CN108028700A - A kind of light source brightness control method and sending ending equipment - Google Patents

A kind of light source brightness control method and sending ending equipment Download PDF

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Publication number
CN108028700A
CN108028700A CN201680054474.1A CN201680054474A CN108028700A CN 108028700 A CN108028700 A CN 108028700A CN 201680054474 A CN201680054474 A CN 201680054474A CN 108028700 A CN108028700 A CN 108028700A
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China
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ofdm
subcarriers
target
enabled
brightness value
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CN201680054474.1A
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Chinese (zh)
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CN108028700B (en
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殷慧
孙方林
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华为技术有限公司
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Priority to PCT/CN2016/072004 priority Critical patent/WO2017127986A1/en
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B10/00Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/11Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
    • H04B10/114Indoor or close-range type systems
    • H04B10/116Visible light communication

Abstract

The embodiment of the invention discloses a kind of light source brightness control method and sending ending equipment, wherein, this method includes:Obtain target brightness value;Determine the target brightness value target to be used enable the quantity of subcarrier, and the target that specified data is carried to the quantity is enabled on subcarrier, obtains orthogonal frequency division multiplex OFDM frequency-region signal;Determine the corresponding OFDM of the target brightness value+The quantity p and the corresponding OFDM of the target brightness value of symbolThe quantity q of symbol, by the p OFDM+Symbol is added on the low current of the pwm signal, and by the q OFDMSymbol is added in the high current of the pwm signal, obtains the driving current signal of light source, and the driving current signal is used to control the present intensity value of the light source to be the target brightness value.The embodiment of the present invention can simplify the whole operation process of receiving device, improve demodulation efficiency.

Description

Light source brightness control method and sending terminal equipment Technical Field
The invention relates to the technical field of communication, in particular to a light source brightness control method and sending end equipment.
Background
Visible Light Communication (VLC) technology is a wireless Communication technology that modulates data on a Light source while illuminating with Visible Light, and transmits the data using the Visible Light as a carrier. Generally, in order to save energy, the user adjusts the illumination brightness of the light source. Maintaining communication while supporting lighting brightness adjustment is an important feature of VLC systems.
The adjustment of the light source brightness in the VLC system can be realized by combining Reverse polarization Optical Orthogonal Frequency Division Multiplexing (RPO-OFDM) with Pulse Width Modulation (PWM). Assume a PWM signal having a period TPWMThe pulse width is T, the PWM signal maintains high current during T time, and the PWM signal maintains high current during T timePWMDuring the non-T time, the PWM signal maintains low current, and the duty ratio of the PWM signal can be defined as T/TPWM. Since the brightness of the light source is proportional to the driving current of the light source, the RPO-OFDM can change the driving current of the light source by changing the duty ratio of the PWM signal, thereby controlling the brightness of the light source.
Specifically, when the PWM signal is in a high current, the polarity of the O-OFDM signal is reversed and then is superposed with the PWM signal, and when the PWM signal is in a low current, the O-OFDM signal is directly superposed with the PWM signal. In this control scheme, the signals superimposed on the high and low currents of the PWM signal are different. For example: assuming that information to be transmitted is X, and O-OFDM obtained after transformation to the time domain is X, then-X is superimposed on the high current of the PWM signal, and X is superimposed on the low current of the PWM signal, however, information to be demodulated by the receiving end device in the frequency domain is X, so that the receiving end device can correctly demodulate the information only by changing the symbol of the frequency domain equalization coefficient correspondingly due to different signals superimposed on the high and low currents of the PWM signal by the transmitting end device, which makes the whole operation process more complicated and the demodulation efficiency lower.
Disclosure of Invention
The embodiment of the invention discloses a light source brightness control method and sending end equipment, which can simplify the whole operation process of receiving end equipment and improve demodulation efficiency.
The first aspect of the embodiments of the present invention discloses a method for controlling brightness of a light source, including:
acquiring a target brightness value, wherein the target brightness value can be set by adjusting a brightness adjusting button on sending end equipment, or the brightness value is set at receiving end equipment;
determining the number of target enabling subcarriers to be used by the target brightness value, and loading specified data to the number of target enabling subcarriers to obtain Orthogonal Frequency Division Multiplexing (OFDM) frequency domain signals;
determining the OFDM corresponding to the target brightness value+The number p of symbols and the OFDM corresponding to the target brightness value-Number of symbols q, wherein the OFDM+The symbol is an OFDM unipolar time domain symbol obtained by zero clearing of a negative value of an OFDM bipolar time domain symbol obtained by converting the OFDM frequency domain signal, wherein the OFDM is-The symbol is an OFDM unipolar time domain symbol obtained by zero clearing of a positive value of the OFDM bipolar time domain symbol, and both p and q are non-negative integers;
the p OFDM signals are processed+Superimposing the symbols onto the low current of the PWM signal, and said q OFDM symbols-And superimposing the symbol on the high current of the PWM signal to obtain a driving current signal of the light source, wherein the driving current signal is used for controlling the brightness value of the light source to be the target brightness value.
Wherein, OFDM bipolar time domain symbols are processed to obtain OFDM+Symbol and OFDM-And (4) a symbol. Regardless of whether the transmitting end device transmits OFDM+Symbol or OFDM-The sign and the frequency domain equalization coefficient adopted by the equalizer of the receiving end equipment do not need sign changing (namely, sign changing), so that the whole operation process of the receiving end equipment can be simplified, and the demodulation efficiency is improved.
With reference to the first aspect of the present embodiment, in a first possible implementation manner of the first aspect of the present embodiment, after determining the number of target enabled subcarriers to be used by the target brightness value, and before carrying the specified data to the number of target enabled subcarriers and obtaining an OFDM frequency domain signal, the method further includes:
if the number of the target enabled subcarriers is smaller than the number of the current enabled subcarriers, closing a first number of subcarriers, wherein the first number is a difference value between the number of the enabled subcarriers corresponding to the current brightness value and the number of the target enabled subcarriers.
Wherein the brightness value of the light source can be adjusted by controlling the manner of enabling the subcarriers (turning off the subcarriers).
With reference to the first aspect of the embodiment of the present invention, in a second possible implementation manner of the first aspect of the embodiment of the present invention, after determining the number of target-enabled subcarriers to be used by the target luminance value, the method further includes:
if the number of the target enabled subcarriers is greater than the number of the current enabled subcarriers, starting a second number of subcarriers, wherein the second number is a difference value between the number of the target enabled subcarriers and the number of the enabled subcarriers corresponding to the current brightness value;
the loading the specified data onto the number of target enabled subcarriers to obtain an Orthogonal Frequency Division Multiplexing (OFDM) frequency domain signal includes:
and carrying the input data on the current enabled subcarriers and carrying a preset pseudorandom sequence on the second number of subcarriers to obtain Orthogonal Frequency Division Multiplexing (OFDM) frequency domain signals.
Wherein the brightness value of the light source can be adjusted by controlling the manner of enabling the sub-carriers (turning on the sub-carriers).
With reference to the second possible implementation manner of the first aspect of the embodiment of the present invention, in a third possible implementation manner of the first aspect of the embodiment of the present invention, the method further includes:
receiving a new enabled subcarrier table sent by receiving end equipment, wherein the new enabled subcarrier table is used for recording the bit number which can be borne by each subcarrier in the second number of subcarriers;
for each of the subcarriers in the second number of subcarriers, carrying on the subcarrier a number of bits matching the subcarrier in the newly enabled subcarrier table;
and updating the current zone bit of the synchronization symbol into a first zone bit, wherein the first zone bit is used for representing that the new enabled subcarrier table takes effect.
Before the newly enabled subcarrier table takes effect, each subcarrier in the second number of subcarriers carries a preset number of bits, after the newly enabled subcarrier table takes effect, the sending end device carries the bit number matched with each subcarrier in the newly enabled subcarrier table on each subcarrier in the second number of subcarriers, and the bit number carried on the currently enabled subcarrier is unchanged, so that the communication rate can be improved.
With reference to the first aspect of the present invention to the third possible implementation manner of the first aspect, in a fourth possible implementation manner of the first aspect of the present invention, the determining the number of target enabled subcarriers to be used by the target brightness value includes:
judging whether the target brightness value belongs to a specified brightness value range or not;
if yes, determining the number of target enabled subcarriers to be used by the target brightness value as the number of all available subcarriers of the OFDM frequency domain signal.
Wherein all available subcarriers are enabled if the target luminance value belongs to the specified luminance value range.
With reference to the fourth possible implementation manner of the first aspect of the embodiment of the present invention, in this document, the first aspect of the present invention is implemented by a computerIn a fifth possible implementation manner of the first aspect of the embodiment of the present invention, the determining the OFDM corresponding to the target brightness value+The number p of symbols and the OFDM corresponding to the target brightness value-A number of symbols, q, comprising:
determining the OFDM according to a formula and p + q ═ N+Number of symbols p and OFDM-A number of symbols q, said a% being the OFDM obtained when all available subcarriers of said OFDM frequency domain signal are enabled+The percentage ratio of the mean current of the symbols to the high current of the PWM signal, where a% is a positive number, x% is the target brightness value, N is the number of OFDM unipolar time domain symbols that can be superimposed on the PWM signal in one period, and N is a positive integer.
Wherein, if the target brightness value belongs to the specified brightness value range, the OFDM is required to be performed+Superimposing the symbols onto the low current of the PWM signal, and OFDM-The sign is superimposed on the high current of the PWM signal.
