Wavelength division multiplexing system, device, wavelength division multiplexing communication method, and medium

Abstract

This application discloses a wavelength division multiplexing (WDM) system, device, WDM communication method, and medium, belonging to the field of wireless communication technology. A multi-wavelength laser is used to generate input light of different wavelengths; a WDM multiplexer is used to combine and modulate the input light to obtain channels with different wavelength intervals; a demultiplexer is used to demultiplex the narrow wavelength interval channels of the WDM multiplexer to increase the number of channels in the system. This application provides a blue-green WDM optical communication system and implementation method based on a demultiplexer, using blue-green light WDM technology to improve system capacity and achieve a high-bandwidth and moderate-attenuation wireless optical communication system. WDM visible light communication is achieved through a multiplexer / demultiplexer with fine wavelength intervals for visible light.

Description

Technical Field

[0001] This application relates to the field of wireless communication technology, and in particular to a blue-green light wavelength division multiplexing system, a wavelength division multiplexing visible light communication method, a blue-green light wavelength division multiplexing device, and a computer-readable storage medium. Background Technology

[0002] Currently, due to the rapid development of underwater resource exploration, data transmission between underwater vehicles and base stations requires a high-speed, robust underwater communication system. Compared with commonly used wireless communication methods such as acoustic communication, optical wireless communication has the advantages of high bandwidth and low latency. Furthermore, compared with radio frequency signals, optical wireless communication experiences less attenuation. Therefore, OWC (Optical Wireless Communication) using blue-green light is a promising candidate for short-to-medium range underwater communication. However, the lack of multiplexers / demultiplexers with fine wavelength spacing for visible light makes wavelength division multiplexing (WDM) visible light communication difficult to implement. Summary of the Invention

[0003] The main objective of this application is to provide a blue-green light wavelength division multiplexing system, a wavelength division multiplexing visible light communication method, a blue-green light wavelength division multiplexing device, and a computer-readable storage medium, aiming to solve the technical problem that wavelength division multiplexing visible light communication is difficult to achieve in conventional technologies.

[0004] To achieve the above objectives, this application provides a blue-green wavelength division multiplexing system, the system comprising:

[0005] A multi-wavelength laser, wherein the multi-wavelength laser is used to generate input light of different wavelengths;

[0006] A wavelength division multiplexer, wherein the wavelength division multiplexer is used to combine and modulate the input light to obtain channels with different wavelength intervals;

[0007] A demultiplexer is used to demultiplex narrow wavelength-spaced channels of the wavelength division multiplexer to increase the number of channels in the system.

[0008] For example, the wavelength division multiplexer is implemented by a multiplexer, and the multiplexer is implemented by an integrated optical phased array.

[0009] For example, the system further includes:

[0010] A cylindrical lens is used to shape the outgoing beam after it has been demultiplexed by the demultiplexer.

[0011] For example, the system further includes:

[0012] Single-photon detector;

[0013] The single-photon detector consists of a custom aperture, a mounting sleeve, and a photomultiplier tube. The custom aperture is mounted to the front end of the photomultiplier tube via the mounting sleeve.

[0014] The customized aperture controls the intensity of the signal light passing through the photomultiplier tube by adjusting the size of the aperture.

[0015] To achieve the above objectives, this application provides a wavelength division multiplexing visible light communication method, which is applied to the system described in any of the preceding claims, and the method includes:

[0016] By combining and modulating input light of different wavelengths, channels with different wavelength intervals can be obtained;

[0017] The narrow wavelength spacing channels of the wavelength division multiplexer will be demultiplexed to increase the number of channels in the system;

[0018] Visible light communication using wavelength division multiplexing is based on the system with increased channel number.

[0019] For example, the steps of performing wavelength division multiplexing in visible light communication include:

[0020] After detection by the optical receiver, a simplified, low-complexity third-order Volterra equalizer is used to compensate for inter-symbol interference and nonlinearity. The simplified Volterra model includes first-order, second-order, and diagonal third-order terms.

