Optical transmission system compatible with ROF and PON

Abstract

The invention provides an optical transmission system compatible with ROF and PON, which comprises an optical line terminal, an analog signal processing unit, an optical distribution network unit and a plurality of user terminals, and is characterized in that the optical line terminal is connected with the optical distribution network unit and is used for sending digital signals to the optical distribution network unit; the analog signal processing unit is connected with the optical distribution network unit and is used for receiving and processing the analog input signal and sending the processed analog signal to the optical distribution network unit; the optical distribution network unit is used for receiving and mixing the digital signal and the analog signal to obtain a mixed signal; before the mixed signals are transmitted to the user terminals, the digital signals and the analog signals are split according to a plurality of preset user channels and then transmitted to each user terminal. The system is simple in architecture, engineering construction and engineering maintenance are convenient, and the wireless coverage system can be rapidly deployed by using the existing optical fiber network at present.

Description

Technical Field

[0001] The present invention relates to the technical field of communication processing, and particularly to an optical transmission system compatible with ROF and PON. Background Art

[0002] Fiber access (FTTx) is widely used as a new generation of network access solution. Among them, PON (Passive Optical Network) is the most popular access method at present. PON is a network applied to the access network, in which an optical line terminal (OLT) and multiple user terminal devices are connected through a passive optical cable, optical splitter / combiner, etc. to form an optical distribution network (ODN).

[0003] Currently, the PON technologies used for broadband access are mainly EPON and GPON, which adopt different standards. Existing PON networks mainly transmit digital signals and require ADC and DAC conversions in the transmission system. With the increase in the form and capacity of network information requirements, the demand for transparent transmission of analog signals is becoming more and more urgent. Transmitting analog radio frequency signals in optical fibers, also known as Radio on Fiber (ROF), is a newly developed communication access technology that combines optical fiber communication and wireless communication. It transmits analog signals without going through ADC and DAC conversions, and transmits broadband signals. The frequency of the transmitted signal can range from dozens of MHz to dozens of GHz, which can be compatible with low frequencies such as television broadcasts, and can also transmit 5G millimeter waves or even 6G signals. It has very important applications especially in 5G and 6G communications, which can simplify the signal conversion process of the entire transmission system, reduce power consumption, and lower costs.

[0004] The cost of re-laying optical fibers to build an ROF network is extremely high. Therefore, there is an urgent need for a processing solution for an ROF network that can be compatible with existing PON access networks to reduce huge costs. Summary of the Invention

[0005] In view of this, the present invention provides an optical transmission system compatible with ROF and PON. One or more embodiments of this specification are simultaneously related to the optical transmission system compatible with ROF and PON to solve the technical defects existing in the prior art.

[0006] According to a first aspect of the present invention, there is provided an optical transmission system compatible with ROF and PON, including an optical line terminal, an analog signal processing unit, an optical distribution network unit, and multiple user terminals. Among them, The optical line terminal is connected to the optical distribution network unit and is used to send digital signals to the optical distribution network unit; The analog signal processing unit is connected to the optical distribution network unit, and is used to receive an analog input signal for processing and send the processed analog signal to the optical distribution network unit; The optical distribution network unit is respectively connected to the optical line terminal, the analog signal processing unit and multiple user terminals, and is used to receive and mix digital signals and analog signals to obtain a mixed signal; before transmitting the mixed signal to the user terminals, the digital signal and the analog signal are respectively split according to a plurality of preset user channels and then transmitted to each user terminal;

