Fiber-distributed wireless signal coverage system based on ROF technique

Abstract

The present invention belongs to the technical field of radio over fiber (ROF) and wireless signal coverage systems. Disclosed is a fiber-distributed wireless signal coverage system based on an ROF technique. The system comprises an intelligent signal access unit, which is used for adjusting the radio frequency signal size of a first wireless signal which is received from a radio frequency interface, then performing radio frequency amplification to obtain a first downlink electrical signal, combining the first downlink electrical signal, an OOK modulated signal and a first radio frequency signal and converting same into an uplink electrical signal, and outputting same to the first fiber interface, and is also used for converting an overall uplink laser signal, which is input from the first fiber interface, into an uplink electrical signal, performing radio frequency amplification and radio frequency signal size adjustment on the uplink electrical signal, and then outputting same from the radio frequency interface; a fiber splitter, which is used for evenly splitting a downlink laser signal, which is input by means of a first optical port, into a plurality of downlink laser sub-signals; and at least one multi-standard remote radio unit. The present invention is low in cost, high in speed, and low in power consumption.

Description

Optical fiber distributed wireless signal coverage system based on ROF technology Technical Field

[0001] The present invention belongs to the technical field of Radio Over Fiber (ROF) and wireless signal coverage systems, and mainly relates to the ROF optical transceiver part, optical passive part, wireless system part, software control part and software monitoring part, and specifically relates to an optical fiber distributed wireless signal coverage system based on ROF technology. Background Art

[0002] Wireless mobile communication technology is increasingly impacting our modern lives. From sending and receiving WeChat messages, short videos, Weibo posts, and TikTok videos, to online payments, map navigation while on the go, and watching HDTV and videos at home, smartphones and mobile networks have enabled us to enjoy a vibrant life. With the growth of mobile data traffic and the increasing number of tools and devices operating across multiple communication platforms using high-bandwidth mobile communication channels, the demand for the internet is changing. While people desire high-bandwidth wireless communications, they also want wireless network communications to support more users and cover wider areas. They crave coverage without signal dead spots, truly achieving ubiquitous high-speed wireless signal coverage. The increasing signal bandwidth and the growing number of device users pose significant challenges to the design, architecture, and operation of wireless signal coverage systems for future broadband wireless networks. Reducing the signal coverage area of ​​a single mobile network, building smaller coverage areas, and increasing wireless carrier frequency and signal strength are key approaches to increasing user access bandwidth and supporting more users.

[0003] Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the present invention provides a fiber optic distributed wireless signal coverage system based on ROF technology with low cost, high speed and low power consumption.

[0005] The technical solutions of the present invention are as follows:

[0006] An optical fiber distributed wireless signal coverage system based on ROF technology, comprising:

[0007] A signal access intelligent unit, comprising a radio frequency interface and a first optical fiber interface; the unit is configured to perform radio frequency signal level adjustment on a first wireless signal received from the radio frequency interface and then perform radio frequency amplification to obtain a first downlink electrical signal; the unit combines the first downlink electrical signal, the OOK modulated signal, and the first radio frequency signal to convert the signal into a downlink laser signal and output the signal to the first optical fiber interface; the unit is further configured to convert the total uplink laser signal input from the first optical fiber interface into an uplink electrical signal, and sequentially perform radio frequency amplification and radio frequency signal level adjustment on the uplink electrical signal before outputting the signal from the radio frequency interface;

[0008] An optical fiber splitter, comprising a first optical port and at least one second optical port, wherein the first optical port is connected to a first optical fiber interface via a first optical fiber; the optical fiber splitter is configured to evenly split a downlink laser signal input via the first optical port into a plurality of downlink laser sub-signals, the downlink laser sub-signals corresponding to the second optical ports in a one-to-one correspondence and outputted from the second optical port; and the optical fiber splitter is configured to combine uplink laser signals input via the second optical ports into a total uplink laser signal, which is outputted from the first optical port.

[0009] At least one multi-standard radio frequency signal extension unit, each of which includes a second optical fiber interface, and the second optical fiber interface is connected one-to-one with the second optical port of the optical fiber splitter through the second optical fiber; it is used to decompose the downlink laser signal and convert it into a second downlink electrical signal, and divide the second downlink electrical signal into a first signal, a second signal, and a third signal, and adjust the radio frequency signal size of the third signal in turn, and then amplify the radio frequency signal and transmit it out; it is also used to filter the received second wireless signal to obtain an uplink radio frequency signal, and perform low-noise amplification and radio frequency signal size adjustment on the uplink radio frequency signal in turn, and then combine it with the second radio frequency signal to convert it into an uplink laser signal, and transmit the uplink laser signal to the second optical fiber interface.

[0010] The signal access intelligent unit also includes:

[0011] a first RF switch / filter, whose input and output ports are electrically connected to the second port of the RF interface;

[0012] a first downlink ATT, whose input port is electrically connected to the output port of the first RF switch / filter;

[0013] a downstream amplifier, whose input port is electrically connected to the output port of the first downstream ATT;

[0014] a first signal coupler, a first input port of which is electrically connected to the output port of the downstream amplifier;

[0015] a large dynamic ROF optical transmitter, the input port of which is electrically connected to the output port of the first signal coupler;

[0016] an OOK modulator, an output port of which is electrically connected to the second input port of the first signal coupler;

[0017] a wavelength division multiplexer, wherein one input port is connected to the output port of the large dynamic ROF optical transmitter via a fourth optical fiber, and the input and output ports are connected to the first optical fiber interface via a fifth optical fiber;

[0018] a first ROF optical receiver, an input port of which is connected to an output port of the wavelength division multiplexer via a sixth optical fiber;

[0019] a second signal coupler, an input port of which is electrically connected to an output port of the first ROF optical receiver;

[0020] a first uplink amplifier, an input port of which is electrically connected to the first output port of the second signal coupler;

[0021] A first uplink ATT, whose input port is electrically connected to the output port of the first uplink amplifier, and whose output port is electrically connected to the input port of the first RF switch / filter;

[0022] a first communication module, whose input port is electrically connected to the second output port of the second signal coupler, and whose output port is electrically connected to the third input port of the first signal coupler;

[0023] The main monitoring unit has a data port connected to the data port of the first RF switch / filter, the data port of the first downstream ATT, the data port of the downstream amplifier, the data port of the large dynamic ROF optical transmitter, the data port of the OOK modulator, the data port of the first communication module, the data port of the first upstream ATT, the data port of the first upstream amplifier, and the data port of the first ROF optical receiver through a first data line.