[0021] For example, before the step of using a simplified, low-complexity third-order Volterra equalizer to compensate for inter-symbol interference and nonlinearity, the method further includes:

[0022] Based on the different data rates in on-off keying modulation and orthogonal frequency division multiplexing modulation, the storage lengths of the first-order kernel, second-order kernel, and third-order kernel of the Volterra equalizer are optimized.

[0023] For example, the step of performing wavelength division multiplexing in visible light communication further includes:

[0024] Based on the signal-to-noise ratio distribution of subcarriers, orthogonal cyclic matrix transformation precoding is used to optimize the bit error rate.

[0025] This application also provides a wavelength division multiplexing (WDM) visible light communication device, the WDM visible light communication device comprising:

[0026] The combination modulation module is used to combine and modulate input light of different wavelengths to obtain channels with different wavelength intervals;

[0027] A demultiplexing module is used to demultiplex the narrow wavelength spacing channels of the wavelength division multiplexer to increase the number of channels in the system;

[0028] An application communication module is used for wavelength division multiplexing visible light communication based on the system with an increased number of channels.

[0029] This application also provides a blue-green light wavelength division multiplexing device, the blue-green light wavelength division multiplexing device comprising: a multi-wavelength laser, a wavelength division multiplexer and a demultiplexer as described in any of the preceding claims, a memory, a processor and a computer program stored in the memory and executable on the processor, the computer program being configured to implement the steps of the wavelength division multiplexing visible light communication method as described in any of the preceding claims.

[0030] This application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the wavelength division multiplexing visible light communication method as described in any of the preceding claims.

[0031] This application discloses a blue-green light wavelength division multiplexing (WDM) system, a WDM visible light communication method, a blue-green light WDM device, and a computer-readable storage medium. It also includes a multi-wavelength laser for generating input light of different wavelengths; a WDM multiplexer for combining and modulating the input light to obtain channels with different wavelength intervals; and a demultiplexer for demultiplexing the narrow wavelength interval channels of the WDM multiplexer to increase the number of channels in the system.

[0032] This application provides a blue-green wavelength division multiplexing (WDM) optical communication system and its implementation method based on a multiplexer / demultiplexer. It utilizes blue-green wavelength division multiplexing technology to improve system capacity and achieve a high-bandwidth and moderately attenuated wireless optical communication system. Wavelength division multiplexing visible light communication is achieved through a multiplexer / demultiplexer with fine wavelength spacing for visible light. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the operating device of the hardware operating environment involved in the embodiments of this application;

[0034] Figure 2 A schematic diagram of an underwater communication system for data transmission between an underwater vehicle and a base station;

[0035] Figure 3 This is a system schematic diagram of an embodiment of the blue-green wavelength division multiplexing system involved in the embodiments of this application;

[0036] Figure 4 This is a schematic diagram of a 4-wavelength laser in an embodiment of the blue-green light wavelength division multiplexing system involved in the present application;

[0037] Figure 5 This is a schematic diagram of a scenario of an embodiment of the blue-green wavelength division multiplexing system involved in the embodiments of this application;

[0038] Figure 6a This is a schematic diagram of the spectrum and normalized frequency response of four LD laser diodes in an embodiment of a blue-green wavelength division multiplexing system according to the present application.

[0039] Figure 6b This is a second schematic diagram showing the spectrum and normalized frequency response of four LD laser diodes in an embodiment of the blue-green light wavelength division multiplexing system involved in this application.

[0040] Figure 7 This is a schematic diagram of a single-photon detector of an embodiment of the blue-green wavelength division multiplexing system involved in the present application;

[0041] Figure 8 This is a flowchart illustrating an embodiment of the wavelength division multiplexing visible light communication method involved in the embodiments of this application;

[0042] Figure 9a This is a schematic diagram of the bit error rate (BER) of four wavelengths under OOK modulation in one embodiment of the wavelength division multiplexing visible light communication method involved in the present application.

[0043] Figure 9b This is a second schematic diagram showing the bit error rate (BER) of four wavelengths under OOK modulation in one embodiment of the wavelength division multiplexing visible light communication method involved in the present application.

