Methods and apparatus for fast and energy-efficient light recovery in a visible light communication (VLC) system

• US 8,620,154 B2
• Filed: 07/16/2010
• Issued: 12/31/2013
• Est. Priority Date: 07/31/2009
• Status: Expired

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Li, Ying, Rajagopal, Sridhar
• Primary Examiner(s): Liu, Li
• Application Number:
  US12/838,240
• Publication Number:
  US 20110026917A1
• Time in Patent Office: 1,264 Days
• Field of Search: 398/1, 398 6- 9, 398 17- 27, 398/103, 398118-130, 398/172, 359/187
• US Class Current: 398/1
• CPC Class Codes: H04B 10/03 Arrangements for fault recovery
• CPC Class Codes: H04B 10/0777 Monitoring line amplifier or line repeater equipment
• CPC Class Codes: H04B 10/0797 Monitoring line amplifier or line repeater equipment
• CPC Class Codes: H04B 10/116 Visible light communication
• CPC Class Codes: H04W 76/19 Connection re-establishment
• CPC Class Codes: H04W 84/10 Small scale networks; Flat hierarchical networks
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A visible light communication (VLC) device is provided for use in a VLC system. The VLC device detect a trigger condition indicating a failure of a VLC link associated with first allocated resources used to communicate with a second VLC device. In response to the detection, the VLC device terminates on the first allocated resources transmission of data to the second VLC device and transmits a fast link recovery (FLR) signal using the first allocated resources. The VLC device receives a fast link recovery response (FLR RSP) signal indicating the second VLC device received the FLR signal and, in response, the VLC device resumes transmission of data to the second VLC device.

Claims

1. For use in a visible light communication (VLC) system, a method of link recovery comprising:

in a first VLC device, communicating with a second device on a VLC link associated with at least one first band among a plurality of bands;

in the first VLC device, detecting a trigger condition indicating a failure of the VLC link associated with the at least one first band;

in the first VLC device, in response to detection of the trigger condition, terminating transmission of data on the at least one first band to the second VLC device;

in the first VLC device, transmitting a plurality of fast link recovery (FLR) signals on all of the plurality of bands;

in the first VLC device, receiving at least one fast link recovery response (FLR RSP) signal on a subset of the plurality of bands, the subset different from the at least one first band, the at least one FLR RSP signal indicating that the second VLC device received the FLR signals; and

in response to reception of the at least one FLR RSP signal, resuming in the first VLC device transmission of data to the second VLC device on at least one of the subset of bands on which the at least one FLR RSP signal was received.

2. The method as set forth in claim 1, wherein the first VLC device is one of:

an access point of a network infrastructure,

a mobile node operable to access an access point of a network infrastructure, and

a mobile node operable to communicate with another mobile node.

3. The method as set forth in claim 2, wherein the trigger condition is one of:

failure to receive in the first VLC device a predetermined number of ACK signals transmitted by the second VLC device,

receipt in the first VLC device of a predetermined number of consecutive NACK signals transmitted by the second VLC device,

failure to receive in the first VLC device at least one of an ACK signal and a NACK signal transmitted by the second VLC device during a predetermined time period,

receipt of consecutive messages containing errors from the second VLC device, and

determining that channel quality of the VLC link is below a threshold.

4. The method as set forth in claim 2, comprising:

in the first VLC device, transmitting to the second VLC device first battery status information associated with a battery of the first VLC device; and

in the first VLC device, receiving from the second VLC device second battery status information associated with a battery of the second VLC device.

5. The method as set forth in claim 4, wherein the first VLC device transmits the FLR signals only if the first battery status and the second battery status indicate that a battery life of the first VLC device is longer than a battery life of the second VLC device.

6. The method as set forth in claim 5, wherein if the first battery status and the second battery status indicate that the battery life of the first VLC device is not longer than the battery life of the second VLC device:

the first VLC device does not transmit the FLR signals to the second VLC device, and

the first VLC device receives an incoming FLR signal from the second VLC device.

