CN114285470A - Visible light communication method and device - Google Patents
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Abstract
The invention provides a visible light communication method and a device, belonging to the technical field of communication, wherein the method comprises the following steps: carrying out OFDM modulation on data to be transmitted in a power line to obtain an OFDM signal; modulating the OFDM signal into a visible light drive current, and driving a light-emitting device in each visible light communication device to send a visible light communication signal according to the visible light drive current; and respectively receiving uplink data of each terminal device through a receiving device in each visible light communication device, and performing OFDM demodulation on the uplink data to obtain target data.
Description
Technical Field
The present invention relates to the field of communications technologies, and in particular, to a visible light communication method and apparatus.
Background
Communication networks can provide convenient communication services in various fields, and users are pursuing better communication quality with the development of communication networks.
Currently, most wireless signal transmission devices are expensive and inefficient, and thus have many limitations. For example: millions of base stations around the world help handsets to boost signals, but most of the energy is expended on cooling, with an efficiency of only 5%.
Visible Light Communication (VLC) is a novel Communication mode combining illumination and optical Communication, and transmits information by using high-speed bright and dark flashing signals which are emitted by fluorescent lamps or Light emitting diodes and cannot be seen by naked eyes, so that illumination cannot be influenced when data are transmitted. VLC is an important technology in future broadband access and short-range communication directions. Achieving low cost visible light communication is an important issue in the industry today.
Disclosure of Invention
The invention provides a visible light communication method and a visible light communication device, which are used for solving the defect of high cost of wireless communication in the prior art.
The invention provides a visible light communication method, which comprises the following steps: carrying out OFDM modulation on data to be transmitted in a power line to obtain an OFDM signal; modulating the OFDM signal into a visible light drive current, and driving a light-emitting device in each visible light communication device to send a visible light communication signal according to the visible light drive current; and respectively receiving uplink data of each terminal device through a receiving device in each visible light communication device, and performing OFDM demodulation on the uplink data to obtain target data.
According to a visible light communication method provided by the present invention, the modulating the OFDM signal into a visible light driving current, and driving a light emitting device in each visible light communication device to transmit a visible light communication signal according to the visible light driving current includes: OOK modulation is carried out on the OFDM signals to obtain modulated OFDM signals; and modulating the modulated OFDM signals into visible light drive current, and driving light emitting devices in each visible light communication device to send visible light communication signals according to the visible light drive current.
According to a visible light communication method provided by the present invention, before the receiving device in each visible light communication device receives uplink data of each terminal device, and performs OFDM demodulation on the uplink data to obtain target data, the method includes: setting a preset time interval before each period of the visible light communication signal through each light-emitting device, and sending the visible light communication signal based on the preset time interval, wherein the preset time interval is related to reducing intersymbol interference of the visible light communication signal.
According to a visible light communication method provided by the present invention, before the receiving device in each visible light communication device receives uplink data of each terminal device, and performs OFDM demodulation on the uplink data to obtain target data, the method further includes:
and processing the data sent by each terminal device through a zero forcing algorithm and/or a minimum mean square error algorithm to generate the uplink data.
According to the visible light communication method provided by the invention, the zero forcing algorithm is as follows:
z＝Wy；
wherein z is the uplink data, y is data sent by the terminal equipment, W is a weighting matrix, k is the number of the light-emitting devices, l is the number of the receiving devices, and H is a channel matrix;
the minimum mean square error algorithm is as follows:
min＝E[||x-z||2]；
W′＝(HHH+N0I)-1HH；
wherein min is a desired minimum value of the mean square error between the linear combination of the visible light communication signal and the uplink data, E [ [ phi ] ]]For the desired value, x is the optical communication signal, W′As another weighting matrix, N0Is the noise of the receiving device.
