Optical orthogonal frequency division multiplexing (O-OFDM) system with pulse-width modulation (PWM) dimming

Patent metadata

Field	Value
Publication number	US-9621268-B2
Application number	US-201414894089-A
Country	US
Kind code	B2
Filing date	Jun 24, 2014
Priority date	Jun 28, 2013
Publication date	Apr 11, 2017
Grant date	Apr 11, 2017

Abstract

An optical orthogonal frequency division multiplexing (O-OFDM) system with pulse-width modulation (PWM) dimming includes a driver responsive to one or more predetermined dimming set points configured to generate PWM signals having a predetermined duty cycle and configured to supply current to one or more light emitting diodes (LEDs). An O-OFDM generator responsive to the one or more predetermined dimming set points and digital data is configured to generate digital inverted O-OFDM signals during on-states of the PWM signals and non-inverted O-OFDM signals during off-states of the PWM signals according to the predetermined duty cycle and convert the digital inverted O-OFDM signals and the digital non-inverted O-OFDM signals to analog output O-OFDM signals. A combiner circuit responsive to the current from the driver and the analog output O-OFDM signals is configured such that the analog output O-OFDM signals modulate the current to the one or more LEDs to provide a high capacity visible light communication link

First claim

What is claimed is:

1. An optical orthogonal frequency division multiplexing (O-OFDM) system with pulse-width modulation (PWM) dimming, the system comprising:
a driver responsive to one or more predetermined dimming set points configured to generate PWM signals having a predetermined duty cycle and configured to supply current to one or more light emitting diodes (LEDs);
an O-OFDM generator responsive to the one or more predetermined dimming set points and digital data configured to generate digital inverted O-OFDM signals during on-states of the PWM signals and non-inverted O-OFDM signals during off-states of the PWM signals according to the predetermined duty cycle and convert the digital inverted O-OFDM signals and the digital non-inverted O-OFDM signals to analog output O-OFDM signals; and
a combiner circuit responsive to the current from the driver and the analog output O-OFDM signals configured such that the analog output O-OFDM signals modulate the current to the one or more LEDs to provide a high capacity visible light communication link.

2. The system of claim 1 in which the O-OFDM generator includes an inverter configured to generate the digital inverted O-OFDM signals during the on-states based on the predetermined duty cycle.

3. The system of claim 1 in which the O-OFDM generator includes a digital to-analog converter for converting the digital inverted O-OFDM signals and the digital- non-inverted O-OFDM signals to the analog output O-OFDM signals.

4. The system of claim 1 in which the combiner circuit includes at least one amplifier transistor configured such that the analog output O-OFDM signals modulate the current to the one or more LEDs to provide the high capacity visible light communication link.

5. The system of claim 1 in which the combiner circuit includes at least one amplifier transistor and at least one switching transistor configured such that the analog output O-OFDM signals modulate the current to the one or more LEDs to provide the high capacity visible light communication link.

6. The system of claim 2 in which the digital inverted O-OFDM signals include a steam of O-OFDM symbols.

7. The system of claim 1 in which the digital non-inverted O-OFDM signals include a steam of O-OFDM symbols.

8. The system of claim 6 in which the inverter is configured to invert a predetermined number of O-OFDM symbols based on the predetermined duty cycle.

9. The system of claim 6 in which the inverter is configured to invert a predetermined number of O-OFDM symbols based on duration of the on-states.

10. The system of claim 1 in which the O-OFDM generator is configured to generate unipolar inverted O-OFDM symbols during the on-states.

11. The system of claim 1 in which the O-OFDM generator is configured to generate unipolar non-inverted O-OFDM symbols during the off-states.

12. The system of claim 1 in which the one or more LEDs are integrated with a luminaire.

13. An optical orthogonal frequency division multiplexing (O-OFDM) method with PWM dimming, the method comprising:
providing one or more predetermined dimming set points and digital data;
generating, in response to the one or more predetermined dimming set points, PWM signals having a predetermined duty cycle;
generating, in response to the predetermined duty cycle and the digital data, digital inverted O-OFDM signals during on-states of the PWM signals and non-inverted O-OFDM signals during off-states of the PWM signals;
converting the digital inverted O-OFDM signals and the digital non-inverted O-OFDM signals to analog output O-OFDM signals; and
modulating the current to the one or more LEDs using the analog output O-OFDM signals to provide a high capacity visible light communication link.

14. The method of claim 13 in which generating the digital inverted O-OFDM includes generating the digital inverted O-OFDM signals during the on-states based on the predetermined duty cycle.

15. The method of claim 13 in which generating the digital inverted O-OFDM signals includes generating a steam of O-OFDM symbols.

16. The method of claim 13 in which generating digital non-inverted O-OFDM signals includes generating a steam of O-OFDM symbols.

17. The method of claim 15 in which combining the digital inverted O-OFDM signals with the PMW signals during the on-states includes inverting a predetermined number of O-OFDM symbols based on the predetermined duty cycle.

18. The method of claim 15 in which combining the digital inverted O-OFDM signals with the PMW signals during the on-states includes inverting a predetermined number of O-OFDM symbols based on duration of the on-states.

19. The method of claim 13 further including generating unipolar inverted O-OFDM symbols during the on-states.

20. The method of claim 13 further including generating unipolar non-inverted O-OFDM symbols during the off-states.

21. The method of claim 13 in which the one or more LEDs are integrated with a luminaire.

Assignees

• Univ Boston

Inventors

• Elgala Hany
• Little Thomas

Classifications

• H04L25/4902

  Pulse width modulation; Pulse position modulation · CPC title

• H04B10/116 Primary

  Visible light communication · CPC title

• H04L27/2697

  in combination with other modulation techniques · CPC title

• H04L27/2627

  Modulators · CPC title