Fast frequency-hopping schedule recovery

• US 9,236,904 B2
• Filed: 11/05/2012
• Issued: 01/12/2016
• Est. Priority Date: 11/05/2012
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Hui, Jonathan W., Hong, Wei, Vasseur, Jean-Philippe
• Primary Examiner(s): Fan, Chieh M
• Assistant Examiner(s): Cadeau, Wednel
• Application Number:
  US13/669,243
• Publication Number:
  US 20140126610A1
• Time in Patent Office: 1,163 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: H04B 1/7156 Arrangements for sequence synchronisation
• CPC Class Codes: H04W 56/001 Synchronization between nodes

Abstract

In one embodiment, a device determines a need to resynchronize a broadcast and unicast frequency-hopping schedules on its network interface. In response to the need, the device may solicit the broadcast schedule from one or more neighbor devices having the synchronized broadcast schedule, and then establishes the unicast schedule for the network interface using communication during the synchronized broadcast schedule.

Claims

1. A method, comprising:

determining, by a network interface, a need to resynchronize one or more broadcast and unicast frequency-hopping schedules on the network interface;

in response to the need, soliciting, by the network interface, an existing broadcast schedule from one or more neighbor devices having a synchronized broadcast schedule;

recovering, by the network interface, the one or more broadcast frequency-hopping schedules on the network interface utilizing the solicited existing broadcast schedule from at least one of the one or more neighbor devices;

establishing a resynchronized or new unicast schedule for the network interface using communication during the one or more recovered broadcast frequency hopping schedules; and

informing the one or more neighbor devices of the resynchronization of the one or more broadcast and unicast frequency hopping schedules by the network interface,

wherein determining the need to resynchronize occurs before an impending de-synchronization occurs and the one or more neighbor devices are informed of an expected impending de-synchronization time of the one or more broadcast and unicast frequency hopping schedules of the network interface.

2. The method as in claim 1, wherein soliciting the existing broadcast schedule comprises:

asynchronously broadcasting a solicitation on all available frequencies.

3. The method as in claim 1, wherein soliciting the existing broadcast schedule comprises:

asynchronously broadcasting a solicitation on a subset of all available frequencies.

4. The method as in claim 1, wherein soliciting the existing broadcast schedule comprises:

asynchronously unicasting a solicitation on all available frequencies to one or more known neighbor devices.

5. The method as in claim 1, wherein soliciting the existing broadcast schedule comprises:

synchronously broadcasting a solicitation within a rough synchronization of a previously known broadcast schedule.

6. The method as in claim 1, wherein soliciting the existing broadcast schedule comprises:

synchronously unicasting a solicitation within a rough synchronization of a previously known unicast schedule.

7. The method as in claim 1, wherein establishing the unicast schedule comprises:

soliciting a previously used unicast schedule from one or more neighbor devices having the unicast schedule of the network interface.

8. The method as in claim 1, wherein establishing the unicast schedule comprises:

establishing a new unicast schedule for the network interface; and

relaying the new unicast schedule to one or more neighbor devices during the recovered broadcast schedule.

9. The method as in claim 1, wherein informing comprises:

pre-soliciting an asynchronous unicast message with resynchronization information for the one or more broadcast and unicast frequency hopping schedules to be sent to the network interface after the impending de-synchronization.

10. The method as in claim 1, wherein soliciting comprises an enhanced beacon request.

11. The method as in claim 2, further comprising:

mitigating responses from the one or more neighbor devices through use of at least one of either filters or random window sizes for the asynchronously broadcasted solicitation.

12. The method as in claim 3, further comprising:

determining the subset based on neighbor density;

number of available frequencies;

or a reliability threshold.

13. An apparatus, comprising:

a network interface to communicate with a frequency-hopping communication network;

a processor coupled to the network interface and adapted to execute one or more processes; and

a memory configured to store a process executable by the processor, the process when executed operable to;

determine a need to resynchronize one or more broadcast and unicast frequency-hopping schedules on the network interface;

in response to the need, solicit an existing broadcast schedule from one or more neighbor devices having a synchronized broadcast schedule;

recover the one or more broadcast frequency-hopping schedules on the network interface utilizing the solicited existing broadcast schedule from at least one of the one or more neighbor devices;

establish a resynchronized or new unicast schedule for the network interface using communication during the one or more recovered broadcast frequency-hopping schedules; and

inform the one or more neighbor devices of the resynchronization of the one or more broadcast and unicast frequency hopping schedules by the network interface,

wherein determining the need to resynchronize occurs before an impending de-synchronization occurs and the one or more neighbor devices are informed of an expected impending de-synchronization time of the one or more broadcast and unicast frequency hopping schedules of the network interface.

14. The apparatus as in claim 13, wherein the process when executed to solicit the existing broadcast schedule is further operable to:

asynchronously broadcast a solicitation on all available frequencies.

15. The apparatus as in claim 13, wherein the process when executed to solicit the existing broadcast schedule is further operable to:

asynchronously broadcast a solicitation on a subset of all available frequencies.

16. The apparatus as in claim 13, wherein the process when executed to solicit the existing broadcast schedule is further operable to:

asynchronously unicast a solicitation on all available frequencies to one or more known neighbor devices.

17. The apparatus as in claim 13, wherein the process when executed to solicit the existing broadcast schedule is further operable to:

synchronously broadcast a solicitation within a rough synchronization of a previously known broadcast schedule.

18. The apparatus as in claim 13, wherein the process when executed to establish the unicast schedule is further operable to:

solicit a previously used unicast schedule from one or more neighbor devices having the unicast schedule of the network interface.

19. The apparatus as in claim 13, wherein the process when executed to establish the unicast schedule is further operable to:

establish a new unicast schedule for the network interface; and

relay the new unicast schedule to one or more neighbor devices during the recovered broadcast schedule;

inform the one or more neighbor devices of the impending de-synchronization of the one or more broadcast and unicast frequency hopping schedules.

20. A tangible, non-transitory, computer-readable media having software encoded thereon, the software, when executed by a processor on an apparatus, operable to:

determine a need to resynchronize one or more broadcast and unicast frequency-hopping schedules on the network interface;

in response to the need, solicit an existing broadcast schedule from one or more neighbor devices having a synchronized broadcast schedule;

recover the one or more broadcast frequency-hopping schedules on the network interface utilizing the solicited existing broadcast schedule from at least one of the one or more neighbor devices;

establish a resynchronized or new unicast schedule for the network interface using communication during the one or more recovered broadcast frequency-hopping schedules; and

inform the one or more neighbor devices of the resynchronization of the one or more broadcast and unicast frequency hopping schedules by the network interface,

wherein determining the need to resynchronize occurs before an impending de-synchronization occurs and the one or more neighbor devices are informed of an expected impending de-synchronization time of the one or more broadcast and unicast frequency hopping schedules of the network interface.