Indoor communication method and system based on Li-Fi and Wi-Fi isomerism

Abstract

The invention discloses an indoor communication method and system based on Li-Fi and Wi-Fi isomerism, and the method comprises the steps: carrying out the index modulation of signals generated by spatial modulators in a plurality of optical line terminal Li-Fi signal generation modules, obtaining a to-be-transmitted electric signal, carrying out the direct modulation laser modulation of the to-be-transmitted electric signal, and obtaining a Li-Fi optical signal; modulating the Li-Fi optical signal and the Wi-Fi signal to obtain a heterogeneous optical signal; synthesizing the heterogeneous optical signals corresponding to the plurality of optical line terminals to obtain a synthesized signal, and transmitting the synthesized signal to an optical network unit terminal through an optical fiber; and converting and recovering the synthesized signal at the optical network unit terminal to respectively obtain electric signals of different frequencies corresponding to the Li-Fi signal and the Wi-Fi signal. According to the invention, simple and low-power-consumption devices are adopted at an indoor air interface side, the complexity of digital signal processing of an optical network unit terminal and the complexity of a radio frequency front end are reduced, the energy consumption and the equipment cost of a system are reduced, and the transmission of Li-Fi and Wi-Fi mixed heterogeneous optical signals through an optical fiber network is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of Li-Fi communication, and particularly relates to an indoor communication method and system based on Li-Fi and Wi-Fi heterogeneity. Background Art

[0002] At present, to meet the diverse Internet of Things (IoT) terminal access and high-capacity data transmission requirements in indoor environments, the academic and industrial communities have proposed relevant technical solutions for constructing indoor heterogeneous networks (HetNets) by integrating Light Fidelity (Li-Fi) signals and Wireless Fidelity (Wi-Fi) signals.

[0003] In some solutions, Li-Fi and Wi-Fi are aggregated and coordinated, and load balancing means are used to improve the throughput of the Wi-Fi network and reduce latency; other work comprehensively considers competition and backoff mechanisms in small cell networks to reduce the average system delay.

[0004] Some other research uses Markov decision processes to implement vertical handover strategies in multi-mode networks to achieve a compromise between energy consumption and latency requirements; other research optimizes the user association strategy of hybrid Li-Fi / Wi-Fi networks through online learning algorithms to improve system throughput.

[0005] Some other work incorporates QoS metrics such as packet loss rate and latency into the load balancing strategy, and proposes a neural network method with adaptive target conditions to address the load imbalance problem in multi-user scenarios, better meeting quality requirements while improving network performance.

[0006] These solutions usually rely on implementing relatively complex signal processing and resource allocation strategies on the indoor air interface side (such as the access end or optical network unit terminal), including the processing of multi-mode signals, network handover decisions, and flexible resource allocation. This not only increases the complexity and energy consumption requirements of local indoor air interface side devices, but also raises the overall cost and maintenance difficulty of the system. Summary of the Invention

[0007] Existing indoor communication technology solutions increase the processing complexity of optical network processing terminals, driving up the energy consumption and overall cost of the system.

[0008] To address the above problems, a method and system for indoor communication based on Li-Fi and Wi-Fi heterogeneity are proposed. By setting a spatial modulator, a direct modulation laser, and a Mach-Zehnder modulator at the optical line terminal, index modulation, direct modulation laser modulation, and Mach-Zehnder modulation are performed on the generated signals to obtain heterogeneous optical signals, which are transmitted through optical fibers. Simple and low-power devices can be used on the indoor air interface side, reducing the complexity of local digital signal processing and radio frequency front-ends, and lowering the energy consumption and equipment costs of the system. The transmission of Li-Fi and Wi-Fi hybrid heterogeneous optical signals through the optical fiber network is achieved. The distributed architecture and passive optical splitter capabilities of the passive optical network system are fully utilized, thereby reducing the economic and maintenance burdens brought by the dense deployment of indoor cells.