[0007] The optical distribution network unit includes a wavelength division multiplexer, a first-level splitter, a plurality of second-level digital signal splitters and at least one second-level analog signal splitter. The first-level splitter is respectively connected to the wavelength division multiplexer, the plurality of second-level digital signal splitters and at least one second-level analog signal splitter. Among them, The wavelength division multiplexer is used to receive and mix digital signals and analog signals to obtain a mixed signal and send the mixed signal to the first-level splitter; A wavelength division multiplexing module is arranged in the first-level splitter. The wavelength division multiplexing module is used to split the mixed signal to obtain a plurality of second-level digital signals and at least one second-level analog signal; the first-level splitter also sends the second-level digital signal and the second-level analog signal to the corresponding second-level digital signal splitter and second-level analog signal splitter according to the preset channels; The second-level digital signal splitter is used to split the received second-level digital signal into a plurality of user digital signals according to the user channels and send them to the corresponding user terminals; The second-level analog signal splitter is used to split the received second-level analog signal into a plurality of user analog signals according to the user channels and send them to the corresponding user terminals.

[0008] In some embodiments, the multiple user terminals include a plurality of digital signal terminals and a plurality of analog signal terminals. Among them, Each digital signal terminal receives the user digital signal of the corresponding channel; Each analog signal terminal receives the user analog signal of the corresponding channel.

[0009] In some embodiments, the wavelength of the analog signal processed by the analog signal processing unit in the upstream band is set to 1400 nm to 1420 nm; the wavelength of the analog signal processed by the analog signal processing unit in the downstream band is set to 1365 nm to 1380 nm.

[0010] In some embodiments, the upstream bands of each different analog signal terminal and analog signal router are set to different wavelengths.

[0011] According to a second aspect of the present invention, there is provided an optical transmission system compatible with ROF and PON, including an optical line terminal, an analog signal processing unit, an optical distribution network unit, and a plurality of user terminals, wherein, The optical line terminal is connected to the optical distribution network unit and is used for sending digital signals to the optical distribution network unit; The analog signal processing unit is connected to the optical distribution network unit and is used for receiving and processing analog input signals and sending the processed analog signals to the optical distribution network unit; The optical distribution network unit is respectively connected to the optical line terminal, the analog signal processing unit, and the plurality of user terminals and is used for receiving and mixing digital signals and analog signals to obtain a mixed signal; before transmitting the mixed signal to the user terminals, splitting the digital signal and the analog signal according to a plurality of preset user channels and then transmitting them to each user terminal; A wavelength division multiplexer is provided between the analog signal processing unit and the optical distribution network unit, and the optical distribution network unit is provided with a primary splitter and a plurality of secondary splitters. The primary splitter is respectively connected to the wavelength division multiplexer and the plurality of secondary splitters, wherein, The wavelength division multiplexer is used for receiving and mixing digital signals and analog signals to obtain a mixed signal and sending the mixed signal to the primary splitter; The primary splitter is used for splitting the mixed signal to obtain a plurality of secondary mixed signals and sending the secondary mixed signals to the corresponding secondary splitters according to preset channels; The secondary splitter is used for further splitting the received secondary mixed signal into a plurality of user signals according to the user channels and sending them to the corresponding user terminals.

[0012] In some embodiments, each of the user terminals is further provided with a terminal wavelength division multiplexer for splitting the received user signal into a terminal digital signal and a terminal analog signal.

[0013] In some embodiments, the terminal wavelength division multiplexer is provided with a common port that allows both digital signals and analog signals to pass through, a digital signal port that only allows digital signals to pass through, and an analog signal port that only allows analog signals to pass through.

[0014] In some embodiments, each of the user terminals is respectively provided with an analog signal router and a digital signal router for receiving the terminal analog signal and the terminal digital signal respectively.

[0015] In some embodiments, the analog signal router is provided with an optical connection port, an analog optical module, and a signal transceiver antenna, wherein, The optical connection port is connected to the terminal wavelength division multiplexer and receives the terminal analog signal sent by the terminal wavelength division multiplexer; The analog optical module stabilizes the wavelength of the analog signal by controlling the temperature; The signal transceiver antenna is used to receive / broadcast analog signals.

[0016] In some embodiments, the wavelength of the analog signal processed by the analog signal processing unit in the upstream band is set to 1400 nm to 1420 nm.

