means for not forwarding the message if the identified number is greater than or equal to a maximum number of hops.

24. The device of claim 21, further comprising means for joining a second ad-hoc network based on the selective scanning.

25. The device of claim 21, wherein the device is a leaf device of the ad-hoc network if the identified number of times is greater than or equal to a maximum number of hops.

26. The device of claim 21, wherein the received message comprises a synchronization message transmitted by a root device.

27. The device of claim 21, wherein the means for selectively scanning selectively scans for other ad-hoc networks by receiving messages outside an availability window for the ad-hoc communications network.

28. The device of claim 21, wherein the means for selective scanning is configured to base the selective scanning on a remaining battery life of the device.

29. The device of claim 27, wherein the means for selectively scanning determines if a particular discovery packet or other message received outside the availability window matches a criteria defined by configuration data.

30. A non-transitory, computer readable medium comprising instructions that when executed cause a processor to perform a method of wireless communication by a leaf device in an ad-hoc communications network, the method comprising:

determining a discovery interval and a paging interval for the first ad-hoc communications network;

receiving, by a device, a message from the first ad-hoc communications network identifying a number of times the message has been forwarded;

remaining awake and processing messages outside the discovery interval and paging interval in response to the number of times the message has been forwarded exceeding a threshold, wherein processing messages outside the discovery window and paging interval comprises;

scanning, by the device, for other ad-hoc networks, and joining a second ad-hoc network based on the scanning; and

entering a sleep state outside the discovery interval and the paging interval in response to the number of times the message has been forwarded being below the threshold.

31. The non-transitory, computer readable medium of claim 30, further comprising incrementing the number of times the received message has been forwarded and forwarding the received message if the identified number is less than a maximum number of hops.

32. The non-transitory, computer readable medium of claim 30, further comprising not forwarding the message if the identified number is greater than or equal to a maximum number of hops.

33. The non-transitory, computer readable medium of claim 30, the method further comprising joining a second ad-hoc network based on the selective scanning.

34. The non-transitory, computer readable medium of claim 30, wherein the device is a leaf device of the ad-hoc network if the identified number of times is greater than or equal to a maximum number of hops.

35. The non-transitory, computer readable medium of claim 30, wherein the received message comprises a synchronization message transmitted by a root device.

36. The non-transitory, computer readable medium device of claim 30, wherein whether to selectively scan is further based on configuration data.

37. The non-transitory, computer readable medium of claim 30, wherein selectively scanning for other ad-hoc networks comprises receiving messages outside an availability window for the ad-hoc communications network.

38. The non-transitory, computer readable medium of claim 37, wherein selectively scanning for other ad-hoc networks further comprises determining if a particular discovery packet or other message received outside the availability window matches a criteria defined by configuration data.

39. A method of wireless communication on an ad-hoc network, comprising:

determining a discovery interval and a paging interval for the first ad-hoc communications network;

receiving, by a first device, a message identifying a geographical location of a root device of a first ad-hoc network;

determining, by the first device, a geographical location of the first device;

determining a distance between the geographical location of the root device and the geographical location of the first device;

remaining awake and processing messages outside the discovery interval and paging interval in response to the distance exceeding a distance threshold, wherein processing messages outside the discovery window and paging interval comprises;

scanning, by the device, for other ad-hoc networks, and joining a second ad-hoc network based on the scanning; and

entering a sleep state outside the discovery interval and the paging interval in response to the distance being below the distance threshold.

40. The method of claim 39, wherein the selective scanning is performed if the distance between the first device and the root device is greater than a threshold distance.

41. The method of claim 40, further comprising joining a second ad-hoc network as a result of the selective scanning.

42. The method of claim 39, wherein the selective scanning is further based on a remaining battery life of the first device.

43. The method of claim 41, further comprising:

determining a window schedule for the second ad-hoc network; and

transmitting a discovery message on the first ad-hoc network, the discovery message indicating the window schedule.

44. The apparatus of claim 41, wherein the processor is further configured to selectively scan based on a remaining battery life of the apparatus.

45. An apparatus for wireless communication on an ad-hoc network, comprising:

a processor configured to determine a discovery interval and a paging interval for the first ad-hoc communications network;

a receiver configured to receive a message identifying a geographic location of a root device of a first ad-hoc network,

wherein the processor is further configured to;

determine a geographic location of the first device; and

determine a distance between the geographical location of the root device and the geographical location of the first device;

remain awake and process messages outside the discovery window and paging interval in response to the distance exceeding a distance threshold, wherein processing messages outside the discovery window and paging interval comprises scanning, by the device, for other ad-hoc networks and joining a second ad-hoc network based on the scanning; and

entering a sleep state outside the discovery interval and the paging interval in response to the distance being below the distance threshold.

46. The apparatus of claim 45, wherein the selective scanning is performed if the distance between the first device and the root device is greater than a threshold distance.

47. The apparatus of claim 46, further comprising a processor configured to join a second ad-hoc network as a result of the selective scanning.

48. The apparatus of claim 47, further comprising:

a processor configured to determine a window schedule for the second ad-hoc network; and

a transmitter configured to transmit a discovery message on the first ad-hoc network, the discovery message indicating the window schedule.

49. An apparatus for wireless communication on an ad-hoc network, comprising:

means for determining a discovery interval and a paging interval for the first ad-hoc communications network, and

means for receiving a message identifying a geographic location of a root device of a first ad-hoc network;

means for determining a geographic location of the first device;

means determining a distance between the geographical location of the root device and the geographical location of the first device;

means for remaining awake and processing messages outside the discovery window and paging interval in response to the distance exceeding a distance threshold, wherein processing messages outside the discovery window and paging interval comprises;

scanning for other ad-hoc networks and joining a second ad-hoc network based on the scanning; and

means for entering a sleep state outside the discovery interval and the paging interval in response to the distance being below the distance threshold.

