A RoF-based passive distributed 5G micro base station system

Abstract

This invention discloses a RoF-based passive distributed 5G micro base station system, comprising: a near-end base station for processing baseband signals, modulating the baseband signals to optical frequency bands, and generating energy signals; a multimode optical fiber for transmitting energy signals between the near-end base station and the far-end FEM; a single-mode optical fiber for transmitting radio frequency signals between the near-end base station and the far-end FEM; and a far-end FEM for receiving the energy signals transmitted through the multimode optical fiber, converting the energy signals into electrical energy for power supply, and receiving optical signals transmitted through the single-mode optical fiber and demodulating them into radio frequency signals. This invention enables long-distance, high-bandwidth, and ultra-high information density 5G signal coverage without external power supply to the far-end FEM.

Description

Technical Field

[0001] This invention relates to the field of communication technology, and in particular to a RoF-based passive distributed 5G micro base station system. Background Technology

[0002] The main drawbacks of existing distributed base station systems include the need for external power supply for the radio frequency remote unit and the complexity of baseband signal processing, resulting in a large equipment architecture and high installation and maintenance costs. In addition, these systems use coaxial cables for signal transmission, resulting in significant path loss, especially at high frequencies, where signal attenuation is significant, limiting long-distance, wide-area coverage capabilities.

[0003] Furthermore, existing optical-signal-energy simultaneous transmission systems suffer from energy transmission efficiency issues; the energy beam easily interferes with the signal beam, leading to a decline in signal quality and stability. While single-fiber optical-signal-energy simultaneous transmission is simple, its low energy signal density cannot meet the demands of high-energy transmission. These technical shortcomings make it difficult for existing systems to achieve high-bandwidth, high-speed, and wide-area coverage 5G networks. Summary of the Invention

[0004] According to one aspect of the present invention, a RoF-based passive distributed 5G micro base station system is provided, wherein the remote FEM does not require external power supply, thereby achieving long-distance, high-bandwidth, and ultra-high information density 5G signal coverage.

[0005] To address the aforementioned technical problems, the first aspect of this invention discloses a RoF-based passive distributed 5G micro base station system, comprising:

[0006] Near-end base stations are used to process baseband signals, modulate baseband signals to optical frequency bands, and generate energy signals.

[0007] Multimode fiber is used to transmit energy signals between the near-end base station and the far-end FEM;

[0008] A single-mode optical fiber is used to transmit radio frequency signals between a near-end base station and a far-end FEM. The single-mode optical fiber includes a first single-mode optical fiber for transmitting downlink optical signals to the far-end FEM and a second single-mode optical fiber for transmitting uplink optical signals returned from the far-end FEM to the near-end base station. The optical modulator of the near-end base station is connected to the optical demodulator of the far-end FEM through the first single-mode optical fiber. The optical modulator of the far-end FEM is connected to the optical demodulator of the near-end base station through the second single-mode optical fiber.

[0009] The remote FEM is used to receive energy signals transmitted through multimode optical fiber, convert the energy signals into electrical energy for power supply, and receive downlink optical signals transmitted through the first single-mode optical fiber, demodulating them into radio frequency signals.

[0010] The remote FEM includes an optical demodulator, an optical modulator, a first remote power amplifier, a second remote power amplifier, a second low-noise amplifier, a first low-noise amplifier, a transmitting filter, a receiving filter, and a photovoltaic power supply; the optical demodulator is sequentially connected to the first remote power amplifier, the second remote power amplifier, the transmitting filter, and the transmitting antenna; the optical modulator is sequentially connected to the second low-noise amplifier, the first low-noise amplifier, the receiving filter, and the receiving antenna.

[0011] The near-end base station is also equipped with a light emitter, which generates an energy signal, and the energy signal is transmitted to the photovoltaic power source of the far-end FEM through a multimode optical fiber.