[0024] The optical fiber splitter also includes:

[0025] 1XN optical splitter, whose input optical port serves as the first optical port of the optical fiber splitter;

[0026] At least one 1X8 optical splitter, whose input optical port is connected to the output optical port of the 1XN optical splitter in a one-to-one correspondence through a third optical fiber, and whose output optical port serves as the second optical port of the optical fiber splitter.

[0027] The multi-standard radio frequency signal remote unit further includes:

[0028] a wavelength division demultiplexer, wherein the input and output ports of the demultiplexer are connected to the second optical fiber interface via a tenth optical fiber;

[0029] a second ROF optical receiver, whose input port is connected to the output port of the de-wavelength division multiplexer via an eighth optical fiber;

[0030] a third signal coupler, an input port of which is electrically connected to the output port of the second ROF optical receiver;

[0031] a second downstream ATT, an input port of which is electrically connected to the first output port of the third signal coupler;

[0032] a downstream PA, an input port of which is electrically connected to an output port of a second downstream ATT;

[0033] a second RF switch / filter, an input port of which is electrically connected to an output port of the downlink PA;

[0034] a filter having a first port electrically connected to the input and output ports of the second RF switch / filter;

[0035] an antenna electrically connected to the second port of the filter;

[0036] an uplink LNA, an input port of which is electrically connected to an output port of the second RF switch / filter;

[0037] a second uplink ATT, an input port of which is electrically connected to the output port of the uplink LNA;

[0038] a fourth signal coupler, a first input port of which is electrically connected to the output port of the second uplink ATT;

[0039] a variable wavelength ROF optical transmitter, whose input port is electrically connected to the output port of the fourth signal coupler, and whose output port is connected to the input port of the demultiplexer via a ninth optical fiber;

[0040] An OOK demodulator, whose input port is electrically connected to the second output port of the third signal coupler, and whose data interface is connected to the second downstream ATT and the downstream PA via the third data line;

[0041] a second communication module, an input port of which is electrically connected to a third output port of the third signal coupler;

[0042] The data port of the slave monitoring unit is connected to the data port of the second ROF optical receiver, the data port of the second downstream ATT, the data port of the downstream PA, the data port of the OOK demodulator, the data port of the second communication module, the data port of the upstream LNA, the data port of the second upstream ATT, and the data port of the variable wavelength ROF optical transmitter through a second data line.

[0043] The beneficial effects of the present invention are as follows:

[0044] The present invention features a simple system architecture, facilitates construction and maintenance, and can rapidly deploy wireless coverage systems utilizing existing fiber optic networks. The present invention can transmit not only Wi-Fi, 4G, and 5G signals, but also millimeter-wave 5G signals and future 6G signals, enabling smooth transitions and facilitating upgrades for various communication systems. The present invention utilizes high-dynamic ROF optical transmission technology to address optical insertion loss issues associated with optical splitters and long-distance transmission. It also utilizes high-dynamic variable-wavelength ROF optical transmission technology to address laser interference issues associated with multiple multi-standard RF signal extension units 3 in the uplink optical combiner. The fiber-optic distributed wireless signal coverage system provided by the present invention, based on ROF technology, consists of three components: a signal access intelligent unit 1, a fiber splitter 2, and a multi-standard RF signal extension unit 3. The fiber connection between the three devices requires only a single, common single-mode optical fiber, resulting in low cost and convenient wiring. The fiber connection between the signal access intelligent unit 1 and the fiber splitter 2 can be tailored to the actual wireless signal coverage needs, potentially utilizing optical fiber cables for long-distance transmission. The present invention can support transmission distances up to 20 km. The optical fiber connection between the optical fiber splitter 2 and the multi-standard radio frequency signal remote unit 3 is generally 200 to 300 meters long, depending on the actual wireless signal coverage requirements, to provide signal coverage for various areas indoors. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] FIG1 is a system architecture diagram of the present invention;

[0046] FIG2 is a block diagram of the signal access intelligent unit of the present invention;

[0047] FIG3 is a functional block diagram of a multi-standard radio frequency signal remote unit according to the present invention;

[0048] FIG4 is a software control flow chart showing the successful wavelength setting of the multi-standard RF signal remote unit 3;

[0049] FIG5 is a software control flow chart of a failure in wavelength setting of a multi-standard radio frequency signal remote unit 3;

[0050] Figure 6 is a system architecture diagram of a traditional digital wireless signal coverage solution;

[0051] FIG7 is a graph showing measured input third-order intercept point data of a large dynamic ROF optical transmitter and a ROF optical receiver directly connected with a 1-meter optical fiber according to the present invention;

[0052] FIG8 is a graph showing measured gain data of a 1-meter optical fiber direct connection of a large dynamic ROF optical transmitter and a ROF optical receiver according to the present invention;

[0053] FIG9 is a graph showing the measured noise figure data of a large dynamic ROF optical transmitter and a ROF optical receiver directly connected with a 1-meter optical fiber according to the present invention;

[0054] FIG10 is a graph showing the measured spurious-free dynamic range data of the large dynamic ROF optical transmitter and the ROF optical receiver according to the present invention when the 1-meter optical fiber is directly connected.

[0055] Markings in the figure: 1. Signal access intelligent unit, 2. Fiber optic splitter, 3. Multi-standard RF signal remote unit, 4. 1XN optical splitter, 5. 1X8 optical splitter, 8. First RF switch / filter, 9. First downlink ATT, 10. Downlink amplifier, 11. First signal coupler, 12. Large dynamic ROF optical transmitter, 13. OOK modulator, 14. Wavelength division multiplexer, 15. First power module, 16. First communication module, 17. Main monitoring unit, 18. First uplink ATT, 19. First uplink amplifier, 20. Second signal coupler, 21. First ROF optical receiver, 2 2. Demultiplexer, 23. Second ROF optical receiver, 24. Third signal coupler, 25. Second downlink ATT, 26. Downlink PA, 27. OOK demodulator, 28. Slave monitoring unit, 29. Second communication module, 30. Second power supply module, 31. Second RF switch / filter, 32. Filter, 33. Antenna, 34. Uplink LNA, 35. Second uplink ATT, 36. Fourth signal coupler, 37. Variable wavelength ROF optical transmitter, 38. RF interface, 39. First optical fiber interface, 40. Second optical fiber interface, 42. First optical port, 43. Second optical port. DETAILED DESCRIPTION

[0056] The present invention will be further described below with reference to specific examples, but is not limited thereto.