The present invention also provides a visible light communication apparatus, comprising:
the first modulation module is used for carrying out OFDM modulation on data to be transmitted in the power line to obtain an OFDM signal;
the driving module is used for modulating the OFDM signals into visible light drive currents and driving light-emitting devices in each visible light communication device to send visible light communication signals according to the visible light drive currents;
and the receiving module is used for respectively receiving the uplink data of each terminal device through a receiving device in each visible light communication device and carrying out OFDM demodulation on the uplink data to obtain target data.
According to the present invention, there is provided a visible light communication apparatus, the apparatus further comprising:
the second modulation module is used for carrying out OOK modulation on the OFDM signal to obtain a modulated OFDM signal;
the driving module is further configured to modulate the modulated OFDM signal into a visible light driving current, and drive a light emitting device in each visible light communication device to send a visible light communication signal according to the visible light driving current.
According to the present invention, there is provided a visible light communication apparatus, the apparatus further comprising:
and the setting module is used for setting a preset time interval before each period of the visible light communication signals through each light-emitting device, and sending the visible light communication signals based on the preset time interval, wherein the preset time interval is related to reducing the intersymbol interference of the visible light communication signals.
According to the present invention, there is provided a visible light communication apparatus, the apparatus further comprising:
and the processing module is further used for processing the data sent by each terminal device through a zero forcing algorithm and/or a minimum mean square error algorithm to generate the uplink data.
According to the visible light communication device provided by the invention, the zero forcing algorithm is as follows:
z＝Wy；
wherein z is the uplink data, y is data sent by the terminal equipment, W is a weighting matrix, k is the number of the light-emitting devices, l is the number of the receiving devices, and H is a channel matrix;
the minimum mean square error algorithm is as follows:
min＝E[||x-z||2]；
W′＝(HHH+N0I)-1HH；
wherein min is a desired minimum value of the mean square error between the linear combination of the visible light communication signal and the uplink data, E [ [ phi ] ]]For the desired value, x is the optical communication signal, W′As another weighting matrix, N0Is the noise of the receiving device.
According to the visible light communication method and device, data transmission is carried out through the power line, visible light communication is achieved, the power line and the visible light communication are combined, electric signals are transmitted to the light source through the power line laid at present, and cost input can be reduced. Furthermore, a plurality of light emitting devices transmit visible light communication signals, and a plurality of receiving devices receive uplink data, and Multiple Input Multiple Output (MIMO) technology is adopted. In addition, in the signal transmission process, a mode of combining MIMO and OFDM is adopted, frequency selective fading and intersymbol interference can be well solved, the frequency spectrum utilization rate is high, the channel equalization technology is simple, and high-speed and reliable data transmission can be realized.
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In order to more clearly illustrate the technical solutions of the present invention or the prior art, the drawings needed for the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
FIG. 1 is a schematic flow chart of a visible light communication method provided by the present invention;
FIG. 2 is a topological diagram of a visible light communication method provided by the present invention;
FIG. 3 is a simulation result diagram of performance comparison between ideal interference cancellation ZF and MMSE detection algorithm of the visible light communication method provided by the present invention;
FIG. 4 is a simulation result diagram of performance comparison between the nonideal interference cancellation ZF and MMSE detection algorithms of the visible light communication method provided by the present invention;
fig. 5 is a schematic structural diagram of a visible light communication device provided by the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. 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, second and the like in the description and in the claims of the present application are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It will be appreciated that the data so used may be interchanged under appropriate circumstances such that embodiments of the application may be practiced in sequences other than those illustrated or described herein, and that the terms "first," "second," and the like are generally used herein in a generic sense and do not limit the number of terms, e.g., the first term can be one or more than one. In addition, "and/or" in the specification and claims means at least one of connected objects, a character "/" generally means that a preceding and succeeding related objects are in an "or" relationship.
A visible light communication method and apparatus provided in the embodiments of the present application are described in detail below with reference to the accompanying drawings through specific embodiments and application scenarios thereof.