[0044] Figure 10a This is a schematic diagram illustrating the relationship between the bit error rate (BER) and data rate of an embodiment of the wavelength division multiplexing visible light communication method involved in this application: 8QAM-OFDM orthogonal frequency division multiplexing modulation.

[0045] Figure 10b This is a schematic diagram illustrating the distribution of subcarrier SNR at 1GSa / s in a 506nm wavelength channel using conventional OFDM orthogonal frequency division multiplexing and OCT precoding in an embodiment of the wavelength division multiplexing visible light communication method involved in this application.

[0046] Figure 11 This is a schematic diagram of a wavelength division multiplexing visible light communication device involved in the embodiments of this application.

[0047] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0048] It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0049] Reference Figure 1 , Figure 1 This is a schematic diagram of the operating device structure of the hardware operating environment involved in the embodiments of this application.

[0050] like Figure 1 As shown, the operating device may include: a processor 1001, such as a central processing unit (CPU), a communication bus 1002, a user interface 1003, a network interface 1004, and a memory 1005. The communication bus 1002 is used to enable communication between these components. The user interface 1003 may include a display screen or an input unit such as a keyboard; optionally, the user interface 1003 may also include a standard wired interface or a wireless interface. The network interface 1004 may optionally include a standard wired interface or a wireless interface (such as a Wi-Fi interface). The memory 1005 may be a high-speed random access memory (RAM) or a stable non-volatile memory (NVM), such as a disk drive. The memory 1005 may also optionally be a storage device independent of the aforementioned processor 1001.

[0051] Those skilled in the art will understand that Figure 1 The structure shown does not constitute a limitation on the operating equipment and may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0052] like Figure 1 As shown, the memory 1005, which serves as a storage medium, may include an operating system, a data storage module, a network communication module, a user interface module, and computer programs.

[0053] exist Figure 1 In the illustrated operating device, the network interface 1004 is mainly used for data communication with other devices; the user interface 1003 is mainly used for data interaction with the user; the processor 1001 and memory 1005 in the operating device of this application can be disposed in the operating device, and the operating device calls the computer program stored in the memory 1005 through the processor 1001 and performs the following operations:

[0054] By combining and modulating input light of different wavelengths, channels with different wavelength intervals can be obtained;

[0055] The narrow wavelength spacing channels of the wavelength division multiplexer will be demultiplexed to increase the number of channels in the system;

[0056] Visible light communication using wavelength division multiplexing is based on the system with increased channel number.

[0057] In one embodiment, the processor 1001 may invoke a computer program stored in the memory 1005 and further perform the following operations:

[0058] The steps for performing wavelength division multiplexing in visible light communication include:

[0059] After detection by the optical receiver, a simplified, low-complexity third-order Volterra equalizer is used to compensate for inter-symbol interference and nonlinearity. The simplified Volterra model includes first-order, second-order, and diagonal third-order terms.

[0060] In one embodiment, the processor 1001 may invoke a computer program stored in the memory 1005 and further perform the following operations:

[0061] Before the step of using a simplified, low-complexity third-order Volterra equalizer to compensate for inter-symbol interference and nonlinearity, the following steps are also included:

[0062] Based on the different data rates in on-off keying modulation and orthogonal frequency division multiplexing modulation, the storage lengths of the first-order kernel, second-order kernel, and third-order kernel of the Volterra equalizer are optimized.

[0063] In one embodiment, the processor 1001 may invoke a computer program stored in the memory 1005 and further perform the following operations:

[0064] The steps for performing wavelength division multiplexing in visible light communication further include:

[0065] Based on the signal-to-noise ratio distribution of subcarriers, orthogonal cyclic matrix transformation precoding is used to optimize the bit error rate.

[0066] Reference Figure 2 In underwater communication systems that transmit data between underwater vehicles and base stations, wavelength division multiplexing (WDM) has been widely used in fiber optic communication systems to greatly improve system capacity. WDM has also been applied to FSO (Free Space Optical Communications) systems and VLC (Visible Light Communication) systems.