[0057] 1 , 2 and 3 , a fiber-optic distributed wireless signal coverage system based on ROF technology among many embodiments of the present invention includes a signal access intelligent unit 1 , a fiber optic splitter 2 and a multi-standard radio frequency signal remote unit 3 .

[0058] The signal access intelligent unit 1 includes a radio frequency interface 38 and a first optical fiber interface 39. The signal access intelligent unit 1 is used to adjust the radio frequency signal received from the radio frequency interface 38, perform radio frequency amplification, and obtain a first downlink electrical signal. The signal access intelligent unit 1 then combines the first downlink electrical signal, the OOK modulated signal F1, and the first radio frequency signal F2 into a downlink laser signal, which is then output to the first optical fiber interface 39. The signal access intelligent unit 1 is also used to convert the total uplink laser signal input from the first optical fiber interface 39 into an uplink electrical signal, perform radio frequency amplification and radio frequency signal adjustment on the uplink electrical signal, and then output it from the radio frequency interface 38.

[0059] The optical fiber splitter 2 includes a first optical port 42 and at least one second optical port 43. The first optical port 42 of the optical fiber splitter 2 is connected to the first optical fiber interface 39 via a first optical fiber. The optical fiber splitter 2 is configured to evenly split the downlink laser signal input through the first optical port 42 into multiple downlink laser sub-signals. The downlink laser sub-signals correspond to the second optical ports 43 and are output from the second optical ports 43 in a one-to-one correspondence. The optical fiber splitter 2 is also configured to combine the uplink laser signals input through the second optical ports 43 into a single uplink laser signal, which is output from the first optical port 42.

[0060] In the embodiment presented in FIG1 , the number of multi-standard radio frequency signal extension units 3 is M, where M is an integer greater than or equal to , and the specific number is determined according to actual needs. The multi-standard radio frequency signal extension unit 3 includes a second optical fiber interface 40, which is connected to the second optical port 43 of the optical fiber splitter 2 via a second optical fiber. The multi-standard radio frequency signal extension unit 3 is used to decompose the downlink laser signal and convert it into a second downlink electrical signal, and to divide the second downlink electrical signal into a first signal F4, a second signal F5, and a third signal, and to sequentially adjust the radio frequency signal level of the third signal, amplify the radio frequency signal, and transmit it. The multi-standard radio frequency signal extension unit 3 is also used to filter the received second wireless signal or switch the radio frequency switch to obtain an uplink radio frequency signal, and to perform low-noise amplification and radio frequency signal level adjustment on the uplink radio frequency signal, and then combine it with the second radio frequency signal F6 to convert it into an uplink laser signal, and transmit the uplink laser signal to the second optical fiber interface 40.

[0061] 2 , the signal access intelligent unit 1 further includes a first RF switch / filter 8, a first downlink ATT 9, a downlink amplifier 10, a first signal coupler 11, a large dynamic ROF optical transmitter 12, an OOK modulator 13, a wavelength division multiplexer 14, a first power supply module 15, a first communication module 16, a main monitoring unit 17, a first uplink ATT 18, a first uplink amplifier 19, a second signal coupler 20, and a first ROF optical receiver 21.

[0062] The input and output ports of the first RF switch / filter 8 are electrically connected to the second port of the RF interface 38 . For example, the input and output ports of the first RF switch / filter 8 are electrically connected to the second port of the RF interface 38 via a first RF line.

[0063] The input port of the first downstream ATT 9 is electrically connected to the output port of the first RF switch / filter 8. For example, the input port of the first downstream ATT 9 is electrically connected to the output port of the first RF switch / filter 8 via a second RF line.

[0064] The input port of the downstream amplifier 10 is electrically connected to the output port of the first downstream ATT 9. For example, the input port of the downstream amplifier 10 is electrically connected to the output port of the first downstream ATT 9 via a third radio frequency line.

[0065] The first input port of the first signal coupler 11 is electrically connected to the output port of the downstream amplifier 10 .

[0066] The input port of the large dynamic ROF optical transmitter 12 is electrically connected to the output port of the first signal coupler 11 .

[0067] The radio frequency output port of the OOK modulator 13 is electrically connected to the input port of the first signal coupler 11 .

[0068] An input port of the wavelength division multiplexer 14 is connected to an output port of the large dynamic ROF optical transmitter 12 via a fourth optical fiber, and the input and output ports of the wavelength division multiplexer 14 are connected to the first optical fiber interface 39 via a fifth optical fiber.

[0069] An input port of the first ROF optical receiver 21 is connected to an output port of the wavelength division multiplexer 14 via a sixth optical fiber.

[0070] An input port of the second signal coupler 20 is electrically connected to an output port of the first ROF optical receiver 21 .

[0071] An input port of the first uplink amplifier 19 is electrically connected to a first output port of the second signal coupler 20 .

[0072] The input port of the first uplink ATT 18 is electrically connected to the output port of the first uplink amplifier 19. For example, the input port of the first uplink ATT 18 is electrically connected to the output port of the first uplink amplifier 19 via a fourth RF line. The output port of the first uplink ATT 18 is electrically connected to the input port of the first RF switch / filter 8. For example, the output port of the first uplink ATT 18 is electrically connected to the input port of the first RF switch / filter 8 via a fifth RF line.

[0073] The input port of the first communication module 16 is electrically connected to the second output port of the second signal coupler 20 , and the output port of the first communication module 16 is electrically connected to the third input port of the first signal coupler 11 .

[0074] The data port of the main monitoring unit 17 is connected to the data port of the first RF switch / filter 8, the data port of the first downlink ATT 9, the data port of the downlink amplifier 10, the data port of the large dynamic ROF optical transmitter 12, the data port of the OOK modulator 13, the data port of the first communication module 16, the data port of the first uplink ATT 18, the data port of the first uplink amplifier 19, and the data port of the first ROF optical receiver 21 through the first data line.

[0075] 1 , the optical fiber splitter 2 further includes a 1XN optical splitter 4 and a 1X8 optical splitter 5 .