[0012] In uplink signal transmission, the remote FEM receives the uplink signal and modulates it to the optical frequency band to form an uplink optical signal, which is then transmitted to the near-end base station through a second single-mode optical fiber.

[0013] In downlink signal transmission, the near-end base station receives the downlink signal and modulates it to the optical frequency band to form a downlink optical signal. The downlink optical signal is transmitted to the far-end FEM through the first single-mode optical fiber, and the far-end FEM demodulates the downlink optical signal into a radio frequency signal.

[0014] In some embodiments, the near-end base station includes a near-end RRU, an optical modulator, an optical demodulator, an attenuator, and a circulator; the near-end RRU is connected to a first port of the circulator, the second port of the circulator is connected to the optical modulator through the attenuator, and the third port of the circulator is connected to the optical demodulator.

[0015] In some embodiments, the optical demodulator or optical modulator is a RoF demodulator or RoF modulator with temperature compensation, respectively.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] This invention provides a RoF-based passive distributed 5G micro base station system. By employing dual-fiber optical signal and energy transmission technology, signals and energy are transmitted through single-mode and multi-mode optical fibers respectively, achieving a passive design where the remote FEM does not require external power supply. This simplifies system layout, reduces installation and maintenance costs, and improves the system's signal isolation and transmission efficiency. It is suitable for 5G network coverage with high information density and can provide stable and high-speed 5G communication services over long distances and large areas. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of an architecture of a RoF-based passive distributed 5G micro base station system provided by the present invention.

[0019] Figure 2A schematic diagram of the downlink signal path of a RoF-based passive distributed 5G micro base station system provided by the present invention;

[0020] Figure 3 This is a schematic diagram of another architecture of a RoF-based passive distributed 5G micro base station system provided by the present invention;

[0021] Figure 4 This is another schematic diagram of the architecture of a RoF-based passive distributed 5G micro base station system provided by the present invention.

[0022] Figure 5 This is a schematic diagram of downlink EVM test results for a RoF-based passive distributed 5G micro base station system provided by the present invention.

[0023] Figure 6 This is a schematic diagram of downlink power testing for a RoF-based passive distributed 5G micro base station system provided by the present invention. Detailed Implementation

[0024] To better understand and implement this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0025] The terms “comprising” and “having” and any variations thereof in this invention are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device that includes a series of steps or modules is not necessarily limited to those steps or modules that are explicitly listed, but may include other steps or modules that are not explicitly listed or that are inherent to such processes, methods, products or devices.

[0026] The present invention discloses a passive distributed 5G micro base station system based on RoF (Radio-over-Fiber) technology, in which the remote FEM (Front End Module) achieves long-distance, high-bandwidth, and ultra-high information density 5G signal coverage without external power supply.

[0027] Traditional methods generate an empty carrier for uplink backhaul at the near end, using a single optical fiber for both transmission and reception. Both the near-end base station and the far-end FEM require combining the transmitted and received signals and using an optical circulator for signal separation, resulting in high isolation requirements, complex structure, and high cost. To address this, this application generates a tunable laser source for downlink transmission at the near-end base station, modulates the downlink RF signal to the optical frequency band, and transmits it to the far-end FEM via a first single-mode fiber. Simultaneously, a tunable laser source for uplink backhaul is generated at the far-end FEM, and the uplink signal is modulated to the optical frequency band and transmitted back to the near-end base station via a second single-mode fiber, achieving full-duplex communication for the far-end 5G micro base station system. This eliminates the need for optical signal combining and separation; the transmitted and received signals are transmitted separately using different optical fibers, and an empty carrier for uplink backhaul is generated at the far end. This results in high isolation, a simple structure, and low cost.

[0028] like Figure 1 As shown, this system includes a near-end base station, a far-end FEM, multimode fiber, and single-mode fiber. The near-end base station is used to process baseband signals, modulate the baseband signals to the optical frequency band, and generate energy signals. The multimode fiber is used to transmit energy signals between the near-end base station and the far-end FEM. The single-mode fiber is used to transmit radio frequency signals between the near-end base station and the far-end FEM. The far-end FEM is used to receive the energy signals transmitted through the multimode fiber, convert the energy signals into electrical energy for power supply, and receive the optical signals transmitted through the single-mode fiber, demodulating them into radio frequency signals.