[0009] In a first aspect, a method for indoor communication based on Li-Fi and Wi-Fi heterogeneity is provided, adopting the following technical solutions, including:

[0010] Step 100: At the optical line terminal, perform index modulation on the signals generated by the spatial modulator in multiple Li-Fi signal generation modules of the optical line terminal to obtain the electrical signals to be transmitted, and perform direct modulation laser modulation on the electrical signals to be transmitted to obtain Li-Fi optical signals;

[0011] Step 200: At the optical line terminal, obtain the Wi-Fi signals to be transmitted, and perform Mach-Zehnder modulation on the Li-Fi optical signals and the Wi-Fi signals to obtain heterogeneous optical signals of Li-Fi optical signals and Wi-Fi signals;

[0012] Step 300: Use a wavelength division multiplexer to synthesize the heterogeneous optical signals corresponding to multiple optical line terminals to obtain a synthesized signal, and transmit the synthesized signal to the optical network unit terminal through an optical fiber;

[0013] Step 400: At the optical network unit terminal, perform conversion and recovery on the synthesized signal to obtain electrical signals of different frequencies corresponding to Li-Fi signals and Wi-Fi signals respectively, and transmit the electrical signals to users through optical devices and wireless transmission devices respectively.

[0014] Combined with the method for indoor communication based on Li-Fi and Wi-Fi heterogeneity described in the first aspect of the present invention, in a first possible implementation manner, the step 100 includes:

[0015] Step 110: Obtain the signal bit stream generated by the spatial modulator in the Li-Fi signal generation module of the optical line terminal;

[0016] Step 120: Divide the signal bit stream into an index bit group and a data bit group;

[0017] Step 130: Perform carrier modulation on the index bit group and the data bit group to obtain the electrical signal to be transmitted.

[0018] Combined with the first possible implementation manner of the first aspect of the present invention, in the second possible implementation manner, step 100 further includes:

[0019] Step 140: Transmit the electrical signal to be transmitted to a directly modulated laser.

[0020] Step 150: The directly modulated laser converts the electrical signal to be transmitted to obtain a Li-Fi optical signal.

[0021] Combined with the second possible implementation manner of the first aspect of the present invention, in the third possible implementation manner, step 150 includes:

[0022] Step 151: The directly modulated laser generates a laser signal with a specified frequency according to the index bit group of the electrical signal to be transmitted.

[0023] Step 152: The directly modulated laser modulates the laser signal according to the data bit group so that the laser signal carries data information to obtain a Li-Fi optical signal.

[0024] Combined with the indoor communication method based on Li-Fi and Wi-Fi heterogeneity described in the first aspect of the present invention, in the fourth possible implementation manner, step 200 includes:

[0025] Step 210: Transmit the Li-Fi optical signal to a Mach-Zehnder modulator.

[0026] Step 220: Transmit the Wi-Fi signal to the Mach-Zehnder modulator through a radio frequency input port.

[0027] Step 230: The Mach-Zehnder modulator modulates the Wi-Fi signal onto the outer sideband of the Li-Fi optical signal through double-sideband modulation.

[0028] Combined with the indoor communication method based on Li-Fi and Wi-Fi heterogeneity described in the first aspect of the present invention, in the fifth possible implementation manner, step 400 includes:

[0029] Step 410: Set a wavelength division multiplexer at the front end of the optical network unit.

[0030] Step 420: Use the wavelength division multiplexer to separate the composite signal into multiple heterogeneous optical signals.

[0031] Combined with the fifth possible implementation manner of the first aspect of the present invention, in the sixth possible implementation manner, step 400 further includes:

[0032] Step 430: Set a photodetector at the output end of the wavelength division demultiplexer;

[0033] Step 440: Use the photodetector to convert the heterogeneous optical signal into an electrical signal of a corresponding frequency;

[0034] Step 450: Perform local oscillator recovery on the electrical signal to respectively obtain electrical signals of different frequencies corresponding to the Li-Fi signal and the Wi-Fi signal.

[0035] In a second aspect, an indoor communication system based on Li-Fi and Wi-Fi heterogeneity includes:

[0036] Optical line terminal;

[0037] Optical network unit terminal;

[0038] The optical network unit terminal is optically communication-connected to the optical line terminal;

[0039] The optical line terminal is used to perform index modulation on the signal generated by the spatial modulator in the Li-Fi signal generation modules of multiple optical line terminals to obtain a to-be-transmitted electrical signal, perform direct modulation laser modulation on the to-be-transmitted electrical signal to obtain a Li-Fi optical signal, acquire the to-be-transmitted Wi-Fi signal, and perform Mach-Zehnder modulation on the Li-Fi optical signal and the Wi-Fi signal to obtain a heterogeneous optical signal of the Li-Fi optical signal and the Wi-Fi signal;

[0040] The optical network unit terminal is used to synthesize the heterogeneous optical signals corresponding to multiple optical line terminals by using a wavelength division multiplexer to obtain a synthesized signal, transmit the synthesized signal to the optical network unit terminal through an optical fiber, perform conversion and recovery on the synthesized signal to respectively obtain electrical signals of different frequencies corresponding to the Li-Fi signal and the Wi-Fi signal, and transmit the electrical signals to users through an optical device and a wireless transmission device respectively.