With reference to the fourth possible implementation manner of the first aspect of the embodiment of the present invention, in a sixth possible implementation manner of the first aspect of the embodiment of the present invention, the method further includes:
if the target brightness value is smaller than the minimum brightness value in the specified brightness value range, determining the number of target enabled subcarriers to be used by the target brightness value according to a formula, wherein round () is an integer function, M is the number of all available subcarriers of the OFDM frequency domain signal, M is a positive integer, x% is the target brightness value, and a% is the OFDM frequency domain signal obtained when all available subcarriers are enabled+A percentage ratio of the mean current of the symbols to the high current of the PWM signal, said a% being a positive number.
If the target brightness value does not belong to the specified brightness value range, only part of the available subcarriers need to be enabled, and the target enabled subcarriers comprise subcarriers and conjugate symmetric subcarriers thereof.
Optionally, the OFDM corresponding to the target brightness value is determined+The number p of symbols and the OFDM corresponding to the target brightness value-A number of symbols, q, comprising:
determining the OFDM corresponding to the target brightness value+The number p of the symbols is N, and OFDM corresponding to the target brightness value is determined-The number of symbols q is zero.
Wherein, if the target brightness value is less than the minimum brightness value in the specified brightness value range, only the OFDM needs to be processed+Superimposing symbols on the low current of the PWM signal without superimposing OFDM-And (4) a symbol.
With reference to the fourth possible implementation manner of the first aspect of the embodiment of the present invention, in an eighth possible implementation manner of the first aspect of the embodiment of the present invention, the method further includes:
if the target brightness value is greater than the maximum brightness value in the specified brightness value range, determining the number of target enabled subcarriers to be used by the target brightness value according to a formula, where round () is an integer function, M is the number of all available subcarriers of the OFDM frequency domain signal, M is a positive integer, x% is the target brightness value, and a% is an OFDM signal obtained when all available subcarriers of the OFDM frequency domain signal are enabled+A percentage ratio of the mean current of the symbols to the high current of the PWM signal, said a% being a positive number.
If the target brightness value does not belong to the specified brightness value range, only part of the available subcarriers need to be enabled, and the target enabled subcarriers comprise subcarriers and conjugate symmetric subcarriers thereof.
Optionally, the OFDM corresponding to the target brightness value is determined+The number p of symbols and the OFDM corresponding to the target brightness value-A number of symbols, q, comprising:
determining the OFDM corresponding to the target brightness value+The number p of the symbols is zero, and the OFDM corresponding to the target brightness value is determined-The number q of symbols is said N.
Wherein if the target brightness value is greater than the maximum brightness in the specified brightness value rangeValue of degree, then only need OFDM-Superimposing symbols on the high current of the PWM signal without the need to superimpose OFDM+And (4) a symbol.
A second aspect of the present embodiment discloses a sending end device, where the sending end device includes a functional unit configured to execute part or all of the steps of any method in the first aspect of the present embodiment. When the sending end device executes part or all of the steps of any one of the methods in the first aspect, the whole operation process of the receiving end device can be simplified, and the demodulation efficiency is improved.
A third aspect of the present invention discloses a sending end device, where the sending end device includes: a processor, an input device, and a memory, the memory configured to store instructions, the processor configured to execute the instructions, the processor executing the instructions to perform some or all of the steps of any of the methods of the first aspect of the embodiments of the present invention. When the sending end device executes part or all of the steps of any one of the methods in the first aspect, the whole operation process of the receiving end device can be simplified, and the demodulation efficiency is improved.
A fourth aspect of the embodiments of the present invention discloses a computer storage medium, which stores a program, where the program specifically includes instructions for executing some or all of the steps of any of the methods of the first aspect of the embodiments of the present invention.
In the embodiment of the present invention, the sending end device may obtain the target brightness value, determine the number of target enabled subcarriers to be used by the target brightness value, and load the specified data onto the number of target enabled subcarriers to obtain the OFDM frequency domain signal, and further, the sending end device may determine the OFDM frequency domain signal corresponding to the target brightness value+Number of symbols p and OFDM corresponding to target luminance value-Number of symbols q, and p OFDM+Superimposing the symbols onto the low current of the PWM signal, and dividing the q OFDM symbols-The symbol is superposed on the high current of the PWM signal to obtain the driving current signal of the light source, so that the control of the brightness of the light source can be realized. Therefore, according to the embodiment of the invention, the sending end equipment converts the obtained OFDObtaining OFDM after zero clearing of negative values of M bipolar time domain symbols+Symbol, zero clearing the positive value of the OFDM bipolar time domain symbol to obtain OFDM-Symbols, after such processing, whether the transmitting end device transmits OFDM+Symbol or OFDM-The sign and the frequency domain equalization coefficient adopted by the equalizer of the receiving end equipment do not need sign changing (namely, sign changing), so that the whole operation process of the receiving end equipment can be simplified, and the demodulation efficiency is improved.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without inventive labor.
Fig. 1 is a schematic network architecture diagram of a visible light communication system according to an embodiment of the present invention;
FIG. 2 is a flowchart illustrating a method for controlling brightness of a light source according to an embodiment of the present invention;
fig. 2.1 is a schematic diagram of an OFDM unipolar time domain symbol disclosed in the embodiment of the present invention;
FIG. 3 is a flow chart illustrating another method for controlling brightness of a light source according to an embodiment of the present disclosure;
FIG. 3.1 is a data frame structure disclosed in an embodiment of the present invention;
fig. 4 is a schematic structural diagram of a sending-end device disclosed in the embodiment of the present invention;
fig. 5 is a schematic structural diagram of another sending-end device disclosed in the embodiment of the present invention;
fig. 6 is a schematic structural diagram of another sending-end device disclosed in the embodiment of the present invention;
fig. 7 is a schematic structural diagram of another sending-end device disclosed in the embodiment of the present invention;
fig. 8 is a schematic structural diagram of another sending-end device disclosed in the embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The terms "first" and "second," and the like in the description and claims of the present invention and the above-described drawings are used for distinguishing between different objects and not for describing a particular order. Furthermore, the terms "include" and "have," as well as any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements listed, but may alternatively include other steps or elements not listed, or inherent to such process, method, article, or apparatus.
The embodiment of the invention discloses a light source brightness control method and sending end equipment, which can simplify the whole operation process of receiving end equipment and improve demodulation efficiency. The following are detailed below.
In order to better understand the embodiment of the present invention, a schematic network architecture diagram of a visible light communication system disclosed in the embodiment of the present invention is described below.
Referring to fig. 1, fig. 1 is a schematic diagram of a network architecture of a Visible Light Communication system according to an embodiment of the present invention, wherein a Visible Light Communication (VLC) technology is a wireless Communication technology that modulates data on a Light source while using Visible Light for illumination, and transmits the data using Visible Light as a carrier.
As shown in fig. 1, the visible light communication system includes a transmitting end device and a plurality of receiving end devices. The sending-end device may include a network connector, a light source, and a controller, where the network connector is used to connect to an external network, such as: routers, switches, etc. the light source is visible light with wavelength in the range of 380 nm-780 nm, which can be directly seen by human eyes, such as: light Emitting Diode (LED), etc., and the controller is used to encode and modulate data to be transmitted, such as: a Programmable Logic Controller (PLC), the receiving end Device may be a user terminal having a function of receiving signals, such as various user terminals including a smart phone, a notebook Computer, a Personal Computer (PC), a Personal Digital Assistant (PDA), a Mobile Internet Device (MID), and an intelligent wearable Device (e.g., a smart watch and a smart bracelet). In the visible light communication system shown in fig. 1, a transmitting-end device is connected to a wired means of the high-speed internet, and a receiving-end device does not need a wired connection. The sending end equipment can acquire data of an external network through the network connector, codes the data to be sent through the controller, modulates the coded data on the light source according to a specified modulation mode, transmits a visible light signal containing a specific identification code to a free space through the light source, and after receiving end equipment receives the visible light signal transmitted by the light source, the data can be recovered through demodulation and decoding, so that visible light communication is realized. In addition, those skilled in the art will understand that, although only one sending end device is shown in fig. 1, the sending end device is not limited to the illustrated embodiment of the present invention, and may include more sending end devices than the illustrated one, and the receiving end devices shown in fig. 1 are only used for representing the plurality of sending end devices, but are not limited to the illustrated embodiment of the present invention, and may include more or less receiving end devices than the illustrated one.
Based on the network architecture shown in fig. 1, the embodiment of the invention discloses a light source brightness control method. Referring to fig. 2, fig. 2 is a schematic flow chart illustrating a method for controlling brightness of a light source according to an embodiment of the present invention. As shown in fig. 2, the method may include the steps of:
201. the sending end equipment acquires a target brightness value.
In the VLC system, a single carrier modulation or a multi-carrier modulation may be used, for example: On-Off Keying (OOK) Modulation, Pulse Position Modulation (PPM), Discrete Multi-Tone (DMT) Modulation, and Orthogonal Frequency Division Multiplexing (OFDM) Modulation, among others.
In order to realize high-speed communication, a multi-carrier modulation scheme is generally adopted for modulation scheme selection, wherein OFDM modulation is one of multi-carrier modulation. The embodiment of the invention combines OFDM Modulation and Pulse Width Modulation (PWM) to realize the adjustment of the light source brightness in a VLC system.
In the embodiment of the present invention, when a user needs to adjust the brightness of the light source, the user may be triggered in various ways, such as: the brightness value is set by adjusting a brightness adjusting button on the sending terminal device, or by adjusting the brightness value at the receiving terminal device. If the user is triggered by adjusting the brightness adjustment button on the sending end device, the sending end device may directly obtain the brightness value (i.e., the target brightness value) set by the user, and if the user is triggered by setting the brightness value on the receiving end device, the sending end device may obtain the brightness value (i.e., the target brightness value) set by the user from the receiving end device. The sending end device can be bound with the receiving end device in advance, and the range of the brightness value set by the user can be 0.1% -100%.
