Digital optical fiber repeater system

Abstract

The invention discloses a digital optical fiber repeater system which comprises an access unit and a far-end unit. Wherein the access unit comprises a TDD (Time Division Duplexing) radio frequency signal processing subsystem, an FDD (Frequency Division Duplexing) radio frequency signal processing subsystem, a multi-channel radio frequency transceiver Transceiver subsystem, an FPGA (Field Programmable Gate Array) processing subsystem, a signal coupler, a signal characteristic analysis and / or time domain synchronization module and an MCU (Microprogrammed Control Unit) core main control module; and the far-end unit comprises an FPGA (Field Programmable Gate Array) processing subsystem, a multi-channel radio frequency transceiver Transsceiver subsystem, a TDD (Time Division Duplexing) radio frequency signal processing subsystem, an FDD (Frequency Division Duplexing) radio frequency signal processing subsystem and an MCU (Microprogrammed Control Unit) core main control module. By adopting the technical scheme of the invention, the signal of the whole bandwidth is not amplified blindly, no prior information is needed, and the characteristic information of the signal system, the frequency band, the frequency point, the bandwidth and the carrier number of actual work can be detected and analyzed in a real-time and self-adaptive manner.

Description

Technical Field

[0001] The invention belongs to the technical field of mobile communications, and in particular relates to a digital optical fiber repeater system. Background Art

[0002] The digital fiber optic repeater consists of a radio access unit and a remote unit, such as Figure 1 As shown. The RF access unit converts the downlink RF signals of the sources such as 4GLTE and 5G NR into digital fiber repeater system through wired coupling, converts them into digital signals, and then transmits them to the remote unit after photoelectric conversion into optical signals. At the same time, the digital signals uploaded by the remote unit are converted into uplink RF signals and transmitted back to the source through wired means. The RF access unit needs to support remote monitoring and management functions and centralized upgrade functions for its remote units. The remote unit converts the digital signals sent by the RF access unit into RF signals to achieve 4G and 5G wireless coverage; at the same time, it converts the uplink RF signals received wirelessly into digital signals and transmits them to the access unit. The digital fiber repeater should support chain networking, star networking and star-chain combined networking. The RF access unit and the remote unit support point-to-multipoint star networking. One RF access unit can connect at least 4 remote units in a star shape. One remote unit should support chain connection of at least 4 remote units. Optical fiber transmission is used between the RF access unit and the remote unit, and the maximum pull-out distance should be greater than 10km.

[0003] Digital repeater is a low-cost indoor and outdoor coverage product that can expand the service scope and eliminate coverage blind spots, such as signal blind spots formed by obstacles such as mountains, buildings, and trees. It can enhance the field strength in suburban areas, expand the coverage of suburban stations, and be set up along highways to enhance coverage efficiency. It can also solve indoor coverage problems, such as signal attenuation blind spots in large buildings, underground shopping malls, tunnels, and other attenuation signal blind spots. In addition, the signals of idle base stations can be led to the coverage area of ​​busy base stations to achieve busyness relief.

[0004] Patent No. CN1719756B "Implementation Method of Mobile Communication Digital Fiber Optic Repeater System" discloses: A method for implementing a mobile communication digital fiber optic repeater system, which includes a near-end relay part and a far-end part. Both the near-end relay and the far-end machine include a radio frequency receiving and transmitting subsystem; an up-conversion and down-conversion subsystem, an ADC / DAC subsystem, a baseband processing subsystem, a fiber optic transceiver, a monitoring subsystem and a power supply subsystem. The near-end relay machine down-converts the received base station downlink signal to a baseband I / Q signal or a low intermediate frequency signal, converts it to a digital signal through the ADC, and packages it into serial data according to a certain frame format, and then sends it to the far-end machine through the fiber optic transceiver and the optical fiber, deframes it through the baseband processing unit, restores the I / Q or low intermediate frequency signal, converts it to an analog signal through the DAC, and then up-converts it to radio frequency, and transmits it through the transmitting subsystem; the far-end machine sends the received mobile terminal uplink signal to the base station receiving end through the above inverse process.

[0005] This patent adopts traditional signal processing methods, including a transceiver chip that uses an ADC / DAC technology solution with a digital intermediate frequency architecture. Therefore, the RF needs to perform analog down-conversion and analog up-conversion processing to meet the technical requirements of the intermediate frequency sampling of the transceiver chip.

[0006] The digital IF architecture transceiver directly converts between analog and digital signals at the IF, and uses digital technology to achieve signal filtering and modulation and demodulation. In the 1990s, the rapid development of ADC and DAC technology laid the foundation for the application of digital IF transceivers; in the late 1990s, broadband IF sampling converters began to be available on the market, and many high-performance receivers began to use IF sampling to simplify radio design and improve performance. At the digital IF receiving end, the ADC digitizes the IF signal, and then enters the digital down-conversion (DDC), and converts the IF signal to baseband through extraction filtering and down-conversion. At the transmitting end, the baseband digital signal is sent to the digital up-conversion (DUC) for interpolation filtering and up-conversion, and then the DAC converts the digital IF signal into an analog signal for output.