Fig. 1 is a schematic flow chart of a visible light communication method provided by the present invention, as shown in fig. 1, including:
the power line described in the embodiments of the present application may particularly refer to a high voltage power line (generally referred to in the field of power carriers as 35kV and above), a medium voltage power line (referred to as 10kV voltage class) or a low voltage distribution line (380/220V subscriber line).
The power line can be recycled, the cost is low, the power line can be detached at any time, and the power line network is short in time consumption, flexible and convenient to construct.
The data to be transmitted described in the embodiment of the present application may be any service data, audio/video data, and the like that need to be transmitted.
Specifically, the data to be transmitted can be loaded in the current of the Power Line through the coupler, and the data is transmitted through the Power Line, so that Power Line Communication (PLC) is realized.
In some non-fixed places, such as markets, exhibitions and the like, when the migration is carried out along with leasing, the PLC technology is particularly suitable due to the convenient characteristic. Meanwhile, the PLC technology is also suitable for some relatively independent places such as trains, cruise ships and the like, or used in indoor interconnection of families. The PLC technology is widely applied to various occasions and has stronger flexibility, which is incomparable with other communication modes.
Ofdm (orthogonal Frequency Division multiplexing), an orthogonal Frequency Division multiplexing technique. The principle is as follows: the channel is divided into a plurality of orthogonal sub-channels, the high-speed data signal is converted into parallel low-speed sub-data streams, and the parallel low-speed sub-data streams are modulated to be transmitted on each sub-channel.
In the embodiment of the present application, OFDM modulation is adopted, which has the following advantages:
(1) higher spectrum utilization. The orthogonal of the symbols is realized in all signal periods by considering the overlapping state of subcarriers in OFDM, and the bandwidth protection strategy is remarkable.
(2) Interference is avoided. In a digital communication system, the ISI often occupies a main structure and represents a state of multiplicative noise, and a good guard interval state can be formed by using the OFDM technique, and each data block is processed, thereby avoiding an interference phenomenon in a mechanism.
(3) Weak resistance to frequency selectivity. When the OFDM system carries out carrier allocation, the automatic control of each sub-channel can be realized through the estimation and feedback of the channel. If the signal-to-noise ratio is in a more remarkable effect, the state of the system can be improved, a complex load balancing strategy is not needed in the whole process, and all functions can be realized under a relatively simple condition.
The OFDM modulation described in the embodiment of the present application may be performed by using an orthogonal frequency division multiplexing modulator, or may be performed by using any other device combination capable of implementing OFDM modulation, which is not specifically limited herein.
It can be understood that, no matter the OFDM modulator or any device combination capable of implementing OFDM modulation is disposed on the power line, and OFDM modulation is performed on data to be transmitted in the power line to obtain an OFDM signal.
Optionally, the OFDM signal is:
wherein x (t) is from t ═ tsThe OFDM signal starting at a time instant,
is as follows
And N is the number of subcarriers, T is the OFDM symbol period, and T is any time.
in modulating the OFDM signal into the visible light driving current in the present application, specifically, the visible light driving current is adjusted for driving the light emitting device according to the characteristics of optical communication of the light emitting device, wherein the OFDM signal is loaded on the visible light driving current.
The light emitting device described in the embodiments of the present application may be a fluorescent lamp or a light emitting diode LED, and specifically, the light emitting device is a device including a driving circuit and a light source assembly.
Specifically, the light emitting devices in the visible light communication devices are driven to send visible light communication signals, the signals can be transmitted by high-speed bright and dark flashing signals which are sent by the light emitting devices and cannot be seen by naked eyes, and illumination is not affected when the signals are transmitted.
More specifically, the visible light communication apparatus includes a plurality of light emitting devices, each of which receives a visible light driving current, i.e., each of which can convert the visible light driving current into an optical communication signal.
Among them, the multiple light emitting devices in the visible light communication device realize the function of the transmitting end in the MIMO technology.