202. The transmitting end device determines the number of target enabled subcarriers to be used by the target luminance value.
In the embodiment of the present invention, it is assumed that a period of a PWM signal is TPWMWith a pulse width T, i.e. during time T, the PWM signal maintains a high current IHAt the TPWMThe PWM signal maintains the low current I in the non-T time of the periodLThis can be described by the following equation (1):
wherein the duty cycle of the PWM signal can be defined as the percentage of the pulse width over the entire period.
The following equation (2) can be used to describe the drive current signal on the light source:
wherein, when the PWM signal is at high current, in order to maintainThe communication speed is not changed and the driving current does not exceed the maximum value IHWill OFDM-The symbol is superimposed on the high current; when the PWM signal is at low current, in order to keep the communication rate unchanged, OFDM is adopted+The symbol is superimposed on the low current. The OFDM+The symbol is an OFDM unipolar time domain symbol obtained by zero clearing of a negative value of the OFDM bipolar time domain symbol, and the OFDM is a symbol with zero clearing-The symbol is an OFDM unipolar time domain symbol obtained by zero clearing of a positive value of the OFDM bipolar time domain symbol.
OFDM obtained assuming that all available subcarriers of an OFDM frequency domain signal are enabled+The percentage ratio of the mean current of the symbols to the high current of the PWM signal is a%, i in equation (2)Light sourceHas a value range of IHOf [ a%, 1-a% ]]. When the duty ratio of the PWM signal is 0, iLight sourceThe brightness of (a) is a minimum value, and the rate is determined only; when the duty ratio of the PWM signal is 1, iLight sourceHas a brightness of 1-a% maximum and a rate of only iOFDM-And (6) determining.
On one hand, since the brightness of the light source is proportional to the driving current of the light source, if the target brightness value that the user wants to adjust is within the brightness value range [ a%, 1-a% ], the sending end device may change the driving current of the light source by changing the duty ratio of the PWM signal, thereby controlling the brightness of the light source.
On the other hand, since the number of subcarriers enabled by the OFDM frequency domain signal is proportional to the average current of the OFDM unipolar time domain symbol, if the target luminance value that the user wants to adjust is outside the luminance value range [ a%, 1-a% ], i.e., [ 0.1% to a%) or (1-a% to 100%), the transmitting end device may change the driving current of the light source by controlling the number of enabled subcarriers (turning off the subcarriers or turning on the subcarriers), thereby controlling the luminance of the light source.
Optionally, the method for determining, by the sending end device, the number of target enabled subcarriers to be used by the target brightness value may specifically be:
judging whether the target brightness value belongs to a specified brightness value range or not;
if yes, the number of the target enabled subcarriers to be used by the target brightness value is determined to be the number of all the available subcarriers of the OFDM frequency domain signal.
In this alternative embodiment, the specified range of luminance values is iLight sourceThe value range of (a) is, for example: [ a%, 1-a% ]]The available subcarriers are subcarriers used for carrying data information, and all the available subcarriers of the OFDM frequency domain signal are enabled within a specified range of brightness values. If the sending end device determines that the target brightness value belongs to the specified brightness value range, the sending end device may determine that the number of target enabled subcarriers to be used by the target brightness value is the number of all available subcarriers of the OFDM frequency domain signal, for example, assuming that the number of all available subcarriers of the OFDM frequency domain signal is 256, and the specified brightness value range is [ 3%, 97%]The target brightness value is 70%, and the transmitting end equipment judges that 70% belongs to [ 3%, 97% ]]The transmitting-end device determines that the number of target-enabled subcarriers to be used by 70% is 256, that is, the number of all available subcarriers of the OFDM frequency-domain signal.
Optionally, the method for determining, by the sending end device, the number of target enabled subcarriers to be used by the target brightness value may specifically be:
judging whether the target brightness value belongs to a specified brightness value range or not;
if the target brightness value is smaller than the minimum brightness value in the specified brightness value range, determining the number of target enabled subcarriers to be used by the target brightness value according to a formula, wherein round () is a rounding function, M is the number of all available subcarriers of the OFDM frequency domain signal, M is a positive integer, x% is the target brightness value, and a% is the OFDM obtained when all available subcarriers of the OFDM frequency domain signal are enabled+The percentage ratio of the mean current of the sign to the high current of the PWM signal, a%, is a positive number.
In this alternative embodiment, the specified range of luminance values is iLight sourceThe value range of (a) is, for example: [ a%, 1-a% ]]The available subcarriers are subcarriers used for carrying data information. If the sending end equipment judges that the target brightness value is smaller than the minimum brightness value in the specified brightness value range, namely the target brightnessIf the value belongs to the luminance value range of [ 0.1% -a%), the transmitting end device may determine the number of target enabled subcarriers (including subcarriers and conjugate symmetric subcarriers thereof) to be used by the target luminance value according to a formula. For example, assuming that M is 256, x% is 1%, a% is 3%, and the transmitting device substitutes M, x% and a% into the formula to obtain a result of 86, so that the number of target enabled subcarriers to be used for 1% of the target luminance value is 86, which includes 43 pairs of subcarriers, and each pair of subcarriers includes subcarriers whose conjugate is symmetric to the subcarrier.
Optionally, the method for determining, by the sending end device, the number of target enabled subcarriers to be used by the target brightness value may specifically be:
judging whether the target brightness value belongs to a specified brightness value range or not;
if the target brightness value is larger than the maximum brightness value in the specified brightness value range, determining the number of target enabled subcarriers to be used by the target brightness value according to a formula, wherein round () is a rounding function, M is the number of all available subcarriers of the OFDM frequency domain signal, M is a positive integer, x% is the target brightness value, and a% is the OFDM obtained when all available subcarriers of the OFDM frequency domain signal are enabled+The percentage ratio of the mean current of the sign to the high current of the PWM signal, a%, is a positive number.
In this alternative embodiment, the specified range of luminance values is iLight sourceThe value range of (a) is, for example: [ a%, 1-a% ]]The available subcarriers are subcarriers used for carrying data information. If the sending end equipment judges that the target brightness value is larger than the maximum brightness value in the specified brightness value range, namely the target brightness value belongs to (1-a%, 100%]The sending end device may determine the number of target enabled subcarriers (including subcarriers and conjugate symmetric subcarriers thereof) to be used by the target brightness value according to a formula. For example, assuming that M is 256, x% is 98%, a% is 3%, the transmitting device substitutes M, x% and a% into the formula to obtain the result of 172, so that the number of target enabled subcarriers to be used for the luminance value of 98% is 172, including 86 pairs of subcarriers, each pair of subcarriers including a subcarrier and its corresponding subcarrierThe symmetric subcarriers are conjugated.
203. And the sending end equipment loads the appointed data to the target enabling subcarriers of the quantity to obtain the orthogonal frequency division multiplexing OFDM frequency domain signal.
In the embodiment of the present invention, after the sending end device determines the number of target enabled subcarriers to be used by the target brightness value, the sending end device may load the specified data onto the number of target enabled subcarriers to obtain 1 OFDM frequency domain signal, and may obtain a plurality of OFDM frequency domain signals by multiple times of load. The designated data may be data input by a user, or the designated data may also include data input by the user and a pre-set Pseudo Random Sequence (PRBS), where the PRBS is a Sequence that is pre-defined by the sending end device and the receiving end device and is used for the receiving end device to calculate a Signal-to-Noise Ratio (SNR). Where the data specified is different for each bearer and thus the OFDM frequency domain signal is different for each OFDM frequency domain signal.
204. Sending end equipment determines OFDM corresponding to target brightness value+Number of symbols p and OFDM corresponding to target luminance value-The number of symbols q.
In the embodiment of the present invention, after the sending end device obtains the OFDM frequency domain signal, the sending end device needs to convert the OFDM frequency domain signal into an OFDM bipolar time domain symbol. Further, the sending end device needs to process the OFDM bipolar time domain symbol to obtain an OFDM unipolar time domain symbol, that is, an OFDM symbol+Symbol and OFDM-And (4) a symbol. The OFDM bipolar time domain symbol has antisymmetry, and based on the symmetry, the receiving end equipment can be according to OFDM+Symbol and OFDM-And recovering the original bipolar OFDM symbol from the symbol.
Referring to fig. 2.1, fig. 2.1 is a schematic diagram of an OFDM unipolar time domain symbol according to an embodiment of the present invention. As shown in fig. 2.1, the OFDM unipolar time domain symbol, that is, the OFDM symbol can be obtained by clearing the negative value of the OFDM bipolar time domain symbol+A symbol; zero clearing the positive value of the OFDM bipolar time domain symbol to obtain the OFDM unipolar timeField symbols, i.e. OFDM-And (4) a symbol.
Let X denote the OFDM frequency domain signal and X denote the OFDM bipolar time domain signal, then there is X ═ fft (X). According to OFDM+Symbol and OFDM-Definition of symbols, OFDM+Symbol representation is then OFDM+The frequency domain signal of the symbol is wherein XclipIs a frequency domain representation of | x |. OFDM system-Symbol representation is then OFDM-The frequency domain signal of the symbol is visible, and after the processing, no matter the sending end equipment sends OFDM+Symbol or OFDM-The symbol and the coefficient in front of X are both 1/2, so the frequency domain equalization coefficient adopted by the equalizer of the receiving end equipment does not need to change the symbol (i.e. sign), thereby simplifying the whole operation process of the receiving end equipment and improving the demodulation efficiency.