[0076] The input optical port of the 1XN optical splitter 4 serves as the first optical port 42 of the optical fiber splitter 2 .

[0077] There are multiple 1X8 optical splitters 5 , and the input optical port of the 1X8 optical splitter 5 is connected to the output optical port of the 1XN optical splitter 4 in a one-to-one correspondence through a third optical fiber. The output optical port of the 1X8 optical splitter 5 serves as the second optical port 43 of the optical fiber splitter 2 .

[0078] 3 , the multi-standard RF signal remote unit 3 further includes a demultiplexer 22, a second ROF optical receiver 23, a third signal coupler 24, a second downlink ATT 25, a downlink PA 26, an OOK demodulator 27, a slave monitoring unit 28, a second communication module 29, a second power supply module 30, a second RF switch / filter 31, a filter 32, an antenna 33, an uplink LNA 34, a second uplink ATT 35, a fourth signal coupler 36, and a variable wavelength ROF optical transmitter 37.

[0079] The input and output ports of the demultiplexer 22 are connected to the second optical fiber interface 40 via a tenth optical fiber.

[0080] The input port of the second ROF optical receiver 23 is connected to the output port of the de-Wavelength Division Multiplexer 22 through an eighth optical fiber.

[0081] The input port of the third signal coupler 24 is electrically connected to the output port of the second ROF optical receiver 23 . For example, the input port of the third signal coupler 24 is electrically connected to the output port of the second ROF optical receiver 23 via a sixth radio frequency line.

[0082] The input port of the second downstream ATT 25 is electrically connected to the first output port of the third signal coupler 24 .

[0083] The input port of the downstream PA 26 is electrically connected to the output port of the second downstream ATT 25 . For example, the input port of the downstream PA 26 is electrically connected to the output port of the second downstream ATT 25 via a seventh radio frequency line.

[0084] The input port of the second RF switch / filter 31 is electrically connected to the output port of the downstream PA 26 . For example, the input port of the second RF switch / filter 31 is electrically connected to the output port of the downstream PA 26 via an eighth RF line.

[0085] The first port of the filter 32 is electrically connected to the input and output ports of the second RF switch / filter 31 . For example, the first port of the filter 32 is electrically connected to the input and output ports of the second RF switch / filter 31 via a ninth RF line.

[0086] The antenna 33 is electrically connected to the second port of the filter 32 .

[0087] The input port of the uplink LNA 34 is electrically connected to the output port of the second RF switch / filter 31 . For example, the first port of the filter 32 is electrically connected to the input and output ports of the second RF switch / filter 31 via a tenth RF line.

[0088] The input port of the second uplink ATT 35 is electrically connected to the output port of the uplink LNA 34 . For example, the first port of the filter 32 is electrically connected to the input and output ports of the second RF switch / filter 31 via an eleventh RF line.

[0089] The first input port of the fourth signal coupler 36 is electrically connected to the output port of the second upstream ATT 35 .

[0090] The input port of the variable wavelength ROF optical transmitter 37 is electrically connected to the output port of the fourth signal coupler 36 , and the output port of the variable wavelength ROF optical transmitter 37 is connected to the input port of the demultiplexer 22 via a ninth optical fiber.

[0091] An input port of the OOK demodulator 27 is electrically connected to the second output port of the third signal coupler 24 .

[0092] The input port of the second communication module 29 is electrically connected to the third output port of the third signal coupler 24 , and the output port of the second communication module 29 is electrically connected to the second input port of the fourth signal coupler 36 .

[0093] The data port of the slave monitoring unit 28 is connected to the data port of the second ROF optical receiver 23, the data port of the second downstream ATT 25, the data port of the downstream PA 26, the data port of the OOK demodulator 27, the data port of the second communication module 29, the data port of the upstream LNA 34, the data port of the second upstream ATT 35, and the data port of the variable wavelength ROF optical transmitter 37 through a second data line.

[0094] As shown in Figure 2, Figure 2 is a principle block diagram of the signal access intelligent unit 1. The first wireless signal such as 4G / 5G / WIFI is input to the first RF switch / filter 8 through the RF interface 38, that is, the first wireless signal such as 4G / 5G / WIFI is input from the first port of the RF interface 38, output from the second port of the RF interface 38 and enters the input and output port of the first RF switch / filter 8. The downlink signal obtained after transmission and filtering by the first RF switch / filter 8 is transmitted through the second RF line to the first downlink ATT9 for RF signal size adjustment, and then enters the downlink amplifier 10 for RF amplification to obtain the first downlink signal. The first downlink electrical signal, the OOK modulated signal F1 output by the OOK modulator 13, and the first RF signal F2 output by the first communication module 16 are combined together by the first signal coupler 11 to obtain a fourth RF signal. The fourth RF signal is transmitted to the large dynamic ROF optical transmitter 12. The large dynamic ROF optical transmitter 12 converts the fourth RF signal into a downlink laser signal, which is multiplexed with the total uplink laser signal in an optical fiber (i.e., the fifth optical fiber) through the wavelength division multiplexer 14. The optical fiber interface 39 transmits the fourth RF signal over a long distance to the multi-standard RF signal remote unit 3 through the first optical fiber, the optical fiber splitter 2, and the second optical fiber in sequence. The total uplink laser signal transmitted from the multi-standard RF signal remote unit 3 is decomposed by the wavelength division multiplexer 14 and transmitted to the first ROF optical receiver 21. The first ROF optical receiver 21 converts the total uplink laser signal into an uplink electrical signal and couples it to the first communication module 16 through the second signal coupler 20 to output signal F3. The remaining uplink electrical signal is output to the first uplink amplifier 19 for RF signal amplification. The signal level is then adjusted by the first uplink ATT 18. Finally, it is output to the RF interface 38 through the first RF switch / filter 8 for external transmission to the 4G / 5G / WIFI signal source. The main monitoring unit 17 in the signal access intelligent unit 1 is the central processing unit. It is responsible for receiving user control commands and synchronization signals from the 4G / 5G / WIFI signal source, controlling the settings of various components in the system according to the system algorithm, monitoring their parameters, storing the monitoring parameters, collecting device alarms, and promptly uploading data to the user monitoring center. The main monitoring unit 17 is also used to modulate the device monitoring data into the first RF signal F2 through the first communication module 16, and modulate the synchronization signal of the 4G / 5G / WIFI source into the OOK modulated signal F1 through the OOK modulator 13. Then, the first RF signal F2, the OOK modulated signal F1 and the first downlink electrical signal are modulated together into a downlink laser signal for optical fiber transmission to monitor the status information of the multi-standard RF signal extension unit 3. The main monitoring unit 17 is used to set various parameters of the multi-standard RF signal extension unit 3. For the downlink, the main monitoring unit 17 reads the downlink output optical power from the large dynamic ROF optical transmitter 12, and compares the optical power value with the preset target optical transmission power value. When the error is greater than the first threshold, the first downlink ATT9 is adjusted accordingly.The monitoring data packets communicated between the master monitoring unit 17 and the slave monitoring unit 28 are modulated into a first radio frequency signal F2 by the first communication module 16 via the first data line. These signals are then coupled to the high-dynamic range of field-of-flight optical transmitter 12 by the first signal coupler 11 to form a downlink laser signal for transmission. For the uplink, the total uplink laser signal is demodulated by the first communication module 16 to obtain monitoring data sent by the slave monitoring unit 28. This data is then transmitted to the master monitoring unit 17 via the first data line. The master monitoring unit 17 interprets the monitoring data and takes appropriate action. Furthermore, the master monitoring unit 17 monitors the output power of the first uplink amplifier to determine whether the uplink output power is within the target range. If the error exceeds a second threshold, the first uplink amplifier 18 is adjusted accordingly.