The terminal devices described in the embodiments of the present application, for example, a mobile phone, a touch screen computer, a palm computer, a wearable Device, a PAD (Portable Android Device), and the like, are specifically terminal devices including an optical receiving Device.
The plurality of terminal devices are devices capable of receiving optical communication signals, wherein each terminal device receives optical communication signals transmitted by corresponding light-emitting devices in the illumination range.
Each terminal device may generate uplink data, and the uplink data may be service data and the like that the terminal device needs to transmit back.
The receiving device in the visible light communication device described in the embodiment of the present application receives the uplink data of each terminal device, which may be a correspondence relationship set in advance by a user, each terminal device only sends the uplink data to the corresponding receiving device, and each receiving device only receives the uplink data sent by the corresponding terminal device. Each receiving device can receive uplink data sent by a plurality of terminal devices.
Among them, the multiple receiving devices in the visible light communication device realize the function of the receiving end in the MIMO technology.
Therefore, the multiple light emitting devices and the multiple receiving devices in the visible light communication equipment jointly realize the multiple-input multiple-output (MIMO) technology, and the transmission rate of signals can be improved.
In addition, the MIMO technology uses multiple transmitting terminals and multiple receiving terminals to transmit and receive signals to be transmitted, so that space resources can be fully utilized, waste of space resources is reduced, and system performance is improved. And a plurality of independent channels are arranged between the sending end and the receiving end, and the independent channels eliminate the signal correlation between the sending ends and the receiving end, improve the link performance of the signals and increase the data throughput.
The OFDM demodulation described in the embodiment of the present application may be performed by using an orthogonal frequency division multiplexing demodulator, or may be performed by using any other device combination capable of implementing OFDM demodulation, which is not specifically limited herein.
It can be understood that, no matter the OFDM demodulator or any device combination capable of implementing OFDM demodulation is disposed on the power line, the OFDM demodulation is performed on the uplink data in the power line to obtain an OFDM signal.
Specifically, the target data is obtained by performing OFDM demodulation on the uplink data, which may be obtained by performing OFDM demodulation corresponding to the OFDM modulation.
Optionally, the target data is:
where k is the kth subcarrier, dk+N/2And modulating data symbols for the k + N/2 th subcarrier.
In the MIMO-OFDM system, a multi-Quadrature Amplitude Modulation (MQAM) is usually performed on signals, and the Modulation technology can fully and effectively utilize each section of system frequency band, so that a receiving end performs final signal detection and signal recovery on received signals when performing coherent demodulation, thereby playing a decisive role.
In the embodiment of the application, data are transmitted through the power line, visible light communication is achieved, the power line and the visible light communication are combined, the electric signal is transmitted to the light source through the power line which is laid at present, and cost input can be reduced. Furthermore, a plurality of light emitting devices transmit visible light communication signals, and a plurality of receiving devices receive uplink data, and Multiple Input Multiple Output (MIMO) technology is adopted. In addition, in the signal transmission process, a mode of combining MIMO and OFDM is adopted, frequency selective fading and intersymbol interference can be well solved, the frequency spectrum utilization rate is high, the channel equalization technology is simple, and high-speed and reliable data transmission can be realized.
Optionally, the modulating the OFDM signal into a visible light driving current, and driving a light emitting device in each visible light communication device to send a visible light communication signal according to the visible light driving current includes:
OOK modulation is carried out on the OFDM signals to obtain modulated OFDM signals;
and modulating the modulated OFDM signals into visible light drive current, and driving light emitting devices in each visible light communication device to send visible light communication signals according to the visible light drive current.
Specifically, binary amplitude keying OOK modulation is used for modulating the characteristics of optical communication of the light emitting device, modulating an OFDM signal into a signal matched with the light emitting device, and modulating the signal into a visible light drive current to drive the light emitting device.
Fig. 2 is a topological diagram of a visible light communication method provided by the present invention, as shown in fig. 2, including:
The OOK modulation described in the embodiments of the present application may be implemented by using an AM modulator, or may be implemented by using any other device combination capable of implementing OOK modulation, which is not limited herein.
