System and method of extending the communication range in a visible light communication system

Patent metadata

Field	Value
Publication number	US-10210750-B2
Application number	US-201313773322-A
Country	US
Kind code	B2
Filing date	Feb 21, 2013
Priority date	Sep 13, 2011
Publication date	Feb 19, 2019
Grant date	Feb 19, 2019

Abstract

A system, remote control device and method are provided herein for communicating with and controlling various devices using visible light communication (VLC). According to one embodiment, a method is provided for extending a communication range of a visible light communication system comprising a remote control device and a plurality of controlled devices. Such a method may include, for example, transmitting a communication message from a remote control device to a first controlled device located within range of the remote control device, wherein the communication message is transmitted through free space using visible light, and extending the communication range of the visible light communication system to a second controlled device, which is located outside of the range of the remote control device, by using the first controlled device to retransmit the communication message through free space using visible light to the second controlled device.

First claim

What is claimed:

1. A visible light communication system comprising:
a remote control device comprising a camera and a light source configured to generate visible light, wherein the remote control device is configured to transmit a first communication message through free space via the light source using visible light, and wherein the first communication message comprises a broadcast message; and
a plurality of lighting fixtures including a first lighting fixture that comprises a first photo-detector and a first light source configured to generate visible light, and a second lighting fixture that comprises a second photo-detector and a second light source configured to generate visible light,
wherein the first lighting fixture is configured to:
turn off the first light source and receive the first communication message from the remote control device via the first photo-detector; and
responsive to receiving the first communication message:
retransmit the first communication message through free space via the first light source using visible light to the second lighting fixture;
determine an identifier assigned to the first lighting fixture; and
transmit a second communication message via the first light source using visible light to the remote control device, wherein the second communication message comprises the identifier assigned to the first lighting fixture;

wherein the second lighting fixture is configured to:
turn off the second light source and receive the first communication message from the first lighting fixture via the second photo-detector; and
responsive to receiving the first communication message:
determine an identifier assigned to the second lighting fixture; and
transmit a third communication message through free space via the second light source using visible light to the remote control device, wherein the third communication message comprises the identifier assigned to the second lighting fixture; and

wherein the remote control device is further configured to:
receive via the camera the second communication message from the first lighting fixture and the third communication message from the second lighting fixture; and
transmit a fifth communication message via the light source of the remote control device using visible light to the first lighting fixture, wherein the fifth communication message comprises an address based on the identifier assigned to the first lighting fixture.

2. The visible light communication system as recited in claim 1 , wherein the first lighting fixture is located within a communication range of the remote control device and the second lighting fixture is located outside of the communication range of the remote control device.

3. The visible light communication system as recited in claim 1 , wherein the remote control device is further configured to transmit a sixth communication message, which is identical to the first communication message, through free space using visible light, and wherein the first and sixth communication messages are transmitted sequentially by the remote control device with a fixed timing between each communication message, and wherein the first lighting fixture is further configured to retransmit the first communication message in synchronization with the sixth communication message.

4. The visible light communication system as recited in claim 1 , wherein the plurality of lighting fixtures are synchronized to a common timing reference, and wherein the first lighting fixture is further configured to retransmit the first communication message to the second lighting fixture in synchronization with the common timing reference.

5. The visible light communication system as recited in claim 4 , wherein each of the plurality of lighting fixtures is coupled to an AC power source, and wherein each of the plurality of lighting fixtures comprises a phase-locked loop (PLL) configured to generate the common timing reference by locking onto an AC signal provided by the AC power source.

6. The visible light communication system as recited in claim 1 , wherein the first communication message comprises information indicating that the first communication message should be retransmitted.

7. The visible light communication system as recited in claim 1 , wherein the first communication message comprises a repeat field that specifies a number of times the first communication message should be retransmitted by the first lighting fixture.

8. The visible light communication system as recited in claim 7 , wherein upon receiving the first communication message from the remote control device, the first lighting fixture is further configured to decrement the number specified in the repeat field of the received message and retransmit the first communication message with the decremented number in the repeat field of the retransmitted message to the second lighting fixture.

9. The visible light communication system as recited in claim 1 , wherein the first communication message comprises a plurality of data fields, which includes one or more of:
a repeat field that specifies a number of times the first communication message should be retransmitted by each lighting fixture that receives the first communication message;
a preamble field containing a unique data sequence that identifies a start of the first communication message;
an address field containing a code specifying one or more lighting fixtures targeted by the first communication message;
a command field containing a code specifying an action to be taken by the targeted lighting fixtures;
a data field containing a data value associated with the command field code; and
a Cyclic Redundancy Check (CRC) checksum field containing a CRC code.

10. The visible light communication system as recited in claim 1 , wherein upon receiving the first communication message from the remote control device, the first lighting fixture is further configured to generate a CRC code and compare the generated CRC code to a CRC code received in the first communication message, and wherein the first lighting fixture is further configured to accept the first communication message when the generated CRC code matches the received CRC code.

11. The visible light communication system as recited in claim 10 , wherein the generated CRC code and the received CRC code are each generated using an identical seed value, and wherein the identical seed value comprises a unique manufacturer identification code, which enables the remote control device to selectively communicate with a specific manufacturer's lighting fixtures.

12. The visible light communication system as recited in claim 11 , wherein upon receiving the first communication message from the remote control device, the first lighting fixture is further configured to generate two different CRC codes using two different seed values, wherein one of the seed values is manufacturer specific and the other seed value is a general seed value, and wherein the first lighting fixture is configured to accept the first communication message when one of the generated CRC codes matches the received CRC code.

13. The visible light communication system as recited in claim 1 , wherein the remote control device further comprises a controller for modulating the visible light generated by the light source of the remote control device with data to produce optically modulated data, which is transmitted through free space from the remote control device as the first communication message.

14. The visible light communication system as recited in claim 13 , wherein the camera of the remote control device is configured to receive

Assignees

• Lutron Ketra Llc
• Lutron Electronics Co

Inventors

• Knapp David J
• Ho Horace C

Classifications

• H04L12/6418

  Hybrid transport · CPC title

• H04L12/282

  based on user interaction within the home (receiver circuitry for displaying additional information being controlled by a remote control apparatus H04N21/42204) · CPC title

• H04L12/2838

  Distribution of signals within a home automation network, e.g. involving splitting/multiplexing signals to/from different paths (adaptations of television systems for transmission by electric cable for domestic distribution H04N7/106; hybrid transport H04L12/6418; home network arrangements specially adapted for distribution of digital video signals H04N7/24) · CPC title

• G08C23/04 Primary

  using light waves, e.g. infrared · CPC title

• H04L2012/2841

  Wireless · CPC title