[0095] The RF interface 38 is used to connect to the 4G / 5G / WIFI signal source device externally. The first RF switch / filter 8 has two options. One is to use an RF switch to switch the uplink signal and the downlink signal, which is used in the TDD communication system. The other is to use a filter to separate the uplink signal and the downlink signal, which is used in the FDD communication system. The first downlink ATT9 is used to adjust the signal size of the first wireless signal. The downlink amplifier 10 is used to amplify the first wireless signal after the signal size is adjusted by the first downlink ATT9, thereby obtaining a first downlink electrical signal. The first signal coupler 11 is used for signal coupling, and couples the OOK modulated signal F1 output by the OOK modulator 13 and the first RF signal F2 output by the first communication module 16 to the downlink link. The large dynamic ROF optical transmitter 12 is used to convert the fourth RF signal into a downlink laser signal and transmit it to the outside through the fourth optical fiber. The wavelength division multiplexer 14 is used to wavelength-division multiplex the downlink laser signal from the large-dynamic ROF optical transmitter 12 and the total uplink laser signal into a single optical fiber, the fifth optical fiber, and output it to the first optical fiber interface 39; the first optical fiber interface 39 is used to connect to an external optical fiber network. The first ROF optical receiver 21 is used to receive the total uplink laser signal, convert it into an uplink electrical signal, and output it to the second signal coupler 20. The second signal coupler 20 is used to couple a small portion of the signal F3 to the first communication module 16. The first uplink amplifier 19 is used to amplify the uplink electrical signal. The first uplink ATT 18 is used to adjust the signal level of the uplink electrical signal after amplification by the first uplink amplifier 19. The main monitoring unit 17 is the processor of the signal access intelligent unit 1, responsible for controlling each module, configuring and monitoring each module, and storing monitoring information. The main monitoring unit 17 is used to transmit monitoring data. The monitoring data signal is modulated into a first radio frequency signal F2 through the first communication module 16 for external transmission and reception. The OOK modulator 13 is used to modulate the synchronization signal of the TDD wireless signal into an OOK modulated signal F1 and transmit the OOK modulated signal F1 to the first signal coupler 11. The first power supply module 15 is used to supply power to each active device.

[0096] As shown in FIG1 , the optical fiber splitter 2 can be a common optical fiber splitter with a single optical fiber. There are no requirements for optical technology. As long as it can meet the conventional technical indicators currently on the market, the cost is very low, and the wiring and construction are very convenient. The current fiber-to-the-home (PON) network can also be used for low-cost signal coverage.

[0097] The fiber optic splitter 2 comprises two stages of optical splitters, a first optical port 42, and multiple second optical ports 43. The first stage is a 1xN optical splitter 4, and the second stage is a 1x8 optical splitter 5. If the first-stage 1xN optical splitter 4 is replaced with a fiber patch cord, the second stage will use one 1x8 optical splitter 5, thus forming a one-to-eight network. If the first-stage 1xN optical splitter 4 is a 1x2 optical splitter, the second stage will use two 1x8 optical splitters 5, thus forming a one-to-sixteen network. If the first-stage 1xN optical splitter 4 is a 1x3 optical splitter, the second stage will use three 1x8 optical splitters 5, thus forming a one-to-twenty-four network. Similarly, a maximum of one-to-sixty-four networks can be formed. These optical splitters can be centralized or distributed, depending on the convenience of construction. The present invention can realize that one signal access intelligent unit 1 realizes 64 multi-standard radio frequency signal remote units 3 devices through one optical fiber to provide wireless signal coverage.

[0098] Because fiber splitter 2 is reversible and can output laser light as well as input it, at least one uplink laser signal is input into 1X8 optical splitter 5 via at least one second optical port 43 via the second optical fiber. It is then combined with the remaining seven uplink laser signals via a third optical fiber and transmitted to 1XN optical splitter 4. 1XN optical splitter 4 then combines the laser signals output by N 1X8 optical splitters 5 into a single uplink laser signal, outputs it to first optical port 42, and is then transmitted to signal access intelligent unit 1 via the first optical fiber. N is an integer greater than or equal to , and the specific number is determined based on actual needs.

[0099] The 1XN optical splitter 4 divides a beam of light into N equal parts by optical splitting an optical fiber. The first-level optical splitter of the present invention can split a beam of light into 8 parts at most, with a power attenuation of 9dB. Adding the additional loss, the budget is 10dB.

[0100] The 1X8 optical splitter 5 divides a beam of light into 8 equal parts through optical splitting of an optical fiber. The power attenuation is 9dB. Adding the additional loss, the budget can be 10dB.