[0067] Free-space optical communication (FSO) typically uses mature infrared light as the optical carrier in WDM (Wavelength Division Multiplexing) systems. Due to the lack of multiplexers / demultiplexers with fine wavelength spacing for visible light, current WDM-VLC visible light communication systems usually use red, green, and blue wavelengths with wide channel spacing, thus limiting the available wavelength channels. Integrated optical phased arrays based on nanograting structures can deflect different wavelengths at different angles, allowing integrated OPAs (Optical Phased Arrays) to be used for wavelength demultiplexing. Because OPAs can demultiplex channels with narrower wavelength spacing, they can significantly increase the number of channels in blue-green light WDM systems.

[0068] Reference Figure 3 In one embodiment of a blue-green wavelength division multiplexing (WDM) system, the blue-green WDM system includes:

[0069] A multi-wavelength laser, wherein the multi-wavelength laser is used to generate input light of different wavelengths;

[0070] In one embodiment, input light from four fiber-mounted laser diodes (LDs) with wavelengths of 492 nm, 506 nm, 518 nm, and 522 nm is combined via a 1×4 coupler. An RF (Radio Frequency) signal is generated by a waveform generator. A DC bias is superimposed on the RF signal through a bias tee, and this superimposed DC and RF signal modulates the LDs. The signal amplitude and bias voltage are optimized for the bit error rate (BER), i.e., the amplitudes of the DC and RF signals are optimized to reduce the BER.

[0071] Reference Figure 4 In one embodiment of the multi-wavelength laser, 200 is a green laser with wavelengths of 492nm, 506nm, 518nm, and 522nm. 201 is a heat sink, which can be made of a metal with good thermal conductivity, such as copper. The laser 200 is fixed to the heat sink 201. 204 is a circuit board used for power supply to the laser 200. 202 is a pressure plate, which can be made of a material with good rigidity and strength. 203 is a base, which can be made of a metal with good thermal conductivity. The pressure plate 202 firmly presses the heat sink 201 onto the base 203, and the base 203 is fixed and tightly attached to the heat sink. This structural design allows the heat from the laser 200 to be quickly conducted to the heat sink, and the heat from the heat sink can be quickly conducted to the surrounding environment, enabling the laser 200 to dissipate heat rapidly and ensuring that the laser 200 remains within its ideal operating temperature range.

[0072] A wavelength division multiplexer, wherein the wavelength division multiplexer is used to combine and modulate the input light to obtain channels with different wavelength intervals;

[0073] In one embodiment, the wavelength division multiplexer is implemented by a multiplexer, and the multiplexer demultiplexer is implemented by an integrated optical phased array. Each channel is modulated separately and combined by the multiplexer. (Refer to...) Figure 5 The OPA multiplexer is located on the base station, and the photon detector is located on the underwater vehicle.

[0074] A demultiplexer is used to demultiplex narrow wavelength-spaced channels of the wavelength division multiplexer to increase the number of channels in the system.

[0075] In one embodiment, a nanograting array integrating an OPA optical phased array deflects signals of different wavelengths at different angles.

[0076] In this embodiment, the blue-green wavelength division multiplexing (WDM) system includes: a multi-wavelength laser for generating input light of different wavelengths; a wavelength division multiplexer for combining and modulating the input light to obtain channels with different wavelength intervals; and a demultiplexer for demultiplexing the narrow wavelength interval channels of the WDM to increase the number of channels in the system. This embodiment provides a blue-green WDM optical communication system and implementation method based on a demultiplexer. The blue-green wireless beam can pass through an underwater channel before entering a single-photon detector for underwater wireless optical communication. Blue-green wavelength division multiplexing technology is used to improve system capacity, achieving a high-bandwidth and moderately attenuated wireless optical communication system. Wavelength division multiplexing visible light communication is achieved through a multiplexer / demultiplexer with fine wavelength intervals for visible light.

[0077] In another embodiment of the blue-green wavelength division multiplexing system of this application, the system further includes:

[0078] A cylindrical lens is used to shape the outgoing beam after it has been demultiplexed by the demultiplexer.