[0029] By employing dual-fiber optical signal-energy simultaneous transmission technology, signal and energy are transmitted separately through single-mode and multi-mode optical fibers, achieving a passive design for the remote FEM that requires no external power supply. This simplifies system layout, reduces installation and maintenance costs, and improves signal isolation and transmission efficiency. It is suitable for high-information-density 5G network coverage, providing stable and high-speed 5G communication services over long distances and large areas. By combining optical signal-energy simultaneous transmission, RoF technology, photonics-wireless convergence, 5G micro base stations, and a passive distributed remote FEM system, long-distance, high-bandwidth, and ultra-high information-density 5G signal coverage is achieved. The remote FEM requires no external power supply, and the equipment is simple to install and deploy.

[0030] The near-end base station includes a near-end RRU, an optical modulator, an optical demodulator, an attenuator, and a circulator. The near-end RRU is connected to the first port of the circulator, the second port of the circulator is connected to the optical modulator through the attenuator, and the third port of the circulator is connected to the optical demodulator. A near-end RRU (Remote Radio Unit) is a terminal device in wireless communication technology, used to receive and transmit wireless signals to mobile terminals or other devices, thus enabling wireless communication. Since the near-end RRU operates in TDD mode, Tx and Rx signals share a single radio frequency port, which is separated by the circulator. The attenuator is connected to the second port of the circulator. When the near-end RRU outputs a downlink signal, the attenuator adjusts the signal strength to prevent the optical modulator from saturating due to excessively strong input signals. During the debugging and optimization of this system, adjusting the attenuator allows for precise control of the signal strength along the signal path, ensuring optimal system performance and stable, efficient operation. Proper use of the attenuator can optimize system performance, extend equipment lifespan, and improve signal transmission quality. The optical modulator is connected to the remote FEM via a first single-mode fiber, and the optical demodulator is connected to the optical demodulator via a second single-mode fiber.

[0031] The remote FEM includes an optical demodulator, an optical modulator, a first remote power amplifier, a second remote power amplifier, a first low-noise amplifier, a second low-noise amplifier, a filter, and a photovoltaic power supply. The optical demodulator is sequentially connected to the first remote power amplifier (remote PA1), the second remote amplifier (remote PA2), the transmit filter (Tx filter), and the transmit antenna. The optical modulator is sequentially connected to the second low-noise amplifier (remote LNA2), the first low-noise amplifier (remote LNA1), the receive filter, and the receive antenna.

[0032] The optical demodulators or modulators of the near-end base station and the far-end FEM respectively adopt RoF demodulators or RoF modulators with temperature compensation. Temperature compensation can ensure that the RoF demodulator and RoF modulator always operate at their optimal operating point, improving energy efficiency and overall system performance, reducing unnecessary energy loss, and increasing energy utilization.

[0033] By monitoring and adjusting operating parameters in real time, the system maintains stable equipment performance under different temperature conditions, improves signal quality, enhances system reliability, extends equipment life, and reduces maintenance costs, thereby ensuring that RoF-based passive distributed 5G micro base station systems can provide high-quality communication services under various environmental conditions.

[0034] The single-mode fiber includes a first single-mode fiber and a second single-mode fiber. The optical modulator of the near-end base station is connected to the optical demodulator of the far-end FEM via the first single-mode fiber; the optical modulator of the far-end FEM is connected to the optical demodulator of the near-end base station via the second single-mode fiber. Transmitting downlink signals via the first single-mode fiber and uplink signals via the second single-mode fiber completely avoids mutual interference between uplink and downlink signals, improving signal quality and stability. A separate fiber path effectively reduces echo and reflection problems, enhancing signal transmission integrity.