[0041] In a first possible implementation manner in combination with the indoor communication system based on Li-Fi and Wi-Fi heterogeneity described in the second aspect of the present invention,

[0042] The optical line terminal includes a Li-Fi signal generation module, a Wi-Fi signal generation module, a direct modulation laser, and a wavelength division multiplexer. The Li-Fi signal generation module includes a spatial modulator, a tunable frequency generator, and a carrier modulator; the Wi-Fi signal generation module includes a Wi-Fi signal source and a Mach-Zehnder modulator;

[0043] The spatial modulator, the tunable frequency generator, and the carrier modulator are communicatively connected to each other for generating a to-be-transmitted electrical signal;

[0044] The directly tunable laser is used to generate a laser signal with a specified frequency according to the index bit group of the to-be-transmitted electrical signal, and modulate the laser signal according to the data bit group, so that the laser signal carries data information, obtain a Li-Fi optical signal and transmit the Li-Fi optical signal to a Mach-Zehnder modulator;

[0045] The Wi-Fi signal source is communicatively connected to the Mach-Zehnder modulator and is used to generate a Wi-Fi signal;

[0046] The Mach-Zehnder modulator is used to modulate the Wi-Fi signal onto the outer sideband of the Li-Fi optical signal through double-sideband modulation;

[0047] The wavelength division multiplexer is used to synthesize the heterogeneous optical signals corresponding to multiple optical line terminals to obtain a synthesized signal.

[0048] Combined with the indoor communication system based on Li-Fi and Wi-Fi heterogeneity described in the second aspect of the present invention, in the second possible implementation manner, the optical network unit terminal includes:

[0049] A wavelength demultiplexer;

[0050] A photodetector;

[0051] A local oscillator;

[0052] The wavelength demultiplexer, the photodetector, and the local oscillator are communicatively connected to each other;

[0053] The wavelength demultiplexer is used to separate the synthesized signal into multiple heterogeneous optical signals;

[0054] The photodetector is used to convert the heterogeneous optical signal into an electrical signal with a corresponding frequency;

[0055] The local oscillator is used to recover the electrical signal to respectively obtain electrical signals with different frequencies corresponding to the Li-Fi signal and the Wi-Fi signal.

[0056] Implementing a Li-Fi and Wi-Fi heterogeneous indoor communication method and system in the present invention. By setting a spatial modulator, a direct modulation laser, and a Mach-Zehnder modulator at the optical line terminal, index modulation, direct modulation laser modulation, and Mach-Zehnder modulation are performed on the generated signal to obtain a heterogeneous optical signal, which is transmitted through an optical fiber. Simple and low-power devices can be used on the indoor air interface side, reducing the complexity of local digital signal processing and radio frequency front-end, and lowering the energy consumption and equipment cost of the system. The transmission of Li-Fi and Wi-Fi hybrid heterogeneous optical signals through an optical fiber network is realized. The distributed architecture and passive optical splitting ability of the passive optical network system are fully utilized, thereby reducing the economic and maintenance burdens brought by the dense deployment of indoor cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] To more clearly illustrate the solutions in this application, the following will briefly introduce the drawings required for the description of the embodiments of this application. Obviously, the drawings in the following description are some embodiments of this application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0058] Figure 1 The structural diagram of an embodiment of a Li-Fi and Wi-Fi heterogeneous indoor communication system of this application;

[0059] Figure 2 The schematic diagram of the heterogeneous process of Li-Fi signals and Wi-Fi signals in this application;

[0060] Figure 3 The schematic diagram of Li-Fi signal communication in this application;

[0061] Figure 4 The flowchart of an embodiment of a Li-Fi and Wi-Fi heterogeneous indoor communication method of this application;

[0062] Figure 5 is Figure 1 The flowchart of a specific implementation manner of S100 in

[0063] Figure 6 is Figure 5 The flowchart of a specific implementation manner after S130 in

[0064] Figure 7 is Figure 6 The flowchart of a specific implementation manner of S150 in

[0065] Figure 8 is Figure 4 The flowchart of a specific implementation manner of S200 in

[0066] Figure 9 is Figure 4 A flowchart of a specific implementation of S400 in

[0067] Figure 10 is Figure 9 A flowchart of a specific implementation after S420 in Specific implementation

[0068] The technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments in the present invention, other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0069] Reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0070] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above drawings are intended to cover non-exclusive inclusion.

