DESC:TECHNICAL FIELD
[0001] The present invention relates to optical wireless data communication and specifically to a visible light data communication method and an apparatus with a light emitting diode (LED) circuitry.

BACKGROUND
[0002] Light emitting diode (LED) is a key element in visible light data communication. LED converts a digital signal into a corresponding light signal that can be illuminated into free space. LED can be switched ON and OFF faster than the human eye can detect, and this invisible ON/OFF activity can be used for data transmission. Data can be transmitted in the form of light pulses by varying the rate at which the LED flickers ON and OFF. This technique of using light pulses to transmit data is typically referred to as visible light communication (VLC).
[0003] EP1643810A1 titled “LED Driving Circuit” mentions an LED driving semiconductor circuit having a first input terminal connected to a light-emitting diode, a switching device block having a first field effective transistor (FET) and a first switching device, a reference voltage terminal, connected to the first FET for outputting reference voltage, and a start/stop circuit for outputting a start signal when the reference voltage is equal to or larger than a predetermined value and for outputting a stop signal when the reference voltage is less than the predetermined value.
[0004] EP2964000A3 titled “LED Driver” mentions a circuit comprising an LED light source and a power supply arranged to power to the LED light source. The circuit includes a feedback controller arranged to provide a feedback signal to the power converter based on the sensed voltage and sensed current. The generation of the regulated power is controlled by the feedback signal.
[0005] US4295226 titled “High Speed Driver for Optoelectronic Devices” mentions a driver circuit for a unidirectional optoelectronic device focussing on fall time characteristic of the optical output of the device. The circuit controls the device to draw a non-zero current when the device is in an “off” state and a larger current when the device is in an “on” state.
[0006] US20100102734A1 mentions titled “Light Emitting Diode Driver and Method” mentions method and apparatus for controlling a plurality of light emitting diodes (LEDs) by using a data communications protocol. An LED driver receives a signal according to the protocol and separates a first command packet from the signal and controls an LED associated with the LED driver in accordance with instructions in the first command packet. The LED driver then outputs the remaining signal for use by one or more subsequent LED drivers.
[0007] US20080088254A1 mentions light emitter driver circuit that adjusts LED luminance by manual input signal. The light emitter driver circuit comprises a Duty Ratio Change Logic, a PWM Generate and Control Logic, an oscillator, and a gate driver. The Duty Ratio Change Logic adjusts the duty cycle of the output signal according to the manual input signal. The PWM Generate and Control Logic generates a PWM signal according to the output signal to control the current of the LED, thus adjusts the luminance of the LED.
[0008] These conventional methods and systems for data communication, however, do not address any issue of heating problems caused in the circuits at high speed communication and thus the circuitry is not safeguarded. Further, controlling of the LED during data transmission is also another limitation as the LED moves into a reverse bias mode.
[0009] Therefore, there is still a need for effective optical data communication system and method using light emitting diode.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
[0010] The detailed description is described with reference to the accompanying figures.
[0011] Fig. 1A illustrates a block diagram of a visible light communication (VLC) transmitter with a modulator unit, a driving unit, a switching unit, a LED unit and a VLC receiver, according to an exemplary embodiment of an apparatus of the present invention.
[0012] Fig. 1B illustrates a detailed block diagram of the modulator unit of the VLC transmitter of the apparatus of Fig. 1.
[0013] Fig. 1C illustrates a circuit diagram of the driving unit and the switching unit, of the VLC transmitter of the apparatus of Fig. 1.
[0014] Figs. 2 illustrates a block diagram of a visible light communication (VLC) transmitter with a modulator unit, a driving unit, a LED unit and a VLC receiver, without a switching unit, according to another exemplary embodiment of an apparatus of the present invention.
[0015] Fig. 3 illustrates a block diagram of a visible light communication (VLC) transmitter with a modulator unit having a multiple output channels, multiple driving units, multiple switching units, multiple LED units and multiple VLC receivers, according to yet another exemplary embodiment of an apparatus of the present invention.
[0016] Fig. 4 illustrates a block diagram of a visible light communication (VLC) transmitter with a modulator unit having multiple output channels, multiple driving units, multiple LED units and multiple VLC receivers, without switching units, according to still another exemplary embodiment of an apparatus of the present invention.
[0017] Fig. 5 illustrates an exemplary implementation of an apparatus of the present invention.
[0018] It should be appreciated by those skilled in the art that any diagrams herein represent conceptual views of illustrative systems embodying the principles of the present invention.