[0007] With the evolution and development of technology, the zero-IF architecture transceiver has also matured. The RF signal does not need to go through the IF stage to directly enter the I / Q demodulation and transform to the baseband signal. No IF signal is generated in the middle, and there are no components such as IF amplifiers and IF filters. Therefore, the architecture is relatively simple, the system size is smaller, and the cost and power consumption are lower. The advantage of zero IF is that it requires fewer devices, is easy to integrate, and has good performance. Except that DC cannot be eliminated in principle, there are almost no disadvantages. Transceivers with zero IF architecture and low IF architecture currently dominate the market due to their small size, low power consumption, low cost, easy integration, and superior performance, such as the GC080X RF integrated transceiver series products produced by Dixin Technology.

[0008] At the same time, the zero-IF architecture transceiver also further integrates digital signal processing algorithms, such as DDC, DUC, CFR and DPD, which greatly reduces the requirements for subsequent algorithm processing chips, such as FPGA, MCU and DSP chips, further reducing system costs.

[0009] In addition, the solution of patent number CN1719756B "Implementation method of mobile communication digital optical fiber repeater system" directly amplifies the signal of the entire frequency band, which is also a common processing method of traditional digital optical fiber repeaters. Traditional methods cannot perform efficient signal amplification processing for useful signal frequency points and frequency bands. On the one hand, energy cannot be concentrated within the bandwidth of useful signals for signal amplification; on the other hand, invalid signals outside the useful signal bandwidth are amplified, and useful energy is wasted. At the same time, noise signals within the non-working bandwidth are amplified, which interferes with useful signals.

[0010] Take China Mobile's 4G and 5G communication standards, frequency bands, and effective working bandwidths as an example, as shown in Table 1.

[0011]

[0012] China Mobile 4G, the specific frequency bands are 900MHz, 1800MHz and 2300MHz, including both TD-LTE and FDD-LTE standards.

[0013] 4G LTE supports different carrier bandwidth configurations. In actual work, it can be configured as: 1.4MHz, 3MHz, 5MHz, 10MHz, 15MHz, 20MHz, etc. These bandwidth configurations determine the system's occupancy in the spectrum and data transmission capacity. Different bandwidth configurations are suitable for different application scenarios and requirements to provide different coverage and transmission capabilities. The bandwidth configuration of LTE describes the different characteristics and usage of its carrier frequency. Among them, 20MHz is the largest bandwidth configuration of LTE without carrier aggregation.

[0014] Similarly, 5G NR bandwidth configuration supports multiple bandwidth options to meet different network requirements and deployment scenarios.

[0015] 5G NR technology allows operators to flexibly configure channel bandwidth based on factors such as network coverage, capacity requirements and cost-effectiveness. According to different deployment scenarios and technical requirements, 5G NR supports a variety of channel bandwidth options from 5MHz to 100MHz. This flexibility enables operators to make fine adjustments based on specific circumstances to optimize network performance and user experience.

[0016] Typical bandwidth configurations for 5G NR include: 5MHz, 10MHz, 15MHz, 20MHz, 30MHz, 50MHz, 60MHz, 80MHz, and 100MHz. In scenarios that do not involve carrier aggregation, 100MHz is the most typical bandwidth configuration for 5G NR.

[0017] The traditional signal processing method of wireless repeater requires obtaining some prior information of the wireless repeater when the operator (such as China Mobile) is known in advance:

[0018] Which standards need to be supported, such as single 5G, or 4G and 5G dual-mode;

[0019] Specific frequency band, such as: 2300MHz

[0020] In the case of a single carrier, the maximum carrier configuration bandwidth, such as 20MHz bandwidth for single-carrier 4G LTE, will no longer distinguish between configurations with signal bandwidths lower than 20MHz, and uniformly process signals for the maximum carrier configuration bandwidth of 20MHz; if the single-carrier 5GNR has a bandwidth of 100MHz, signal processing will be uniformly performed for the maximum carrier configuration bandwidth of 100MHz within the frequency band.

[0021] Under the same standard, in the case of multi-carrier (M carriers) configuration, the maximum carrier configuration bandwidth (Max_BW) is defined. That is, under the same standard, the maximum bandwidth to be processed is: M*Max_BW.

[0022] From the perspective of maximum frequency band configuration, China Mobile's 2600MHz band has a total bandwidth of 160MHz, of which 2515-2615MHz is commonly used for the 100MHz 5G NR band; from 2615MHz to 2675MHz, there is a total of 60MHz, which can support a maximum of 3 20MHz LTE carriers.

[0023] The traditional signal processing method of digital repeaters for 5G NR is: no matter how large the bandwidth of 5G NR is configured in actual work, the signal amplification processing is uniformly performed on the 100MHz bandwidth, because in actual work, in order to reduce interference, the actual configuration may be 80MHz of the 5G NR bandwidth of the 100MHz total bandwidth between 2515-2615MHz. On the one hand, the energy cannot be concentrated in the bandwidth of the useful signal (80MHz bandwidth) for signal amplification; on the other hand, the redundant 20MHz invalid signal is amplified, and the useful energy is wasted. At the same time, the noise signal in the non-working bandwidth (such as the non-working 20MHz bandwidth) is amplified, which also interferes with the actual working signal.