[0071] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of this application, "a plurality" means two or more unless otherwise specifically defined.

[0072] Term explanation

[0073] Li-Fi: Light Fidelity, optical fidelity technology;

[0074] Wi-Fi: Wireless Fidelity, wireless fidelity;

[0075] PON: Passive Optical Network, passive optical network;

[0076] OLT: Optical Line Terminal, Optical Line Terminal;

[0077] ONU: Optical Network Unit, Optical Network Unit Terminal;

[0078] MUX: Multiplexer, Wavelength Division Multiplexer;

[0079] DEMUX: Demultiplexer, Wavelength Division Demultiplexer;

[0080] PD: Photodiode, Photoelectric Detector;

[0081] SM: Spatial Modulation, Spatial Modulator;

[0082] MZM: Mach-Zehnder Modulator, Mach-Zehnder Modulator.

[0083] MUX: Multiplexer, Wavelength Division Multiplexer;

[0084] DEMUX: Demultiplexer, Wavelength Division Demultiplexer;

[0085] PD: Photodiode, Photoelectric Detector;

[0086] SM: Spatial Modulation, Spatial Modulator;

[0087] MZM: Mach-Zehnder Modulator, Mach-Zehnder Modulator.

[0088] In the existing indoor communication technology, the processing of multi-mode signals, network switching decisions, and resource allocation schemes increase the processing complexity of the optical network processing terminal, and drive up the system energy consumption and overall cost.

[0089] In view of the above problems, an indoor communication method and system based on the heterogeneity of Li-Fi and Wi-Fi are proposed.

[0090] In a first aspect, an indoor communication method based on the heterogeneity of Li-Fi and Wi-Fi is provided, and the following technical solutions are adopted, such as Figure 4 , Figure 4 is a flowchart of an embodiment of an indoor communication method based on the heterogeneity of Li-Fi and Wi-Fi in this application; including:

[0091] S100. At the optical line terminal, index modulation is performed on the signals generated by the spatial modulators in multiple optical line terminal Li-Fi signal generation modules to obtain the electrical signal to be transmitted. Direct modulation laser modulation is performed on the electrical signal to be transmitted to obtain the Li-Fi optical signal.

[0092] Such as Figure 1 , Figure 1 is a structural diagram of an embodiment of an indoor communication system based on Li-Fi and Wi-Fi heterogeneity in this application. The system includes: an optical line terminal OLT and an optical network unit terminal ONU. The optical line terminal OLT of each user includes a Li-Fi signal generation module, a Wi-Fi signal generation module, a directly modulated laser, and a wavelength division multiplexer (MUX). The Li-Fi signal generation module includes a spatial modulator (Li-Fi SM DSP Block), a tunable frequency generator, and a carrier modulator. The Wi-Fi signal generation module includes a Wi-Fi signal source and a Mach-Zehnder modulator (MZM). Among them, the Mach-Zehnder modulator is a device for inputting Wi-Fi signals. The optical network unit terminal ONU includes: a wavelength division demultiplexer (DEMUX), a photodetector (PD), and a local oscillator.

[0093] In the embodiment of this application, the spatial modulators and Wi-Fi signal sources of different users are adjusted and controlled through an adaptive controller. In this embodiment, in order to reduce the complexity and power consumption of the optical network unit terminal in the system, a spatial modulator and a directly modulated laser are set at the optical line terminal to obtain the Li-Fi optical signal.

[0094] In a preferred embodiment, such as Figure 5 , Figure 5 is Figure 1 a flowchart of a specific implementation manner of S100 in Figure 1 . S100 includes: S110. Obtain the signal bit stream generated by the spatial modulator in the Li-Fi signal generation module of the optical line terminal; S120. Divide the signal bit stream into an index bit group (Carrier Selection Bits) and a data bit group (Data Bits); S130. Perform carrier modulation on the index bit group (Carrier Selection Bits) and the data bit group (Data Bits) to obtain the electrical signal to be transmitted, such as Figure 1The CSB in it is the Carrier Selection Bits, which can also be called carrier selection bits.