SUMMARY
[0019] This summary is provided to introduce concepts of the present invention. This summary is neither intended to identify essential features of the present invention nor is it intended for use in determining or limiting the scope of the present invention.
[0020] In accordance with an embodiment of the present invention, there is provided an apparatus for switching an LED for high speed data communication. The apparatus comprises: a modulator unit configured to receive data from an external device and at least encode the received data; a driving unit connected to the modulator unit and configured generate a pulsed signal based on the encoded data received from the modulator unit; a switching unit connected to the driving unit and configured to generate a switching signal based on the pulsed signal received from the driving unit; and an LED unit connected to the switching unit and configured to be illuminated at high speed based on the switching signal to generate visible light for high speed data communication.
[0021] In an aspect, the modulator unit comprises: a source encoder configured to compress the received data from the external device to avoid redundancy of unstructured data in the received data; an encryption unit configured to receive compressed data from the source encoder and encrypt the compressed data; a channel encoder configured to receive encrypted data from the encryption unit and encode the encrypted data by adding structured data into the encrypted data; and a parallel to serial converter configured to receive encoded data from the channel encoder and convert the encoded data into serial data format.
[0022] Typically, the pulsed signal has two levels of intensity generated based on a threshold voltage, wherein the two levels of intensity correspond to ON/OFF signal format.
[0023] Typically, the switching unit modulates intensity of light of the LED unit by switching the intensity of light between the two levels to generate optical data in the form of visible light.
[0024] In an aspect, the apparatus further comprises a voltage source configured to supply current to the driving unit and the LED unit, and wherein the optical data in the form of visible light generated through illumination of the LED unit is transmitted to a receiver. The receiver comprises: a photodiode detector configured to detect the transmitted light and convert the light into current; and a processing unit configured to process the current into voltage to further process the data as received from the photodiode.
[0025] In accordance with another embodiment of the present invention, there is provided an apparatus for switching an LED for high speed data communication, wherein the modulator unit comprises a plurality of data output channels, a plurality of driving units are connected to the modulator unit, a plurality of switching units are connected to the driving units respectively, and a plurality of LED units are connected to the switching units respectively to illuminate the LED units with varying intensity to generate varying optical data in the form of varying visible light.
[0026] In accordance with yet another embodiment of the present invention, there is provided an apparatus for switching an LED for high speed data communication, the apparatus comprising: a modulator unit configured to receive data from an external device and at least encode the received data; a driving unit connected to the modulator unit and configured generate a pulsed signal based on the encoded data received from the modulator unit; and an LED unit connected to the driving unit and configured to be illuminated at high speed based on the pulsed signal to generate visible light for data communication.
[0027] In accordance with still another embodiment of the present invention, there is provided an apparatus for switching an LED for high speed data communication, wherein the modulator unit comprises a plurality of data output channels, a plurality of driving units are connected to the modulator unit, and a plurality of LED units are connected to the driving units respectively to illuminate the LED units with varying intensity to generate varying optical data in the form of varying visible light.
[0028] In accordance with one more embodiment of the present invention, there is provided a method for switching an LED for high speed data communication. The method comprises: encoding, by a modulator unit, data received from an external device; generating, by a driving unit, a pulsed signal based on the encoded data received from the modulator unit; generating, by a switching unit, a switching signal based on the pulsed signal received from the driving unit; and illuminating, based on the switching signal, an LED unit at high speed to generate visible light for high speed data communication.
[0029] In an aspect, the step of encoding comprises: compressing, by a source encoder, the received data from the external device to avoid redundancy of unstructured data in the received data; encrypting, by an encryption unit, the compressed data received from the source encoder; encoding, by a channel encoder, the encrypted data received from the encryption unit by adding structured data into the encrypted data; and converting, by a parallel to serial converter, the encoded data received from the channel encoder into serial data format.