In the embodiment of the invention, in order to realize the control of the light source brightness, the sending end equipment needs to use OFDM+Superimposing the symbols onto the low current of the PWM signal, and OFDM-The symbol is superimposed on the high current of the PWM signal, so that the sending end equipment needs to determine the OFDM corresponding to the target brightness value+Number of symbols p and OFDM corresponding to target luminance value-The number of symbols q. Wherein p and q are both non-negative integers.
Optionally, if it is determined in 202 that the target brightness value belongs to the specified brightness value range, the sending end device determines the OFDM corresponding to the target brightness value+Number of symbols p and OFDM corresponding to target luminance value-The number of symbols q may be in the form of:
determining the OFDM according to a formula and p + q ═ N+Number of symbols p and OFDM-A number of symbols q, said a% being the OFDM obtained when all available subcarriers of said OFDM frequency domain signal are enabled+The percentage ratio of the mean current of the symbols to the high current of the PWM signal, where a% is a positive number, x% is the target brightness value, N is the number of OFDM unipolar time domain symbols that can be superimposed on the PWM signal in one period, and N is a positive integer.
In this optional embodiment, if it is determined in 202 that the target brightness value belongs to the specified brightness value range, the sending end device may determine that all available subcarriers are enabled, and at this time, the sending end device only needs to adjust the duty ratio of the PWM signal.
For example, assuming that a% is 3%, x% is 70%, N is 100, a% and x% are substituted, and p + q is 100, the transmitting device may calculate p is 28, q is 72, that is, to achieve 70% of brightness, only the duty ratio of the PWM signal needs to be adjusted to 0.72.
It should be noted that OFDM+Symbol and OFDM-The symbols are from different OFDM bipolar time domain symbols, such as: assuming that there are 100 OFDM bipolar time domain symbols, OFDM-The symbols are from the first 90 OFDM bipolar time domain symbols, which are OFDM+The symbols are from the last 10 OFDM bipolar time domain symbols.
Optionally, if it is determined in 202 that the target brightness value is smaller than the minimum brightness value in the specified brightness value range, the sending end device determines the OFDM corresponding to the target brightness value+Number of symbols p and OFDM corresponding to target luminance value-The number of symbols q may be in the form of:
determining OFDM corresponding to target brightness value+The number p of the symbols is N, and OFDM corresponding to the target brightness value is determined-The number of symbols q is zero.
In this alternative embodiment, when the duty cycle of the PWM signal is 0, the entire PWM signal is at a low current, with a brightness that is the minimum brightness value in the specified range of brightness values. If the target brightness value is determined to be smaller than the minimum brightness value in the specified brightness value range in step 202, the sending end device cannot change the duty ratio of the PWM signal, and can only adjust the brightness value of the light source by controlling the number of enabled subcarriers. At this time, the OFDM unipolar time domain symbol superimposed on the low current of the PWM signal is OFDM+Symbols without superposition of OFDM-The symbol is used, so that the sending end equipment can determine the OFDM corresponding to the target brightness value+The number p of the symbols is N, and OFDM corresponding to the target brightness value is determined-The number of symbols q is zero.
Alternatively, if the target is determined in 202If the brightness value is greater than the maximum brightness value in the specified brightness value range, the sending end device determines the OFDM corresponding to the target brightness value+Number of symbols p and OFDM corresponding to target luminance value-The number of symbols q may be in the form of:
determining OFDM corresponding to target brightness value+The number p of the symbols is zero, and OFDM corresponding to the target brightness value is determined-The number of symbols q is N.
In this alternative embodiment, when the duty cycle of the PWM signal is 1, the entire PWM signal is at a high current, with a brightness that is the maximum brightness value in the specified range of brightness values. If it is determined in 202 that the target brightness value is greater than the maximum brightness value in the specified brightness value range, the sending end device cannot change the duty ratio of the PWM signal, and can only adjust the brightness value of the light source by controlling the number of enabled subcarriers. At this time, the OFDM unipolar time domain symbol superimposed on the high current of the PWM signal is OFDM-Symbols without superposition of OFDM+The symbol is used, so that the sending end equipment can determine the OFDM corresponding to the target brightness value-The number q of the symbols is N, and OFDM corresponding to the target brightness value is determined+The number p of symbols is zero.
205. The sending end equipment sends p OFDM+Superimposing the symbols onto the low current of the PWM signal, and adding q OFDM symbols-The sign is superimposed on the high current of the PWM signal to obtain the driving current signal of the light source.
In the embodiment of the invention, the sending end equipment determines the OFDM corresponding to the target brightness value+Number of symbols p and OFDM corresponding to target luminance value-After the number q of symbols, the transmitting end device can transmit p OFDM symbols+Superimposing the symbols onto the low current of the PWM signal, and dividing the q OFDM symbols-And superimposing the symbol on the high current of the PWM signal to obtain a driving current signal of the light source, wherein the driving current signal is used for controlling the brightness value of the light source to be a target brightness value, so that the brightness value of the light source is adjusted.
In the method flow described in fig. 2, the sending end device may obtain the target brightness value and determine the target brightness valueThe number of target enabled subcarriers to be used by the target brightness value is obtained, and the specified data is loaded on the target enabled subcarriers of the number to obtain an Orthogonal Frequency Division Multiplexing (OFDM) frequency domain signal, and further, the sending end device can determine the OFDM corresponding to the target brightness value+Number of symbols p and OFDM corresponding to target luminance value-Number of symbols q, and p OFDM+Superimposing the symbols onto the low current of the PWM signal, and dividing the q OFDM symbols-The symbol is superposed on the high current of the PWM signal to obtain the driving current signal of the light source, so that the control of the brightness of the light source can be realized. Therefore, according to the embodiment of the invention, the sending end equipment obtains the OFDM after the negative value of the OFDM bipolar time domain symbol obtained by conversion is cleared+Symbol, zero clearing the positive value of the OFDM bipolar time domain symbol to obtain OFDM-Symbols, after such processing, whether the transmitting end device transmits OFDM+Symbol or OFDM-The sign and the frequency domain equalization coefficient adopted by the equalizer of the receiving end equipment do not need sign changing (namely, sign changing), so that the whole operation process of the receiving end equipment can be simplified, and the demodulation efficiency is improved.
Based on the network architecture shown in fig. 1, the embodiment of the invention discloses a light source brightness control method. Referring to fig. 3, fig. 3 is a schematic flow chart of another method for controlling brightness of a light source according to an embodiment of the present invention. As shown in fig. 3, the method may include the steps of:
301. the sending end equipment acquires a target brightness value.
302. The transmitting end device determines the number of target enabled subcarriers to be used by the target luminance value.
303. The sending end equipment compares the size relation between the number of the target enabled subcarriers and the number of the current enabled subcarriers.
In the embodiment of the invention, the number of the enabled subcarriers required by different brightness values is different. Based on a scene in which the brightness value of the light source is to be adjusted, before the adjustment, the brightness value of the light source is referred to as a current brightness value, where the method for adjusting the brightness value of the light source specifically is as follows: and adjusting the brightness value of the light source from the current brightness value to the target brightness value. The enabled subcarrier corresponding to the current brightness value is referred to as a current enabled subcarrier, that is, a currently enabled subcarrier.
It should be noted that, in the embodiment of the present invention, the currently enabled subcarriers are all based on the subcarriers being enabled at the same time (i.e., before the adjustment).
304. If the number of the target enabled subcarriers is smaller than the number of the current enabled subcarriers, the sending end device closes the first number of subcarriers.
In this embodiment of the present invention, if the number of target enabled subcarriers is smaller than the number of currently enabled subcarriers, that is, to achieve that the luminance value of the light source is the target luminance value, the sending end device needs to turn off a first number of subcarriers, where the first number is a difference between the number of currently enabled subcarriers and the number of target enabled subcarriers.
For example, if the current brightness value is 2%, the number of the current enabled subcarriers is 172, the target brightness value is 1%, and the number of the target enabled subcarriers to be used by the target brightness value is 86, the sending end device needs to turn off 86 subcarriers (including the subcarriers and their conjugate symmetric subcarriers) to control the brightness value of the light source to be 1%.
305. And the sending end equipment loads the appointed data to the target enabling subcarriers of the quantity to obtain Orthogonal Frequency Division Multiplexing (OFDM) frequency domain signals, and 308-309 is executed.
Specifically, the sending end device loads data input by a user onto a target enabled subcarrier to obtain 1 OFDM frequency domain signal, and multiple OFDM frequency domain signals can be obtained by multiple loads. Wherein, the data input by the user is different each time, so that each OFDM frequency domain signal is different.
306. And if the number of the target enabled subcarriers is larger than that of the current enabled subcarriers, the sending end equipment starts a second number of subcarriers.
In the embodiment of the present invention, if the number of target enabled subcarriers is greater than the number of currently enabled subcarriers, that is, to achieve that the luminance value of the light source is the target luminance value, the sending end device needs to turn on a second number of subcarriers, where the second number is a difference between the number of target enabled subcarriers and the number of currently enabled subcarriers.
For example, if the current brightness value is 99%, the number of the current enabled subcarriers is 86, the target brightness value is 98%, and the number of the target enabled subcarriers to be used by the target brightness value is 172, the sending end device needs to turn on 86 subcarriers (including the subcarriers and their conjugate symmetric subcarriers) to control the brightness value of the light source to be 98%.
307. And the sending end equipment loads the input data on the current enabled subcarriers and loads the preset pseudorandom sequences on a second number of subcarriers to obtain Orthogonal Frequency Division Multiplexing (OFDM) frequency domain signals, and 308-309 is executed.
In the embodiment of the invention, the sending end equipment modulates the data input by the user to the current enabled subcarriers and modulates the preset pseudorandom sequence to the subcarriers of the second number to obtain 1 OFDM frequency domain signal, and multiple OFDM frequency domain signals can be obtained by carrying for multiple times. Wherein, the data input by the user is different each time, so that each OFDM frequency domain signal is different.
