Claims:
1. A method to transmit data from a transmitter to a receiver, said method comprising the steps of:
using, at the transmitter end, a carrier frequency signal with an ON time (Ton) for a cycle during which said signal is of a positive amplitude, and an OFF time (Toff ) for said cycle during which said signal is of zero or negative amplitude; and
transmitting, from said transmitter, said data during said Toff, wherein said Toff is varied so as to vary the amount of data transmitted in said cycle.
2. The method of claim 1, wherein said signal comprises visible light (VL), radio waves or infrared waves, and is a pulse width modulated (PWM) signal.
3. The method of claim 1, wherein said method enables multiple bits of data to be transmitted per cycle of said signal.
4. The method of claim 1, wherein said method enables said data transmission only when at least one byte of said data is transmitted in said Toff .
5. The method of claim 4, wherein said at least one byte comprises eight bits of information, one start bit and one stop bit.
6. The method of claim 4, wherein the method further allows said data transmission only of a complete number of bytes during said Toff.
7. The method of claim 4, wherein time taken to transfer one byte (T1byte) is 10/baud rate, and wherein said baud rate is so selected that said T1byte is less than said Toff.
8. The method of claim 1, wherein the method further comprises the step of using, in combination to the varying the Toff to vary the amount of data, a second modulation technique on said data.
9. A transmitter configured to transmit data to a receiver, said transmitter configured to:
incorporate a carrier frequency signal with an ON time (Ton) for a cycle during which said signal is of a positive amplitude, and an OFF time (Toff ) for said cycle during which said signal is of zero or negative amplitude; and
transmit said data during said Toff, wherein said Toff is varied so as to vary the amount of data transmitted in said cycle.
10. The transmitter of claim 9, wherein said signal comprises visible light (VL), radio waves or infrared waves, and is a pulse width modulated (PWM) signal.
, Description:
FIELD OF DISCLOSURE
[0001] The present disclosure relates to data transmissions systems and methods. In particular it pertains to a novel method that can be used to transfer digital data using wired/wireless communication media.

BACKGROUND OF THE DISCLOSURE
[0002] The background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] Usage of electromagnetic (EM) waves for transfer of data is well known. EM waves are created as a result of vibrations between an electric field and a magnetic field. Electromagnetic waves are formed when an electric field comes in contact with a magnetic field. They are hence known as ‘electromagnetic’ waves. The electric field and magnetic field of an electromagnetic wave are perpendicular (at right angles) to each other. They are also perpendicular to the direction of the EM wave. EM waves travel with a constant velocity of 3.00 x 108 ms-1 in vacuum. They are deflected neither by the electric field, nor by the magnetic field. An electromagnetic wave can travel through anything - be it air, a solid material or vacuum. It does not need a medium to propagate or travel from one place to another. EM waves are 'transverse' waves. This means that they are measured by their amplitude (height) and wavelength (distance between the highest/lowest points of two consecutive waves).
[0004] The highest point of a wave is known as 'crest', whereas the lowest point is known as 'trough'. Electromagnetic waves can be split into a range of frequencies. This is known as the electromagnetic spectrum.
[0005] Electromagnetic waves are used to transmit long/short/FM wavelength radio waves, and TV/telephone/wireless signals or energies. They are also responsible for transmitting energy in the form of microwaves, infrared radiation (IR), visible light (VL), ultraviolet light (UV), X-rays, and gamma rays.
[0006] By themselves, electromagnetic waves have very regular patterns, and hence termed as periodic waveforms. Generally they keep the same amplitude or frequency all the time. (Amplitude is the "height" of the radio wave, frequency is how close the waves are to each other.)
[0007] Radio waves are very commonly used for transmitting data such as radio broadcasts and the like. Typically, there are two ways of transmitting data using an electromagnetic wave. They are called Amplitude Modulation ( AM) and Frequency Modulation ( FM)
[0008] In amplitude modulation, information is put into a radio wave by varying the amplitude. For example, if all we wanted to do was send 1's and 0's, we could have just two different levels of amplitude that correspond to these numbers--1 being high, 0 being low. Similarly, in frequency modulation the amplitude is kept constant and the frequency is varied to convey information.