DETAILED DESCRIPTION
[0030] The various embodiments of the present invention provide a method and an apparatus for driving and switching of light emitting diode (LED) for high speed data communication as well maintaining illumination of the LED. Unutilized and unlicensed visible spectrum having ranges from 380nm to 780nm are explored for data communication as well maintaining the illumination. The principle of data transmission is by varying the intensity of light i.e., data is modulated for transmission through light. Accordingly, the present invention discloses switching the light emitting diode at high speed with the help of a driving circuitry. According to an embodiment, an LED is switched fastly by a driving circuitry based on received data from a modulator. According to the present invention, a transmitter includes a modulator unit, a driving circuit and a switching circuit for transmitting the data signal through the LED. According to another embodiment, the same circuitry is extended to switch multiple channels. The circuitry is configured to take multiple inputs and to connect to different visible lights operating at different wavelengths.
[0031] In the following description, for purpose of explanation, specific details are set forth in order to provide an understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without these details. One skilled in the art will recognize that embodiments of the present invention, some of which are described below, may be incorporated into a number of systems.
[0032] However, the systems and methods are not limited to the specific embodiments described herein. Further, structures and devices shown in the figures are illustrative of exemplary embodiments of the present invention and are meant to avoid obscuring of the present invention.
[0033] Furthermore, connections between components and/or modules within the figures are not intended to be limited to direct connections. Rather, these components and modules may be modified, re-formatted or otherwise changed by intermediary components and modules.
[0034] References in the present invention to “embodiment” or “implementation” mean that a particular feature, structure, characteristic, or function described in connection with the embodiment or the implementation is included in at least one embodiment or implementation of the invention. The appearances of the phrase “in an embodiment” in various places in the specification are not necessarily all referring to the same embodiment.
[0035] In general, a light emitting diode (LED), switches, normally with the help of a field effect transistor (FET) depending on data fed to it directly or with a pulse width modulation (PWM) signal.
[0036] The present invention claims the approach of switching the LED at high speed with the help of a driving circuitry/unit along with a switching unit/circuitry. With the technical solution provided by the present invention the switching unit is safeguarded from heating issues when driven at high speed and also effective controlling of LED to prevent the LED from going into reverse bias mode is made possible. The same methodology is utilized for switching multiple channels of LEDs.
[0037] In an exemplary embodiment, a method of driving and switching the light emitting diode at high speed for high speed data communication is disclosed.
[0038] In the present exemplary embodiment, the method comprises connecting one terminal of the LED, typically a positive terminal, in series with a resistor that is connected to a voltage source to provide current source at a positive terminal, and other terminal of LED, typically a negative terminal, is connected to a switching unit.
[0039] In the present exemplary embodiment, the method comprises configuring the switching unit, wherein at one end, input is connected to a driving unit and the other end is connected to a ground terminal, and output of the switching unit is connected to the negative terminal of LED. Typically, the switching unit is an n-channel power MOSFET (Metal Oxide Semiconductor Field Effect Transistor).
[0040] In the present exemplary embodiment, the method comprises the driving unit configured to accept data from a modulator unit. The output of the driving unit is connected in series with the switching unit to switch the LED. The driving unit output data is generated with respect to the threshold voltage in a pulsed ON and OFF format that is sent to the switching circuit. One end of voltage source is connected to the driving unit.
[0041] In the exemplary embodiment, the method further comprises configuring a receiver with a photodiode to detect a transmitted light and convert the light to current and a processing unit to convert current into voltage to further process the data as received from the photodiode.
[0042] According to another exemplary embodiment, a method of switching the light emitting diode at high speed without the switching unit is disclosed. A driving unit alone switches the LED unit in this embodiment. According to the embodiment, the method comprises connecting the driving unit directly in series with the LED unit for switching operation.
[0043] In the exemplary embodiment, modulated data is processed at the driver unit as received, then the driving unit generates the ON and OFF signals. The direct connection of the driving unit to the LED unit increases the switching rate and illumination. The method further comprises configuring a receiver with photodiode to detect a transmitted light and convert the light into current and a processing unit to convert current into voltage to further process the data as received from the photodiode.
[0044] According to another exemplary embodiment, a method of switching the light emitting diode at high speed is disclosed. The method comprises a modulator unit having multiple data paths to multiple driver units. The method comprises connecting multiple driver units in series with multiple switching units able to switch the multiple LED’s with different data.
[0045] In the exemplary embodiment, the method further comprises configuring multiple receivers each having a photodiode to detect a transmitted light with different wavelength (frequency) channels and convert the light to current, and a processing unit to convert current into voltage also process the data as received from the photodiode.