[0095] In a preferred embodiment, such as Figure 6 , Figure 6 is Figure 5 a flowchart of a specific embodiment after S130 in in (t):

[0096]

[0097] In the formula, P Laser is the laser optical power, is the optical carrier angular frequency, represents the Li-Fi signal center angular frequency for driving the modulator, t is the signal transmission time, and e is the natural constant.

[0098] For each group of users, the wavelengths of the optical carriers of different users are different, which can be achieved by adjusting the center frequency of the tunable laser in the OLT.

[0099] In a preferred embodiment, such as Figure 7 , Figure 7 is Figure 6 a flowchart of a specific embodiment of S150 in

[0100] Such as Figure 3 , Figure 3 is a schematic diagram of Li-Fi signal communication in this application; in this embodiment, taking 4 LED (optical devices) as an example, at the optical line terminal, according to the Carrier Selection Bits, the data bits are loaded onto the carrier frequencies of the corresponding frequencies, and two frequency index bits are a Carrier Selection Bits group. Figure 3The index bit groups therein are from 00 to 11, representing transmission carrier frequencies f1 to f4 respectively. After transmission through the proposed Passive Optical Network (PON), the signals of the four frequencies are respectively subjected to index modulation transmission using four LEDs. At the same time, only one LED is communicating. At the receiving end (optical network unit terminal), the index bit group (Carrier Selection Bits) and data bit group (Data Bits) can be demodulated by using the maximum likelihood ratio according to the received signals and by using channel estimation technology, completing the communication of Li-Fi signals.

[0101] S200. At the optical line terminal, obtain the Wi-Fi signal to be transmitted, and perform Mach-Zehnder modulation on the Li-Fi optical signal and the Wi-Fi signal to obtain a heterogeneous optical signal of the Li-Fi optical signal and the Wi-Fi signal.

[0102] In a preferred embodiment, as Figure 8 , Figure 8 is Figure 4 a flowchart of a specific implementation manner of S200 in

[0103] In this embodiment, the Mach-Zehnder modulator first converts the input Wi-Fi signal into an optical signal, and through double-sideband modulation, modulates the Wi-Fi signal onto the outer sideband of the Li-Fi optical signal. Since the frequency of Li-Fi and the frequency corresponding to the Wi-Fi signal are in different frequency bands, the communication quality will not be affected by each other.

[0104] In this embodiment, in order to transmit multiple signals in the optical fiber, meet the communication and positioning requirements of different users, and achieve low-power multi-service transmission, a Mach-Zehnder modulator is set at the optical line terminal to perform Mach-Zehnder modulation (MZM) on the Wi-Fi signal and the Li-Fi optical signal, and fuse them together to obtain a heterogeneous signal

[0105]

[0106] (In equation (2), represents the central angular frequency of the Wi-Fi signal driving the modulator, V π is the half-wave voltage of the modulator, V dr is the amplitude of the Wi-Fi radio frequency signal, denotes the Bessel function of the first kind of order N. It can be seen from this formula that through direct laser modulation and MZM modulation, the Li-Fi / Wi-Fi signals are successfully modulated onto the same spectrum. is the angular frequency of the optical carrier. denotes the central angular frequency of the Li-Fi signal driving the modulator. t is the time of signal transmission, and E in (t) is the Li-Fi optical signal.

[0107] The heterogeneous fusion process of Li-Fi / Wi-Fi signals is as shown in Figure 2 , Figure 2 which is a schematic diagram of the heterogeneous process of Li-Fi signals and Wi-Fi signals in this application. Figure 2 It includes two groups of user optical line terminals. The signals in the dotted box are used for Li-Fi optical communication. The four carrier frequencies are f1 - f4 respectively. The outermost sideband signal from the spectrum is the Wi-Fi signal with a carrier frequency of f5. ③ is the Li-Fi / Wi-Fi heterogeneous signal that can be easily demultiplexed from the two groups of optical signals centered at λ1 and λ2 in by using a demultiplexer. In the subsequent optical network unit terminals, Li-Fi index modulation and Wi-Fi transmission are respectively performed.

[0108] Figure 2 In, ①, ④, ⑤, and ⑦ are respectively the Li-Fi optical signals converted from the two groups of users, ② and ⑥ are respectively the heterogeneous signals obtained through Mach-Zehnder modulation (MZM), and ③ is the demultiplexed Li-Fi / Wi-Fi heterogeneous signal.

[0109] S300. Use a wavelength division multiplexer to synthesize the heterogeneous optical signals corresponding to multiple optical line terminals to obtain a synthesized signal, and transmit the synthesized signal to the optical network unit terminal through an optical fiber.