In the embodiment of the application, the OFDM signal is OOK modulated to obtain the modulated OFDM signal, and the modulated OFDM signal is modulated into the visible light driving current, so that the light-emitting device can be better driven to transmit the visible light communication signal, and the effectiveness of visible light communication is improved.
Optionally, before the receiving device in each visible light communication device respectively receives uplink data of each terminal device, and performs OFDM demodulation on the uplink data to obtain target data, the method includes:
setting a preset time interval before each period of the visible light communication signal through each light-emitting device, and sending the visible light communication signal based on the preset time interval, wherein the preset time interval is related to reducing intersymbol interference of the visible light communication signal.
Specifically, each light-emitting device designs a required guard interval before each period of the visible light communication signal, and as the signal transmission period increases, the period Ts after the setting becomes Ts ═ T + Δ, T is the signal period before the adjustment, and Δ is the preset duration interval.
Where Δ is a delay tolerance threshold caused by the guard interval, and is an important parameter, and if the corresponding ISI is smaller than this value, a certain orthogonality condition can be ensured.
Furthermore, a plurality of receiving devices in the visible light communication equipment process the added redundant information, the whole information extraction process ensures useful signals in the whole period, and the mutual interference of the signals can be effectively avoided.
If the delta is continuously enhanced, the stability of the information can be satisfied under a better condition, and if the guard interval is excessively increased, unnecessary resource waste can be caused.
In order to further clarify the spectrum resources and improve the utilization rate, the guard interval of each transmission signal needs to be designed and calculated. Normally, the carrier state is also considered in the design process of the guard interval, and after the whole symbol period is N times the original one, the speed of the signal is changed to 1/N, which is the time with good ISI.
In this embodiment, by setting a preset duration interval before each period of the visible light communication signal, the transmission period of the signal is increased, so that the visible light communication is more stable, and the inter-symbol interference is effectively reduced.
Optionally, before the receiving device in each visible light communication device respectively receives uplink data of each terminal device, and performs OFDM demodulation on the uplink data to obtain target data, the method further includes:
and processing the data sent by each terminal device through a zero forcing algorithm and/or a minimum mean square error algorithm to generate the uplink data.
Specifically, Zero Forcing (ZF) and Minimum Mean Square Error (MMSE) are detection algorithms, and may be used to reduce interference, which may cause data errors, on signals transmitted during operation of the visible light communication device.
Further, the zero forcing algorithm is as follows:
z＝Wy；
wherein z is the uplink data, y is data sent by the terminal equipment, W is a weighting matrix, k is the number of the light-emitting devices, l is the number of the receiving devices, and H is a channel matrix;
the minimum mean square error algorithm is as follows:
min＝E[||x-z||2]；
W′＝(HHH+N0I)-1HH；
wherein min is a mean square error between the linear combination of the visible light communication signal and the uplink dataDesired minimum value of (A), E [ 2 ]]For the desired value, x is the optical communication signal, W′As another weighting matrix, N0Is the noise of the receiving device.
Both of the above algorithms are based on the following assumptions:
each light emitting device interval and each receiving device interval are at least half wavelength;
(2) rayleigh Fading channel (Rayleigh Fading channel);
(3) there is perfect channel estimation at the receiving device for channel equalization.
In the MIMO system, a linear detection algorithm ZF algorithm and an MMSE algorithm are used for detecting signals. The MMSE criterion is to minimize the desired value of the mean square error between the linear combinations of the transmitted and received signals, and to achieve an optimal signal-to-interference-plus-noise ratio. The ZF algorithm is simple, noise is amplified, and the performance is poor; the MMSE algorithm considers noise factors, and the overall algorithm performance is good.