[0046] According to another exemplary embodiment, a method of switching the light emitting diode at high speed without the switching unit for a modulator unit having multiple data paths to multiple driver units is disclosed. Each of multiple driving units is directly connected to the LED.
[0047] In the exemplary embodiment, the method further comprises configuring multiple receivers each having a photodiode to detect a transmitted light with different wavelength (frequency) channels with different data encoded into light and convert the light into current and a processing unit to process the data as received from the photodiode.
[0048] According to one more exemplary embodiment, an apparatus for driving and switching of LED at high speed for high speed data communication, comprises a modulator unit, a driving unit, a switching unit, a LED (Light Emitting Diode) unit and a receiver unit.
[0049] In the exemplary embodiment, the modulator unit, the driving unit, and the switching unit are connected in series with LED unit. The receiver unit includes a photodiode and a processing unit. The receiver unit detects the transmitted light with photodiode and processing unit is configured to process the received data.
[0050] In the exemplary embodiment, the driving unit output required for switching unit to switch the LED is in a pulsed ON and OFF format and controlling the speed of the LED is done by having both driving and switching units.
[0051] According to another exemplary embodiment, the apparatus is extended for driving multiple channels of LED at different wavelengths i.e., multiple data paths as inputs to multiple driver units, then connected in series with the corresponding multiple switching units to switch multiple LED's with different data.
[0052] In the exemplary embodiment, multiple LED data is received by multiple photodiodes to detect the transmitted light with different frequency channels and multiple processing units to process the data.
[0053] With the teaching of the present invention the switching unit is protected from saturation due to heat generation. The method and apparatus disclosed herein further ensures that LED does not enter into reverse bias due to high speed switching by connecting the switching unit with driving unit. As the reverse biasing is avoided, heat is not generated and thus protects the switching unit. Therefore, the present invention addresses to solve both heating and reverse bias issues arising due to high speed switching.
[0054] Fig. 1A illustrates a block diagram (100) of an apparatus for driving and switching of LED for high speed data communication according to an exemplary embodiment of the present invention. According to the exemplary embodiment, the apparatus (100) is in the form of a visible light communication (VLC) transmitter comprising a modulator unit (110), a driving unit (120), a switching unit (130), an LED unit (140) and a VLC receiver (160).
[0055] According to the exemplary embodiment, as seen in the block diagram of the apparatus (100), the modulator unit (110), the driving unit (120), and the switching unit (130) are connected in series with LED unit (140). The modulator unit (110) receives data for communication from an external device (not particularly shown) and at least encodes the received data. A voltage source (150) configured to provide current, is connected to both the LED unit (140) at one end and the driving unit (120) at other end. The voltage source (150) is connected typically to the positive terminal of the LED unit (140), and the negative terminal of the LED unit (140) is connected to the switching unit (130). The receiver unit (160) includes a photodiode (161) and a processing unit (not particularly shown). The receiver unit (160) detects the transmitted light with the photodiode (161) and the processing unit is configured to process the received data.
[0056] Fig. 1B illustrates a detailed block diagram of the modulator unit (110) and Fig. 1C illustrates a circuit diagram of the driving unit (120) and the switching unit (130), of the apparatus (100) of Fig. 1. The modulator unit (110) comprises a source encoder (111), an encryption unit (112), a channel encoder (113) and parallel to serial converter (114). The source encoder (111) compresses the data received from the external device to avoid redundancy of unstructured input data stream. The encryption unit (112) secures the data by encrypting the compressed data received from the source encoder (111), and the channel encoder (113) encodes encrypted data received from the encryption unit (112) to make it more reliable by adding structured data to the encrypted data to improve protection against errors during transmission. The LED unit (140) accepts serial data, and accordingly the parallel to serial converter (114) is used to perform the serial to parallel operation on the encoded data received from the channel encoder (113) and provide the serial data to the driving unit (120) which generates a pulsed signal in pulsed ON/OFF format based on the encoded serial data received from the modulator unit (110). The pulsed signal from the driving unit (110) has two levels of intensity generated based on a threshold voltage, and these two levels of intensity correspond to pulsed ON/OFF signal format which is provided to the switching unit (130) which generates a switching signal based on the pulsed signal. The switching signal from the switching unit (130) is provided to the LED unit (140) such that the LED unit (140) is illuminated at high speed based on the switching signal to generate visible light for data communication.
[0057] Fig. 2 a block diagram (200) of an apparatus for driving and switching of LED for high speed data communication according to another exemplary embodiment of the present invention. According to the exemplary embodiment, the apparatus (200) is in the form of a visible light communication (VLC) transmitter comprising a modulator unit (210), a driving unit (220), an LED unit (230) and an VLC receiver (250), without the switching unit.