In the embodiment of the present invention, the pseudorandom sequence is predefined by the sending end device and the receiving end device, and is used for the receiving end device to calculate the SNR, and at this time, each subcarrier of the second number of subcarriers carries a preset number (for example, 2 bits).
308. Sending end equipment determines OFDM corresponding to target brightness value+Number of symbols p and OFDM corresponding to target luminance value-The number of symbols q.
309. The sending end equipment superposes p OFDM + symbols on the low current of the PWM signal and superposes q OFDM-symbols on the high current of the PWM signal to obtain a driving current signal of the light source.
In the embodiment of the present invention, when the target luminance value does not belong to the specified luminance value range, the number of enabled subcarriers may change, so that the transmitting end device and the receiving end device need to interact with the enabled subcarriers. The transmitting end device may transmit data to the receiving end device in the form of data frames.
Referring to fig. 3.1, fig. 3.1 is a data frame structure according to an embodiment of the present invention. As shown in fig. 3.1, the data frame may include H, S, P and D, where H represents a frame header, which indicates the length of the current frame (e.g. the number of included symbols) and the current luminance value, S represents a synchronization symbol, when the target luminance value does not fall within the specified luminance value range and the number of enabled subcarriers is changed from small to large, S may be used to indicate whether a new enabled subcarrier table is in effect, where the new enabled subcarrier table is used to record the number of bits that each subcarrier in the new enabled subcarrier can actually carry, P represents a pre-emphasis symbol used to send and receive synchronization and measure SNR, and D represents a data symbol used to carry specified data.
In this embodiment of the present invention, the sending end device may update the brightness value to the target brightness value in the frame header H of the data frame, or the sending end device may update the brightness value to the target brightness value in another location (for example, on a designated symbol in the data frame), which is not limited in this embodiment of the present invention.
When the target brightness value is smaller than the minimum brightness value in the specified brightness value range, the sending end device may close the data symbols and the pre-emphasis symbols to the subcarriers of the first number, and after the receiving end device receives the data frame sent by the sending end device, the receiving end device may calculate the number of the actual enabled subcarriers according to the brightness value in the frame header H of the data frame.
When the target brightness value is greater than the maximum brightness value in the specified brightness value range, the sending end device may open a second number of subcarriers for the data symbol and the pre-emphasis symbol, the second number of subcarriers carry a preset pseudorandom sequence, each subcarrier in the second number of subcarriers carries a preset number of bits (e.g., 2 bits), and after the receiving end device receives the data frame sent by the sending end device, the receiving end device may estimate the SNR of the second number of subcarriers and calculate a new enabled subcarrier table.
For example, it is assumed that the information received by the receiving end device on a certain subcarrier in the frequency domain is y ═ x + z, where x is data actually transmitted by the transmitting end device, and z is noise introduced during transmission. The sending end device sends a pseudo-random sequence on the subcarrier, the pseudo-random sequence is a sequence preset by both sides, so x is known to the receiving end device, and the receiving end device can calculate the noise size to be y-x. Since the noise is random, the variation of each symbol is large, and after receiving a plurality of symbols, the receiving end device can calculate the average energy of the noise, and then the average energy of the noise is divided by the energy of the signal to obtain the SNR.
After the receiving end device estimates the SNR, it can be determined according to shannon formula b ═ log2(1+ SNR) a new enabled subcarrier table is calculated, and table 1 below is an example of the new enabled subcarrier table:
table 1 table of newly enabled subcarriers
i 0 1 2 3 4 5 6 7 8
bi 0 4 5 2 1 2 3 5 5
In table 1, i represents an index value of a subcarrier, and bi represents the number of bits carried by the subcarrier with the index value of i.
As an optional implementation manner, if the number of target enabled subcarriers is greater than the number of current enabled subcarriers, after 309, the method may further include the following steps:
11) receiving a new enabled subcarrier table sent by receiving end equipment, wherein the new enabled subcarrier table is used for recording the bit number which can be borne by each subcarrier in the second number of subcarriers;
12) for each of the subcarriers in the second number of subcarriers, carrying on the subcarrier the number of bits matching the subcarrier in the newly enabled subcarrier table;
13) and updating the current zone bit of the synchronization symbol into a first zone bit, wherein the first zone bit is used for representing that the newly enabled subcarrier table takes effect.
In this optional embodiment, after the receiving end device calculates the new enabled subcarrier table, the receiving end device may send the new enabled subcarrier table to the sending end device, and after the sending end device receives the new enabled subcarrier table sent by the receiving end device, the sending end device may load, on each subcarrier in the second number of subcarriers, the number of bits that is matched with the subcarrier in the new enabled subcarrier table. For example, assuming that the new enabled subcarrier table is shown in table 1, the sending end device carries 0bit for the subcarrier with the index value of 0, 4bit for the subcarrier with the index value of 1, 5bit for the subcarrier with the index value of 2, 2bit for the subcarrier with the index value of 3, 1bit for the subcarrier with the index value of 4, 2bit for the subcarrier with the index value of 5, 3bit for the subcarrier with the index value of 6, 5bit for the subcarrier with the index value of 7, and 5bit for the subcarrier with the index value of 8.
Meanwhile, the sending end device needs to update the current flag bit of the synchronization symbol to a first flag bit, where the first flag bit is used to represent that the new enabled subcarrier table is valid. Assuming that data 01 is transmitted on each subcarrier at the beginning of a synchronization symbol, if the transmitting-end device uses a new enabled subcarrier table, the synchronization symbol transmits different data (e.g. 10) from the previous frame on each subcarrier, so that the update of the flag bit of the synchronization symbol is realized. When the receiving end device finds that the data carried by each subcarrier on the synchronization symbol is different from a previous frame, the receiving end device can determine that the sending end device uses a new enabled subcarrier table, namely the new enabled subcarrier table is effective at the sending end device, so that the receiving end device demodulates the next symbol according to the new enabled subcarrier table.
Before the newly enabled subcarrier table takes effect, each subcarrier in the second number of subcarriers carries a preset number of bits, after the newly enabled subcarrier table takes effect, the sending end device carries the bit number matched with each subcarrier in the newly enabled subcarrier table on each subcarrier in the second number of subcarriers, and the bit number carried on the currently enabled subcarrier is unchanged, so that the communication rate can be improved.
In the method flow described in fig. 3, the sending end device may compare the magnitude relationship between the number of target enabled subcarriers and the number of current enabled subcarriers, and if the two numbers are not equal, may implement control over the light source brightness by using a manner of controlling the enabled subcarriers (turning off the subcarriers or turning on the subcarriers).
Based on the network architecture shown in fig. 1, an embodiment of the present invention discloses a sending end device. Referring to fig. 4, fig. 4 is a schematic structural diagram of a sending end device according to an embodiment of the present invention. The transmitting end device shown in fig. 4 may be used to execute the light source brightness control method disclosed in fig. 2. As shown in fig. 4, the transmitting-end device 400 may include:
an acquisition unit 401 configured to acquire a target luminance value;
a first determining unit 402, configured to determine the number of target enabled subcarriers to be used by the target luminance value;
a carrying unit 403, configured to carry specified data onto the number of target enabled subcarriers to obtain an orthogonal frequency division multiplexing OFDM frequency domain signal;
a second determining unit 404, configured to determine the OFDM corresponding to the target brightness value+The number p of symbols and the OFDM corresponding to the target brightness value-Number of symbols q, said OFDM+The symbol is an OFDM unipolar time domain symbol obtained by zero clearing of a negative value of the OFDM bipolar time domain symbol obtained by conversion, wherein the OFDM unipolar time domain symbol is obtained by zero clearing of the negative value of the OFDM bipolar time domain symbol obtained by conversion-The symbol is an OFDM unipolar time domain symbol obtained by zero clearing of a positive value of the OFDM bipolar time domain symbol, and both p and q are non-negative integers;
a superposition unit 405 for combining the p OFDM+Superimposing a symbol onto the low current of the PWM signal, and the q OFDM symbols-And superimposing the symbol on the high current of the PWM signal to obtain a driving current signal of the light source, wherein the driving current signal is used for controlling the current brightness value of the light source to be the target brightness value.
Based on the network architecture shown in fig. 1, an embodiment of the present invention discloses a sending end device. Referring to fig. 5, fig. 5 is a schematic structural diagram of another sending-end device disclosed in the embodiment of the present invention. The transmitting end device shown in fig. 5 may be used to execute the light source brightness control method disclosed in fig. 3. The sending end device shown in fig. 5 is obtained by further optimizing on the basis of the sending end device shown in fig. 4, and compared with the sending end device shown in fig. 4, the sending end device shown in fig. 5 may further include, in addition to all units of the sending end device shown in fig. 4:
a closing unit 406, configured to close a first number of subcarriers if the number of target enabled subcarriers is smaller than the number of current enabled subcarriers after the first determining unit 402 determines the number of target enabled subcarriers to be used by the target luminance value and before the carrying unit 403 carries specified data onto the number of target enabled subcarriers to obtain an OFDM frequency domain signal, where the first number is a difference between the number of enabled subcarriers corresponding to the current luminance value and the number of target enabled subcarriers.