[0017] In some embodiments, the wavelength of the analog signal processed by the analog signal processing unit in the downstream band is set to 1365 nm to 1380 nm.

[0018] The present invention proposes a digital-analog hybrid ROF PON optical transmission system, which transmits ROF analog signals through the existing PON access network, enabling the existing access network to simultaneously transmit digital and analog signals. On the one hand, the system architecture in the present invention is simple, facilitating engineering construction and maintenance, and a wireless coverage system can be quickly deployed using the existing optical fiber network. The present invention can not only transmit WIFI, 4G, and 5G signals, but also transmit millimeter-wave 5G signals and future 6G signals, allowing for smooth transition and convenient upgrade of each communication system. On the other hand, the present invention adopts specific ROF upstream and downstream wavelengths, avoiding interference with the PON network. A multi-wavelength scheme is adopted at the upstream end to solve the laser interference problem of multiplexing multiple multi-mode radio frequency signals in the upstream optical combiner. On yet another hand, the present invention uses a mobile wavelength division multiplexing device for the upstream and downstream of ROF signals, which is convenient for installation, reduces the impact on the existing network during equipment installation, and can also be used in elevators, shopping malls, airports, and parking lots with weak existing network signals, as well as in families with diverse network requirements. Description of the Drawings

[0019] Figure 1 is a schematic diagram of the simple structure of an optical transmission system compatible with ROF and PON provided by some embodiments of this specification; Figure 2 is a schematic diagram of the simple structure of an optical transmission system compatible with ROF and PON provided by some other embodiments of this specification; Figure 3 is a schematic diagram of the simple structure of the terminal wavelength division multiplexer in an optical transmission system compatible with ROF and PON provided by some embodiments of this specification; Figure 4 is a schematic diagram of the simple structure of the analog signal router in an optical transmission system compatible with ROF and PON provided by some embodiments of this specification; Figure 5 is a schematic diagram of the common bands of EPON and 10AG EPON provided by some embodiments of this specification; Figure 6It is a schematic diagram of the common wavelength bands of GPON and 10AG GPON provided by some embodiments of this specification. Detailed implementation manners

[0020] In the following description, many specific details are set forth in order to provide a thorough understanding of this specification. However, this specification can be implemented in many other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the connotation of this specification. Therefore, this specification is not limited by the specific implementations disclosed below.

[0021] In this disclosure, unless otherwise clearly defined and limited, terms such as "installed", "connected", "coupled", "fixed", etc. shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection, an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the internal communication of two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in this disclosure can be understood according to specific circumstances.

[0022] In this disclosure, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature can be that the first feature is directly above or obliquely above the second feature, or simply indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "below" and "beneath" the second feature can be that the first feature is directly below or obliquely below the second feature, or simply indicates that the first feature has a lower horizontal height than the second feature.

[0023] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or there can also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are only for the purpose of illustration and do not represent the only implementation manners.

[0024] First, the noun terms related to one or more embodiments of this specification are explained.

[0025] IEEE: Institute of Electrical and Electronics Engineers; EFM: Ethernet in the First Mile

[0026] The PON access transmission system mainly consists of three parts: an optical line terminal, an optical distribution network unit, and a user terminal. The existing PON network construction has been very mature, but the cost of building a new fiber optic network is very high. This technical solution adds ROF radio frequency transmission to the existing PON access network.