[0101] As shown in FIG3 , the multi-standard RF signal remote unit 3 demultiplexes the downlink laser signal transmitted from the optical fiber splitter 2 through the wavelength division multiplexer 22 and outputs the demultiplexed signal to the second ROF optical receiver 23 . The second ROF optical receiver 23 converts the downlink laser signal into a second downlink electrical signal and outputs it to the third signal coupler 24. The third signal coupler 24 divides the second downlink electrical signal into a first signal, a second signal, and a third signal. The first signal is signal F4, which is given to the OOK demodulator 27 to demodulate the synchronization signal of the wireless signal; the second signal is signal F5, which is given to the second communication module 29 to demodulate the monitoring information of the signal access intelligent unit 1 and give it to the slave monitoring unit 28; the third signal is the second downlink electrical signal after coupling by the third signal coupler 24, which is output to the second downlink ATT25 for RF signal size adjustment, and then amplified by the downlink PA26, and then output to the second RF switch / filter 31, and then filtered by the filter 32. Finally, it is output to the antenna 33, and the filtered second downlink electrical signal is transmitted to provide 4G / 5G / WIFI and other wireless signal coverage to the coverage space. The user's second wireless signal, such as 4G / 5G / Wi-Fi, is received by antenna 33. The uplink RF signal is extracted through filter 32 and second RF switch / filter 31. The signal is then low-noise amplified by uplink LNA 34 and then RF-conditioned by second uplink ATT 35. The uplink RF signal, conditioned by the second uplink ATT 35, is then coupled with the second RF signal F6 output by second communication module 29 via fourth signal coupler 36 to produce a third RF signal. The third RF signal is then output to variable-wavelength ROF optical transmitter 37 for electro-optical conversion, converting the third RF signal into an uplink laser signal. The signal is then multiplexed onto a single optical fiber, the tenth optical fiber, for transmission via wavelength division multiplexer 22. The slave monitoring unit 28 of the multi-standard RF signal remote unit 3 controls the parameters of each component, monitors the information of each component, and stores it in memory. This information is then transmitted in real time to the signal access intelligent unit 1 via second communication module 29. The second power supply module 30 of the multi-standard RF signal remote unit 3 provides power to the active devices of the device.

[0102] The second optical fiber interface 40 is used to connect to an external optical fiber network. The demultiplexer 22 decomposes the downlink laser signal and multiplexes the total uplink laser signal. The second ROF optical receiver 23 receives the downlink laser signal, converts it into a second downlink electrical signal, and outputs it to the third signal coupler 24. The third signal coupler 24 couples a small portion of the signal (signal F4 and signal F5) to the second communication module 29 and the OOK demodulator 27. The second downlink ATT 25 adjusts the amplitude of the third signal. The downlink PA 26 amplifies the third signal. The OOK demodulator 27 demodulates the OOK signal and extracts the synchronization signal of the first wireless signal. The slave monitoring unit 28 is the processor of the multi-standard RF signal remote unit 3. It controls each module, configures and monitors each module, stores monitoring information, and can also transmit monitoring data. The second communication module 29 modulates the data signal from the slave monitoring unit 28 into the second RF signal F6 for external transmission and reception. On the downlink, the slave monitoring unit 28 monitors the output power of the downlink PA 26 and determines whether it is within the target range. If the error exceeds a third threshold, the second downlink ATT 25 is adjusted. Simultaneously, the slave monitoring unit 28 receives monitoring data sent by the master monitoring unit 17 after demodulation by the second communication module 29, interprets it, and performs corresponding operations. Upon receiving a wavelength assignment command from the master monitoring unit 17, the slave monitoring unit 28 configures the variable-wavelength ROF optical transmitter 37 via the second data line to operate at the specified optical wavelength. On the uplink, the slave monitoring unit 28 monitors the output power of the uplink LNA 34 and determines whether it is within the target range. If the error exceeds a fourth threshold, the slave monitoring unit 17 adjusts the second uplink ATT 35 via the second data line. The second power supply module 30 supplies power to various active components. The second RF switch / filter 31 has two options: one employs an RF switch to switch between uplink and downlink signals, suitable for TDD communication systems; the other employs a filter to separate the uplink and downlink signals, suitable for FDD communication systems. Filter 32 filters the second wireless signal and the second downlink electrical signal to remove out-of-band spurious signals. Antenna 33 is used to receive the second wireless signal and transmit the second downlink electrical signal. Uplink LNA 34 is used for low-noise amplification of the uplink RF signal. Second uplink ATT 35 is used to adjust the amplitude of the uplink RF signal. Fourth signal coupler 36 is used to combine the second RF signal F6 output by the second communication module 29 with the uplink RF signal to produce a third RF signal. Variable wavelength ROF optical transmitter 37 is used to convert the third RF signal into an uplink laser signal and also has a wavelength tuning function.

[0103] The following describes in detail the implementation of system wavelength allocation management.

[0104] In the implementation of wavelength allocation management, as shown in Figures 1, 2, and 3, the signal access intelligent unit 1 and the multi-standard RF signal remote unit 3 are each equipped with a monitoring unit. The monitoring unit in the signal access intelligent unit 1 is the master monitoring unit 17, and the monitoring unit in the multi-standard RF signal remote unit 3 is the slave monitoring unit 28. The master monitoring unit 17 is responsible for managing and allocating optical wavelengths, while the slave monitoring unit 28 cooperates with the master monitoring unit 17 in adjusting the optical wavelengths.

[0105] The specific optical wavelength allocation process is as follows:

[0106] In the initial state, the main monitoring unit 17 maintains the following wavelength resource state as shown in Table 1.

[0107] Table 1 Wavelength resource status table

[0108] In the above table, λ0 is used as the system initial wavelength request, and n is an integer greater than or equal to 1, with a maximum value of 64.

[0109] In the initial state, the wavelength resource states maintained by the main monitoring unit 17 include λ1, λ2, ..., λ n-1 They are all marked as "unused". When the master monitoring unit 17 responds to the wavelength allocation request and allocates the corresponding wavelength to the slave monitoring unit, the master monitoring unit 17 will mark the usage status of the wavelength as "used". When the wavelength resource is recovered, it will be marked as "unused".

[0110] During operation, the master monitoring unit 17 and the slave monitoring unit 28 monitor the operating status of the channels. If the master monitoring unit 17 detects an abnormal operation of a wavelength channel, it reclaims the wavelength resource and marks its status as "unused." If the slave monitoring unit 28 detects an abnormal operation of the current wavelength channel, it re-initiates the wavelength allocation request process.