Based on the network architecture shown in fig. 1, an embodiment of the present invention discloses a sending end device. Referring to fig. 6, fig. 6 is a schematic structural diagram of another sending-end device disclosed in the embodiment of the present invention. The transmitting end device shown in fig. 6 may be used to execute the light source brightness control method disclosed in fig. 3. The sending end device shown in fig. 6 is obtained by further optimizing on the basis of the sending end device shown in fig. 4, and compared with the sending end device shown in fig. 4, the sending end device shown in fig. 6 may further include, in addition to all units of the sending end device shown in fig. 4:
a starting unit 407, configured to, after the first determining unit 402 determines the number of target enabled subcarriers to be used by the target luminance value, if the number of target enabled subcarriers is greater than the number of current enabled subcarriers, start a second number of subcarriers, where the second number is a difference between the number of target enabled subcarriers and the number of enabled subcarriers corresponding to the current luminance value;
the manner in which the carrying unit 403 carries the specified data to the number of target enabled subcarriers to obtain the OFDM frequency domain signal specifically is as follows:
and carrying the input data on the current enabled subcarriers and carrying a preset pseudorandom sequence on the second number of subcarriers to obtain Orthogonal Frequency Division Multiplexing (OFDM) frequency domain signals.
Optionally, the sending-end device shown in fig. 6 may further include:
a receiving unit 408, configured to receive a new enabled subcarrier table sent by a receiving end device, where the new enabled subcarrier table is used to record the number of bits that can be carried by each subcarrier in the second number of subcarriers;
the carrying unit 403, further configured to, for each of the subcarriers in the second number of subcarriers, carry on the subcarrier a number of bits matching the subcarrier in the newly enabled subcarrier table;
an updating unit 409, configured to update the current flag bit of the synchronization symbol to a first flag bit, where the first flag bit is used to represent that the new enabled subcarrier table takes effect.
Based on the network architecture shown in fig. 1, an embodiment of the present invention discloses a sending end device. Referring to fig. 7, fig. 7 is a schematic structural diagram of another sending-end device according to an embodiment of the present invention. The transmitting end device shown in fig. 7 may be used to execute the light source brightness control method disclosed in fig. 1 or fig. 2. The sending end device shown in fig. 6 is further optimized based on the sending end device shown in fig. 4, and compared with the sending end device shown in fig. 4, the sending end device shown in fig. 7 includes all the elements of the sending end device shown in fig. 4, and the first determining unit 402 may include:
a judgment subunit 4021, configured to judge whether the target brightness value belongs to a specified brightness value range;
a determining subunit 4022, configured to determine, when the determining subunit 4021 determines that the target luminance value belongs to a specified luminance value range, the number of target enabled subcarriers to be used by the target luminance value to be the number of all available subcarriers of the OFDM frequency domain signal.
The second determining unit 404 determines the OFDM corresponding to the target brightness value+The number p of symbols and the OFDM corresponding to the target brightness value-The manner of the number q of symbols is specifically:
determining the OFDM according to a formula and p + q ═ N+Number of symbols p and OFDM-A number of symbols q, said a% being the OFDM obtained when all available subcarriers of said OFDM frequency domain signal are enabled+The percentage ratio of the mean current of the symbols to the high current of the PWM signal, where a% is a positive number, x% is the target brightness value, N is the number of OFDM unipolar time domain symbols that can be superimposed on the PWM signal in one period, and N is a positive integer.
Optionally, the determining subunit 4022 is further configured to determine the number of target enabled subcarriers to be used by the target luminance value according to a formula if the target luminance value is smaller than the minimum luminance value in the specified luminance value range, where round () is an integer function, and M isIs the number of all available subcarriers of the OFDM frequency domain signal, wherein M is a positive integer, x% is the target brightness value, and a% is the OFDM obtained when all available subcarriers of the OFDM frequency domain signal are enabled+A percentage ratio of the mean current of the symbols to the high current of the PWM signal, said a% being a positive number.
The second determining unit 404 determines the OFDM corresponding to the target brightness value+The number p of symbols and the OFDM corresponding to the target brightness value-The manner of the number q of symbols is specifically:
determining the OFDM corresponding to the target brightness value+The number p of the symbols is N, and OFDM corresponding to the target brightness value is determined-The number of symbols q is zero.
Optionally, the determining subunit 4022 is further configured to determine, according to a formula, the number of target enabled subcarriers to be used by the target luminance value if the target luminance value is greater than a maximum luminance value in the designated luminance value range, where round () is an integer function, M is the number of all available subcarriers of the OFDM frequency-domain signal, M is a positive integer, x% is the target luminance value, and a% is an OFDM symbol obtained when all available subcarriers of the OFDM frequency-domain signal are enabled+A percentage ratio of the mean current of the symbols to the high current of the PWM signal, said a% being a positive number.
The second determining unit 404 determines the OFDM corresponding to the target brightness value+The number p of symbols and the OFDM corresponding to the target brightness value-The manner of the number q of symbols is specifically:
determining the OFDM corresponding to the target brightness value+The number p of the symbols is zero, and the OFDM corresponding to the target brightness value is determined-The number q of symbols is said N.
In the transmitting-end device 400 described in fig. 4 to 7, the acquisition unit 401 may acquire a target luminance value, the first determination unit 402 determines the number of target-enabled subcarriers to be used by the target luminance value, and the carrying unit 403 carries specified data to the numberObtaining the OFDM frequency domain signal on the target enabled sub-carrier, and further, the second determining unit 404 may determine the OFDM corresponding to the target brightness value+Number of symbols p and OFDM corresponding to target luminance value-Number of symbols q, superposition unit 405 will be p OFDM+Superimposing the symbols onto the low current of the PWM signal, and dividing the q OFDM symbols-The symbol is superposed on the high current of the PWM signal to obtain the driving current signal of the light source, so that the control of the brightness of the light source can be realized. Therefore, according to the embodiment of the invention, the sending end equipment obtains the OFDM after zero clearing of the negative value of the OFDM bipolar time domain symbol obtained by converting the OFDM frequency domain signal+Symbol, zero clearing positive value of OFDM bipolar time domain symbol to obtain OFDM-Symbols, after such processing, whether the transmitting end device transmits OFDM+Symbol or OFDM-The symbol and the frequency domain equalization coefficient adopted by the equalizer of the receiving end equipment do not need to be changed in number, so that the whole operation process of the receiving end equipment can be simplified, and the demodulation efficiency is improved.
Referring to fig. 8, fig. 8 is a schematic structural diagram of another sending-end device according to an embodiment of the present invention. The sending-end device shown in fig. 8 may be used to execute the method for controlling brightness of a light source disclosed in the embodiment of the present invention. As shown in fig. 8, the transmitting-end device 800 may include: at least one processor 801, such as a CPU (Central Processing Unit), at least one input device 802, memory 803, and a communication bus 804. Wherein a communication bus 804 is used to enable communication connections between these components. The memory 803 may be a high-speed RAM memory or a non-volatile memory (non-volatile memory). Those skilled in the art will appreciate that the architecture of the transmitting device 800 shown in fig. 8 is not intended to limit the present invention, and may be a bus architecture, a star architecture, a combination of more or fewer components than those shown in fig. 8, or a different arrangement of components.
The processor 801 is a control center of the sender apparatus 800, and may be a Central Processing Unit (CPU), and the processor 801 connects various parts of the whole sender apparatus 800 by using various interfaces and lines, and executes or executes software programs and/or modules stored in the memory 803, and calls program codes stored in the memory 803 to perform the following operations:
obtaining a target brightness value through the input device 802;
determining the number of target enabling subcarriers to be used by the target brightness value, and loading specified data to the number of target enabling subcarriers to obtain Orthogonal Frequency Division Multiplexing (OFDM) frequency domain signals;
determining the OFDM corresponding to the target brightness value+The number p of symbols and the OFDM corresponding to the target brightness value-Number of symbols q, said OFDM+The symbol is an OFDM unipolar time domain symbol obtained by zero clearing of a negative value of the OFDM bipolar time domain symbol obtained by conversion, wherein the OFDM unipolar time domain symbol is obtained by zero clearing of the negative value of the OFDM bipolar time domain symbol obtained by conversion-The symbol is an OFDM unipolar time domain symbol obtained by zero clearing of a positive value of the OFDM bipolar time domain symbol, and both p and q are non-negative integers;
the p OFDM signals are processed+Superimposing a symbol onto the low current of the PWM signal, and the q OFDM symbols-And superimposing the symbol on the high current of the PWM signal to obtain a driving current signal of the light source, wherein the driving current signal is used for controlling the brightness value of the light source to be the target brightness value.
Optionally, after the processor 801 determines the number of target-enabled subcarriers to be used by the target luminance value, and before the processor 801 loads the specified data onto the number of target-enabled subcarriers to obtain the OFDM frequency domain signal, the processor 801 is further configured to call the program code stored in the memory 803, so as to perform the following steps:
if the number of the target enabled subcarriers is smaller than the number of the current enabled subcarriers, closing a first number of subcarriers, wherein the first number is a difference value between the number of the enabled subcarriers corresponding to the current brightness value and the number of the target enabled subcarriers.
Optionally, after the processor 801 determines the number of target enabled subcarriers to be used by the target luma value, the processor 801 is further configured to call the program code stored in the memory 803, for performing the following steps:
if the number of the target enabled subcarriers is greater than the number of the current enabled subcarriers, starting a second number of subcarriers, wherein the second number is a difference value between the number of the target enabled subcarriers and the number of the enabled subcarriers corresponding to the current brightness value;
wherein each of the OFDM frequency domain signals is obtained by carrying input data on the currently enabled subcarriers and carrying a preset pseudo random sequence on the second number of subcarriers.
Optionally, the processor 801 is further configured to call the program code stored in the memory 803, so as to perform the following steps:
receiving, by the input device 802, a new enabled subcarrier table sent by a receiving end device, where the new enabled subcarrier table is used to record the number of bits that can be carried by each of the subcarriers in the second number of subcarriers;
for each of the subcarriers in the second number of subcarriers, carrying on the subcarrier a number of bits matching the subcarrier in the newly enabled subcarrier table;
and updating the current zone bit of the synchronization symbol into a first zone bit, wherein the first zone bit is used for representing that the new enabled subcarrier table takes effect.