[0024] The traditional processing method for 4G LTE is: regardless of the actual operation, how many carriers are configured for 4G LTE, and how much bandwidth is configured for LTE, the signal amplification processing is uniformly performed on 60MHz. On the one hand, the energy cannot be concentrated in the bandwidth of the useful signal for signal amplification; on the other hand, the energy is wasted, and the noise signal in the non-working bandwidth (such as the non-working 20MHz bandwidth) is amplified, which also interferes with the actual working signal. Especially for this 60MHz bandwidth, LTE with three carriers is rarely configured, and even if there are two LTE carriers, each carrier is not necessarily configured to 20MHz. It is also necessary to combine the actual application scenario, and the LTE working bandwidth needs to be appropriately changed. Therefore, directly amplifying the signal of the 60MHz bandwidth brings a lot of energy waste, and also amplifies the noise signal in the non-working bandwidth. Summary of the invention

[0025] The technical problem to be solved by the present invention is to provide a digital optical fiber repeater system, which does not blindly amplify the signal of the entire bandwidth, nor does it require any prior information (communication standard, frequency band, bandwidth, number of carriers, etc.). By adding an intelligent analysis module in the system: a signal feature analysis module, the feature information of the signal standard, frequency band, frequency point, bandwidth, number of carriers, etc. that is actually working at present can be detected and analyzed in real time and adaptively. Combined with the signal feature information obtained by the detection, the uplink and downlink signals are efficiently amplified and processed for a specific standard, a specific frequency point, a specific bandwidth, and a specific number of carriers, thereby reducing energy waste and greatly reducing costs. In addition, for FDD standard (FDD: Frequency Division Duplexing) signals, it is only necessary to add a signal feature analysis module. For TDD standard (TDD: Time Division Duplexing) signals, the time domain synchronization function can be integrated into the signal feature analysis module to complete two different functions, further reducing costs.

[0026] To achieve the above object, the present invention adopts the following technical solution:

[0027] A digital optical fiber repeater system, which is an FDD digital optical fiber repeater system, comprises: an access unit and a remote unit; wherein the access unit comprises: an uplink and downlink radio frequency signal processing subsystem, a radio frequency transceiver subsystem, an FPGA processing subsystem, a signal coupler, a signal feature analysis module and an MCU core main control module; the remote unit comprises: an FPGA processing subsystem, a radio frequency transceiver subsystem, an uplink and downlink radio frequency signal processing subsystem connected in sequence, the FPGA processing subsystem, the radio frequency transceiver subsystem, and the uplink and downlink radio frequency signal processing subsystems are respectively connected to the MCU core main control module; the uplink and downlink radio frequency signal processing subsystems, the radio frequency transceiver subsystem, and the FPGA processing subsystem are connected in sequence to form a main link for uplink and downlink signal processing of the access unit; the access unit and the RRU signal source realize signal transceiving communication with the RRU by means of wired signal coupling; wherein,

[0028] The output of the FPGA processing subsystem is the baseband IQ signal after protocol conversion, the control word of optical fiber link synchronization and data conversion, and the control word of signal characteristics, which are input to the remote unit to realize signal transmission and communication; among which, the control word of signal characteristics is: the MCU core main control module of the access unit processes the format, frequency band, frequency point, bandwidth, and carrier number information of the effective working signal to obtain the specific frequency band, frequency point, center frequency point, and bandwidth that need to be amplified for the effective working signal;

[0029] The signal characteristic analysis module couples the RF signal from the RRU source through a coupler, performs RF down-conversion, analog conversion, digital down-conversion and baseband signal processing to obtain the characteristics of the baseband signal, including: the communication standard of the signal, RSRP, SINR, the frequency point information of the signal, the frequency band information of the signal, the bandwidth of the signal, and the number of carriers;

[0030] Among them, baseband signal processing includes:

[0031] (1) The digital signal processor (DSP) further processes the converted digital signal, including digital filtering, synchronization, equalization, etc.

[0032] (2) It also includes channel estimation and decoding of error correction coding to recover the original data.

[0033] (3) Baseband demodulation: In the digital signal processing stage, the baseband demodulator demodulates the signal according to the modulation method (such as QAM, PSK, etc.). The demodulation process includes extracting the amplitude, frequency or phase information of the signal to restore the original baseband data.

[0034] (4) Data decoding and output: The demodulated baseband data is decoded to restore the original user information or control signal. Decoding includes steps such as deinterleaving, descrambling, and decryption. Finally, the decoded data is output to the feature analysis module.

[0035] Preferably, the signal feature analysis module determines the valid signal of 4G LTE including:

[0036] 1. Perform baseband demodulation on the full-band 4G LTE signals to obtain the signal characteristics of the corresponding signals: frequency band, frequency point, bandwidth, number of carriers, RSRP (Reference Signal Receiving Power), and SINR. Among them, only the demodulated signal can obtain RSRP and SINR information;

[0037] 2. Set the signal thresholds Th_RSRP_LTE and Th_SINR_LTE. If RSRP ≥ Th_RSRP_LTE and SINR ≥ Th_SINR_LTE, it is considered as a valid working signal.