[0027] See Figure 1 , Figure 1 shows a simplified schematic structural diagram of an optical transmission system compatible with ROF and PON according to some embodiments of the present application, showing a simplified single-channel transmission system (for example, the splitter in the figure is set to a simple 1×N mode). The optical transmission system includes an optical line terminal 1, an analog signal processing unit 7, an optical distribution network unit 2, and a plurality of user terminals 3. Among them, the optical line terminal 1 is connected to the optical distribution network unit 2 for sending digital signals to the optical distribution network unit 2. The analog signal processing unit 7 is connected to the optical distribution network unit 2 for receiving and processing analog input signals and sending the processed analog signals to the optical distribution network unit 2. The optical distribution network unit 2 is respectively connected to the optical line terminal 1, the analog signal processing unit 7, and a plurality of user terminals 3 for receiving and mixing digital signals and analog signals to obtain a mixed signal. Before transmitting the mixed signal to the user terminal, the digital signal and the analog signal are split according to a plurality of preset user channels and then transmitted to each user terminal 3. The analog input signal may refer to an analog signal emitted by a signal source or a relay device. For example, the analog input signal may be a signal emitted by a base station, or an analog signal emitted by a signal processing device such as a router or a wavelength division multiplexer. The mixed signal may refer to a signal obtained by mixing the digital signal and the analog signal of the optical fiber. The above-mentioned first-level / second-level splitter may be a splitter that divides into multiple paths, such as 8 paths, 16 paths, 32 paths, 64 paths, etc. Through the above settings, the existing PON access network and the ROF transmission network can be made compatible, and the existing fiber optic network can be used for rapid deployment of a wireless coverage system.

[0028] In some alternative embodiments, such as Figure 1As shown in the figure, the optical distribution network unit includes a wavelength division multiplexer 5, a first-level splitter 6, a plurality of second-level digital signal splitters 10A, and at least one second-level analog signal splitter 10B. The first-level splitter 6 is respectively connected to the wavelength division multiplexer 5, the plurality of second-level digital signal splitters 10A, and at least one second-level analog signal splitter 10B. Among them, the wavelength division multiplexer 5 is used to receive and mix digital signals and analog signals to obtain a mixed signal, and send the mixed signal to the first-level splitter 6; a wavelength division multiplexing module (not shown in the figure) is provided in the first-level splitter 6, and the wavelength division multiplexing module is used to split the mixed signal to obtain a plurality of second-level digital signals and at least one second-level analog signal; the first-level splitter 6 also sends the second-level digital signal and the second-level analog signal to the corresponding second-level digital signal splitter 10A and second-level analog signal splitter 10B respectively according to a preset channel, and the preset channel may refer to the channels corresponding to each second-level splitter set in advance. The second-level digital signal splitter 10A is used to split the received second-level digital signal into a plurality of user digital signals according to the user channel, and send them to the corresponding user terminal 3. The second-level analog signal splitter 10B is used to split the received second-level analog signal into a plurality of user analog signals according to the user channel, and send them to the corresponding user terminal 3.

[0029] In some optional implementation manners, the user side can be divided into terminals that only receive digital signals (optical fiber signals) and terminals that only receive analog signals. At this time, as Figure 1 shown, the user terminal 3 may include a plurality of digital signal terminals and a plurality of analog signal terminals. Each digital signal terminal receives the user digital signal (PON) of the corresponding channel; each analog signal terminal receives the user analog signal (ROF) of the corresponding channel. Among them, the analog signal receiving terminal may be an MRU (Multiple Resource Unit).

[0030] To further illustrate the present invention, the uplink and downlink during the operation of the foregoing system will be further explained through an embodiment as follows: As Figure 1 shown, when the foregoing system operates on the downlink: It accesses the optical distribution network unit 2 (for example, ODU: Optical Data Unit) through the wavelength division multiplexer 5 from the analog signal processing unit 7. The optical distribution network unit 2 has a PON channel and an ROF channel, and is distributed into the second-level splitter 10 through the optical splitter of the first-level splitter 6. The ROF signal after passing through the splitter is transmitted to the analog signal terminal 4 that receives the analog signal. In this transmission network, the optical distribution network unit 2 in the transmission network is shared with the user terminal 3 composed of array optical network units.