[0009] This process of varying one or more properties of a periodic waveform (interchangeably termed as a carrier signal) to carry information ( that may be carried in/ derived from another signal called the modulating signal ) is called modulation. Most current radio systems, for instance, use frequency modulation (FM) or amplitude modulation (AM) to make the carrier carry the radio broadcast.
[00010] Using basic principles of AM and FM, many other modulationmethods or their combinations have been developed over the years. These include Phase Modulation, Quadrature Amplitude Modulation, Space Modulation, Single Sideband Modulation etc. .for analog signals, and Amplitude-Shift Keying, Continuous Phase Modulation and Frequency Shift Keying etc. for digital signals.
[00011] Pulse-width modulation (PWM), or pulse-duration modulation (PDM), is another modulation method used to encode a message/data/information into a pulsing signal such as a periodic waveform. As applied to square waveforms, PWM is very frequently used in control power supplied to electrical devices.
[00012] PWM has also been used in certain communication systems where its duty cycle has been used to convey information over a communications channel.
[00013] However, all present modulation methods can enable only one bit of data transfer per cycle. Further they use both ON and OFF time period of the cycle and do not allow for variation of any of the time periods according to application needs for more efficient utilization of available cycles. Further, one modulation method cannot be combined with another to make a hybrid modulation method with more advantages.
[00014] Hence there is a need in the art for a modulation method that allows for data transfer higher than a bit per cycle, uses only OFF period of the cycle and can combine with itself other modulation methods as required.
[00015] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
[00016] In some embodiments, the numbers expressing quantities or dimensions of items, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.
[00017] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[00018] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all groups used in the appended claims.

OBJECTS OF THE DISCLOSURE
[00019] Some of the objects of the present disclosure, which at least one embodiment herein satisfies are as listed herein below.
[00020] It is an object of the present disclosure to provide for a method to transmit data that enables data transfer higher than a bit per cycle of the carrier signal.
[00021] It is an object of the present disclosure to provide for a method to transmit data that uses only OFF period of the carrier signal.
[00022] It is an object of the present disclosure to provide for a method to transmit data that can be combined with other modulation techniques as required.
[00023] It is an object of the present disclosure to provide for a method to transmit data that is highly suitable for visible light (VL) communication.

SUMMARY
[00024] This summary is provided to introduce simplified concepts of a hybrid variable length partial pulse modulation data transmission method. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended for use in determining/limiting the scope of the claimed subject matter.
[00025] The present disclosure pertains to a novel method to transfer digital data from source to destination via wired / wireless communication media. The method is highly suitable for optical communication systems using visible light and uses control of one/more visible light pulses to transfer data.
[00026] In an aspect, present disclosure elaborates upon a method to transmit data from a transmitter to a receiver. The method includes the steps of: using, at the transmitter end, a carrier frequency signal with an ON time (Ton) for a cycle during which the signal is of a positive amplitude, and an OFF time (Toff ) for the cycle during which the signal is of zero or negative amplitude; and transmitting, from the transmitter, the data during the Toff, wherein the Toff can be varied so as to vary the amount of data transmitted in the cycle.
[00027] In another aspect, the signal can include visible light (VL), radio waves or infrared waves, and can be a pulse width modulated (PWM) signal.
[00028] In yet another aspect, the method can enable multiple bits of data to be transmitted per cycle of the signal.
[00029] In an aspect, the method can enable the data transmission only when at least one byte of the data is transmitted in the Toff .
[00030] In another aspect, the at least one byte can include eight bits of information, one start bit and one stop bit.
[00031] In yet another aspect, the method can further allow the data transmission only of a complete number of bytes during the Toff.
[00032] In an aspect, time taken to transfer one byte (T1byte) can be 10/baud rate, and wherein the baud rate can be so selected that the T1byte is less than the Toff.