[0038] 3. In conjunction with the operator, determine the final effective working signal and its signal characteristics;

[0039] The signal feature analysis module determines the valid signal of 5G NR, including the following processing steps:

[0040] 1. Demodulate the 5G NR signals of the full frequency band to obtain the signal characteristics of the corresponding signals: frequency band, frequency point, bandwidth, number of carriers, RSRP, and SINR;

[0041] 2. Set the signal thresholds Th_RSRP_NR and Th_SINR_NR. RSRP ≥ Th_RSRP_NR and SINR ≥ Th_SINR_NR are considered valid working signals.

[0042] 3. Combined with the specific operator, determine the final effective working signal and its signal characteristics.

[0043] Preferably, the FPGA processing subsystem of the remote unit receives the control words for baseband IQ signal optical fiber link synchronization and data conversion and the control words for signal characteristics from the access unit, performs CPRI decapsulation processing, encodes the IQ data into a format adapted to the RF transceiver subsystem, and inputs it to the RF transceiver subsystem; at the same time, the FPGA processing subsystem transmits the control words for signal characteristics obtained by decapsulation to the MCU core main control module of the remote unit, and the MCU core main control module configures parameters of the FPGA processing subsystem, the RF transceiver subsystem and the uplink and downlink RF signal processing subsystems of the remote unit, and performs signal filtering and amplification processing on the effective working signals.

[0044] The present invention also provides a digital optical fiber repeater system, which is a TDD digital optical fiber repeater system, comprising: an access unit and a remote unit; wherein the access unit comprises: an uplink and downlink radio frequency signal processing subsystem, a radio frequency transceiver subsystem, an FPGA processing subsystem, a signal coupler, a signal feature analysis and time domain synchronization module and an MCU core main control module; the remote unit comprises: an FPGA processing subsystem, a radio frequency transceiver subsystem, an uplink and downlink radio frequency signal processing subsystem connected in sequence, the FPGA processing subsystem, the radio frequency transceiver subsystem, and the uplink and downlink radio frequency signal processing subsystems are respectively connected to the MCU core main control module; the uplink and downlink radio frequency signal processing subsystems, the radio frequency transceiver The subsystem and the FPGA processing subsystem are connected in sequence to form the main link of the uplink and downlink signal processing of the access unit; the access unit and the RRU source realize the signal receiving and sending communication with the RRU through the wired signal coupling method; the FPGA processing subsystem outputs the control words of the baseband IQ signal optical fiber link synchronization and data conversion after protocol conversion, the control words of the signal characteristics and the control words of the time domain synchronization, which are input to the remote unit of the digital repeater to realize signal transmission and communication; among which, the control words of the signal characteristics are: the MCU core main control module of the access unit processes the data of the format, frequency band, frequency point, bandwidth and number of carriers of the effective working signal to obtain the specific frequency band, frequency point, center frequency point and bandwidth that need to be amplified for the effective working signal; the control words of the time domain synchronization are: the control word information of the time domain synchronization-time slot switching information.

[0045] Preferably, the FPGA processing subsystem of the remote unit receives the control words for baseband IQ signal optical fiber link synchronization and data conversion, signal characteristic control words and time domain synchronization control words from the access unit, performs CPRI decapsulation processing, encodes the IQ data into a format adapted to the RF transceiver subsystem, and inputs it to the RF transceiver subsystem; at the same time, the FPGA processing subsystem transmits the signal characteristic control words and time domain synchronization control words obtained by decapsulation to the MCU core main control module of the remote unit, and the MCU core main control module performs parameter configuration, time slot switching operations, and signal filtering and amplification processing on the effective working signals for the FPGA processing subsystem, RF transceiver subsystem and uplink and downlink RF signal processing subsystems of the remote unit.

[0046] The present invention introduces a signal characteristic analysis module, which does not blindly amplify the signal of the entire bandwidth, nor does it require any prior information (standard, frequency band, bandwidth, number of carriers, etc.), and can detect and analyze the characteristic information of the actual working signal standard, frequency band, frequency point, bandwidth, number of carriers, etc. in real time and adaptively, and then for a specific standard, specific frequency point, specific bandwidth, specific number of carriers, efficient uplink and downlink signal amplification processing is carried out, which reduces energy waste and greatly reduces costs. The same set of circuits supports full-band, multi-standard signal processing, covering 4G LTE and 5GNR, and can also be expanded upward to 6G, and derived downward to 3G and 2G, and can be expanded and derived as needed to adapt to more application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0048] Figure 1 This is a schematic diagram of the structure of an access unit of a digital optical fiber repeater system according to Embodiment 1 of the present invention;

[0049] Figure 2 This is a schematic diagram of the structure of a remote unit of a digital optical fiber repeater system according to Embodiment 1 of the present invention;

[0050] Figure 3 This is a schematic diagram of the structure of an access unit of an FDD-based digital optical fiber repeater system according to Embodiment 2 of the present invention;

[0051] Figure 4 This is a schematic diagram of the structure of a remote unit of an FDD-based digital optical fiber repeater system according to Embodiment 2 of the present invention;

[0052] Figure 5 This is a schematic diagram of the structure of an access unit of a TDD-standard digital optical fiber repeater system according to Embodiment 2 of the present invention. DETAILED DESCRIPTION

[0053] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0055] Embodiment 1:

[0056] The embodiment of the present invention provides a digital optical fiber repeater system, which supports FDD and TDD multi-standards and multi-frequency bands, and includes an access unit and a remote unit.