[0031] When the foregoing system runs on the uplink, the signal of the analog signal terminal 4 accesses the optical distribution network unit 2 through the first-level splitter 6 and the second-level splitter 10, and then enters the analog signal processing unit 7 through the wavelength division multiplexer 5. It also shares the optical distribution network unit 2 in the transmission network with the user terminal 3 composed of an array of optical network units.

[0032] Next, please refer to Figure 2 , which shows a simplified structural schematic diagram of an optical transmission system compatible with ROF and PON provided according to other embodiments of the present application, and shows another simplified single-path transmission system (similarly, the splitter in the figure is set to a simple 1×N mode). The optical transmission system includes an optical line terminal 1, an analog signal processing unit 7, an optical distribution network unit 2, and a plurality of user terminals 3. Different from the system in Figure 1 , a wavelength division multiplexer 5 is provided between the analog signal processing unit 7 and the optical distribution network unit 2, rather than setting the wavelength division multiplexer 5 in the optical distribution network unit 2. In some alternative implementation manners, the wavelength division multiplexer 5 can use a mobile wavelength division multiplexer (Wavelength Division Multiplexing, WDM) as shown in Figure 2 . The optical distribution network unit 2 is provided with a first-level splitter 6 and a plurality of second-level splitters 10. The first-level splitter 6 is respectively connected to the wavelength division multiplexer 5 and the plurality of second-level splitters 10. In addition, the first-level splitter 6 is also different from the setting in the system in Figure 1 . It does not set a wavelength division multiplexing module, but only splits the mixed signal to obtain a plurality of second-level mixed signals, and sends the second-level mixed signals to the corresponding second-level splitters 10 according to the preset channels. The second-level mixed signal can refer to the same mixed signal evenly split from the mixed signal, that is, the second-level mixed signal contains the same digital signal and analog signal. The second-level splitter 10 is used to further split the received second-level mixed signal into a plurality of user signals according to the user channels and send them to the corresponding user terminals 3. This kind of optical distribution network unit 2 has the same specifications as those commonly used in the prior art, that is, the system shown in Figure 2 does not need to make any modifications to the optical distribution network unit 2. Each of the user terminals 3 is further provided with a terminal wavelength division multiplexer 11 for splitting the received user signal into a terminal digital signal and a terminal analog signal. The system in the above invention can use the existing optical fiber network to quickly deploy a wireless coverage system without modifying the optical distribution network unit 2, thereby greatly reducing the laying cost and adding 5G or even 6G signals at a lower cost.

[0033] In some alternative implementation manners, each of the user terminals 3 is respectively provided with an analog signal router 9 and a digital signal router 8, which are respectively used to receive the terminal analog signal and the terminal digital signal.

[0034] In some alternative implementations, such as Figure 3 shown, the terminal wavelength division multiplexer 11 is provided with a common port 1101 that allows both digital signals and analog signals to pass through, a digital signal port 1102 that only allows digital signals to pass through, and an analog signal port 1103 that only allows analog signals to pass through. During the engineering implementation process, the common port 1101 can be connected to the original PON network, the digital signal port 1102 is connected to the existing digital signal router 8, and the analog signal port 1103 is connected to the new analog signal router 9. Without affecting the existing digital PON network, seamless connection can be achieved, and the operation is convenient.

[0035] Such as Figure 4 shown, in some alternative implementations, the analog signal router is provided with an analog optical module 901, a signal transceiver antenna 902, and an optical connection port 903. The analog optical module 901 controls the temperature to stabilize the wavelength of the analog signal. The signal transceiver antenna 902 is used to receive / broadcast analog signals. The optical connection port 903 is connected to the terminal wavelength division multiplexer 11 to receive the terminal analog signal sent by the terminal wavelength division multiplexer 11. Since the change in temperature during the operation of the signal will cause wavelength drift, affecting the stability and distance of signal transmission, the temperature can be controlled by setting the analog optical module 901 to ensure the stability of the analog signal.