7. The method as set forth in claim 2, wherein the plurality of bands comprises a plurality of available color bands.

8. The method as set forth in claim 1, wherein the subset of bands on which the at least on FLR RSP signal was received comprises at least two color bands.

9. The method as set forth in claim 8, wherein resuming in the first VLC device transmission of data to the second VLC device on the at least one of the subset of bands comprises resuming transmission on one of the at least two color bands.

10. The method as set forth in claim 2, wherein transmitting the FLR signals comprises transmitting from the first VLC device the plurality of FLR signals in a plurality of directions.

11. The method as set forth in claim 10, wherein receiving the at least one FLR RSP signal comprises receiving in the first VLC device the at least one FLR RSP signal transmitted by the second VLC device in at least one of the plurality of directions.

12. The method as set forth in claim 11, wherein resuming in the first VLC device transmission of data to the second VLC device comprises resuming transmission on a selected one of the at least one of the plurality of directions.

13. For use in a visible light communication (VLC) system, a first VLC device configured to:

communicate with a second device on a VLC link associated with at least one first band among a plurality of bands;

detect a trigger condition indicating a failure of the VLC link associated with the at least one first band;

in response to the detection, terminate on the at least one first band transmission of data to the second VLC device;

transmit a plurality of a fast link recovery (FLR) signals on all of the plurality of bands;

receive at least one fast link recovery response (FLR RSP) signal from a subset of the plurality of bands, the subset different from the at least one first band, the at least one FLR RSP signal indicating the second VLC device received the PLR signals; and

in response to reception of the at least one FLR RSP signal, resume transmission of data to the second VLC device on at least one of the subset of bands on which the at least one of FLR RSP signal was received.

14. The first VLC device as set forth in claim 13, wherein the first VLC device is one of:

an access point of a network infrastructure, and

a mobile node operable to access an access point of a network infrastructure, and

a mobile node operable to communicate with another mobile node.

15. The first VLC device as set forth in claim 14, wherein the trigger condition is one of:

failure to receive in the first VLC device a predetermined number of ACK signals transmitted by the second VLC device,

receipt in the first VLC device of a predetermined number of consecutive NACK signals transmitted by the second VLC device,

failure to receive in the first VLC device at least one of an ACK signal and a NACK signal transmitted by the second VLC device during a predetermined time period,

receipt of consecutive messages containing errors from the second VLC device, and

determining that channel quality of the VLC link is below a threshold.

16. The first VLC device as set forth in claim 14, wherein the first VLC device is further configured to transmit to the second VLC device first battery status information associated with a battery of the first VLC device and to receive from the second VLC device second battery status information associated with a battery of the second VLC device.

17. The first VLC device as set forth in claim 16, wherein the first VLC device transmits the FLR signals only if the first battery status and the second battery status indicate that the battery life of the first VLC device is longer than the battery life of the second VLC device.

18. The first VLC device as set forth in claim 17, wherein if the first battery status and the second battery status indicate that the battery life of the first VLC device is not longer than the battery life of the second VLC device, the first VLC device does not transmit the FLR signals to the second VLC device and the first VLC device receives an incoming FLR signal from the second VLC device.

19. The first VLC device as set forth in claim 14, wherein the plurality of bands comprises a plurality of available color bands.

20. The first VLC device as set forth in claim 13, wherein the subset of bands on which the at least on FLR RSP signal was received comprises at least two color bands.

21. The first VLC device as set forth in claim 20, wherein the first VLC device resumes transmission on one of the at least two color bands.

22. The first VLC device as set forth in claim 14, wherein the first VLC device transmits the plurality of FLR signals in a plurality of directions.

23. The first VLC device as set forth in claim 22, wherein the first VLC device receives the at least one FLR RSP signal transmitted by the second VLC device in at least one of the plurality of directions.

24. The first VLC device as set forth in claim 23, wherein the first VLC device resumes transmission on a selected one of the at least one of the plurality of directions.