[0035] The first and second single-mode fibers can carry uplink and downlink data transmissions respectively, making the bandwidth utilization of each fiber more efficient. Independent fiber transmission reduces signal loss, increases transmission distance and signal quality, and achieves higher data transmission rates, meeting the high-capacity, high-speed 5G communication requirements and improving bandwidth and capacity. Using two single-mode fibers simplifies the design of optical modulators and demodulators, reducing complexity and lowering design and implementation difficulty. Independent uplink and downlink transmission paths make system debugging and troubleshooting more convenient, allowing for quick problem location and resolution, and facilitating system debugging and maintenance. A failure in one fiber will not affect the transmission of the other, improving the overall robustness and reliability of the system. The bandwidth and transmission distance of the uplink and downlink fibers can be flexibly configured according to different application requirements, meeting the communication requirements of different scenarios, facilitating future system expansion and upgrades. The number of fibers and transmission parameters can be increased or adjusted as needed, offering strong scalability.

[0036] The near-end base station is also equipped with a laser emitter that generates energy laser light, which is transmitted to the far-end FEM via multimode fiber. The emitter converts the laser light into an optical signal using an internal light source, such as a laser diode, for transmission through the fiber. The selection of the emitter requires that the effective transmission power exceed the power consumption requirements of the far-end radio frequency unit, where the effective transmission power Pl = emitter output power Po * photoelectric conversion efficiency. Transmitting the optical signal via multimode fiber means sending the modulated optical signal to the far-end device, achieving high-speed, long-distance data transmission. In the optical signal-energy co-transmission system, the emitter generates high-power laser light, which is transmitted to the far-end FEM via multimode fiber. The far-end device converts the light energy into electrical energy using photovoltaic cells for its own use. The emitter supports high-frequency signal transmission, adapting to the high bandwidth requirements of 5G networks, ensuring efficient system operation and coverage performance. The far-end FEM requires no external power supply, enabling long-distance, high-bandwidth, and ultra-high information density 5G signal coverage. The equipment is simple and deployment is straightforward.

[0037] Multimode fiber is used for energy transmission. With its larger core diameter and higher power transmission capability, multimode fiber can transmit high-power lasers, meeting the power supply needs of remote FEMs and related equipment. The high-power optical signal transmitted via multimode fiber is converted into electrical energy at the remote end using photovoltaic cells or photoelectric conversion devices, providing a stable power supply to the remote equipment. This enables centralized power supply at the remote end, eliminating the need for external power supplies, simplifying installation and maintenance, and efficiently converting transmitted optical energy into electrical energy, reducing energy loss. Using a single multimode fiber for energy transmission simplifies fiber optic cabling design in the system, reducing cabling complexity and cost. The energy transmission path is independent of the signal transmission path, avoiding interference from high-power optical signals to data transmission signals, improving the overall reliability and stability of the system. The optical power of the multimode fiber can be flexibly adjusted according to the power consumption requirements of the remote equipment, adapting to the power supply needs of different devices and application scenarios.

[0038] In uplink signal transmission, such as Figure 2 As shown, the remote FEM receives the uplink signal and modulates it to the optical frequency band to form an optical carrier signal. The optical carrier signal is transmitted to the near-end base station through the second single-mode fiber. The Rx antenna receives the wireless signal from the user terminal UE, converts it into a radio frequency signal, filters out out-of-band interference through the remote filter, amplifies it through the remote low-noise amplifier, and enters the optical modulator to modulate the radio frequency signal to the optical frequency band. It is then transmitted back to the near-end base station through the second single-mode fiber. At the near-end base station, the radio frequency signal is recovered by the optical demodulator, and then passes through the circulator to the Rx channel of the near-end RRU.