[0111] After the slave monitoring unit 28 in the multi-standard RF signal remote unit 3 is powered on, it is in the initial state. At this time, the operating wavelength of the multi-standard RF signal remote unit 3 has not yet been assigned. It uses the system reserved wavelength λ0 to communicate with the master monitoring unit, triggering the wavelength allocation request process. The specific process is as follows:

[0112] 1) The slave monitoring unit 28 initiates a wavelength allocation request message on the wavelength λ0 channel and starts a message response timeout timer;

[0113] 2) The main monitoring unit 17 receives the wavelength assignment request message and verifies the message integrity;

[0114] (1) If the message is complete, the master monitoring unit 17 allocates an unused wavelength from the optical wavelength resource table to the slave monitoring unit 28 according to a certain principle;

[0115] (2) If the message is incomplete, the main monitoring unit 17 does not respond;

[0116] 3) When the slave monitoring unit 28 receives a response message from the master monitoring unit 17 within the message response timer, and the message is complete, it responds with a success message to the master monitoring unit 17 and sets the multi-standard RF signal remote unit 3 to operate at the newly allocated wavelength in the response message, as shown in FIG4 ;

[0117] 4) If the response message timer of the slave monitoring unit 28 times out or the response message is incomplete, to avoid conflict with messages from other slave monitoring units 28, the slave monitoring unit 28 will delay for a random time and restart the wavelength assignment request process, as shown in FIG5 .

[0118] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0119] The present invention adopts ROF technology, without ADC and DAC conversion, digital baseband processing, digital optical modules, and digital HUB (router), but analog transparent transmission, with a working bandwidth of up to 10MHz to 18GHz. 4G, 5G, WIFI, and millimeter 5G can all be optically transmitted together and transmitted to the multi-standard radio frequency signal extension unit 3 for separate radio frequency amplification, so as to provide multi-standard signal coverage for the coverage area. Taking advantage of the 10MHz to 18GHz working bandwidth of ROF technology, the instantaneous bandwidth of the wireless signal is up to 800MHz, and frequency shifting can be used in the system to achieve 2x2MIMO, 4x4MIMO, and millimeter 5G signal coverage. The optical fiber network of the optical transmission of the present invention only needs to use an ordinary optical distribution network with one optical fiber to achieve up to 64 multi-standard radio frequency signal extension units 3, as shown in Figure 1 below.

[0120] As shown in Figure 6, the digital fiber optic near-end unit in a traditional digital wireless signal coverage solution utilizes digital ADCs and DACs, digital baseband processing, and digital optical modules; the digital fiber optic remote unit also utilizes digital ADCs and DACs, digital baseband processing, and digital optical modules. To expand the unit, a digital hub (switch) is required. For expansion to 32 units, up to four digital hubs are required, making the entire system complex. To achieve simultaneous transmission of 4G, 5G, Wi-Fi, and 5G, the digital transmission rate must reach 400 Gb / s, which is very costly. Miniaturization of the remote unit system is difficult, and power consumption is also relatively high.

[0121] After comprehensive comparison, the fiber-optic distributed wireless signal coverage system based on RoF technology has a simpler architecture than traditional digital wireless signal coverage solutions. It does not require high-speed ADCs and DACs, digital baseband processing, high-speed digital optical modules, or high-speed hubs. It only requires large-dynamic ROF optical transmitters, ROF optical receivers, variable-wavelength ROF optical transmitters, other conventional RF amplifiers, switches, and filters. It can achieve the transmission of 4G, 5G, WIFI, and millimeter-wave 5G wireless signals together. It is easy to design and construct, with low construction investment and low overall cost, making it suitable for large-area wireless signal coverage.

[0122] The present invention adopts large dynamic ROF optical transmission technology, the input P-1 of the optical link is as high as 32dBm, the input IP3 is as high as 50dBm, and the transmission SFDR (spurious free dynamic range) is as high as 123dB / Hz. 2 / 3 The transmitted optical power is as high as 50mW, about 17dBm. After passing through 26dB of optical insertion loss in the optical link (20dB optical insertion loss caused by 64-way splitting of one optical fiber and 6dB optical insertion loss caused by 20km of optical fiber at 1550nm optical transmission, a total of 26dB optical insertion loss), there is still -9dBm at the ROF optical receiver 23. After being amplified by the RF amplifier at the subsequent amplifier, the measured 5G signal meets the 3GPP requirements. This is where the technical advantages of the traditional solution are most obvious.

[0123] FIG7 is a graph showing the measured input third-order intercept point data of the large dynamic ROF optical transmitter and the ROF optical receiver according to the present invention when the optical fiber is directly connected with one meter; FIG8 is a graph showing the measured gain data of the large dynamic ROF optical transmitter and the ROF optical receiver according to the present invention when the optical fiber is directly connected with one meter; FIG9 is a graph showing the measured noise figure data of the large dynamic ROF optical transmitter and the ROF optical receiver according to the present invention when the optical fiber is directly connected with one meter; FIG10 is a graph showing the measured spurious-free dynamic range data of the large dynamic ROF optical transmitter and the ROF optical receiver according to the present invention when the optical fiber is directly connected with one meter.

[0124] The maximum RF bandwidth of the large dynamic ROF optical transmission link can reach 18 GHz.

[0125] The present invention adopts variable wavelength ROF optical transmission technology. Because a single optical fiber optical division network can achieve access to a maximum of 64 multi-standard radio frequency signal remote units 3, if all 64 multi-standard radio frequency signal remote units 3 use the same wavelength of uplink laser, then the 64 uplink lasers will form optical interference in the optical division network, and the entire system will not work properly. The signal access intelligent unit 1 of the present invention automatically assigns an uplink laser wavelength to each multi-standard radio frequency signal remote unit 3 according to the number of multi-standard radio frequency signal remote units 3 connected, ensuring the uniqueness of the wavelength of each multi-standard radio frequency signal remote unit 3 and different wavelengths from other multi-standard radio frequency signal remote units 3, thus avoiding the optical interference of the 64 uplink lasers in the optical division network. This is the core technology of the present invention.