[0058] According to the exemplary embodiment, as seen in the block diagram of the apparatus (200), the modulator unit (210) and the driving unit (220) are connected in series with the LED unit (230). A voltage source (240) configured to provide current, is connected to both the LED unit (230) at one end and the driving unit (220) at other end. The voltage source (240) is connected typically to the positive terminal of the LED unit (230), and the negative terminal of the LED unit (230) is connected to the driving unit (220). The receiver unit (250) includes a photodiode (251) and a processing unit (not particularly shown). The receiver unit (250) detects the transmitted light with the photodiode (251) which converts light into current and the processing unit is configured to process the received data.
[0059] Fig. 3 illustrates a block diagram (300) of an apparatus for driving and switching of LED for high speed data communication according to yet another exemplary embodiment of the present invention. According to the exemplary embodiment, the apparatus (300) is in the form of a visible light communication (VLC) transmitter comprising a modulator unit (310) having multiple output channels (310a… 310n), multiple driving units (320a… 320n), multiple switching units (330a… 330n), multiple LED units (340a… 340n) and multiple VLC receivers (360a… 360n).
[0060] According to the exemplary embodiment, as seen in the block diagram of the apparatus (300), the modulator unit (310), with each of the driving units (320a… 320n) and each of the switching units (330a… 330n) are connected in series with each of the LED units (340a… 340n) respectively. Multiple voltage sources (350a… 350n) configured to provide current, are each connected to the LED units (340a… 340n) at one end and the driving units (320a… 320n) at the other end respectively. The voltage sources (350a… 350n) are each connected typically to the positive terminal of each LED unit (340a… 340n), and the negative terminal of each LED unit (340a… 340n) is connected to each switching unit (330a… 330b). Each receiver unit (360a… 360n) includes a photodiode (361a… 361n) and a processing unit (not particularly shown). Each receiver unit (360a… 360n) detects the transmitted light with photodiode (361a… 361n) and the processing units are configured to process the received data. Thus, different wavelength channels (frequencies) are detected.
[0061] Fig. 4 illustrates a block diagram (400) of an apparatus for driving and switching of LED for high speed data communication according to still another exemplary embodiment of the present invention. According to the exemplary embodiment, the apparatus (400) is in the form of a visible light communication (VLC) transmitter comprising a modulator unit (410) having multiple output channels (410a… 410n), multiple driving units (420a… 420n), multiple LED units (430a… 430n) and multiple VLC receivers (450a… 450n), without the switching units.
[0062] According to the exemplary embodiment, as seen in the block diagram of the apparatus (400), the modulator unit (410), with each of the driving units (420a… 420n) is connected in series with each of the LED units (430a… 430n) respectively. Multiple voltage sources (440a… 440n) configured to provide current, are each connected to the LED units (430a… 430n) at one end and the driving units (420a… 420n) at the other end respectively. The voltage sources (440a… 440n) are each connected typically to the positive terminal of each LED unit (430a… 430n), and the negative terminal of each LED unit (430a… 430n) is connected to each driving unit (420a… 420b). Each driving unit alone switches each LED unit in this embodiment. Connecting each driving unit directly in series with each LED unit for switching increases the switching rate and illumination. Each receiver unit (450a… 450n) includes a photodiode (451a… 451n) and a processing unit (not particularly shown). Each receiver unit (450a… 450n) detects the transmitted light with photodiode (451a… 451n) and the processing unit is configured to process the received data. Thus, different wavelength channels (frequencies) are detected.
[0063] Fig. 5 illustrates an exemplary implementation of the apparatus (100) for driving and switching of LED for high speed data communication and the method performed by the apparatus, according to the present invention. The exemplary implementation is a use case scenario involving transmission of text from one personal computer (PC) to another PC. The transmitting source LEDs are basically semiconductor devices illuminated by applying variable current, can be switched at very high speed which cannot be noticed by human eye. The PC UART is used as an input data source and it provides serial data to a modulator unit, where data is encoded, processed and transmitted to a driving unit. The driving unit receives the serial data and sends two levels of intensity corresponding to pulsed ON/OFF signal to a switching unit. The switching unit consists of n-channel MOSFET, based on the input levels it generates the switching signal to switch the intensity of light between two levels and this is called intensity modulation where whole data is modulated based on intensity to generate optical data through LED. The current in LED can be varied depending on the modulation technique used. In Intensity Modulation Direct Detection (IM-DD) On-Off Keying (OOK), the modulation is based on intensity and direct detection is based on received power levels. The modulated 1’s and 0’s fluctuate the LED to ON and OFF and the modulated data in a visible light / optical form is transmitted to the receiver where the data gets demodulated from optical to electrical data format. At a receiver side, a photo-diode is used to receive the visible light from LED Bulb and the photodiode converts this variation in light intensity into electrical data. The output of the receiver is connected to the ‘Rx’ terminal of the UART and the output is observed in the PC.
[0064] The foregoing description of the invention has been set merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to person skilled in the art, the invention should be construed to include everything within the scope of the invention.