[0079] In WDM (Wavelength Division Multiplexing) transmission, narrower wavelength spacing can increase the number of channels, at the cost of deteriorating channel crosstalk. Therefore, when OPA (Optical Phased Array) is used for demultiplexing, the wavelength spacing needs to be optimized. Too small a spacing can easily cause channel crosstalk, while too large a spacing will reduce the number of channels. At the same time, beam shaping and aperture stops are used to define the receiving spot.

[0080] In one embodiment, after the four combined wavelengths are demultiplexed by the OPA optical phased array, a cylindrical lens with a focal length of 15 cm is used to shape the outgoing beam. Then, a transimpedance amplifier converts the photocurrent into a voltage and amplifies the received signal. Finally, the signal is captured by an oscilloscope for further offline processing. The beam spot before and after shaping is shown below. Figure 6a and Figure 6b As shown in the illustration.

[0081] In another embodiment of the blue-green wavelength division multiplexing system of this application, the system further includes:

[0082] Single-photon detector;

[0083] The single-photon detector consists of a custom aperture, a mounting sleeve, and a photomultiplier tube. The custom aperture is mounted to the front end of the photomultiplier tube via the mounting sleeve.

[0084] The customized aperture controls the intensity of the signal light passing through the photomultiplier tube by adjusting the size of the aperture.

[0085] Reference Figure 7 In one embodiment, the single-photon detector consists of a custom aperture 100, a mounting sleeve 101, and a photomultiplier tube 102. The custom aperture 100 is mounted on the front end of the photomultiplier tube 102 through the mounting sleeve 101. The custom aperture 100 controls the intensity of the signal light passing through the photomultiplier tube 102 by adjusting the size of the aperture.

[0086] In an application example of the wavelength division multiplexing (WDM) visible light communication method of this application, an OPA optical phased array with splittable narrow-channel blue-green wavelength spacing (as small as 4 nm) was used to realize a blue-green light WDM wavelength division multiplexing-VLC visible light communication system to improve system capacity. Its channel spacing is as small as 4 nm, and an advanced DSP (Digital Signal Processing) scheme is employed to achieve capacity enhancement. By using simplified third-order Volterra equalization and OCT precoding, a BER of 2.0 × 10⁻⁶ is achieved. -2 At the same time, the data rate can be increased from 3 Gbit / s to 4.5 Gbit / s, showing a 50% capacity enhancement and verifying the potential of OPA optical phased array in future high-capacity WDM wavelength division multiplexing-UOWC.

[0087] Reference Figure 8 In one embodiment of the wavelength division multiplexing visible light communication method, the method is applied to the system as described in any of the preceding claims, the method comprising:

[0088] Step S10: Combine and modulate input light of different wavelengths to obtain channels with different wavelength intervals.

[0089] In one embodiment, input light from four fiber-mounted laser diodes (LDs) with wavelengths of 492 nm, 506 nm, 518 nm, and 522 nm is combined via a 1×4 coupler. An RF (Radio Frequency) signal is generated by a waveform generator. A DC bias is superimposed on the RF signal through a bias tee, and this superimposed DC and RF signal modulates the LD laser diodes. The signal amplitude and bias voltage are optimized for the BER (Bit Error Rate), i.e., the amplitudes of the DC and RF signals are optimized to reduce the BER.

[0090] Step S20 involves demultiplexing the narrow wavelength spacing channels of the wavelength division multiplexer to increase the number of channels in the system.

[0091] In one embodiment, a nanograting array integrating an OPA optical phased array deflects signals of different wavelengths at different angles. The deflection angle is characterized by sinθ = n eff -λ / Λ, where n eff λ is the effective refractive index of the guided mode, λ is the wavelength of light, Λ is the grating period, and θ is the angle between the output beam and the direction perpendicular to the chip.

[0092] After isolating the light spot by a value d in free space, the position of the light spot relative to the center point can be determined by the formula:

[0093] l=d×tanθ=d×tan(arcsin(n eff -λ / Λ))

[0094] The calculation is performed. Then the spacing between two adjacent wavelength channels can be derived. Here, l is the spatial distance spacing. The above formula is used to derive the distance spacing l from the wavelength spacing and is used for demultiplexing.