[0039] In downlink signal transmission, the near-end base station modulates the signal onto an optical carrier and transmits it through the first single-mode fiber to the far-end FEM. The far-end FEM demodulates the optical carrier signal into a radio frequency (RF) signal. The downlink signal output from the near-end RRU passes through a circulator and attenuator before being sent to an optical modulator to modulate the RF signal onto the optical frequency band. This signal is then extended through the first single-mode fiber and retracted to the far-end FEM. At the far-end FEM, the RF signal is recovered by an optical demodulator, amplified by a far-end power amplifier, filtered to remove out-of-band spurious signals, and finally output as a wireless signal through a Tx antenna.

[0040] Furthermore, this application can also be applied to FDD mode. For example... Figure 3 As shown, in FDD mode, the receiving antenna and transmitting antenna are set separately. The near-end RRU is connected to a duplexer to separate the Tx and Rx RF signals. The far-end FEM uses a Tx filter to filter out out-of-band spurious signals, avoiding interference with the Rx channel in the Rx band. At the same time, an Rx filter is used to filter out out-of-band interference and large signal interference in the Tx band, allowing the Rx channel to operate in the linear region. The operating principle of other parts is the same as in TDD mode.

[0041] Furthermore, in FDD mode, such as Figure 4As shown, the receiving and transmitting antennas share a common antenna. The near-end RRU is connected to a duplexer to separate the Tx and Rx RF signals. The far-end FEM uses a duplexer to combine the Tx and Rx signals into a single antenna. The Tx channel filters out out-of-band spurious signals, preventing interference with the Rx channel in the Rx band. Simultaneously, the Rx channel filters out out-of-band interference and large-signal interference in the Tx band, allowing the Rx channel to operate in the linear region. The operating principle of other parts is the same as in TDD mode.

[0042] 5G NR (5G New Radio, a global 5G standard based on a new OFDM air interface design) has TDD mode frequencies of 2515-2675MHz, 3300-3400MHz, 3400-3600MHz, and 4800-5000MHz (BW=100MHz / 160MHz), while the FDD mode frequency band is 703~803MHz (uplink 703~748MHz, downlink 758~803MHz, BW=30MHz / 45MHz). Different architectures can be selected for different frequency bands. Due to the large bandwidth of TDD mode, this mode has high data rates and high information density. The lower frequency band of FDD mode results in lower path loss, thus providing a wider wireless coverage area. In practical applications, the mode used can be determined according to specific communication requirements; this application does not impose any limitations.

[0043] The downlink peak rate was tested on this system. Figure 1 This represents the connection method for one transceiver channel in this system. In the verification experiment, four transceiver channels were built, namely one near-end RRU plus a four-channel remote FEM, realizing full-duplex communication with four transmit and four receive channels. The operating frequency was 4800MHz~5000MHz, the signal bandwidth was 100MHz, the peak rate was greater than 1000Mbps, and the EVM was less than 2.8%.

[0044] Figure 2 The network diagram for downlink peak rate testing shows that after UE1 connects to this system, it goes through the following link: server -> switch -> BBU -> RRU -> remote FEM -> wireless side -> UE1 to achieve downlink peak rate packet injection service.

[0045] The downlink signal output from the near-end RRU passes through a circulator and attenuator to the optical modulator, which modulates the radio frequency signal to the optical frequency band. The signal is then extended through the first single-mode fiber and recovered by the optical demodulator at the far-end FEM. The signal is then amplified by the far-end PA, filtered to remove out-of-band spurious signals, and finally output as a wireless signal through the Tx antenna.

[0046] During uplink signal transmission, the Rx antenna receives the UE's wireless signal, converts it into a radio frequency signal, filters out out-of-band interference, amplifies it through the remote LNA, and sends it to the optical modulator to modulate the radio frequency signal onto the optical frequency band. Then, it is transmitted back to the near end through single-mode fiber 2. At the near end, the radio frequency signal is recovered by the optical demodulator, and then sent to the RRU's Rx channel through the circulator.

