Optical orthogonal frequency division multiplexing (o-ofdm) system with pulse-width modulation (pwm) dimming

Patent metadata

Field	Value
Publication number	US-2016134366-A1
Application number	US-201414894089-A
Country	US
Kind code	A1
Filing date	Jun 24, 2014
Priority date	Jun 28, 2013
Publication date	May 12, 2016
Grant date	—

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

• H04L27/2627

  Modulators · CPC title

• H04L27/2697

  in combination with other modulation techniques · CPC title

• H04B10/116 Primary

  Visible light communication · CPC title