[0095] Step S30: Perform wavelength division multiplexing visible light communication based on the system after increasing the number of channels.

[0096] In one embodiment, underwater communication is achieved using enhanced blue-green wavelength division multiplexing light based on an integrated optical phased array.

[0097] This embodiment provides a wavelength division multiplexing (WDM) visible light communication method. It combines and modulates input light of different wavelengths to obtain channels with different wavelength intervals. The narrow wavelength interval channels of the WDM multiplexer are demultiplexed to increase the number of channels in the system. Based on the system with the increased number of channels, WDM visible light communication is performed. This embodiment also provides a blue-green WDM optical communication system and implementation method based on a multiplexer / demultiplexer. Blue-green wireless beams can pass through an underwater channel before entering a single-photon detector for underwater wireless optical communication. Blue-green wavelength division multiplexing technology is used to improve system capacity, achieving a high-bandwidth and moderately attenuated wireless optical communication system. WDM visible light communication is achieved through a multiplexer / demultiplexer with fine wavelength intervals for visible light.

[0098] In another embodiment of the wavelength division multiplexing visible light communication method of this application, the step of performing wavelength division multiplexing visible light communication includes:

[0099] After detection by the optical receiver, a simplified, low-complexity third-order Volterra equalizer is used to compensate for inter-symbol interference and nonlinearity. The simplified Volterra model includes first-order, second-order, and diagonal third-order terms.

[0100] Among them, the optical receiver can refer to Figure 3 Single-photon detectors in Figure 4 The photon detector in the middle.

[0101] After detection by the optical receiver, a low-complexity third-order Volterra equalizer can be used to compensate for ISI (Inter-Symbol Interference) and nonlinearity [8]. The simplified Volterra model includes only first-order, second-order, and diagonal third-order terms, and is expressed as:

[0102]

[0103] in, x and x(n) are the equalizer output and received signals at time n, respectively, and w k (·) are the coefficients of the k-th order kernel, M k This is the storage length of the k-th order kernel. Data is recovered after equalization, and the BER (Bit Error Rate) for each channel is derived.

[0104] For example, before the step of using a simplified, low-complexity third-order Volterra equalizer to compensate for inter-symbol interference and nonlinearity, the method further includes:

[0105] Based on the different data rates in on-off keying modulation and orthogonal frequency division multiplexing modulation, the storage lengths of the first-order kernel, second-order kernel, and third-order kernel of the Volterra equalizer are optimized.

[0106] In one embodiment, during the BER (Bit Error Rate) measurement of the channel, the channel and its adjacent channels with narrow wavelength spacing are loaded with different modulated signals at the same sampling rate. The remaining two wavelength channels are in CW (Concurrent Wavelength) mode. The remaining channels are turned on and off to study crosstalk in specific channels, and negligible BER variations are observed. The optical powers received at the 492nm, 506nm, 518nm, and 522nm spots are 140nW, 712nW, 316nW, and 239nW, respectively. Optical losses are mainly due to insertion losses on the WDM (Wavelength Division Multiplexing) coupler and OPA (Optical Phased Array) plate. One hundred data packets were collected for data analysis at different data rates and modulation formats. Each data packet contains 16,383 symbols modulated using On-Off Keying (OOK) or 32,640 symbols modulated using DC-biased Orthogonal Frequency Division Multiplexing (DCO-OFDM).

[0107] For different data rates in OOK (On-Off Keying) and OFDM (Orthogonal Frequency Division Multiplexing) modulation, the M1, M2, and M3 equalizers of Volterra were optimized. Specifically, M1, M2, and M3 were optimized separately for different communication rates to reduce the bit error rate (BER). 1000 symbols of OOK modulation and 2000 symbols of OFDM were used to estimate w. k The training symbol (·). The bit error rate (BER) of the four wavelengths under OOK modulation is as follows: Figure 9a and Figure 9b The figures show the situation before and after equilibrium, respectively.