[00033] In another aspect, the method can further include the step of using, in combination to the varying the Toff to vary the amount of data, a second modulation technique on the data.
[00034] In an aspect, present disclosure elaborates upon a transmitter configured to transmit data to a receiver, the transmitter configured to: incorporate a carrier frequency signal with an ON time (Ton) for a cycle during which the signal is of a positive amplitude, and an OFF time (Toff ) for the cycle during which the signal is of zero or negative amplitude; and transmit the data during the Toff, wherein the Toff can be varied so as to vary the amount of data transmitted in the cycle.
[00035] In another aspect of the transmitter, the signal can include visible light (VL), radio waves or infrared waves, and can be a pulse width modulated (PWM) signal.
[00036] Various objects, features, aspects and advantages of the present disclosure will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like features.
[00037] Within the scope of this application it is expressly envisaged that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible.

BRIEF DESCRIPTION OF DRAWINGS
[00038] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.The diagrams are for illustration only, which thus is not a limitation of the present disclosure, and wherein:
[00039] FIGs. 1A to 1C illustrate by means of graph the hybrid variable length partial pulse modulation (HVLPPM) method proposed in accordance with an exemplary embodiment of the present disclosure.
[00040] FIG.2 elaborates upon a method to determine feasible baud rate for data transfer using method proposed, in accordance with an exemplary embodiment of the present disclosure.
[00041] FIG.3 elaborates upon total data that can be transmitted per cycle for a PWM carrier signal of frequency 10 KHz, assuming a 50 % duty cycle, different transmitting baud rates and corresponding receiving bandwidths
[00042] FIG. 4A and 4B illustrate how a higher data transmission can be achieved using proposed method in accordance with an exemplary embodiment of the present disclosure.
[00043] FIG.5 illustrates a system proposed in accordance with an exemplary embodiment of the present disclosure.
[00044] FIG. 6 illustrates method proposed in accordance with an exemplary embodiment of the present disclosure.

DETAILED DESCRIPTION
[00045] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[00046] In the following description, numerous specific details are set forth in order to provide a thorough understanding of embodiments of the present invention. It will be apparent to one skilled in the art that embodiments of the present invention may be practiced without some of these specific details.
[00047] Embodiments of the present invention include various steps, which will be described below. The steps may be performed by hardware components or may be embodied in machine-executable instructions, which may be used to cause a general-purpose or special-purpose processor programmed with the instructions to perform the steps. Alternatively, steps may be performed by a combination of hardware, software, and firmware and/or by human operators.
[00048] Embodiments of the present invention may be provided as a computer program product, which may include a machine-readable storage medium tangibly embodying thereon instructions, which may be used to program a computer (or other electronic devices) to perform a process. The machine-readable medium may include, but is not limited to, fixed (hard) drives, magnetic tape, floppy diskettes, optical disks, compact disc read-only memories (CD-ROMs), and magneto-optical disks, semiconductor memories, such as ROMs, PROMs, random access memories (RAMs), programmable read-only memories (PROMs), erasable PROMs (EPROMs), electrically erasable PROMs (EEPROMs), flash memory, magnetic or optical cards, or other type of media/machine-readable medium suitable for storing electronic instructions (e.g., computer programming code, such as software or firmware).
[00049] Various methods described herein may be practiced by combining one or more machine-readable storage media containing the code according to the present invention with appropriate standard computer hardware to execute the code contained therein. An apparatus for practicing various embodiments of the present invention may involve one or more computers (or one or more processors within a single computer) and storage systems containing or having network access to computer program(s) coded in accordance with various methods described herein, and the method steps of the invention could be accomplished by modules, routines, subroutines, or subparts of a computer program product.
[00050] If the specification states a component or feature “may”, “can”, “could”, or “might” be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic.
