Controlled synchronizing of sensor devices in a wireless sensor network based on received drift information

Patent metadata

Field	Value
Publication number	US-2016374043-A1
Application number	US-201514740892-A
Country	US
Kind code	A1
Filing date	Jun 16, 2015
Priority date	Jun 16, 2015
Publication date	Dec 22, 2016
Grant date	—

Abstract

In one embodiment, a method comprises receiving, by an apparatus from each of a plurality of wireless sensor devices in a wireless sensor network, clock drift information associated with a clock in the corresponding wireless sensor device; determining for each wireless sensor device, by the apparatus, an expected clock drift based at least on the clock drift information from the corresponding wireless sensor device; and sending, by the apparatus to each wireless sensor device, a corresponding drift compensation command for correcting the corresponding expected clock drift, enabling controlled synchronization of the corresponding wireless sensor device within the wireless sensor network.

First claim

1 . A method comprising:
receiving, by an apparatus from each of a plurality of wireless sensor devices in a wireless sensor network, clock drift information associated with a clock in the corresponding wireless sensor device; determining for each wireless sensor device, by the apparatus, an expected clock drift based at least on the clock drift information from the corresponding wireless sensor device; and sending, by the apparatus to each wireless sensor device, a corresponding drift compensation command for correcting the corresponding expected clock drift, enabling controlled synchronization of the corresponding wireless sensor device within the wireless sensor network.

2 . The method of claim 1 , further comprising determining network traffic information for identifying a drift effect on one or more of the wireless sensor devices, the determining including determining the expected clock drift based on at least a portion of the network traffic information.

3 . The method of claim 2 , wherein the network traffic information includes an identification of at least one of a lost data packet, or a retransmitted data packet by the one or more wireless sensor devices.

4 . The method of claim 1 , wherein the drift compensation command to one or more of the wireless sensor devices specifies a corresponding clock compensation value to be used by the one or more wireless sensor device to correct for the corresponding expected clock drift for a specified compensation time period.

5 . The method of claim 1 , wherein the drift compensation command to one or more of the wireless sensor devices specifies a corresponding guard time adjustment to be used for communications with an identified neighbor wireless sensor device.

6 . The method of claim 1 , wherein the drift compensation command to one or more of the wireless sensor devices specifies a listen command for promiscuous listening to an identified neighbor wireless sensor device at one or more prescribed times, the promiscuous listening enabling the one or more wireless sensor devices to synchronize to the identified neighbor wireless sensor device.

7 . The method of claim 1 , wherein the drift compensation command to one or more of the wireless sensor devices specifies a forced beacon sync command for beacon synchronization by the one or more wireless sensor devices with an identified neighbor wireless sensor device at one or more prescribed times.

8 . The method of claim 1 , wherein the drift compensation command to one or more of the wireless sensor devices specifies a leaf command that causes the one or more of the wireless sensor devices to reposition as a leaf node within the wireless sensor network.

9 . An apparatus comprising:
a device interface circuit configured for receiving, from each of a plurality of wireless sensor devices in a wireless sensor network, clock drift information associated with a clock in the corresponding wireless sensor device; and a processor circuit configured for determining, for each wireless sensor device, an expected clock drift based at least on the clock drift information from the corresponding wireless sensor device, the processor circuit further configured for generating, for transmission by the device interface circuit to each wireless sensor device, a corresponding drift compensation command for correcting the corresponding expected clock drift, enabling controlled synchronization of the corresponding wireless sensor device within the wireless sensor network.

10 . The apparatus of claim 9 , wherein the processor circuit further is configured for determining network traffic information for identifying a drift effect on one or more of the wireless sensor devices, including determining the expected clock drift based on at least a portion of the network traffic information.

11 . The apparatus of claim 10 , wherein the network traffic information includes an identification of at least one of a lost data packet, or a retransmitted data packet by the one or more wireless sensor devices.

12 . The apparatus of claim 9 , wherein the drift compensation command to one or more of the wireless sensor devices specifies a corresponding clock compensation value to be used by the one or more wireless sensor device to correct for the corresponding expected clock drift for a specified compensation time period.

13 . The apparatus of claim 9 , wherein the drift compensation command to one or more of the wireless sensor devices specifies a corresponding guard time adjustment to be used for communications with an identified neighbor wireless sensor device.

14 . The apparatus of claim 9 , wherein the drift compensation command to one or more of the wireless sensor devices specifies a listen command for promiscuous listening to an identified neighbor wireless sensor device at one or more prescribed times, the promiscuous listening enabling the one or more wireless sensor devices to synchronize to the identified neighbor wireless sensor device.

15 . The apparatus of claim 9 , wherein the drift compensation command to one or more of the wireless sensor devices specifies a forced beacon sync command for beacon synchronization by the one or more wireless sensor devices with an identified neighbor wireless sensor device at one or more prescribed times.

16 . The apparatus of claim 9 , wherein the drift compensation command to one or more of the wireless sensor devices specifies a leaf command that causes the one or more of the wireless sensor devices to reposition as a leaf node within the wireless sensor network.

17 . One or more non-transitory tangible media encoded with logic for execution by a machine and when executed by the machine operable for:
receiving, by the machine from each of a plurality of wireless sensor devices in a wireless sensor network, clock drift information associated with a clock in the corresponding wireless sensor device; determining for each wireless sensor device, by the machine, an expected clock drift based at least on the clock drift information from the corresponding wireless sensor device; and sending, by the machine to each wireless sensor device, a corresponding drift compensation command for correcting the corresponding expected clock drift, enabling controlled synchronization of the corresponding wireless sensor device within the wireless sensor network.

18 . The one or more non-transitory tangible media of claim 17 , further operable for determining network traffic information for identifying a drift effect on one or more of the wireless sensor devices, the determining including determining the expected clock drift based on at least a portion of the network traffic information.

19 . The one or more non-transitory tangible media of claim 17 , wherein the drift compensation command to one or more of the wireless sensor devices specifies a corresponding clock compensation value to be used by the one or more wireless sensor device to correct for the corresponding expected clock drift for a specified compensation time period.

20 . The one or more non-transitory tangible media of claim 17 , wherein the drift compensation command to one or more of the wireless sensor devices specifies a corresponding guard time adjustment to be used for communications with an identified neighbor wireless sensor device.

21 - 23 . (canceled)

Assignees

• Cisco Tech Inc

Inventors

• Wetterwald Patrick
• Thubert Pascal
• Levy-Abegnoli Eric Michel

Classifications

• H04Q9/04

  Arrangements for synchronous operation · CPC title

• H04W4/005

  Electricity · mapped topic

• H04W56/0045 Primary

  compensating for timing error by altering transmission time · CPC title

• H04W4/70

  Services for machine-to-machine communication [M2M] or machine type communication [MTC] · CPC title