Optionally, the way for the processor 801 to determine the number of target enabled subcarriers to be used by the target luminance value is specifically as follows:
judging whether the target brightness value belongs to a specified brightness value range or not;
if yes, determining the number of target enabled subcarriers to be used by the target brightness value as the number of all available subcarriers of the OFDM frequency domain signal.
Optionally, the processor 801 determines an OFD corresponding to the target brightness valueM+The number p of symbols and the OFDM corresponding to the target brightness value-The manner of the number q of symbols is specifically:
determining the OFDM according to a formula and p + q ═ N+Number of symbols p and OFDM-A number of symbols q, said a% being the OFDM obtained when all available subcarriers of said OFDM frequency domain signal are enabled+The percentage ratio of the mean current of the symbols to the high current of the PWM signal, where a% is a positive number, x% is the target brightness value, N is the number of OFDM unipolar time domain symbols that can be superimposed on the PWM signal in one period, and N is a positive integer.
Optionally, the processor 801 is further configured to call the program code stored in the memory, and is configured to perform the following steps:
if the target brightness value is smaller than the minimum brightness value in the specified brightness value range, determining the number of target enabled subcarriers to be used by the target brightness value according to a formula, wherein round () is an integer function, M is the number of all available subcarriers of the OFDM frequency domain signal, M is a positive integer, x% is the target brightness value, and a% is the OFDM frequency domain signal obtained when all available subcarriers are enabled+A percentage ratio of the mean current of the symbols to the high current of the PWM signal, said a% being a positive number.
Optionally, the processor 801 determines the OFDM corresponding to the target brightness value+The number p of symbols and the OFDM corresponding to the target brightness value-The manner of the number q of symbols is specifically:
determining the OFDM corresponding to the target brightness value+The number p of the symbols is N, and OFDM corresponding to the target brightness value is determined-The number of symbols q is zero.
Optionally, the processor 801 is further configured to call the program code stored in the memory 803, so as to perform the following steps:
if the target brightness value is greater than the maximum brightness value in the specified brightness value range, based onDetermining the number of target enabled subcarriers to be used by the target brightness value according to a formula, wherein the round () is a rounding function, the M is the number of all available subcarriers of the OFDM frequency domain signal, the M is a positive integer, the x% is the target brightness value, and the a% is the OFDM obtained when all available subcarriers of the OFDM frequency domain signal are enabled+A percentage ratio of the mean current of the symbols to the high current of the PWM signal, said a% being a positive number.
Optionally, the processor 801 determines the OFDM corresponding to the target brightness value+The number p of symbols and the OFDM corresponding to the target brightness value-The manner of the number q of symbols is specifically:
determining the OFDM corresponding to the target brightness value+The number p of the symbols is zero, and the OFDM corresponding to the target brightness value is determined-The number q of symbols is said N.
It should be noted that, for simplicity of description, the above-mentioned embodiments of the method are described as a series of acts or combinations, but those skilled in the art will recognize that the present invention is not limited by the order of acts, as some steps may occur in other orders or concurrently depending on the application. Further, those skilled in the art should also appreciate that the embodiments described in the specification are preferred embodiments and that the acts and modules referred to are not necessarily required in this application.
In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.
The steps in the method of the embodiment of the invention can be sequentially adjusted, combined and deleted according to actual needs. The units in the device of the embodiment of the invention can be merged, divided and deleted according to actual needs.
Those skilled in the art will appreciate that all or part of the steps in the methods of the above embodiments may be implemented by associated hardware instructed by a program, which may be stored in a computer-readable storage medium, and the storage medium may include: flash disks, Read-Only memories (ROMs), Random Access Memories (RAMs), magnetic or optical disks, and the like.
The light source brightness control method and the transmitting terminal device provided by the embodiment of the present invention are described in detail above, and a specific example is applied in the text to explain the principle and the embodiment of the present invention, and the description of the above embodiment is only used to help understanding the method and the core idea of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.

Claims (24)

  1. A method for controlling brightness of a light source, comprising:
    acquiring a target brightness value;
    determining the number of target enabling subcarriers to be used by the target brightness value, and loading specified data to the number of target enabling subcarriers to obtain Orthogonal Frequency Division Multiplexing (OFDM) frequency domain signals;
    determining the OFDM corresponding to the target brightness value+The number p of symbols and the OFDM corresponding to the target brightness value-Number of symbols q, said OFDM+The symbol is an OFDM unipolar time domain symbol obtained by zero clearing of a negative value of an OFDM bipolar time domain symbol obtained by converting the OFDM frequency domain signal, wherein the OFDM is-The symbol is an OFDM unipolar time domain symbol obtained by zero clearing of a positive value of the OFDM bipolar time domain symbol, and both p and q are non-negative integers;
    the p OFDM signals are processed+Superimposing the symbols onto the low current of the PWM signal, and said q OFDM symbols-And superimposing the symbol on the high current of the PWM signal to obtain a driving current signal of the light source, wherein the driving current signal is used for controlling the brightness value of the light source to be the target brightness value.
  2. The method according to claim 1, wherein after determining the number of target-enabled subcarriers to be used by the target luminance value and before carrying the specified data onto the number of target-enabled subcarriers to obtain the OFDM frequency domain signal, the method further comprises:
    if the number of the target enabled subcarriers is smaller than the number of the current enabled subcarriers, closing a first number of subcarriers, wherein the first number is a difference value between the number of the current enabled subcarriers and the number of the target enabled subcarriers.
  3. The method of claim 1, wherein after determining the number of target enabled subcarriers to be used by the target luminance value, the method further comprises:
    if the number of the target enabled subcarriers is larger than the number of the current enabled subcarriers, starting a second number of subcarriers, wherein the second number is the difference value between the number of the target enabled subcarriers and the number of the current enabled subcarriers;
    the loading the specified data onto the number of target enabled subcarriers to obtain an Orthogonal Frequency Division Multiplexing (OFDM) frequency domain signal includes:
    and carrying the input data on the current enabled subcarriers and carrying a preset pseudorandom sequence on the second number of subcarriers to obtain Orthogonal Frequency Division Multiplexing (OFDM) frequency domain signals.
  4. The method of claim 3, further comprising:
    receiving a new enabled subcarrier table sent by receiving end equipment, wherein the new enabled subcarrier table is used for recording the bit number which can be borne by each subcarrier in the second number of subcarriers;
    for each of the subcarriers in the second number of subcarriers, carrying on the subcarrier a number of bits matching the subcarrier in the newly enabled subcarrier table;
    and updating the current zone bit of the synchronization symbol into a first zone bit, wherein the first zone bit is used for representing that the new enabled subcarrier table takes effect.
  5. The method according to any of claims 1 to 4, wherein the determining the number of target enabled subcarriers to be used by the target luminance value comprises:
    judging whether the target brightness value belongs to a specified brightness value range or not;
    if yes, determining the number of target enabled subcarriers to be used by the target brightness value as the number of all available subcarriers of the OFDM frequency domain signal.
  6. The method of claim 5, wherein the determining the OFDM corresponding to the target brightness value+The number p of symbols and the OFDM corresponding to the target brightness value-A number of symbols, q, comprising:
    determining the OFDM according to a formula and p + q ═ N+Number of symbols p and OFDM-A number of symbols q, said a% being the OFDM obtained when all available subcarriers of said OFDM frequency domain signal are enabled+The percentage ratio of the mean current of the symbols to the high current of the PWM signal, where a% is a positive number, x% is the target brightness value, N is the number of OFDM unipolar time domain symbols that can be superimposed on the PWM signal in one period, and N is a positive integer.
  7. The method of claim 5, further comprising:
    if the target brightness value is smaller than the minimum brightness value in the specified brightness value range, determining the number of target enabled subcarriers to be used by the target brightness value according to a formula, wherein round () is an integer function, M is the number of all available subcarriers of the OFDM frequency domain signal, M is a positive integer, x% is the target brightness value, and a% is the OFDM frequency domain signal obtained when all available subcarriers are enabled+A percentage ratio of the mean current of the symbols to the high current of the PWM signal, said a% being a positive number.
  8. The method of claim 5, further comprising:
    if the target brightness value is greater than the maximum brightness value in the specified brightness value range, determining the number of target enabled subcarriers to be used by the target brightness value according to a formula, where round () is an integer function, M is the number of all available subcarriers of the OFDM frequency domain signal, M is a positive integer, x% is the target brightness value, and a% is an OFDM signal obtained when all available subcarriers of the OFDM frequency domain signal are enabled+A percentage ratio of the mean current of the symbols to the high current of the PWM signal, said a% being a positive number.
  9. A transmitting-end device, comprising:
    an acquisition unit configured to acquire a target luminance value;
    a first determining unit configured to determine the number of target enabled subcarriers to be used by the target luminance value;
    the bearing unit is used for bearing the appointed data on the target enabling subcarriers of the quantity to obtain Orthogonal Frequency Division Multiplexing (OFDM) frequency domain signals;
    a second determining unit for determining the OFDM corresponding to the target brightness value+The number p of symbols and the OFDM corresponding to the target brightness value-Number of symbols q, said OFDM+The symbol is an OFDM unipolar time domain symbol obtained by zero clearing of a negative value of an OFDM bipolar time domain symbol obtained by converting the OFDM frequency domain signal, wherein the OFDM is-The symbol is an OFDM unipolar time domain symbol obtained by zero clearing of a positive value of the OFDM bipolar time domain symbol, and both p and q are non-negative integers;
    a superposition unit for combining the p OFDM+Superimposing the symbols onto the low current of the PWM signal, and said q OFDM symbols-And superimposing the symbol on the high current of the PWM signal to obtain a driving current signal of the light source, wherein the driving current signal is used for controlling the brightness value of the light source to be the target brightness value.