[00051] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[00052] Exemplary embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments are shown. These exemplary embodiments are provided only for illustrative purposes and so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those of ordinary skill in the art. The invention disclosed may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Various modifications will be readily apparent to persons skilled in the art. The general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the invention. Moreover, all statements herein reciting embodiments of the invention, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future (i.e., any elements developed that perform the same function, regardless of structure). Also, the terminology and phraseology used is for the purpose of describing exemplary embodiments and should not be considered limiting. Thus, the present invention is to be accorded the widest scope encompassing numerous alternatives, modifications and equivalents consistent with the principles and features disclosed. For purpose of clarity, details relating to technical material that is known in the technical fields related to the invention have not been described in detail so as not to unnecessarily obscure the present invention.
[00053] Thus, for example, it will be appreciated by those of ordinary skill in the art that the diagrams, schematics, illustrations, and the like represent conceptual views or processes illustrating systems and methods embodying this invention. The functions of the various elements shown in the figures may be provided through the use of dedicated hardware as well as hardware capable of executing associated software. Similarly, any switches shown in the figures are conceptual only. Their function may be carried out through the operation of program logic, through dedicated logic, through the interaction of program control and dedicated logic, or even manually, the particular technique being selectable by the entity implementing this invention. Those of ordinary skill in the art further understand that the exemplary hardware, software, processes, methods, and/or operating systems described herein are for illustrative purposes and, thus, are not intended to be limited to any particular named element.
[00054] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[00055] All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[00056] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
[00057] In an aspect, present disclosure elaborates upon a method to transmit data from a transmitter to a receiver. The method includes the steps of: using, at the transmitter end, a carrier frequency signal with an ON time (Ton) for a cycle during which the signal is of a positive amplitude, and an OFF time (Toff ) for the cycle during which the signal is of zero or negative amplitude; and transmitting, from the transmitter, the data during the Toff, wherein the Toff can be varied so as to vary the amount of data transmitted in the cycle.
[00058] In another aspect, the signal can include visible light (VL), radio waves or infrared waves, and can be a pulse width modulated (PWM) signal.
[00059] In yet another aspect, the method can enable multiple bits of data to be transmitted per cycle of the signal.
[00060] In an aspect, the method can enable the data transmission only when at least one byte of the data is transmitted in the Toff .
[00061] In another aspect, the at least one byte can include eight bits of information, one start bit and one stop bit.
[00062] In yet another aspect, the method can further allow the data transmission only of a complete number of bytes during the Toff.
[00063] In an aspect, time taken to transfer one byte (T1byte) can be 10/baud rate, and wherein the baud rate can be so selected that the T1byte is less than the Toff.
[00064] In another aspect, the method can further include the step of using, in combination to the varying the Toff to vary the amount of data, a second modulation technique on the data.
[00065] In an aspect, present disclosure elaborates upon a transmitter configured to transmit data to a receiver, the transmitter configured to: incorporate a carrier frequency signal with an ON time (Ton) for a cycle during which the signal is of a positive amplitude, and an OFF time (Toff ) for the cycle during which the signal is of zero or negative amplitude; and transmit the data during the Toff, wherein the Toff can be varied so as to vary the amount of data transmitted in the cycle.
[00066] In another aspect of the transmitter, the signal can include visible light (VL), radio waves or infrared waves, and can be a pulse width modulated (PWM) signal.
[00067] In an aspect, present disclosure elaborates upon a method for data transmission. The method is termed as hybrid variable length partial pulse modulation (HVLPPM) method due reasons as explained further. Method proposed uses OFF time period/duration (Toff) of a PWM (pulse width modulated) wave for modulation/ data transmission. The OFF time period /duration can as well be used for carrying out any of present encoding / modulation technique while keeping constant/unchanged the positive portion of PWM wave.
[00068] In another aspect, the duration of the positive pulse of the PWM wave (Ton) and so that of Toff can be varied according to the application. Further, other modulation techniques can be combined with proposed method. Hence the method is termed hybrid variable length partial pulse modulation. The modulation method elaborated herein can be used for any wave transmission method, particularly those using ‘optical communication’ and ‘visible light communication’.
