Apparatus configured for visible-light communications (VLC) using under-sampled frequency shift on-off keying (UFSOOK)

• US 9,838,121 B2
• Filed: 04/19/2016
• Issued: 12/05/2017
• Est. Priority Date: 11/14/2011
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Roberts, Richard D., Walma, Mathys C., Gopalakrishnan, Praveen
• Primary Examiner(s): PASCAL, LESLIE C
• Application Number:
  US15/132,612
• Publication Number:
  US 20160294470A1
• Time in Patent Office: 595 Days
• Field of Search: 398172
• CPC Class Codes: H04B 10/116 Visible light communication
• CPC Class Codes: H04B 10/502 LED transmitters
• CPC Class Codes: H04B 10/524 Pulse modulation
• CPC Class Codes: H04B 10/5563 Digital frequency modulation
• CPC Class Codes: H04B 10/60 Receivers
• CPC Class Codes: H04L 1/08 by repeating transmission, e.g. Verdan system H04L1/1858 and H04L1/189 take precedence
• CPC Class Codes: H04L 25/4902 Pulse width modulation; Pulse position modulation
• CPC Class Codes: H04L 27/02 Amplitude-modulated carrier systems, e.g. using on-off keying; Single sideband or vestigial sideband modulation H04L27/32 takes precedence
• CPC Class Codes: H04L 27/10 Frequency-modulated carrier systems, i.e. using frequency-shift keying H04L27/32 takes precedence
• CPC Class Codes: H04L 27/12 Modulator circuits; Transmitter circuits
• CPC Class Codes: H04L 27/144 with demodulation using spectral properties of the received signal, e.g. by using frequency selective- or frequency sensitive elements
• CPC Class Codes: H04L 27/2096 Arrangements for directly or externally modulating an optical carrier optical modulation H04B10/503
• CPC Class Codes: H04L 27/223 Demodulation in the optical domain optical demodulation H04B10/676

Abstract

Embodiments may provide a way of communicating via an electromagnetic radiator, or light source, that can be amplitude modulated such as light emitting diode (LED) lighting and receivers or detectors that can determine data from light received from the amplitude modulated electromagnetic radiator. Some embodiments may provide a method of transmitting/encoding data via modulated LED lighting and other embodiments may provide receiving/decoding data from the modulated LED lighting by means of a device with a low sampling frequency such as a relatively inexpensive camera (as might be found in a smart phone). Some embodiments are intended for indoor navigation via photogrammetry (i.e., image processing) using self-identifying LED light anchors. In many embodiments, the data signal may be communicated via the light source at amplitude modulating frequencies such that the resulting flicker is not perceivable to the human eye.

Claims

1. An apparatus of a wireless communication device configured for visible-light communications (VLC), the apparatus comprising:

memory; and

processing circuitry, configured to;

decode a data frame in accordance with under-sampled frequency shift on-off keying (UFSOOK), the data frame conveyed by visible light, the data frame comprising a start frame delimiter followed by data in which a first logical level is represented by a first on-off keying (OOK) frequency and second logical level is represented by a second OOK frequency;

wherein, in accordance with the UFSOOK, the processing circuitry is to;

configure light detection circuitry to under-sample the visible light at a sampling frequency (Fs) to generate samples, the first OOK frequency being an integer multiple of the sampling frequency, the second OOK frequency being an integer plus half multiple of the sampling frequency; and

decode the samples to provide output data,

wherein a predetermined timber of samples are decoded to represent each bit of the output data, and

wherein to decode the samples, the processing circuitry is configured to generate the first logical level when an output of the light detection circuitry does not change state over the predetermined number of samples, and generate the second logical level when the output of the light detection circuitry changes state over the predetermined number of samples.

2. The apparatus of claim 1 wherein the sampling frequency corresponds to a sample rate, and

wherein each bit of the output data is represented by at least two of the samples to provide a bit rate that is less than or equal to half the sample rate.

3. The apparatus of claim 2 wherein the samples correspond to camera frames that are generated at a camera frame rate and each bit of output data is represented by at least two camera frames.

4. The apparatus of claim 2 wherein the processing circuitry is configured to decode the start frame delimiter, the start frame delimiter comprising two samples of high-frequency OOK followed by two samples of UFSOOK at the second OOK frequency, the high frequency OOK comprising a frequency higher than a highest of the first and second OOK frequencies.

5. The apparatus of claim 4 wherein the first logical level corresponds to a logical zero and the second logical level corresponds to a logical one.

6. The apparatus of claim 4 wherein the first logical level corresponds to a logical one and the second logical level corresponds to a logical zero.

7. The apparatus of claim 4 wherein the data is encoded on visible light at a transmitter in which the first logical level corresponds to an even number of cycles per bit transmitted for one bit period, and a second logical level corresponds to an odd number of cycles per bit transmitted for one bit period.