[0057] like Figure 1 As shown, the access unit includes: a TDD radio frequency signal processing subsystem, an FDD radio frequency signal processing subsystem, a multi-channel radio frequency transceiver subsystem, an FPGA processing subsystem, a signal coupler, a signal feature analysis and / or time domain synchronization module, and an MCU core main control module.

[0058] Among them, the RF transceiver subsystem adopts a multi-channel RF transceiver. These channels can process TDD and FDD standards in parallel, or all of them can be used for TDD signal processing, or all of them can be used for FDD signal processing. The TDD RF signal processing subsystem specializes in filtering and amplifying RF signals of the TDD standard, and the FDD RF signal processing subsystem specializes in filtering and amplifying RF signals of the FDD standard. The FPGA processing subsystem uniformly encapsulates the FDD and TDD IQ data output by the multi-channel RF transceiver subsystem, the time domain synchronization information output by the signal feature analysis and time domain synchronization module, and the frequency and bandwidth information of the effective working signal output by the MCU core main control module, and transmits them to the remote unit of the digital repeater. The FPGA processing subsystem performs protocol encapsulation and needs to process three types of data: the digital IQ signal of the multi-channel RF transceiver subsystem (including TDD and FDD IQ signals), the frequency band and bandwidth information of the effective working signal calculated by the MCU core control module, and the signal feature analysis and time slot switching information output by the time domain synchronization module.

[0059] like Figure 2 As shown, the remote unit includes: FPGA processing subsystem, multi-channel RF transceiver subsystem, TDD RF signal processing subsystem, FDD RF signal processing subsystem and MCU core main control module.

[0060] Among them, the FPGA processing subsystem of the remote unit of the digital repeater station receives the baseband IQ signal and control word from the access unit, performs CPRI decapsulation processing, encodes the IQ data into a format adapted by the RF transceiver subsystem, and inputs it to the RF transceiver subsystem; at the same time, the FPGA processing subsystem decapsulates the control word obtained: the specific frequency, bandwidth and time slot switching information of the effective working signal, etc., and transmits this information to the MCU core main control module of the remote unit. The MCU core main control module configures the parameters of the FPGA processing subsystem, the RF transceiver subsystem and the uplink and downlink RF signal processing subsystems to filter, amplify, and switch time slots of the effective working signal.

[0061] The functions of the multi-channel RF transceiver subsystem, TDD RF signal processing subsystem, and FDD RF signal processing subsystem of the remote unit of the digital repeater are the same as those of the access unit and will not be repeated here.

[0062] The digital fiber repeater system supports multiple modes, covering 4G LTE and 5G NR. Of course, it can also be expanded upward to 6G and derived downward to 3G and 2G. It can be expanded and derived as needed to adapt to more application scenarios.

[0063] This digital fiber repeater system supports multiple frequencies. Taking China Mobile as an example, it can support 700MHz 5G NR, 900MHz 4G LTE and re-farming to 5G NR, 1800MHz 4G LTE, 2300MHz 4G LTE, 2600MHz 4G LTE and 5G NR, as well as 5G NR expanded to 4.9GHz, etc.

[0064] Embodiment 2:

[0065] The embodiment of the present invention provides a digital optical fiber repeater system, comprising: an access unit and a remote unit.

[0066] For FDD digital optical fiber repeater system, such as Figure 3 As shown, the access unit includes: an uplink and downlink RF signal processing subsystem, a RF transceiver subsystem, an FPGA processing subsystem, a signal coupler, a signal feature analysis module and an MCU core main control module; wherein the uplink and downlink RF signal processing subsystem, the RF transceiver subsystem and the FPGA processing subsystem are sequentially connected to form a main link for uplink and downlink signal processing of the access unit of the digital repeater; the access unit and the RRU signal source realize signal transceiver communication with the RRU through wired signal coupling.

[0067] The input and output of the uplink and downlink RF signal processing subsystems are both high-frequency RF signals, such as 2300MHz RF signals; the FPGA processing subsystem outputs the baseband IQ signal after protocol conversion, the control word for optical fiber link synchronization and data conversion, and the control word for signal characteristics, which are input into the remote unit of the digital repeater to achieve signal transmission and communication; among them, the control word for signal characteristics refers to: the MCU core main control module of the access unit processes data on the format, frequency band, frequency point, bandwidth, number of carriers and other information of the effective working signal to obtain the specific frequency band, frequency point, center frequency point and bandwidth required to amplify the effective working signal.

[0068] The signal coupler, signal feature analysis module and MCU core main control module are connected in sequence to form the core functions of the signal feature analysis link and the control signal processing main link.

[0069] The signal feature analysis module couples the RF signal from the RRU source through a coupler, performs RF down-conversion, analog conversion, digital down-conversion and baseband signal processing, and obtains some characteristics of the baseband signal, including: the communication standard of the signal, RSRP (Reference Signal Receiving Power), SINR (Signal to Interference plus Noise Ratio), signal frequency information, signal frequency band information, signal bandwidth, carrier number information, etc. The signal feature analysis module is full-band and full-standard, and can identify signal characteristics of all standards and all frequency bands.