[0108] By applying Volterra equalization, the bit error rate of OOK modulation is 2.0 × 10⁻⁶. -2At the (SD-FEC threshold), the data rate can be increased from 1.8 Gbit / s to 3.5 Gbit / s. The number of lasers and their wavelength spacing are limited by the available lasers, and system capacity can be enhanced by adding additional lasers. To further maximize system capacity, DCO-OFDM orthogonal frequency division multiplexing is used for the 506 nm LD laser diodes because it exhibits the highest output power and best BER performance under OOK modulation. IFFT (Inverse Fast Fourier Transform) is performed after S / P (series / parallel) conversion and 8QAM (Quadrature Amplitude Modulation) mapping. The CP (Cyclic Prefix) length occupies 1 / 8 of an OFDM orthogonal frequency division multiplexing symbol, and 255 of the 512 subcarriers have OFDM orthogonal frequency division multiplexing symbols.

[0109] In another embodiment of the wavelength division multiplexing visible light communication method of this application, the step of performing wavelength division multiplexing visible light communication further includes:

[0110] Based on the signal-to-noise ratio distribution of subcarriers, orthogonal cyclic matrix transformation precoding is used to optimize the bit error rate.

[0111] Because the SNR (Signal to Noise Ratio) distribution of subcarriers is non-uniform, Orthogonal Cyclic Matrix Transform (OCT) precoding is applied to optimize the BER (Bit Error Rate) performance. The 8QAM-mapped signal is multiplied by the orthogonal cyclic matrix, and the signal is recovered at the receiver by multiplying by the inverse OCT matrix. Figure 10a shows the relationship between the BER and data rate of 8QAM-OFDM orthogonal frequency division multiplexing modulation. Figure 10b The distribution of subcarrier SNR at 1 GSa / s in a 506 nm wavelength channel using conventional OFDM orthogonal frequency division multiplexing and OCT precoding. As expected, OCT precoding effectively averages the SNR distribution of subcarriers, thus outperforming conventional OFDM schemes. Combining Volterra equalization further improves performance. Overall, at BER = 2.0 × 10⁻⁶... -2 At that time, the data rate increased from 3 Gbit / s to 4.5 Gbit / s, achieving a 50% capacity enhancement.

[0112] Reference Figure 11 Furthermore, embodiments of this application also provide a wavelength division multiplexing (WDM) visible light communication device, the WDM visible light communication device comprising:

[0113] The combination modulation module M1 is used to combine and modulate input light of different wavelengths to obtain channels with different wavelength intervals;

[0114] Demultiplexing module M2 is used to demultiplex the narrow wavelength spacing channels of the wavelength division multiplexer to increase the number of channels in the system;

[0115] The application communication module M3 is used for wavelength division multiplexing visible light communication based on the system after the number of channels is increased.

[0116] For example, the application communication module is further configured to:

[0117] After detection by the optical receiver, a simplified, low-complexity third-order Volterra equalizer is used to compensate for inter-symbol interference and nonlinearity. The simplified Volterra model includes first-order, second-order, and diagonal third-order terms.

[0118] For example, the application communication module is further configured to:

[0119] Based on the different data rates in on-off keying modulation and orthogonal frequency division multiplexing modulation, the storage lengths of the first-order kernel, second-order kernel, and third-order kernel of the Volterra equalizer are optimized.

[0120] For example, the application communication module is further configured to:

[0121] Based on the signal-to-noise ratio distribution of subcarriers, orthogonal cyclic matrix transformation precoding is used to optimize the bit error rate.

[0122] The wavelength division multiplexing (WDM) visible light communication device provided in this application employs the WDM visible light communication method described in the above embodiments, solving the technical problem of difficulty in implementing WDM visible light communication in the prior art. Compared with the prior art, the beneficial effects of the WDM visible light communication device provided in this application are the same as those of the WDM visible light communication method provided in the above embodiments, and other technical features in this WDM visible light communication device are the same as those disclosed in the methods of the above embodiments, and will not be repeated here.