[00069] As is known, Pulse-width modulation (PWM) is a modulation process/method/technique used in many communication systems for encoding digital data/information right into a pulse width or duration of a signal ( termed as carrier signal ) , for transmission.
[00070] FIGs. 1A to 1C illustrate by means of graph the hybrid variable length partial pulse modulation (HVLPPM) method proposed in accordance with an exemplary embodiment of the present disclosure.
[00071] In an aspect, proposed method uses visible light as generated by an LED to create a PWM carrier signal. A cyclic light wave can be created by switching the LED ‘on’ or ‘off’ in a regular pattern. Percentage time the LED remains on during one cycle can be termed as duty cycle of the PWM carrier signal. Any other electromagnetic wave (such as radio waves or infrared waves) can be similarly used along with appropriate switches instead of LEDs as elaborated in example herein.
[00072] For instance, one cycle can be of a total duration of 1 second. During this time period, electric supply to the LED can be so switched ON or OFF such that during that period of 1 second, the LED is ON for 40 % of the time (that is, for0.4 seconds, such duration herein termed as Ton) and OFF for the remaining (that is, 0.6 seconds such duration herein termed as Toff). The pattern can repeat for next one second time periods in a similar manner. Such a duty cycle can be termed as 40% duty cycle.
[00073] The waveform/ pattern/ generated by switching of the LED as elaborated above can be represented as 102 in FIG. 1A. The carrier signal hence can be represented by 102. As can be seen, at time ‘0’ the LED can be switched on to its full brightness illustrated as 1 (at 104) along Y axis (that represents amplitude of signal being described, while time may be plotted along X axis, as illustrated). After remaining on for 0.4 seconds, the LED can switch off, as shown at 106. For next period of 0.6 seconds, the LED can remain off and then be switched on again, as shown at 108. Hence an ON period, shown as Ton (118) and an OFF period, shown as Toff (120) of the carrier signal 102 can be achieved in every cycle of the carrier signal 102
[00074] As can be readily appreciated, instead of a cycle of 1 second, the cycle can be configured to be, for instance, 1µs or any other time period required and so, cycles being elaborated herein are only exemplary. Further, in example elaborated since the LED is on only 40 % of the time during one cycle, its brightness to the human eye can seem to be only about 40 % of its normal, full brightness. As the duration of a cycle is lessened, switching of LED will occur faster and may be ultimately indistinguishable to the human eye, with the difference in different cycles being noticed as variation in LED brightness, if at all.
[00075] Proposed method uses duration /time period during which the LED is off (Toff) to transmit data. The data signal can be in the form of bits of data, with a start bit(illustrated as 110) and a stop bit(illustrated as 112). In an exemplary embodiment, the data signal can comprise encoded bytes of data, one byte having 8 bits of data, one start bit and another stop bit (i.e., one byte may be made of 10 bits of data ). This one byte of data signal can be as illustrated at 114.
[00076] As can be readily understood, Toff is required to be at least sufficient to accommodate time taken to transfer the one byte (i.e. T1byte) of data signal. T1bytein turn depends upon the frequency of the data signal, higher the frequency, lower theT1byte.Hence, if Toff is reduced, as elaborated further, to transfer same 1 byte of data, a data signal of higher frequency may be required.
[00077] The modulated signal formed by combination of the carrier signal 102 and the data signal 114 can be represented as waveform 116.
[00078] As can be understood, waveform 116 has been formed using a Variable Length Partial Pulse Modulation (VLPPM) method wherein variable length signifies that ‘length’ ( duration) of Toff can be varied ( by varying duty cycle of the carrier signal ) and partial pulse signifies that the method uses partially only the pulse generated by the carrier signal. Further, other modulation methods can be used to modulate waveform 116 during the period Toff and so, the method can be completely named as hybrid variable length partial pulse modulation (HVLPPM).