[0110] S400. At the optical network unit terminal, convert and recover the synthesized signal to respectively obtain electrical signals of different frequencies corresponding to the Li-Fi signal and the Wi-Fi signal, and transmit the electrical signals to the users through an optical device and a wireless transmission device respectively.

[0111] In a preferred embodiment, as shown in Figure 9 , Figure 9 is Figure 4 a flowchart of a specific implementation manner of S400 in. S400 includes S410. Set a wavelength demultiplexer at the front end of the optical network unit terminal; S420. Use the wavelength demultiplexer to separate the synthesized signal into multiple heterogeneous optical signals.

[0112] In a preferred embodiment, as shown in Figure 10 , Figure 10 is Figure 9Flowchart of a specific implementation after S420. S400 further includes: S430, setting a photodetector at the output end of the wavelength division demultiplexer; S440, converting the heterogeneous optical signals into electrical signals of corresponding frequencies by using the photodetector; S450, performing local oscillator recovery on the electrical signals to respectively obtain electrical signals of different frequencies corresponding to the Li-Fi signal and the Wi-Fi signal.

[0113] In this embodiment, all the heterogeneous optical signals generated by users are combined into a single optical signal through a wavelength division multiplexer for transmission in the optical fiber. At the front end of the optical network unit terminal, the heterogeneous optical signals of two central frequencies are separated again through a wavelength division demultiplexer. The two separated optical signals pass through a photodetector in the optical network unit to complete the optoelectronic conversion. Then, the electrical signals are restored to the original signals through local oscillators of different frequencies, and then they are respectively transmitted through an LED and an antenna for Li-Fi and Wi-Fi communications. In the whole system, we use passive devices to implement a multi-service integrated PON system for low-power Li-Fi and Wi-Fi communications.

[0114] By setting a spatial modulator, a directly modulated laser, and a Mach-Zehnder modulator at the optical line terminal, performing index modulation, directly modulated laser modulation, and Mach-Zehnder modulation on the generated signals to obtain heterogeneous optical signals, and transmitting them through the optical fiber, simple and low-power devices can be used on the indoor air interface side, reducing the complexity of local digital signal processing and radio frequency front-end, and reducing the energy consumption and equipment cost of the system. The transmission of Li-Fi and Wi-Fi hybrid heterogeneous optical signals through the optical fiber network is realized. The distributed architecture and passive optical splitting ability of the passive optical network system are fully utilized, thereby reducing the economic and maintenance burdens brought by the dense deployment of indoor cells.

[0115] In a second aspect, an indoor communication system based on Li-Fi and Wi-Fi heterogeneity includes an optical line terminal and an optical network unit terminal; the optical network unit terminal is optically communicatively connected to the optical line terminal; the optical line terminal is used for performing index modulation on the signals generated by the spatial modulator in the Li-Fi signal generation module of multiple optical line terminals to obtain the electrical signals to be transmitted, performing directly modulated laser modulation on the electrical signals to be transmitted to obtain Li-Fi optical signals, obtaining the Wi-Fi signals to be transmitted, and performing Mach-Zehnder modulation on the Li-Fi optical signals and the Wi-Fi signals to obtain the heterogeneous optical signals of the Li-Fi optical signals and the Wi-Fi signals;

[0116] The optical network unit terminal is used to synthesize heterogeneous optical signals corresponding to multiple optical line terminals by using a wavelength division multiplexer to obtain a synthesized signal, transmit the synthesized signal to the optical network unit terminal through an optical fiber, convert and recover the synthesized signal to respectively obtain electrical signals with different frequencies corresponding to the Li-Fi signal and the Wi-Fi signal, and transmit the electrical signals to users through an optical device and a wireless transmitting device respectively.

[0117] Preferably, the optical line terminal includes a Li-Fi signal generation module, a Wi-Fi signal generation module, a directly modulated laser, and a wavelength division multiplexer. The Li-Fi signal generation module includes a spatial modulator, a tunable frequency generator, and a carrier modulator; the Wi-Fi signal generation module includes a Wi-Fi signal source and a Mach-Zehnder modulator;

[0118] The spatial modulator, the tunable frequency generator, and the carrier modulator are communicatively connected to each other for generating an electrical signal to be transmitted;

[0119] The directly modulated laser is used to generate a laser signal with a specified frequency according to the index bit group of the electrical signal to be transmitted, and modulate the laser signal according to the data bit group so that the laser signal carries data information, obtain a Li-Fi optical signal and transmit the Li-Fi optical signal to the Mach-Zehnder modulator;

[0120] The Wi-Fi signal source is communicatively connected to the Mach-Zehnder modulator for generating a Wi-Fi signal;

[0121] The Mach-Zehnder modulator is used to modulate the Wi-Fi signal onto the outer sideband of the Li-Fi optical signal through double-sideband modulation;

[0122] The wavelength division multiplexer is used to synthesize heterogeneous optical signals corresponding to multiple optical line terminals to obtain a synthesized signal.