[0070] The signal feature analysis module determines the valid signal. The specific process includes the 4G LTE processing process:

[0071] 1. Perform baseband demodulation on the full-band 4G LTE signals to obtain the signal characteristics of the corresponding signals: frequency band, frequency point, bandwidth, number of carriers, RSRP, and SINR. Among them, only the demodulated signals can obtain RSRP and SINR information;

[0072] 2. Set the signal thresholds Th_RSRP_LTE and Th_SINR_LTE. RSRP ≥ Th_RSRP_LTE and SINR ≥ Th_SINR_LTE are considered as valid working signals. The detection of whether it is a valid signal generally needs to be performed multiple times, such as 5-10 times. It is considered as a valid working signal only when the number of times that meet the requirements is greater than 80%;

[0073] 3. Combined with the specific operator (for example, if the application scenario is China Mobile, the effective working signal of China Mobile is recorded), determine the final effective working signal and its signal characteristics: frequency band, frequency point, bandwidth, and number of carriers;

[0074] The signal characteristics are output to the MCU core main control module, which controls the subsequent signal processing.

[0075] The signal feature analysis module determines the valid signal. The specific process includes the 5G NR processing process:

[0076] 1. Demodulate the 5G NR signals of the full frequency band to obtain the signal characteristics of the corresponding signals: frequency band, frequency point, bandwidth, number of carriers, RSRP, and SINR;

[0077] 2. Set the signal thresholds Th_RSRP_NR and Th_SINR_NR. RSRP ≥ Th_RSRP_NR and SINR ≥ Th_SINR_NR are considered as valid working signals. The detection of whether it is a valid signal generally needs to be performed multiple times, such as 5-10 times. It is considered as a valid working signal only when the number of times that meet the requirements is greater than 80%;

[0078] 3. Combined with the specific operator (for example, if the application scenario is China Mobile, the effective working signal of China Mobile is recorded), determine the final effective working signal and its signal characteristics: frequency band, frequency point, bandwidth, and number of carriers;

[0079] The signal characteristics are output to the MCU core main control module, which controls the subsequent signal processing.

[0080] The MCU core main control module obtains the effective signal and its signal characteristics: frequency band, frequency point, bandwidth, number of carriers, calculates the frequency band and bandwidth of the signal to be processed, and the signal processing requirements (such as signal filtering requirements, power amplification requirements, delay requirements, etc.), and sends instructions to the uplink and downlink RF signal processing subsystems, RF transceiver subsystems, and FPGA processing subsystems, so as to process the effective working signal frequency band and bandwidth in a targeted manner, including: signal filtering, signal amplification, etc.

[0081] The uplink and downlink RF signal processing subsystem includes the following two key functions, one of which is: the uplink and downlink RF signal processing subsystem receives the RF signal from the duplexer at the donor end, which is generally a high-frequency band, such as China Mobile's 2600MHz RF signal, and obtains a moderately filtered and amplified high-frequency signal through a low-noise amplifier LNA, which is convenient for the subsequent RF transceiver subsystem to process. This solution directly adopts a zero intermediate frequency RF transceiver solution.

[0082] The traditional solution uses a digital intermediate frequency transceiver solution. The high-frequency RF signal passes through a low-noise amplifier (LNA) and then passes through an RF down-conversion module to perform RF down-conversion processing on the RF signal amplified by the LNA, outputting a zero intermediate frequency analog signal, and finally processing the signal through the RF transceiver transceiver subsystem.

[0083] The low noise amplifier LNA receives control instructions from the MCU core main control module and only amplifies the frequency band and bandwidth of the effective working signal, rather than using traditional signal processing methods to amplify the full-band signal.

[0084] Another function of the uplink and downlink RF signal processing subsystem: the uplink and downlink RF signal processing subsystem receives the analog signal of the high frequency band from the RF transceiver subsystem, directly amplifies it through the uplink power amplifier, and outputs the amplified high frequency signal. Among them, the uplink power amplifier receives the control instruction from the MCU core main control module, and only amplifies the frequency band and bandwidth of the effective working signal, instead of using the traditional signal processing method to amplify the full-band signal, which reduces the index requirements for the uplink power amplifier. At the same time, it only amplifies the useful signal in the band, and does not amplify the noise signal outside the effective bandwidth, which greatly improves the system performance.

[0085] The traditional processing solution adopts the digital intermediate frequency transceiver solution. The analog intermediate frequency signal output by the RF transceiver subsystem is first processed by the RF up-conversion module to achieve the conversion from the analog intermediate frequency signal to the high-frequency RF signal, and then the signal is amplified by the uplink power amplifier and output to the donor-end duplexer.

[0086] Zero-IF (Zero-IF) architecture RF transceivers include Low-IF (Low-IF), a variant of Zero-IF. Zero-IF is also called direct frequency conversion, which means that the RF signal does not need to go through the IF stage to directly enter the I / Q demodulation and convert to the baseband signal. No IF signal is generated in the middle, and there are no components such as IF amplifiers and IF filters. Therefore, the architecture is relatively simple, the system size is smaller, and the cost and power consumption are lower. The advantage of Zero-IF is that fewer components are needed, it is easy to integrate, and the performance is good. Except that DC cannot be eliminated in principle, there are almost no disadvantages.

