FAST FREQUENCY-HOPPING SCHEDULE RECOVERY

• US 20140126610A1
• Filed: 11/05/2012
• Published: 05/08/2014
• 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
• Granted Patent: US 9,236,904 B2
• Time in Patent Office: Days
• US Class Current: 375/134
• 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 a need to resynchronize a broadcast and unicast frequency-hopping schedules on a network interface;

in response to the need, soliciting the broadcast schedule from one or more neighbor devices having the synchronized broadcast schedule; and

establishing the unicast schedule for the network interface using communication during the synchronized broadcast schedule.

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

asynchronously broadcasting a solicitation on all available frequencies.

3. 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.

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

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

5. The method as in claim 4, further comprising:

determining the subset based on one or more factors selected from a group consisting of;

neighbor density;

number of available frequencies; and

a reliability threshold.

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

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

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

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

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

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

9. 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.

10. 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 synchronized broadcast schedule.

11. The method as in claim 1, further comprising:

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

12. The method as in claim 1, wherein determining the need to resynchronize occurs before an impending de-synchronization, the method further comprising:

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

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

informing the one or more neighbor devices of an expected time for the impending de-synchronization of the broadcast and unicast schedules.

14. The method as in claim 12, wherein informing comprises:

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

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

16. 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 a broadcast and unicast frequency-hopping schedules on the network interface;

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

establish the unicast schedule for the network interface using communication during the synchronized broadcast schedule.

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

asynchronously broadcast a solicitation on all available frequencies.

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

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

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

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

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

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

21. The apparatus as in claim 16, 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.

22. The apparatus as in claim 16, 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 synchronized broadcast schedule.

23. The apparatus as in claim 16, wherein determining the need to resynchronize occurs before an impending de-synchronization, and wherein the process when executed is further operable to:

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

24. A method, comprising:

receiving a notice that a neighbor device has an impending de-synchronization of its broadcast and unicast frequency-hopping schedules with an expected time for the impending de-synchronization;

awaiting expiration of the expected time; and

in response to expiration of the expected time, asynchronously unicasting a message with resynchronization information for the broadcast and unicast schedules to the neighbor device.

25. 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;

receive a notice that a neighbor device has an impending de-synchronization of its broadcast and unicast frequency-hopping schedules with an expected time for the impending de-synchronization;

await expiration of the expected time; and

in response to expiration of the expected time, asynchronously unicast a message with resynchronization information for the broadcast and unicast schedules to the neighbor device.