[00079] FIG. 1B illustrates the effect of varying the duty cycle upon the data signal that can be passed. If the LED as elaborated above is on for 60 % of total cycle time(i.e. PWM carrier signal created is of 60 % duty cycle), Toff reduces, as shown at 122, as against Toff for 40 % duty cycle. As described above, Toff is required to be at least sufficient to accommodate time taken to transmit the one byte (i.e. T1byte) of data signal and T1byte in turn depends upon the frequency of the data signal, higher the frequency, lower theT1byte.Hence, upon reduction of Toff, frequency of data signal that can pass one byte of data may increase as shown at 124, as against frequency of data signal earlier, as shown at 114.
[00080] Similarly, as shown at FIG.1C, if the LED as elaborated above is on for 80 % of total cycle time ( i.e. PWM carrier signal created is of 80 % duty cycle), Toff further reduces, as shown at 126. As described above, Toff is required to be at least sufficient to accommodate time taken to transmit the one byte (i.e. T1byte) of data signal and T1byte in turn depends upon the frequency of the data signal, higher the frequency, lower theT1byte. Hence, upon reduction of Toff frequency of data signal that can pass one byte of data may increase as shown at 128, as against frequency of data signal earlier, as shown at 114 or 124.
[00081] FIG.2 elaborates upon a method to determine feasible baud rate for data transfer using method proposed, in accordance with an exemplary embodiment of the present disclosure.
[00082] In an aspect, following steps can be taken to find a feasible baud rate for data transfer using method proposed herein.
[00083] Step 202 can include determination of off time (Toff) of the PWM carrier signal based upon duty cycle proposed of the carrier signal.
[00084] For instance, for a PWM carrier signal of frequency 10 KHz total period (Ttotal ) of one cycle of the wave is 100 µs ( 1/10,000 = 100 µs)
[00085] In an exemplary embodiment, if the duty cycle proposed of the PWM carrier is 50%, and it has a frequency of 10KHz, Toff can be Ttotal/2, ie. 100 /2= 50 µs
[00086] As elaborated, a byte may include 8 bits of data, one start bit and another stop bit, i. e. total 10 bits. Therefore, time taken to transfer 1 byte, T1byte = 10 / baud rate, where baud rate could be any supported baud rate. In telecommunication and electronics baud is a common measure of the speed of communication over a data channel. Technically speaking, it is the unit for symbol rate or modulation rate in symbols per second or pulses per second. It is the number of distinct symbol changes (signaling events) made to the transmission medium per second in a digitally modulated signal or a line code.
[00087] If baud rate is taken as ‘b’, time taken to transmit 1 byte :
T1byte= 10/b…..(1)
[00088] It can be readily understood that for at least one byte to be transmitted, Toff must be greater or equal to T1byte . That is, Toff must be at least equal to T1byteand such a substitution can be made in equation (1) above.
[00089] So, taking equation (1) as Toff= 10/b ? b=10/Toff = 10/50/106= 107/ 50 = 200,000 can be the minimum baud rate in this example
[00090] As can be appreciated from above, when Toff is reduced (by increasing Ton) of a PWM carrier wave (that maybe a visible light wave created by an LED), minimum supported baud rate increases.
[00091] As elaborated above, Toff must be at least equal to T1byte for at least one byte data to be transmitted. Hence, step 204 can include determining T1byteusing T1byte = 10/baud rate. Further, step 206 can include comparing Toff and T1byte to determine if a suggested baud rate can be supported by duty cycle of the PWM carrier proposed. If Toff is greater than or equal to T1byte, the suggested baud rate can be supported by duty cycle of the PWM carrier proposed, as illustrated at 210. However, ifToff is less than T1byte the suggested baud rate cannot be supported by duty cycle of the PWM carrier proposed, as illustrated at 212.
[00092] As can be readily understood, duty cycle of the PWM carrier signal can be varied to accommodate higher/lower baud rates as required. For example, if duty cycle is set at 90 %, TOff will reduce and therefore the minimum baud rate supported can be higher. If duty cycle is set at 10 %, Toff will increase and consequently minimum baud rate supported will be lower.