[0047]

[0048] The downlink peak rate test results are shown below:

[0049] 10.00-11.00 sec 115MBytes 966Mblts / sec

[0050] 11.00-12.00 sec 124MBytes 1.04Gblts / sec

[0051] 12.00-13.00 sec 122MBytes 1.02Gblts / sec

[0052] 13.00-14.00 sec 119MBytes 998Mblts / sec

[0053] 14.00-15.00 sec 117MBytes 983Mblts / sec

[0054] 15.00-16.00 sec 112MBytes 942Mblts / sec

[0055] 16.00-17.00 sec 107MBytes 896Mblts / sec

[0056] 17.00-18.00 sec 131MBytes 1.10Gblts / sec

[0057] 18.00-19.00 sec 97.4MBytes 817Mblts / sec

[0058] 19.00-20.00 sec 123MBytes 1.01Gblts / sec

[0059] 20.00-21.00 sec 97.1MBytes 832Mblts / sec

[0060] 21.00-22.00 sec 126MBytes 1.06Gblts / sec

[0061] 22.00-23.00 sec 137MBytes 1.15Gblts / sec

[0062] 23.00-24.00 sec 124MBytes 1.04Gblts / sec

[0063] 24.00-25.00 sec 123MBytes 1.03Gblts / sec

[0064] 25.00-26.00 sec 134MBytes 1.12Gblts / sec

[0065] 26.00-27.00 sec 127MBytes 1.06Gblts / sec

[0066] 27.00-28.00 sec 116MBytes 973Mblts / sec

[0067] 28.00-29.00 sec 126MBytes 1.06Gblts / sec

[0068] 29.00-30.00 sec 112MBytes 934Mblts / sec

[0069] 30.00-31.00 sec 105MBytes 882Mblts / sec

[0070] 31.00-32.00 sec 137MBytes 1.15Gblts / sec

[0071] 32.00-33.00 sec 137MBytes 1.15Gblts / sec

[0072] 33.00-34.00 sec 139MBytes 1.17Gblts / sec

[0073] 34.00-35.00 sec 116MBytes 970Mblts / sec

[0074] 35.00-36.00 sec 108MBytes 874Mblts / sec

[0075] 36.00-37.00 sec 106MBytes 920Mblts / sec

[0076] As can be seen from the test results above, the peak rate reached 1Gbps.

[0077] In the downlink power test, it can be seen that, as Figure 6 As shown, the transmission power is not less than 24dBm, which is 250mW. (For example...) Figure 5 As shown, the downlink EVM test results are: EVM < 2.8%.

[0078] The relationship between EVM and input energy optical power is shown in the table below. It can be seen that EVM is independent of changes in input energy optical power.

[0079] Table 1 Relationship between EVM and Input Energy Optical Power

[0080]

[0081] The power transmission efficiency test results for 1km optical fiber are as follows, showing that the power transmission efficiency of 1km optical fiber is >10.3%.

[0082] Table 2 shows the power transmission efficiency test results for 1km optical fiber:

[0083] Table 2. Power Transmission Efficiency Test Results for 1km Fiber Optics

[0084]

[0085] This application employs dual-fiber optical signal and energy simultaneous transmission technology, transmitting uplink and downlink signals separately through single-mode optical fibers and efficiently transmitting energy through a single multimode optical fiber. This achieves a passive design for the remote FEM that does not require external power supply, simplifies system layout, reduces installation and maintenance costs, and improves signal isolation and transmission efficiency. It is suitable for 5G network coverage with high information density and can provide stable and high-speed 5G communication services over long distances and large areas.

[0086] The system's processing method can be referred to the description of the above method, and will not be repeated here.

[0087] The present invention also provides an apparatus, which may include: a memory storing executable program code;

[0088] A processor coupled to memory;

[0089] A transceiver used to communicate with other devices or communication networks and to receive or send network messages;

[0090] A bus used to connect memory, processor, and transceiver for internal communication.