50. The apparatus of claim 49, wherein the selective scanning is performed if the distance between the first device and the root device is greater than a threshold distance.

51. The apparatus of claim 50, further comprising means for joining a second ad-hoc network as a result of the selective scanning.

52. The apparatus of claim 51, further comprising:

means for determining a window schedule for the second ad-hoc network; and

means for transmitting a discovery message on the first ad-hoc network, the discovery message indicating the window schedule.

53. The apparatus of claim 51, wherein the means for selectively scanning is configured to selectively scan based on a remaining battery life of the apparatus.

54. A non-transitory, computer readable medium comprising instructions that when executed cause a processor to perform a method of wireless communication on an ad-hoc network, the method comprising:

determining a discovery interval and a paging interval for the first ad-hoc communications network;

receiving, by a first device, a message identifying a geographic location of a root device of a first ad-hoc network;

determining, by the first device, a geographic location of the first device; and

determining a distance between the geographical location of the root device and the geographical location of the first device;

remaining awake and processing messages outside the discovery window and paging interval in response to the distance exceeding a distance threshold, wherein processing messages outside the discovery window and paging interval comprises;

scanning, by the device, for other ad-hoc networks, and joining a second ad-hoc network based on the scanning; and

entering a sleep state outside the discovery interval and the paging interval in response to the distance being below the distance threshold.

55. The non-transitory, computer readable medium of claim 54, wherein the selective scanning is performed if the distance between the first device and the root device is greater than a threshold distance.

56. The non-transitory, computer readable medium of claim 55, the method further comprising joining a second ad-hoc network as a result of the selective scanning.

57. The non-transitory, computer readable medium of claim 56, the method further comprising:

determining a window schedule for the second ad-hoc network; and

transmitting a discovery message on the first ad-hoc network, the discovery message indicating the window schedule.

58. The non-transitory, computer readable medium of claim 56, wherein the selective scanning is based on a remaining battery life.

59. A method of wireless communication on a first ad-hoc network, comprising:

joining, by a device, the first ad-hoc network;

receiving a synchronization message from the first ad-hoc network, the synchronization message indicating a first window schedule for the first ad-hoc network, the window schedule indicating a first timing reference for a first availability window during which communication occurs between nodes of the first ad-hoc network;

receiving a synchronization message from a second ad-hoc network, the synchronization message indicating a second window schedule, the second window schedule providing a second timing reference for a second availability window during which communication occurs between nodes of the second ad-hoc network; and

transmitting, by the device, a discovery message on the first ad-hoc network, the discovery message indicating the second window schedule of the second ad-hoc network.

60. The method of claim 59, further comprising determining, by the device, a second window schedule for a third ad-hoc network, wherein the discovery message indicates the second window schedule.

61. An apparatus for wireless communication on a first ad-hoc network, comprising:

a processor configured to join the ad-hoc network;

a processor configured to;

receive a synchronization message from the first ad-hoc network, the synchronization message indicating a first window schedule for the first ad-hoc network, the window schedule indicating a first timing reference for a first availability window during which communication occurs between nodes of the first ad-hoc network;

receive a synchronization message from a second ad-hoc network, the synchronization message indicating a second window schedule, the second window schedule providing a second timing reference for a second availability window during which communication occurs between nodes of the second ad-hoc network; and

a transmitter configured to transmit a discovery message on the first ad-hoc network, the discovery message indicating the second window schedule of the second ad-hoc network.

62. The apparatus of claim 61, further comprising a processor configured to determine a second window schedule for a third ad-hoc network, wherein the transmitter is configured to transmit the discovery message further indicating the second window schedule.

63. An apparatus for wireless communication on a first ad-hoc network, comprising:

means for joining the ad-hoc network;

means for receiving a synchronization message from the first ad-hoc network, the synchronization message indicating a first window schedule for the first ad-hoc network, the window schedule indicating a first timing reference for a first availability window during which communication occurs between nodes of the first ad-hoc network;

means for receiving a synchronization message from a second ad-hoc network, the synchronization message indicating a second window schedule, the second window schedule providing a second timing reference for a second availability window during which communication occurs between nodes of the second ad-hoc network; and

means for transmitting a discovery message on the first ad-hoc network, the discovery message indicating the second window schedule for the second ad-hoc network.

64. The apparatus of claim 63, further comprising means for determining a second window schedule for a third ad-hoc network, wherein the means for transmitting is configured to transmit the discovery message further indicating the second window schedule.

65. A non-transitory computer readable medium comprising instructions that when executed cause a processor to perform a method of wireless communication on a first ad-hoc network, the method comprising:

joining the ad-hoc network;

and

receiving a synchronization message from the first ad-hoc network, the synchronization message indicating a first window schedule for the first ad-hoc network, the window schedule indicating a first timing reference for a first availability window during which communication occurs between nodes of the first ad-hoc network;

receiving a synchronization message from a second ad-hoc network, the synchronization message indicating a second window schedule, the second window schedule providing a second timing reference for a second availability window during which communication occurs between nodes of the second ad-hoc network;

transmitting a discovery message on the first ad-hoc network, the discovery message indicating the second window schedule for the second ad-hoc network.

66. The non-transitory computer readable medium of claim 65, the method further comprising determining a second window schedule for a third ad-hoc network, wherein the discovery message indicates the second window schedule.