[0123] Furthermore, embodiments of this application also provide a blue-green light wavelength division multiplexing device, the blue-green light wavelength division multiplexing device comprising: a multi-wavelength laser, a wavelength division multiplexer and a demultiplexer as described in any of the preceding claims, a memory, a processor and a computer program stored in the memory and executable on the processor, the computer program being configured to implement the steps of the wavelength division multiplexing visible light communication method as described in any of the preceding claims.

[0124] Furthermore, embodiments of this application also provide a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the wavelength division multiplexing visible light communication method as described in any of the preceding claims.

[0125] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0126] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes several instructions to cause a terminal device (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of this application.

[0127] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A blue-green wavelength division multiplexing system, characterized by, The system includes: A multi-wavelength laser, wherein the multi-wavelength laser is used to generate input light of different wavelengths; A wavelength division multiplexer is used to combine and modulate the input light to obtain channels with different wavelength intervals; the wavelength division multiplexer is implemented by a multiplexer, and the multiplexer is implemented by an integrated optical phased array. A demultiplexer is used to demultiplex narrow-wavelength-spaced channels of the wavelength division multiplexer to increase the number of channels in the system; wherein, an integrated optical phased array of nanogratings deflects signals of different wavelengths at different angles, the deflection angle being characterized by... , It is the effective refractive index of the guided mode. It is the wavelength of light. It is the grating period. It is the angle between the output beam and the direction perpendicular to the chip; after being isolated in free space by d, the position of the light spot relative to the center point is given by the formula: To calculate; The system also includes: Single-photon detector; The single-photon detector consists of a custom aperture, a mounting sleeve, and a photomultiplier tube. The custom aperture is mounted to the front end of the photomultiplier tube via the mounting sleeve. The customized aperture controls the intensity of the signal light passing through the photomultiplier tube by adjusting the size of the aperture.

2. The blue-green wavelength division multiplexing system of claim 1, wherein, The system also includes: A cylindrical lens is used to shape the outgoing beam after it has been demultiplexed by the demultiplexer.

3. A wavelength division multiplexed visible light communication method, characterized by, The method is applied to the system as described in any one of claims 1 to 2, the method comprising: By combining and modulating input light of different wavelengths, channels with different wavelength intervals can be obtained; The narrow wavelength interval channels of the wavelength division multiplexer are demultiplexed to increase the number of channels in the system; wherein, the nanograting array of the integrated optical phased array deflects signals of different wavelengths at different angles, the deflection angle being characterized by... , It is the effective refractive index of the guided mode. It is the wavelength of light. It is the grating period. It is the angle between the output beam and the direction perpendicular to the chip; after being isolated in free space by d, the position of the light spot relative to the center point is given by the formula: To calculate; Visible light communication using wavelength division multiplexing is based on the system with increased channel number. 4.The WDM VLC method of claim 3, wherein, The steps for performing wavelength division multiplexing in visible light communication include: After detection by the optical receiver, a simplified, low-complexity third-order Volterra equalizer is used to compensate for inter-symbol interference and nonlinearity. The simplified Volterra model includes first-order, second-order, and diagonal third-order terms. 5.The WDM VLC method of claim 4, wherein, Before the step of using a simplified, low-complexity third-order Volterra equalizer to compensate for inter-symbol interference and nonlinearity, the following steps are also included: Based on the different data rates in on-off keying modulation and orthogonal frequency division multiplexing modulation, the storage lengths of the first-order kernel, second-order kernel, and third-order kernel of the Volterra equalizer are optimized. 6.The WDM VLC method of claim 3, wherein, The steps for performing wavelength division multiplexing in visible light communication further include: Based on the signal-to-noise ratio distribution of subcarriers, orthogonal cyclic matrix transformation precoding is used to optimize the bit error rate.

7. A blue-green wavelength division multiplexing apparatus, characterized by comprising: The blue-green light wavelength division multiplexing device includes: a multi-wavelength laser, a wavelength division multiplexer and a demultiplexer as described in any one of claims 1 to 2, a memory, a processor and a computer program stored in the memory and executable on the processor, the computer program being configured to implement the steps of the wavelength division multiplexing visible light communication method as described in any one of claims 3 to 6.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of the wavelength division multiplexing visible light communication method as described in any one of claims 3 to 6.

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