Claims

1. A fiber-optic distributed wireless signal coverage system based on ROF technology, characterized in that: include: A signal access intelligent unit (1) comprising a radio frequency interface (38) and a first optical fiber interface (39); It is used to adjust the radio frequency signal size of a first wireless signal received from a radio frequency interface (38) and then perform radio frequency amplification to obtain a first downlink electrical signal, combine the first downlink electrical signal, the OOK modulation signal (F1) and the first radio frequency signal (F2) together to convert the signal into a downlink laser signal and output it to a first optical fiber interface (39); it is also used to convert the total uplink laser signal input from the first optical fiber interface (39) into an uplink electrical signal, perform radio frequency amplification and radio frequency signal size adjustment on the uplink electrical signal in sequence, and then output it from the radio frequency interface (38); An optical fiber splitter (2) includes a first optical port (42) and at least one second optical port (43), wherein the first optical port (42) is connected to a first optical fiber interface (39) via a first optical fiber; the optical fiber splitter is used to evenly split a downlink laser signal input via the first optical port (42) into a plurality of downlink laser sub-signals, wherein the downlink laser sub-signals correspond to the second optical port (43) on a one-to-one basis and are output from the second optical port (43); and the optical fiber splitter is also used to combine uplink laser signals input via the second optical port (43) into a total uplink laser signal and output the signal from the first optical port (42); At least one multi-standard radio frequency signal remote unit (3), each of which includes a second optical fiber interface (40), and the second optical fiber interface (40) is connected to the second optical port (43) of the optical fiber splitter (2) in a one-to-one correspondence through a second optical fiber; it is used to decompose the downlink laser signal and convert it into a second downlink electrical signal, and to divide the second downlink electrical signal into a first signal (F4), a second signal (F5), and a third signal, and to sequentially adjust the radio frequency signal size of the third signal, amplify the radio frequency signal, and then transmit it; It is also used to filter the received second wireless signal to obtain an uplink radio frequency signal, perform low-noise amplification on the uplink radio frequency signal, adjust the radio frequency signal level, and then combine it with the second radio frequency signal to convert it into an uplink laser signal, and transmit the uplink laser signal to the second optical fiber interface (40).

2. The fiber-optic distributed wireless signal coverage system based on ROF technology according to claim 1 is characterized in that: The signal access intelligent unit (1) further comprises: a first radio frequency switch / filter (8), the input and output ports of which are electrically connected to the second port of the radio frequency interface (38); a first downlink ATT (9), the input port of which is electrically connected to the output port of the first RF switch / filter (8); a downstream amplifier (10), the input port of which is electrically connected to the output port of the first downstream ATT (9); a first signal coupler (11), a first input port of which is electrically connected to an output port of the downlink amplifier (10); A large dynamic ROF optical transmitter (12), the input port of which is electrically connected to the output port of the first signal coupler (11); An OOK modulator (13), an output port of which is electrically connected to the second input port of the first signal coupler (11); A wavelength division multiplexer (14), one input port of which is connected to the output port of the large dynamic ROF optical transmitter (12) via a fourth optical fiber, and the input and output ports of which are connected to the first optical fiber interface (39) via a fifth optical fiber; a first ROF optical receiver (21), an input port of which is connected to an output port of the wavelength division multiplexer (14) via a sixth optical fiber; a second signal coupler (20), the input port of which is electrically connected to the output port of the first ROF optical receiver (21); a first uplink amplifier (19), the input port of which is electrically connected to the first output port of the second signal coupler (20); A first uplink ATT (18), whose input port is electrically connected to the output port of the first uplink amplifier (19), and whose output port is electrically connected to the input port of the first RF switch / filter (8); a first communication module (16), whose input port is electrically connected to the second output port of the second signal coupler (20), and whose output port is electrically connected to the third input port of the first signal coupler (11); The main monitoring unit (17) has a data port connected to the data port of the first radio frequency switch / filter (8), the data port of the first downlink ATT (9), the data port of the downlink amplifier (10), the data port of the large dynamic range-of-flight (ROF) optical transmitter (12), the data port of the OOK modulator (13), the data port of the first communication module (16), the data port of the first uplink ATT (18), the data port of the first uplink amplifier (19), and the data port of the first ROF optical receiver (21) via a first data line.

3. The fiber-optic distributed wireless signal coverage system based on ROF technology according to claim 1 is characterized in that: The optical fiber splitter (2) further comprises: A 1XN optical splitter (4), the input optical port of which serves as the first optical port (42) of the optical fiber splitter (2); At least one 1X8 optical splitter (5), whose input optical port is connected to the output optical port of the 1XN optical splitter (4) in a one-to-one correspondence via a third optical fiber, and whose output optical port serves as the second optical port (43) of the optical fiber splitter (2).

4. The fiber-optic distributed wireless signal coverage system based on ROF technology according to claim 1 is characterized in that: The multi-standard radio frequency signal remote unit (3) further includes: a demultiplexer (22), the input and output ports of which are connected to the second optical fiber interface (40) via a tenth optical fiber; a second ROF optical receiver (23), the input port of which is connected to the output port of the de-wavelength division multiplexer (22) via an eighth optical fiber; a third signal coupler (24), an input port of which is electrically connected to an output port of the second ROF optical receiver (23); a second downstream ATT (25), the input port of which is electrically connected to the first output port of the third signal coupler (24); a downstream PA (26), an input port of which is electrically connected to an output port of the second downstream ATT (25); a second RF switch / filter (31), the input port of which is electrically connected to the output port of the downlink PA (26); a filter (32) having a first port electrically connected to the input and output ports of the second radio frequency switch / filter (31); an antenna (33) electrically connected to the second port of the filter (32); an uplink LNA (34), the input port of which is electrically connected to the output port of the second RF switch / filter (31); a second uplink ATT (35), the input port of which is electrically connected to the output port of the uplink LNA (34); a fourth signal coupler (36), a first input port of which is electrically connected to an output port of the second uplink ATT (35); a variable wavelength ROF optical transmitter (37), the input port of which is electrically connected to the output port of the fourth signal coupler (36), and the output port of which is connected to the input port of the demultiplexer (22) via a ninth optical fiber; An OOK demodulator (27), whose input port is electrically connected to the second output port of the third signal coupler (24), and whose data interface is respectively connected to the second downlink ATT (25) and the downlink PA (26) via a third data line; a second communication module (29), an input port of which is electrically connected to a third output port of a third signal coupler (24); The data port of the slave monitoring unit (28) is connected to the data port of the second ROF optical receiver (23), the data port of the second downlink ATT (25), the data port of the downlink PA (26), the data port of the OOK demodulator (27), the data port of the second communication module (29), the data port of the uplink LNA (34), the data port of the second uplink ATT (35), and the data port of the variable wavelength ROF optical transmitter (37) via a second data line.

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