[0087] The RF transceiver subsystem adopts a zero intermediate frequency digital-analog processing solution, which further improves the system integration, reduces the system complexity, and reduces the system cost. The RF transceiver subsystem adopts a single-chip solution, which can use a domestically produced chip solution, integrating ADC module, digital up-conversion, digital down-conversion, peak clipping CFR, and DAC module. The input and output of the RF transceiver subsystem are both zero intermediate frequency RF signals.

[0088] Due to the high integration of the RF transceiver subsystem, the requirements for the FPGA processing subsystem are greatly reduced. The FPGA processing subsystem is mainly responsible for the timing adjustment and encoding of the digital IQ signal of the RF transceiver subsystem, as well as the protocol encapsulation and decapsulation of IQ data, control words for optical fiber link synchronization and data conversion, and control words for signal characteristics, such as using the CPRI protocol (CPRI (Common Public Radio Interface)). The signal characteristic control word transmitted by the CPRI protocol includes: the MCU core main control module of the access unit processes data for the format, frequency band, frequency point, bandwidth, number of carriers and other information of the effective working signal, and obtains the specific frequency band, frequency point, center frequency point and bandwidth that need to be amplified for the effective working signal. The signal characteristic control word is the basis for the technical requirements of the signal processing of the remote unit of the digital repeater.

[0089] The MCU core control module can configure and manage the frequency band, bandwidth, filter parameters, delay parameters, chip startup and shutdown parameters, and timing control parameters of the RF transceiver subsystem. Based on the effective working signal obtained by the signal feature analysis module and its signal characteristics: frequency band, frequency point, bandwidth, number of carriers, the MCU core control module calculates the frequency band and bandwidth of the effective working signal to be processed, as well as other parameter requirements (filter parameters, delay parameters, etc.), and sends them to the RF transceiver subsystem through instructions. The RF transceiver subsystem processes the effective signal in a targeted manner according to the instructions issued.

[0090] FPGA needs to process two types of data for protocol encapsulation: the digital IQ signal of the RF transceiver subsystem and the frequency band and bandwidth information of the effective working signal calculated by the MCU core control module.

[0091] For FDD digital optical fiber repeater system, such as Figure 4As shown, the remote unit includes: an FPGA processing subsystem, a RF transceiver subsystem, and an uplink and downlink RF signal processing subsystem, which are connected in sequence. The FPGA processing subsystem, the RF transceiver subsystem, and the uplink and downlink RF signal processing subsystem are respectively connected to the MCU core main control module. Among them, since the corresponding data information for the frequency and bandwidth information of the useful working signal has been obtained at the near end of the digital repeater, it is only necessary to transmit the data information from the access unit to the remote unit through the protocol. There is no need to add a signal feature analysis module, which further reduces the cost of the system.

[0092] The FPGA processing subsystem of the remote unit receives the control words for baseband IQ signal fiber link synchronization and data conversion, as well as the control words for signal characteristics, from the access unit, performs CPRI decapsulation processing, encodes the IQ data into a format adapted to the RF transceiver subsystem, and inputs it to the RF transceiver subsystem; at the same time, the FPGA processing subsystem decapsulates the obtained control words for signal characteristics: the specific frequency and bandwidth of the effective working signal, and transmits this information to the MCU core control module of the remote unit, which configures appropriate parameters for the FPGA processing subsystem, RF transceiver subsystem, and uplink and downlink RF signal processing subsystems of the remote unit to filter, amplify, and process the effective working signal.

[0093] The functions of the RF transceiver subsystem and the uplink and downlink RF signal processing subsystem of the remote unit of the digital repeater are the same as those of the access unit and will not be described in detail here.

[0094] For TDD signals, the present invention proposes another digital optical fiber repeater system, which can integrate the time domain synchronization function into the signal characteristic analysis module to complete two different functions and further reduce costs.

[0095] For TDD digital optical fiber repeater system, such as Figure 5 As shown, the access unit structure includes: uplink and downlink RF signal processing subsystem, RF transceiver subsystem, FPGA processing subsystem, signal coupler, signal feature analysis and time domain synchronization module and MCU core main control module.

[0096] Among them, the uplink and downlink RF signal processing subsystem, RF transceiver subsystem, and FPGA processing subsystem are connected in sequence to form the main link of uplink and downlink signal processing of the access unit of the digital repeater. The access unit of the digital repeater and the RRU signal source realize signal transmission and reception communication with the RRU through wired signal coupling.

[0097] The input and output of the uplink and downlink RF signal processing subsystems are both high-frequency RF signals, such as 2300MHz RF signals; the FPGA processing subsystem outputs the baseband IQ signal after protocol conversion, the control words for optical fiber link synchronization and data conversion, the control words for signal characteristics, the time domain synchronization control words, etc., which are input into the remote unit of the digital repeater to realize signal transmission and communication.

[0098] Among them, the control word of the signal characteristic refers to: the MCU core main control module of the access unit processes data on the standard, frequency band, frequency point, bandwidth, number of carriers and other information of the effective working signal, and obtains the specific frequency band, frequency point, center frequency point and bandwidth required to amplify the effective working signal.

[0099] The time domain synchronization control word refers to: time domain synchronization control word information-time slot switching information.

[0100] Among them, the signal coupler, signal feature analysis and time domain synchronization module and MCU core main control module are connected in sequence to form the core functions of the signal feature analysis link and the control signal processing main link.