,CLAIMS:
1) An apparatus (100) for switching an LED for high speed data communication, said apparatus comprising:
a modulator unit (110) configured to receive data from an external device and at least encode the received data;
a driving unit (120) connected to said modulator unit (110) and configured generate a pulsed signal based on the encoded data received from said modulator unit (110);
a switching unit (130) connected to said driving unit (120) and configured to generate a switching signal based on the pulsed signal received from said driving unit (120); and
an LED unit (140) connected to said switching unit (130) and configured to be illuminated at high speed based on the switching signal to generate visible light for high speed data communication.

2) The apparatus (100) as claimed in claim 1, wherein said modulator unit (110) comprises:
a source encoder (111) configured to compress the received data from said external device to avoid redundancy of unstructured data in the received data;
an encryption unit (112) configured to receive compressed data from said source encoder (111) and encrypt the compressed data;
a channel encoder (113) configured to receive encrypted data from said encryption unit (112) and encode the encrypted data by adding structured data into the encrypted data; and
a parallel to serial converter (114) configured to receive encoded data from said channel encoder (113) and convert the encoded data into serial data format.

3) The apparatus (100) as claimed in claim 1, wherein said pulsed signal has two levels of intensity generated based on a threshold voltage, wherein said two levels of intensity correspond to ON/OFF signal format.

4) The apparatus (100) as claimed in claim 3, wherein said switching unit modulates intensity of light of said LED unit (140) by switching the intensity of light between the two levels to generate optical data in the form of visible light.

5) The apparatus (100) as claimed in claims 1 to 4, wherein said apparatus comprises a voltage source (150) configured to supply current to said driving unit (120) and said LED unit (140), and
wherein said optical data in the form of visible light generated through illumination of said LED unit (140) is transmitted to a receiver (160), said receiver (160) comprising:
a photodiode detector (161) configured to detect the transmitted light and convert the light into current; and
a processing unit configured to process the current into voltage to further process the data as received from the photodiode.

6) The apparatus as claimed in claim 1, wherein said modulator unit comprises a plurality of data output channels (310a… 310n), a plurality of driving units (320a… 320n) are connected to said modulator unit (310), a plurality of switching units (330a… 330n) are connected to said driving units (320a… 320n) respectively, and a plurality of LED units (340a… 340n) are connected to said switching units (330a… 330n) respectively to illuminate said LED units (340a… 340n) with varying intensity to generate varying optical data in the form of varying visible light.

7) An apparatus (200) for switching an LED for high speed data communication, said apparatus (200) comprising:
a modulator unit (210) configured to receive data from an external device and at least encode the received data;
a driving unit (220) connected to said modulator unit (210) and configured generate a pulsed signal based on the encoded data received from said modulator unit (210); and
an LED unit (230) connected to said driving unit (220) and configured to be illuminated at high speed based on the pulsed signal to generate visible light for data communication.

8) The apparatus as claimed in claim 8, wherein said modulator unit comprises a plurality of data output channels (410a… 410n), a plurality of driving units (420a… 420n) are connected to said modulator unit (410), and a plurality of LED units (430a… 430n) are connected to said driving units (420a… 420n) respectively to illuminate said LED units (430a… 430n) with varying intensity to generate varying optical data in the form of varying visible light.

9) A method for switching an LED for high speed data communication, the method comprising:
encoding, by a modulator unit (110), data received from an external device;
generating, by a driving unit (120), a pulsed signal based on the encoded data received from said modulator unit (110);
generating, by a switching unit (130), a switching signal based on the pulsed signal received from said driving unit (120); and
illuminating, based on the switching signal, an LED unit (140) at high speed to generate visible light for high speed data communication.

10) The method as claimed in claim 10, wherein the step of encoding comprises:
compressing, by a source encoder (111), the received data from said external device to avoid redundancy of unstructured data in the received data;
encrypting, by an encryption unit (112), the compressed data received from said source encoder (111);
encoding, by a channel encoder (113), the encrypted data received from said encryption unit (112) by adding structured data into the encrypted data; and
converting, by a parallel to serial converter (114), the encoded data received from said channel encoder (113) into serial data format.