In the embodiment, the nominal data sent by the terminal equipment is processed through a zero forcing algorithm and/or a minimum mean square error algorithm, uplink data is generated, and the method has good anti-noise interference capability, realizes the interference suppression of multiple receiving devices, and further reduces the probability of error codes.
FIG. 3 is a simulation result diagram of performance comparison between ideal interference cancellation ZF and MMSE detection algorithm of the visible light communication method provided by the present invention; fig. 4 is a simulation result diagram of performance comparison between the non-ideal interference cancellation ZF and the MMSE detection algorithm of the visible light communication method provided by the present invention. As shown in fig. 3 and 4, the bit error rate increases with the increase of the detection layer under the same snr. However, the layer reliability detected first is not high, and the layer reliability detected later is relatively high. In general, the MMES detection algorithm can minimize the system error rate.
The following describes the visible light communication device provided by the present invention, and the visible light communication device described below and the visible light communication method described above may be referred to correspondingly.
Fig. 5 is a schematic structural diagram of a visible light communication device provided by the present invention, and as shown in fig. 5, the device includes: a first modulation module 501, a driving module 502 and a receiving module 503; the first modulation module 501 is configured to perform OFDM modulation on data to be transmitted in a power line to obtain an OFDM signal; a driving module 502, configured to modulate the OFDM signal into a visible light driving current, and drive a light emitting device in each visible light communication device to send a visible light communication signal according to the visible light driving current; a receiving module 503, configured to receive uplink data of each terminal device through a receiving apparatus in each visible light communication device, and perform OFDM demodulation on the uplink data to obtain target data.
Optionally, the apparatus further comprises:
the second modulation module is used for carrying out OOK modulation on the OFDM signal to obtain a modulated OFDM signal;
the driving module is further configured to modulate the modulated OFDM signal into a visible light driving current, and drive a light emitting device in each visible light communication device to send a visible light communication signal according to the visible light driving current.
Optionally, the apparatus further comprises:
and the setting module is used for setting a preset time interval before each period of the visible light communication signals through each light-emitting device, and sending the visible light communication signals based on the preset time interval, wherein the preset time interval is related to reducing the intersymbol interference of the visible light communication signals.
Optionally, the apparatus further comprises:
and the processing module is further used for processing the data sent by each terminal device through a zero forcing algorithm and/or a minimum mean square error algorithm to generate the uplink data.
Optionally, the zero forcing algorithm is:
z＝Wy；
wherein z is the uplink data, y is data sent by the terminal equipment, W is a weighting matrix, k is the number of the light-emitting devices, l is the number of the receiving devices, and H is a channel matrix;
the minimum mean square error algorithm is as follows:
min＝E[||x-z||2]；
W′＝(HHH+N0I)-1HH；
wherein min is a desired minimum value of the mean square error between the linear combination of the visible light communication signal and the uplink data, E [ [ phi ] ]]For the desired value, x is the optical communication signal, W′As another weighting matrix, N0Is the noise of the receiving device.
The visible light communication device provided by the invention can transmit data through the power line, realize visible light communication, combine the power line and the visible light communication, and transmit an electric signal to the light source through the currently laid power line, so that the cost input can be reduced. Furthermore, a plurality of light emitting devices transmit visible light communication signals, and a plurality of receiving devices receive uplink data, and Multiple Input Multiple Output (MIMO) technology is adopted. In addition, in the signal transmission process, a mode of combining MIMO and OFDM is adopted, frequency selective fading and intersymbol interference can be well solved, the frequency spectrum utilization rate is high, the channel equalization technology is simple, and high-speed and reliable data transmission can be realized.
The above-described embodiments of the apparatus are merely illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the embodiments or some parts of the embodiments.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A visible light communication method, comprising:
carrying out OFDM modulation on data to be transmitted in a power line to obtain an OFDM signal;
modulating the OFDM signal into a visible light drive current, and driving a light-emitting device in each visible light communication device to send a visible light communication signal according to the visible light drive current;
and respectively receiving uplink data of each terminal device through a receiving device in each visible light communication device, and performing OFDM demodulation on the uplink data to obtain target data.