[0091] The transceiver receives messages transmitted over the network and passes them to the processor via the bus. The processor then calls the executable program code stored in the memory via the bus to process the messages and passes the processing results back to the transceiver via the bus for transmission, thereby realizing the system provided in this application embodiment.

[0092] This application also provides a non-transitory machine-readable storage medium storing an executable program, which, when run by a processor, causes the processor to execute the system provided in the above embodiments.

[0093] This invention discloses a computer-readable storage medium storing a computer program for electronic data interchange, wherein the computer program causes a computer to execute the described system.

[0094] This invention discloses a computer program product including a non-transitory computer-readable storage medium storing a computer program operable to cause a computer to execute a described system.

[0095] The embodiments described above are merely illustrative. The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical modules; that is, they may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0096] Through the detailed description of the above embodiments, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, including read-only memory (ROM), random access memory (RAM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), one-time programmable read-only memory (OTPROM), electrically-Erasable Programmable Read-Only Memory (EEPROM), compact disc read-only memory (CD-ROM) or other optical disc storage, disk storage, magnetic tape storage, or any other computer-readable medium that can be used to carry or store data.

[0097] Finally, it should be noted that the embodiments disclosed in this invention are merely preferred embodiments of this invention and are only used to illustrate the technical solutions of this invention, not to limit it. Although this invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this invention.

Claims

1. A RoF-based passive distributed 5G micro base station system, characterized in that, include: Near-end base stations are used to process baseband signals and modulate them into optical frequency bands; And generate energy signals; Multimode fiber is used to transmit energy signals between the near-end base station and the far-end FEM; Single-mode fiber is used to transmit radio frequency signals between the near-end base station and the far-end FEM. The single-mode fiber includes a first single-mode fiber for transmitting downlink optical signals to the remote FEM and a second single-mode fiber for transmitting uplink optical signals returned from the remote FEM to the near-end base station. The optical modulator of the near-end base station is connected to the optical demodulator of the remote FEM through the first single-mode fiber. The optical modulator of the remote FEM is connected to the optical demodulator of the near-end base station via a second single-mode optical fiber. The remote FEM is used to receive energy signals transmitted through multimode optical fiber, convert the energy signals into electrical energy for power supply, and receive downlink optical signals transmitted through the first single-mode optical fiber, demodulating them into radio frequency signals. The remote FEM includes an optical demodulator, an optical modulator, a first remote power amplifier, a second remote power amplifier, a second low-noise amplifier, a first low-noise amplifier, a transmitting filter, a receiving filter, and a photovoltaic power supply; the optical demodulator is sequentially connected to the first remote power amplifier, the second remote power amplifier, the transmitting filter, and the transmitting antenna; the optical modulator is sequentially connected to the second low-noise amplifier, the first low-noise amplifier, the receiving filter, and the receiving antenna. The near-end base station is also equipped with a light emitter, which generates an energy signal, and the energy signal is transmitted to the photovoltaic power source of the far-end FEM through a multimode optical fiber. In uplink signal transmission, the remote FEM receives the uplink signal and modulates it to the optical frequency band to form an uplink optical signal, which is then transmitted to the near-end base station through a second single-mode optical fiber. In downlink signal transmission, the near-end base station receives the downlink signal and modulates it to the optical frequency band to form a downlink optical signal. The downlink optical signal is transmitted to the far-end FEM through the first single-mode optical fiber, and the far-end FEM demodulates the downlink optical signal into a radio frequency signal.

2. The RoF-based passive distributed 5G micro base station system according to claim 1, characterized in that, The near-end base station includes a near-end RRU, an optical modulator, an optical demodulator, an attenuator, and a circulator; the near-end RRU is connected to the first port of the circulator, the second port of the circulator is connected to the optical modulator through the attenuator, and the third port of the circulator is connected to the optical demodulator.

3. A RoF-based passive distributed 5G micro base station system according to claim 2, characterized in that, The optical demodulator or optical modulator is a RoF demodulator or RoF modulator with temperature compensation, respectively.

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