8. The apparatus of claim 7 wherein the cycles comprise on-off cycles of visible light.

9. The apparatus of claim 8 wherein the first and second OOK frequencies are greater than a persistence of a human eye.

10. The apparatus of claim 9 wherein the first and second OOK frequencies are greater than 60 Hz.

11. The apparatus of claim 9 wherein the first and second OOK frequencies are greater than 100 Hz.

12. The apparatus of claim 1 further comprising the light detection circuitry, the light detection circuitry configured to receive the visible light, the light detection circuitry comprising a light detector;

and

wherein the processing circuitry comprises a UFSOOK decoder.

13. The apparatus of claim 1 wherein the frame is configured in accordance with an IEEE 802.15 standard for wireless visible light communication (VLC).

14. A non-transitory computer-readable storage medium that stores instructions for execution by processing circuitry of a wireless device configured for visable-light communications, the instructions to configure the wireless communication device to perform operations to:

decode a data frame of visible light in accordance with under-sampled frequency shift on-off keying (UFSOOK), the data frame comprising a start frame delimiter followed by data in which a first logical level is represented by a first on-off keying (OOK) frequency and second logical level is represented by a second OOK frequency;

wherein, in accordance with the UFSOOK, the processing circuitry is to;

under-sample the visible light at a sampling frequency (Fs) to generate samples, the first OOK frequency being an integer multiple of the sampling frequency, the second OOK frequency being an integer plus half multiple of the sampling frequency; and

decode the samples to provide output data,

wherein a predetermined number of samples are decoded to represent each bit of the output data, and

wherein to decode the samples, the processing circuitry is configured to generate the first logical level when the sample value does not change over the predetermined number of samples, and generate the second logical level when the sample value changes over the predetermined number of samples.

15. The non-transitory computer-readable storage medium of claim 14,

wherein the processing circuitry is to configure light-detection circuitry to under-sample the visible light at the sampling frequency (Fs) to generate the samples, and

wherein to decode the samples, the processing circuitry is configured to generate the first logical level when an output of the light detection circuitry does not change state over the predetermined number of samples, and generate the second logical level when the output of the light detection circuitry changes state over the predetermined number of samples.

16. The non-transitory computer-readable storage medium of claim 15 wherein the sampling frequency corresponds to a sample rate, and

wherein each bit of the output data is represented by at least two of the samples to provide a bit rate that is less than or equal to half the sample rate.

17. The non-transitory computer-readable storage medium of claim 16 wherein the samples correspond to camera frames that are generated at a camera frame rate and each bit of output data is represented by at least two camera frames.

18. The non-transitory computer-readable storage medium of claim 16 wherein the processing circuitry is configured to decode the start frame delimiter, the start frame delimiter comprising two samples of high-frequency OOK followed by two samples of UFSOOK at the second OOK frequency, the high frequency OOK comprising a frequency higher than a highest of the first and second OOK frequencies.

19. An apparatus of a wireless communication device configured for light communications, the apparatus comprising:

memory; and

processing circuitry, the processing circuitry comprising an on-off keying (OOK) encoder, the processing circuitry configured to;

encode a data frame for modulation on light, the data frame to include a start frame delimiter followed by data in which a first logical level is represented by a first OOK frequency and a second logical level is represented by a second OOK frequency, the first OOK frequency being an integer multiple of a sampling frequency for decoding in accordance with under-sampled frequency shift on-off keying (UFSOOK), the second OOK frequency being an integer plus half multiple of the sampling frequency; and

modulate an optical source for transmission of the data frame at a light wavelength,

wherein the first logical level corresponds to an even number of cycles per bit transmitted for one bit period, and the second logical level corresponds to an odd number of cycles per bit transmitted for one bit period.

20. The apparatus of claim 19 wherein each bit period corresponds to a predetermined number samples.

21. The apparatus of claim 20 wherein the start frame delimiter comprises two samples of high-frequency OOK followed by two samples of UFSOOK at the second OOK frequency, the high frequency OOK comprising a frequency higher than a highest of the first and second OOK frequencies.

22. The apparatus of claim 21 wherein the light comprises either ultraviolet light or infrared light.

23. The apparatus of claim 21 wherein the light comprises visible light,

wherein the cycles comprise on-off cycles of visible light, and

wherein the first and second OOK frequencies are greater than a persistence of a human eye.

24. The apparatus of claim 23 wherein a duty cycle of the first OOK frequency and the second OOK frequency is fifty percent.

25. The apparatus of claim 24 wherein the processing circuitry is configured to reduce the duty cycle for dimming.

26. The apparatus of claim 19 wherein the first logical level corresponds to a logical zero and the second logical level corresponds to a logical one.

27. The apparatus of claim 19 wherein the first logical level corresponds to a logical one and the second logical level corresponds to a logical zero.