  10. The sender device of claim 9, wherein the sender device further comprises:
    a closing unit, configured to close a first number of subcarriers if the number of target enabled subcarriers is smaller than the number of currently enabled subcarriers after the first determining unit determines the number of target enabled subcarriers to be used by the target luminance value and before the carrying unit carries the specified data to the number of target enabled subcarriers to obtain the OFDM frequency domain signal, where the first number is a difference between the number of currently enabled subcarriers and the number of target enabled subcarriers.
  11. The sender device of claim 9, wherein the sender device further comprises:
    a starting unit, configured to, after the first determining unit determines the number of target enabled subcarriers to be used by the target luminance value, if the number of target enabled subcarriers is greater than the number of currently enabled subcarriers, start a second number of subcarriers, where the second number is a difference between the number of target enabled subcarriers and the number of currently enabled subcarriers;
    the method for the carrying unit to carry the designated data to the number of target enabled subcarriers to obtain the OFDM frequency domain signal specifically includes:
    and carrying the input data on the current enabled subcarriers and carrying a preset pseudorandom sequence on the second number of subcarriers to obtain Orthogonal Frequency Division Multiplexing (OFDM) frequency domain signals.
  12. The sender device of claim 11, wherein the sender device further comprises:
    a receiving unit, configured to receive a new enabled subcarrier table sent by a receiving end device, where the new enabled subcarrier table is used to record the number of bits that can be carried by each subcarrier in the second number of subcarriers;
    the carrying unit is further configured to, for each of the subcarriers in the second number of subcarriers, carry on the subcarrier a number of bits matching the subcarrier in the newly enabled subcarrier table;
    and the updating unit is used for updating the current zone bit of the synchronization symbol into a first zone bit, and the first zone bit is used for representing that the new enabled subcarrier table takes effect.
  13. The sender device according to any one of claims 9 to 12, wherein the first determining unit includes:
    the judging subunit is used for judging whether the target brightness value belongs to a specified brightness value range;
    a determining subunit, configured to determine, when the determining subunit determines that the target luminance value belongs to a specified luminance value range, that the number of target enabled subcarriers to be used by the target luminance value is the number of all available subcarriers of the OFDM frequency domain signal.
  14. The transmitting-end device of claim 13, wherein the second determining unit determines the OFDM corresponding to the target brightness value+The number p of symbols and the OFDM corresponding to the target brightness value-The manner of the number q of symbols is specifically:
    determining the OFDM according to a formula and p + q ═ N+Number of symbols p and OFDM-A number of symbols q, said a% being the OFDM obtained when all available subcarriers of said OFDM frequency domain signal are enabled+A percentage ratio of a mean current of the symbols to a high current of the PWM signal, where a% is a positive number, x% is the target brightness value, N is a number of OFDM unipolar time domain symbols on which the PWM signal can be superimposed in one period, and N is a positive integerAnd (4) counting.
  15. The transmitting-end device of claim 13, wherein the determining subunit is further configured to determine the number of target-enabled subcarriers to be used by the target luminance value according to a formula if the target luminance value is smaller than the minimum luminance value in the specified luminance value range, wherein the round () is an integer function, M is the number of all available subcarriers of the OFDM frequency-domain signal, M is a positive integer, x% is the target luminance value, and a% is an OFDM symbol obtained when all available subcarriers of the OFDM frequency-domain signal are enabled+A percentage ratio of the mean current of the symbols to the high current of the PWM signal, said a% being a positive number.
  16. The transmitting-end device of claim 13, wherein the determining subunit is further configured to determine the number of target-enabled subcarriers to be used by the target luminance value according to a formula if the target luminance value is greater than a maximum luminance value in the specified luminance value range, wherein the round () is an integer function, M is the number of all available subcarriers of the OFDM frequency-domain signal, M is a positive integer, x% is the target luminance value, and a% is an OFDM symbol obtained when all available subcarriers of the OFDM frequency-domain signal are enabled+A percentage ratio of the mean current of the symbols to the high current of the PWM signal, said a% being a positive number.
  17. A transmitting-end device, comprising: the device comprises a processor, an input device and a memory, wherein the processor, the input device and the memory are respectively connected with a communication bus, a group of program codes are stored in the memory, and the processor is used for calling the program codes stored in the memory and executing the following steps:
    acquiring a target brightness value through the input device;
    determining the number of target enabling subcarriers to be used by the target brightness value, and loading specified data to the number of target enabling subcarriers to obtain Orthogonal Frequency Division Multiplexing (OFDM) frequency domain signals;
    determining the OFDM corresponding to the target brightness value+The number p of symbols and the OFDM corresponding to the target brightness value-Number of symbols q, said OFDM+The symbol is an OFDM unipolar time domain symbol obtained by zero clearing of a negative value of an OFDM bipolar time domain symbol obtained by converting the OFDM frequency domain signal, wherein the OFDM is-The symbol is an OFDM unipolar time domain symbol obtained by zero clearing of a positive value of the OFDM bipolar time domain symbol, and both p and q are non-negative integers;
    the p OFDM signals are processed+Superimposing the symbols onto the low current of the PWM signal, and said q OFDM symbols-And superimposing the symbol on the high current of the PWM signal to obtain a driving current signal of the light source, wherein the driving current signal is used for controlling the current brightness value of the light source to be the target brightness value.
  18. The transmitting-end device of claim 17, wherein after the processor determines the number of target-enabled subcarriers to be used by the target luminance value and before the processor carries the specified data onto the number of target-enabled subcarriers to obtain the OFDM frequency-domain signal, the processor is further configured to call the program code stored in the memory for performing the following steps:
    if the number of the target enabled subcarriers is smaller than the number of the current enabled subcarriers, closing a first number of subcarriers, wherein the first number is a difference value between the number of the current enabled subcarriers and the number of the target enabled subcarriers.
  19. The transmitting-end device of claim 17, wherein after the processor determines the number of target-enabled subcarriers to be used by the target luminance value, the processor is further configured to call program code stored in the memory for performing the steps of:
    if the number of the target enabled subcarriers is larger than the number of the current enabled subcarriers, starting a second number of subcarriers, wherein the second number is the difference value between the number of the target enabled subcarriers and the number of the current enabled subcarriers;
    the processor loads the designated data to the target enabled subcarriers of the number, and the mode of obtaining the Orthogonal Frequency Division Multiplexing (OFDM) frequency domain signal specifically comprises the following steps:
    and carrying the input data on the current enabled subcarriers and carrying a preset pseudorandom sequence on the second number of subcarriers to obtain Orthogonal Frequency Division Multiplexing (OFDM) frequency domain signals.
  20. The sender device of claim 19, wherein the processor is further configured to invoke the program code stored in the memory for performing the steps of:
    receiving, by the input device, a new enabled subcarrier table sent by a receiving end device, where the new enabled subcarrier table is used to record the number of bits that can be carried by each subcarrier in the second number of subcarriers;
    for each of the subcarriers in the second number of subcarriers, carrying on the subcarrier a number of bits matching the subcarrier in the newly enabled subcarrier table;
    and updating the current zone bit of the synchronization symbol into a first zone bit, wherein the first zone bit is used for representing that the new enabled subcarrier table takes effect.
  21. The transmitting end device according to any one of claims 17 to 20, wherein the processor determines the number of target enabled subcarriers to be used by the target luminance value specifically by:
    judging whether the target brightness value belongs to a specified brightness value range or not;
    if yes, determining the number of target enabled subcarriers to be used by the target brightness value as the number of all available subcarriers of the OFDM frequency domain signal.
  22. The transmitting end device of claim 21, wherein the processor determines the OFDM corresponding to the target brightness value+The number p of symbols and the OFDM corresponding to the target brightness value-The manner of the number q of symbols is specifically:
    determining the OFDM according to a formula and p + q ═ N+Number of symbols p and OFDM-A number of symbols q, said a% being the OFDM obtained when all available subcarriers of said OFDM frequency domain signal are enabled+The percentage ratio of the mean current of the symbols to the high current of the PWM signal, where a% is a positive number, x% is the target brightness value, N is the number of OFDM unipolar time domain symbols that can be superimposed on the PWM signal in one period, and N is a positive integer.
  23. The sender device of claim 21, wherein the processor is further configured to invoke the program code stored in the memory to perform the steps of:
    if the target brightness value is smaller than the minimum brightness value in the specified brightness value range, determining the number of target enabled subcarriers to be used by the target brightness value according to a formula, wherein round () is an integer function, M is the number of all available subcarriers of the OFDM frequency domain signal, M is a positive integer, x% is the target brightness value, and a% is the OFDM frequency domain signal obtained when all available subcarriers are enabled+A percentage ratio of the mean current of the symbols to the high current of the PWM signal, said a% being a positive number.
  24. The sender device of claim 21, wherein the processor is further configured to invoke the program code stored in the memory to perform the steps of:
    if the target brightness value is greater than the maximum brightness value in the specified brightness value range, determining the target brightness value to be used according to a formulaA number of target enabled subcarriers, wherein the round () is a rounding function, the M is a number of all available subcarriers of the OFDM frequency domain signal, the M is a positive integer, the x% is the target luminance value, and the a% is an OFDM symbol obtained when all available subcarriers of the OFDM frequency domain signal are enabled+A percentage ratio of the mean current of the symbols to the high current of the PWM signal, said a% being a positive number.
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