[0036] In addition, the current PON technologies used for broadband access mainly include EPON (Ethernet Passive Optical Network) and GPON (Gigabit-Capable PON), which meet the IEEE / EFM standard for Ethernet packet data. Among them, the commonly used signal wavelength bands for each technology are as follows: For 10G GPON, the uplink uses a wavelength of 1260 - 1280 nm, and the downlink uses a wavelength of 1575 - 1580 nm; For GPON, the uplink uses a wavelength of 1290 - 1350 nm, and the downlink uses a wavelength of 1480 - 1500 nm; For 10G EPON, the uplink uses a wavelength of 1260 - 1280 nm, and the downlink uses a wavelength of 1575 - 1580 nm; For EPON, the uplink uses a wavelength of 1280 - 1360 nm, and the downlink uses a wavelength of 1480 - 1500 nm.

[0037] In addition, it is also necessary to consider the water vapor absorption wavelength (usually between 850 nm and 940 nm) and the influence of fiber dispersion in long-distance transmission (usually near 1550 nm). Therefore, considering the above influences, the uplink band of the wavelength for analog signal processing in this application is set to 1400 - 1420 nm, and the downlink band is set to 1365 - 1380 nm. Thus, as Figure 5 shown, in the above embodiments, the uplink band of the wavelength of the analog signal processed by the analog signal processing unit 9 is required to be set to 1400 nm to 1420 nm, and the downlink band is required to be set to 1365 nm to 1380 nm.

[0038] As Figure 1 shown in or 2, compared with the signal burst mode of digital signals, the power of analog signals is relatively large, and there is a problem of crosstalk of the same wavelength during the propagation of multiple signals, especially in the uplink. Therefore, in this case, wavelength management technology is introduced, and the uplink bands of each different analog signal terminal 4 are set to different wavelengths, and the uplink bands of each different analog signal processing unit 7 are set to different wavelengths.

[0039] In some optional implementation manners, the different wavelengths can be evenly divided according to the band. For example, the analog signal terminal 4 can adopt different wavelengths λ1, λ2... λn. The uplink wavelength range of 1400 - 1420 nm can accommodate 64 or even 128 multiple access users. Taking 128 channels as an example, the interval between channels is 0.156 nm. The specific implementation of the channel interval can be achieved through chip growth and temperature control.

[0040] The preferred embodiments of the present specification disclosed above are only used to help explain the present specification. The optional embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of the present invention. The present specification selects and specifically describes these embodiments to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and utilize the present specification well. The present specification is only limited by the claims and their full scope and equivalents.

Claims

1. An optical transmission system compatible with ROF and PON, characterized in that, It includes an optical line terminal, an analog signal processing unit, an optical distribution network unit, and multiple user terminals. Among them, The optical line terminal is connected to the optical distribution network unit and is used to send digital signals to the optical distribution network unit; The analog signal processing unit is connected to the optical distribution network unit and is used to receive and process analog input signals and send the processed analog signals to the optical distribution network unit; The optical distribution network unit is respectively connected to the optical line terminal, the analog signal processing unit, and multiple user terminals and is used to receive and mix digital signals and analog signals to obtain a mixed signal; before transmitting the mixed signal to the user terminals, it splits the digital signals and analog signals according to multiple preset user channels and then transmits them to each user terminal; The optical distribution network unit includes a wavelength division multiplexer, a first-stage splitter, multiple second-stage digital signal splitters, and at least one second-stage analog signal splitter. The first-stage splitter is respectively connected to the wavelength division multiplexer, multiple second-stage digital signal splitters, and at least one second-stage analog signal splitter. Among them, The wavelength division multiplexer is used to receive and mix digital signals and analog signals to obtain a mixed signal and send the mixed signal to the first-stage splitter; A wavelength division multiplexing module is provided in the first-stage splitter. The wavelength division multiplexing module is used to split the mixed signal to obtain multiple second-stage digital signals and at least one second-stage analog signal; the first-stage splitter also sends the second-stage digital signals and second-stage analog signals to the corresponding second-stage digital signal splitters and second-stage analog signal splitters according to the preset channels; The second-stage digital signal splitter is used to split the received second-stage digital signals into multiple user digital signals according to the user channels and send them to the corresponding user terminals; The second-stage analog signal splitter is used to split the received second-stage analog signals into multiple user analog signals according to the user channels and send them to the corresponding user terminals.

