Visible light communication using colour shift keying

Abstract

The present invention provides a visible light communication transmitter (13), a visible light communication receiver (14), a visible light communication system (2), and a method of visible light communication, wherein the transmitter, the receiver, the system and the method are suitable for colour shift keying (CSK), as well as providing a method of colour shift keying. The visible light communication transmitter (13) comprises at least six, preferably seven, and more preferably eight, graphene-based light emitting devices (LED-1, LED-2,... LED-8) of different peak transmission wavelengths from each other. The visible light communication receiver (14) comprises a corresponding number of graphene-based photodetectors (PD-1, PD-2,... PD-8) of different peak reception wavelengths from each other. A visible light communication system according to the invention comprises such a transmitter and such a receiver, wherein each respective one of the different peak reception wavelengths of the six graphene-based photodetectors corresponds to a respective one of the different peak transmission wavelengths of the graphene-based light emitting devices. Such a system allows a method of visible light communication, preferably using colour shift keying, with a colour constellation of at least six, maybe seven, or even eight base colours. These can provide an increased number of symbols, a reduced symbol error rate and an improved signal-to-noise ratio in comparison to traditional visible light communication systems for colour shift keying, which use a colour constellation of only three orfour base colours.

Description

[0001] The present invention relates to the visible light communication transmitter according to claim 1, the visible light communication receiver according to claim 6, the visible light communication system according to claim 11, the visible light communication method according to claim 12 and The color shift keying method according to claim 15. Background technique

[0002] It is known to transmit information using visible light by encoding the information using constellations of different colors. This is called color shift keying (CSK). Prior art systems may use color constellations of three or four primary colors. Such a system can be implemented using LEDs of different colors, the number of said LEDs can be three, in which case the system is called a three-LED or T-LED system, or the number of said LEDs can be four, In this case the system is called a quad-LED or Q-LED system. For example, WO 2012 / 097885 describes coding schemes and methods for color shift keying const...

Examples

Embodiment Construction

[0041] Figure 1A Elements of a prior art visible light communication system 1 for color shift keying are schematically shown. The visible light communication system 1 includes a transmitter 3 and a receiver 4 . The emitter 3 comprises a plurality of light emitting diodes (LEDs), the number of said LEDs may be three, in which case the system is called a three-LED or T-LED system, or the number of said LEDs may be four, In this case the system is called a quad-LED or Q-LED system. Light is emitted by each of the LEDs at their respective peak emission wavelengths, such as Figure 1A The smooth curve in the graph of , which plots the output power of the LED against the wavelength λ. These peak emission wavelengths represent the primary colors of a color constellation, which may be, for example, the red-green-blue (RGB) color space. However, since LEDs emit visible light at only three or four peak wavelengths, any other color of light than that defined by the peak wavelengths ca...

[0001] The present invention relates to the visible light communication transmitter according to claim 1, the visible light communication receiver according to claim 6, the visible light communication system according to claim 11, the visible light communication method according to claim 12 and The color shift keying method according to claim 15. Background technique

[0002] It is known to transmit information using visible light by encoding the information using constellations of different colors. This is called color shift keying (CSK). Prior art systems may use color constellations of three or four primary colors. Such a system can be implemented using LEDs of different colors, the number of said LEDs can be three, in which case the system is called a three-LED or T-LED system, or the number of said LEDs can be four, In this case the system is called a quad-LED or Q-LED system. For example, WO 2012 / 097885 describes coding schemes and methods for color shift keying const...

Examples

Embodiment Construction

[0041] Figure 1A Elements of a prior art visible light communication system 1 for color shift keying are schematically shown. The visible light communication system 1 includes a transmitter 3 and a receiver 4 . The emitter 3 comprises a plurality of light emitting diodes (LEDs), the number of said LEDs may be three, in which case the system is called a three-LED or T-LED system, or the number of said LEDs may be four, In this case the system is called a quad-LED or Q-LED system. Light is emitted by each of the LEDs at their respective peak emission wavelengths, such as Figure 1A The smooth curve in the graph of , which plots the output power of the LED against the wavelength λ. These peak emission wavelengths represent the primary colors of a color constellation, which may be, for example, the red-green-blue (RGB) color space. However, since LEDs emit visible light at only three or four peak wavelengths, any other color of light than that defined by the peak wavelengths ca...

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