[00093] In an exemplary embodiment, if baud rate is 921600, time taken totransmit 1byte will be: T1byte = 10 / 921600 = = 10.8µs. As can be readily understood, this means that with a 921600 baud rate signal, 1 byte takes 10.8µs to get transmitted.
[00094] Since Toff is 50 µs, it is more than T1byte and so, data transmission is possible. Further, total number of bytes (Nbytes) transferred in one off period (Toff) can be :
Nbytes=Toff / T1byte = 50µs/ 10.8 µs = = 4.629
[00095] As partial bytes cannot be transmitted, above figure has to be rounded to the lower numeral and so, it can be determined that 4 bytes can be sent.
[00096] FIG.3 elaborates upon total data that can be transmitted per cycle for a PWM carrier signal of frequency 10 KHz, assuming a 50 % duty cycle, different transmitting baud rates and corresponding receiving bandwidths.
[00097] In an aspect, for a PWM wave of frequency 10 KHz total period (Ttotal ) of one cycle of the wave is 100 µs ( 1/10,000 = 100 µs)
[00098] Since the wave is configured with a 50 % duty cycle, Toff can be 100 /2= 50 µs. As already elaborated, a byte can have a total 10 bits of data.
[00099] As shown at 302, a transmitting wave ( data signal ) can have a baud rate 230,400 and so, time taken to transmit 1 byte (T1byte ) can be =10/230400 = 43.4 µs , as shown at 304. Since this is less than Toff, data transmission at this baud rate is possible. However, in one cycle of the carrier signal, number of bytes that can be sent can only be 1 ( Toff/T1byte, rounded to the lower number),as shown at 306. As shown at 308 an equipment/channel of bandwidth 80kbs can receive such a signal.
[000100] Similarly, as shown at 310, a transmitting wave can have a baud rate 460800 and so, time taken to transmit 1 byte (T1byte ) can be =10/460800 = 21.7 µs , as shown at 312. Since this is less than Toff, data transmission at this baud rate is possible. However, in one cycle of the carrier signal, number of bytes that can be sent can only be 2 ( Toff/T1byte, rounded to the lower number), as shown at 314 . Receiving bandwidth can be 160 kbs, showing at 316.
[000101] Similarly, as shown at 318, a transmitting wave can have a baud rate 921600 and so, time taken to transmit 1 byte (T1byte ) can be =10/921600 = 10.8 µs , as shown at 320. Since this is less than Toff, data transmission at this baud rate is possible. However, in one cycle of the carrier signal, number of bytes that can be sent can only be 4 (Toff/T1byte, rounded to the lower number), as shown at 322 . Receiving bandwidth can be 320 kbs, showing at 324.
[000102] FIG. 4A and 4B illustrate how a higher data transmission can be achieved using proposed method in accordance with an exemplary embodiment of the present disclosure.
[000103] As illustrated in FIG.4A, a data stream 402 can be subjected to a HVLPPM (Hybrid Variable Length partial Pulse Modulation) method 404 as elaborated above. Data stream output of process/method 404 can be provided to a constant current driver 406 and can in turn be used to drive a red LED 408, a green LED 410, a blue LED 412 and a white /amber LED 414 , as shown.
[000104] Further, an RGBW CCT combination data encoding table as shown in FIG. 4B can be used in the proposed method. As illustrated in FIG.4B, column452 can carry CCT value while column 454 can carry corresponding data. As is known, CCT (correlated color temperature) is a measure of the color appearance of a white light source. CCT is measured on the Kelvin absolute temperature scale. White lighting products are most commonly available from 2700K (warm white) to 7000K (cold white).
[000105] As elaborated, HVLPPM method enables multiple bits of data to be carried in a cycle. Each color temperature can carry 3 bit of information during multiple bit transmission using HVLPPM method proposed, as described hereunder.