2. The system according to claim 1, wherein The multiple user terminals include multiple digital signal terminals and multiple analog signal terminals. Among them, Each digital signal terminal receives the user digital signals of the corresponding channel; Each analog signal terminal receives the user analog signals of the corresponding channel.

3. The system according to any one of claims 1 to 2, characterized in that The wavelength of the analog signal processed by the analog signal processing unit in the upstream band is set to 1400 nm to 1420 nm; the wavelength of the analog signal processed by the analog signal processing unit in the downstream band is set to 1365 nm to 1380 nm.

4. The system according to claim 2, wherein The upstream bands of each different analog signal terminal and analog signal router are set to different wavelengths.

5. An optical transmission system compatible with ROF and PON, characterized in that, It includes an optical line terminal, an analog signal processing unit, an optical distribution network unit, and multiple user terminals. Among them, The optical line terminal is connected to the optical distribution network unit and is used to send digital signals to the optical distribution network unit; The analog signal processing unit is connected to the optical distribution network unit and is used to receive and process analog input signals and send the processed analog signals to the optical distribution network unit; The optical distribution network unit is respectively connected to the optical line terminal, the analog signal processing unit and multiple user terminals, and is used to receive and mix digital signals and analog signals to obtain a mixed signal; before transmitting the mixed signal to the user terminals, the digital signal and the analog signal are respectively split according to a plurality of preset user channels and then transmitted to each user terminal; A wavelength division multiplexer is provided between the analog signal processing unit and the optical distribution network unit. The optical distribution network unit is provided with a primary splitter and a plurality of secondary splitters. The primary splitter is respectively connected to the wavelength division multiplexer and the plurality of secondary splitters. Among them, the wavelength division multiplexer is used to receive and mix digital signals and analog signals to obtain a mixed signal, and send the mixed signal to the primary splitter; the primary splitter is used to split the mixed signal to obtain a plurality of secondary mixed signals, and send the secondary mixed signals to the corresponding secondary splitters according to the preset channels; the secondary splitter is used to further split the received secondary mixed signal into a plurality of user signals according to the user channels, and send them to the corresponding user terminals.

6. The system according to claim 5, wherein Each of the user terminals is further provided with a terminal wavelength division multiplexer, which is used to split the received user signal into a terminal digital signal and a terminal analog signal.

7. The system according to claim 6, wherein Each of the user terminals is respectively provided with an analog signal router and a digital signal router, which are respectively used to receive the terminal analog signal and the terminal digital signal.

8. The system according to claim 7, wherein, The terminal wavelength division multiplexer is provided with a common port that allows both digital signals and analog signals to pass through, a digital signal port that only allows digital signals to pass through, and an analog signal port that only allows analog signals to pass through.

9. The system according to claim 8, characterized in that, The analog signal router is provided with an analog optical module, a signal transceiver antenna and an optical connection port. Among them, the analog optical module stabilizes the wavelength of the analog signal by controlling the temperature; the signal transceiver antenna is used to receive / broadcast analog signals; the optical connection port is connected to the terminal wavelength division multiplexer and receives the terminal analog signal sent by the terminal wavelength division multiplexer.

10. The system according to any one of claims 5 to 9, characterized in that, The wavelength of the analog signal processed by the analog signal processing unit is set to 1400 nm to 1420 nm in the upstream band; the wavelength of the analog signal processed by the analog signal processing unit is set to 1365 nm to 1380 nm in the downstream band.

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