[0123] Preferably, the optical network unit terminal includes a wavelength demultiplexer, a photodetector, and a local oscillator; the wavelength demultiplexer, the photodetector, and the local oscillator are communicatively connected to each other; the wavelength demultiplexer is used to separate the synthesized signal into multiple heterogeneous optical signals; the photodetector is used to convert the heterogeneous optical signal into an electrical signal with a corresponding frequency; the local oscillator is used to perform local oscillator recovery on the electrical signal to respectively obtain electrical signals with different frequencies corresponding to the Li-Fi signal and the Wi-Fi signal.

[0124] Implementing an indoor communication method and system based on Li-Fi and Wi-Fi heterogeneity in the present invention. By setting a spatial modulator, a direct modulation laser, and a Mach-Zehnder modulator at the optical line terminal, index modulation, direct modulation laser modulation, and Mach-Zehnder modulation are performed on the generated signal to obtain a heterogeneous optical signal, which is transmitted through an optical fiber. Simple and low-power devices can be used on the indoor air interface side, reducing the complexity of local digital signal processing and radio frequency front-end, and lowering the energy consumption and equipment cost of the system. The transmission of Li-Fi and Wi-Fi hybrid heterogeneous optical signals through an optical fiber network is realized. The distributed architecture and passive optical splitting ability of the passive optical network system are fully utilized, thereby reducing the economic and maintenance burdens brought by the dense deployment of indoor cells.

[0125] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A heterogeneous indoor communication method based on Li-Fi and Wi-Fi, comprising: Step 100: In an optical line terminal, index modulate the signals generated by the spatial modulators in the Li-Fi signal generating modules of the multiple optical line terminals to obtain electrical signals to be transmitted, and directly modulate the electrical signals to be transmitted by laser to obtain Li-Fi optical signals; Step 200: At the optical line terminal, obtain the Wi-Fi signal to be transmitted, perform Mach-Zehnder modulation on the Li-Fi optical signal and the Wi-Fi signal, and obtain heterogeneous optical signals of the Li-Fi optical signal and the Wi-Fi signal; Step 300: synthesize the heterogeneous optical signals corresponding to the plurality of optical line terminals using a wavelength division multiplexer to obtain a synthesized signal, and transmit the synthesized signal to an optical network unit terminal through an optical fiber; Step 400: Convert and restore the synthesized signal at the optical network unit terminal to obtain electrical signals of different frequencies corresponding to the Li-Fi signal and the Wi-Fi signal, respectively, and transmit the electrical signals to the user through optical equipment and wireless transmission equipment, respectively.

2. The indoor communication method based on heterogeneous Li-Fi and Wi-Fi according to claim 1, characterized in that: The step 100 comprises: Step 110: Obtain a signal bit stream generated by a spatial modulator in a Li-Fi signal generating module of the optical line terminal; Step 120, dividing the signal bit stream into an index bit group and a data bit group; Step 130: Carrier modulate the index bit group and the data bit group to obtain an electrical signal to be transmitted.

3. The indoor communication method based on heterogeneous Li-Fi and Wi-Fi according to claim 2, characterized in that: The step 100 further includes: Step 140, transmitting the electrical signal to be transmitted to the direct-modulated laser; Step 150: The directly modulated laser converts the electrical signal to be transmitted to obtain a Li-Fi optical signal.

4. The indoor communication method based on heterogeneous Li-Fi and Wi-Fi according to claim 3, characterized in that: The step 150 includes: Step 151, the directly modulated laser generates a laser signal of a specified frequency according to the index bit group of the electrical signal to be transmitted; Step 152: The directly modulated laser modulates the laser signal according to the data bit group so that the laser signal carries data information to obtain a Li-Fi optical signal.