[000106] As an example, at step 1, a 16 bit data input as under can be provided :
0000 0101 0011 1001
[000107] At step 2, a 3 bit group as under can be made out of above 16 bit data as under :
1 000 001 010 011 1001 1
[000108] At step 3, using Table 4A, LED color temperature can be varied using constant current driver 406 and HVLPPM method 404 for multiple LEDs. For instance, a 3 bit group 000 can be associated with a CCT of 3000, 001 can be associated with 3500, 010 with 4000, 011 with 4500, 100 with 5000 and 1 with 2700. In this manner, 16 bit data (in step 1) can be compressed to 6 bits of information (the six CCT values derived above).
[000109] At a receiver end, these CCT values can be converted back to original 16bit data by referring table 4B above and hence generating :
0000 0101 0011 1001
[000110] Hence, as elaborated above, the encoding / HVLPPM method described above increases bandwidth by three times. This is achieved by transmitting three bits of data in one cycle, as against one bit of data per cycle permitted by other methods.
[000111] FIG.5 illustrates a system proposed in accordance with an exemplary embodiment of the present disclosure.
[000112] In an aspect, system proposed can include a transmitter 502 configured to transmit data 506 to a receiver 508.Transmitter 502 can be configured to incorporate a carrier frequency signal 504 with an ON time (Ton) for a cycle during which the signal is of a positive amplitude, and an OFF time (Toff ) for the cycle during which the signal is of zero or negative amplitude; and transmit the data during said Toff, wherein the Toff can be varied so as to vary the amount of data transmitted in the cycle.
[000113] In another aspect, the signal 504 can include visible light (VL), radio waves or infrared waves.
[000114] In an aspect, transmitter 502 can implement hybrid variable length partial pulse modulation method described above on signal 504 and data 506 to generate a modulated signal 510.
[000115] In another aspect, modulated signal 510 can be received by receiver 508. Receiver 508 can extract data 506 from the modulated signal 510.
[000116] As can be readily understood, transmitter 502 itself can generate cyclic signal of appropriate baud rate as required. The signal can be a PWM signal.
[000117] FIG. 6 illustrates method proposed in accordance with an exemplary embodiment of the present disclosure.
[000118] In an aspect, method proposed to transmit data from a transmitter to a receiver can include, at step 602, using, at the transmitter end, a carrier frequency signal with an ON time (Ton) for a cycle during which the signal is of a positive amplitude, and an OFF time (Toff ) for the cycle during which the signal is of zero or negative amplitude.
[000119] The method can further include, at step 604 transmitting, from the transmitter, the data during the Toff, wherein the Toff can be varied so as to vary the amount of data transmitted in the cycle.
[000120] In another aspect, the signal can include visible light (VL), radio waves or infrared waves and can be a pulse width modulated (PWM) signal.
[000121] In yet another aspect, the method proposed can enable multiple bits of data to be transmitted per cycle of the signal.
[000122] As used herein, and unless the context dictates otherwise, the term “coupled to” is intended to include both direct coupling (in which two elements that are coupled to each other or in contact each other) and indirect coupling (in which at least one additional element is located between the two elements). Therefore, the terms “coupled to” and “coupled with” are used synonymously. Within the context of this document terms “coupled to” and “coupled with” are also used euphemistically to mean “communicatively coupled with” over a network, where two or more devices are able to exchange data with each other over the network, possibly via one or more intermediary device.
[000123] Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refers to at least one of something selected from the group consisting of A, B, C ….and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc.
[000124] While some embodiments of the present disclosure have been illustrated and described, those are completely exemplary in nature. The disclosure is not limited to the embodiments as elaborated herein only and it would be apparent to those skilled in the art that numerous modifications besides those already described are possible without departing from the inventive concepts herein. All such modifications, changes, variations, substitutions, and equivalents are completely within the scope of the present disclosure. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims.

ADVANTAGES OF THE INVENTION
[000125] The present disclosure provides for a method to transmit data that enables data transfer higher than a bit per cycle of the carrier signal.
[000126] The present disclosure provides for a method to transmit data that uses only OFF period of the carrier signal.
[000127] The present disclosure provides for a method to transmit data that can be combined with other modulation techniques as required.
[000128] The present disclosure provides for a method to transmit data that is highly suitable for visible light (VL) communication.