2. The visible light communication method according to claim 1, wherein the modulating the OFDM signal into a visible light driving current and driving a light emitting device in each visible light communication device to transmit the visible light communication signal according to the visible light driving current comprises:
OOK modulation is carried out on the OFDM signals to obtain modulated OFDM signals;
and modulating the modulated OFDM signals into visible light drive current, and driving light emitting devices in each visible light communication device to send visible light communication signals according to the visible light drive current.
3. The visible light communication method according to claim 1, wherein before the receiving device in each visible light communication device receives uplink data of each terminal device, and OFDM demodulates the uplink data to obtain target data, the method comprises:
setting a preset time interval before each period of the visible light communication signal through each light-emitting device, and sending the visible light communication signal based on the preset time interval, wherein the preset time interval is related to reducing intersymbol interference of the visible light communication signal.
4. The visible light communication method according to claim 1, wherein before the receiving device in each visible light communication device receives uplink data of each terminal device, and OFDM demodulates the uplink data to obtain target data, the method further comprises:
and processing the data sent by each terminal device through a zero forcing algorithm and/or a minimum mean square error algorithm to generate the uplink data.
5. The visible light communication method according to claim 4,
the zero forcing algorithm is as follows:
z＝Wy；
wherein z is the uplink data, y is data sent by the terminal equipment, W is a weighting matrix, k is the number of the light-emitting devices, l is the number of the receiving devices, and H is a channel matrix;
the minimum mean square error algorithm is as follows:
min＝E[||x-z||2]；
W′＝(HHH+N0I)-1HH；
wherein min is a desired minimum value of the mean square error between the linear combination of the visible light communication signal and the uplink data, E [ [ phi ] ]]For the desired value, x is the optical communication signal, W' is another weighting matrix, N0Is the noise of the receiving device.
6. A visible light communication device, comprising:
the first modulation module is used for carrying out OFDM modulation on data to be transmitted in the power line to obtain an OFDM signal;
the driving module is used for modulating the OFDM signals into visible light drive currents and driving light-emitting devices in each visible light communication device to send visible light communication signals according to the visible light drive currents;
and the receiving module is used for respectively receiving the uplink data of each terminal device through a receiving device in each visible light communication device and carrying out OFDM demodulation on the uplink data to obtain target data.
7. The visible light communication device of claim 6, wherein the device further comprises:
the second modulation module is used for carrying out OOK modulation on the OFDM signal to obtain a modulated OFDM signal;
the driving module is further configured to modulate the modulated OFDM signal into a visible light driving current, and drive a light emitting device in each visible light communication device to send a visible light communication signal according to the visible light driving current.
8. The visible light communication device of claim 6, wherein the device further comprises:
and the setting module is used for setting a preset time interval before each period of the visible light communication signals through each light-emitting device, and sending the visible light communication signals based on the preset time interval, wherein the preset time interval is related to reducing the intersymbol interference of the visible light communication signals.
9. The visible light communication device of claim 6, wherein the device further comprises:
and the processing module is further used for processing the data sent by each terminal device through a zero forcing algorithm and/or a minimum mean square error algorithm to generate the uplink data.
10. Visible light communication device according to claim 9,
the zero forcing algorithm is as follows:
z＝Wy；
wherein z is the uplink data, y is data sent by the terminal equipment, W is a weighting matrix, k is the number of the light-emitting devices, l is the number of the receiving devices, and H is a channel matrix;
the minimum mean square error algorithm is as follows:
min＝E[||x-z||2]；
W′＝(HHH+N0I)-1HH；
wherein min is a desired minimum value of the mean square error between the linear combination of the visible light communication signal and the uplink data, E [ [ phi ] ]]For the desired value, x is the optical communication signal, W' is another weighting matrix, N0Is the noise of the receiving device.
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