5. The indoor communication method based on heterogeneous Li-Fi and Wi-Fi according to claim 1, characterized in that: The step 200 comprises: Step 210: transmitting the Li-Fi optical signal to a Mach-Zehnder modulator; Step 220: transmitting the Wi-Fi signal to the Mach-Zehnder modulator through a radio frequency input port; Step 230: The Mach-Zehnder modulator modulates the Wi-Fi signal onto an outer sideband of the Li-Fi optical signal through double-sideband modulation.

6. The indoor communication method based on heterogeneous Li-Fi and Wi-Fi according to claim 1, characterized in that: The step 400 includes: Step 410, setting a wavelength division multiplexer at the front end of the optical network unit; Step 420: Use a wavelength division multiplexer to separate the synthesized signal into a plurality of heterogeneous optical signals.

7. The indoor communication method based on heterogeneous Li-Fi and Wi-Fi according to claim 6, characterized in that: The step 400 further includes: Step 430, providing a photodetector at the output end of the WDM; Step 440: using the photodetector to convert the heterogeneous optical signal into an electrical signal of a corresponding frequency; Step 450: Perform local oscillation recovery on the electrical signal to obtain electrical signals of different frequencies corresponding to the Li-Fi signal and the Wi-Fi signal.

8. An indoor communication system based on heterogeneous Li-Fi and Wi-Fi, adopting the indoor communication method based on heterogeneous Li-Fi and Wi-Fi according to any one of claims 1 to 7, characterized in that: include: Optical Line Terminal; Optical Network Unit Terminal; The optical network unit terminal is connected to the optical line terminal through optical communication; The optical line terminal is used to index modulate the signals generated by the spatial modulators in the Li-Fi signal generating modules of the multiple optical line terminals to obtain the electrical signals to be transmitted, perform direct laser modulation on the electrical signals to be transmitted to obtain the Li-Fi optical signals, obtain the Wi-Fi signals to be transmitted, and perform Mach-Zehnder modulation on the Li-Fi optical signals and the Wi-Fi signals to obtain heterogeneous optical signals of the Li-Fi optical signals and the Wi-Fi signals; The optical network unit terminal is used to synthesize the heterogeneous optical signals corresponding to the multiple optical line terminals using a wavelength division multiplexer to obtain a synthesized signal, transmit the synthesized signal to the optical network unit terminal through an optical fiber, convert and restore the synthesized signal to obtain electrical signals of different frequencies corresponding to the Li-Fi signal and the Wi-Fi signal, respectively, and transmit the electrical signals to the user through optical equipment and wireless transmission equipment, respectively.

9. The indoor communication system based on heterogeneous Li-Fi and Wi-Fi according to claim 8, characterized in that: The optical line terminal includes a Li-Fi signal generating module, a Wi-Fi signal generating module, a directly modulated laser and a wavelength division multiplexer. The Li-Fi signal generating module includes a spatial modulator, an adjustable frequency generator and a carrier modulator; the Wi-Fi signal generating module includes a Wi-Fi signal source and a Mach-Zehnder modulator; The spatial modulator, the adjustable frequency generator, and the carrier modulator are communicatively connected to each other and are used to generate an electrical signal to be transmitted; The directly modulated laser is used to generate a laser signal of a specified frequency according to the index bit group of the electrical signal to be transmitted, and modulate the laser signal according to the data bit group so that the laser signal carries data information, obtains a Li-Fi optical signal, and transmits the Li-Fi optical signal to a Mach-Zehnder modulator; The Wi-Fi signal source is communicatively connected to the Mach-Zehnder modulator to generate a Wi-Fi signal; The Mach-Zehnder modulator is used to modulate the Wi-Fi signal onto an outer sideband of the Li-Fi optical signal by double-sideband modulation; The wavelength division multiplexer is used to synthesize heterogeneous optical signals corresponding to a plurality of optical line terminals to obtain a synthesized signal.

10. The indoor communication system based on heterogeneous Li-Fi and Wi-Fi according to claim 8, characterized in that: The optical network unit terminal comprises: Wavelength division multiplexer; Photodetectors; Local oscillator; The wavelength division multiplexer, the photoelectric detector and the local oscillator are communicatively connected with each other; The wavelength division multiplexer is used to separate the composite signal into multiple heterogeneous optical signals; The photodetector is used to convert the heterogeneous optical signal into an electrical signal of corresponding frequency; The local oscillator is used to recover the electrical signal to obtain electrical signals of different frequencies corresponding to the Li-Fi signal and the Wi-Fi signal.

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