[0101] For time division duplex (TDD) systems, all systems need to process transmit and receive signals separately in different time slices. In the transmit time slice, the focus is on the coupling and transmission of the transmit signal; in the receive time slice, the focus is on the coupling and transmission of the receive signal.

[0102] Among them, since it involves the control of the TDD time slot switching function, the MCU core main control module is connected to the donor-end RF switch, the uplink and downlink RF signal processing subsystem A, the RF transceiver subsystem, the uplink and downlink RF signal processing subsystem B, and the retransmitting end RF switch to control these modules.

[0103] Among them, for the time domain synchronization of the TDD system:

[0104] This is not enough for TDD systems, so in addition to clock synchronization technology, there is also a TDD uplink and downlink switch synchronization in the TDD system, which can also be called time domain synchronization. That is, find a point where the reference remains unchanged, and then the system resumes switching at this point.

[0105] The switch synchronization of the TDD standard is a step up from the frequency domain clock synchronization, and synchronization is also required in the time domain. For the TDD standard, if the uplink and downlink of the terminal and the base station are inconsistent, the signal quality will be affected, or even no signal will be present.

[0106] There are several ways to synchronize in the time domain:

[0107] 1. Envelope detection: In TD-SCDMA of the 3G era, there is a constant envelope position as a reference point, so you only need to detect this point to use it as the reference for the system switch, and then generate the uplink and downlink switches of the repeater. This cost is relatively cheap.

[0108] 2. Coarse synchronization

[0109] Similar to the LTE standard, no matter how the TDD system configuration changes, there is a fixed frequency domain area in the PSS synchronization series, and this position can be found as a reference point. The autocorrelation characteristics of the ZC sequence are used for synchronization. Synchronization involves signal filtering, sampling, extraction and related calculations, which requires a corresponding hardware platform, which will also increase the corresponding cost. This cost requires ADC and FPGA, but if it is a digital system, it has ADC and FPGA chips, so there is actually no cost.

[0110] 3. Analyze baseband signal source

[0111] This is similar to mobile phone terminals, directly parsing the baseband signal source, which requires high-performance FPGA chips or DSP chips, which is the most expensive. But it also has advantages, which can obtain relevant information about the base station cell, such as Cell ID, RSRP, SINR, PLMN, etc., which is very convenient for engineers.

[0112] The present invention adopts a TDD time domain synchronization solution for analyzing baseband information sources, and the signal feature analysis is also performed by analyzing the signal features through the solution of analyzing baseband information sources. In this way, the signal feature analysis module can integrate the function of time domain synchronization, and integrate the two functions into one module, thereby improving the module integration and reducing the system cost.

[0113] Among them, the FPGA processing subsystem performs protocol encapsulation and needs to process three types of data: the digital IQ signal of the RF transceiver subsystem, the frequency band and bandwidth information of the effective working signal calculated by the MCU core main control module, and the signal feature analysis and time slot switching information output by the time domain synchronization module.

[0114] The specific functional implementation scheme of the TDD digital optical fiber repeater system access unit is consistent with the implementation scheme of the FDD digital optical fiber repeater system access unit mentioned above, and will not be repeated here.

[0115] For the remote unit of the TDD digital fiber optic repeater system, its system structure is exactly the same as that of the FDD digital fiber optic repeater system, except that the control word part of the FPGA processing subsystem is increased: time domain synchronized control word information - time slot switching information.

[0116] The control word information is encapsulated by the CPRI protocol in the access unit, and then decapsulated by the CPRI protocol in the remote unit and output to the MCU core control module. The MCU core control module configures the parameters of the FPGA processing subsystem, the RF transceiver subsystem, and the uplink and downlink RF signal processing subsystem, and performs time slot switching operations to filter and amplify the effective working signal.

[0117] Among them, the signal feature analysis module detects and analyzes the actual working signal format, frequency band, frequency point, bandwidth, number of carriers and other characteristic information in real time and adaptively. Combined with the signal characteristic information obtained by the detection, the uplink and downlink signal processing circuits then amplify and process the uplink and downlink signals efficiently according to the specific format, specific frequency point, specific bandwidth and specific number of carriers, which reduces energy waste and greatly reduces costs.

[0118] The embodiments described above are only descriptions of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A digital optical fiber repeater system, characterized in that: The digital fiber optic repeater system is a digital fiber optic repeater system of FDD standard, including: an access unit and a remote unit; wherein the access unit includes: an uplink and downlink radio frequency signal processing subsystem, a radio frequency transceiver subsystem, an FPGA processing subsystem, a signal coupler, a signal feature analysis module and an MCU core main control module; the remote unit includes: an FPGA processing subsystem, a radio frequency transceiver subsystem, an uplink and downlink radio frequency signal processing subsystem connected in sequence, and the FPGA processing subsystem, the radio frequency transceiver subsystem, and the uplink and downlink radio frequency signal processing subsystems are respectively connected to the MCU core main control module; the uplink and downlink radio frequency signal processing subsystems, the radio frequency transceiver subsystem, and the FPGA processing subsystem are connected in sequence to form the main link of the uplink and downlink signal processing of the access unit; the access unit and the RRU source realize the signal transceiver communication with the RRU through wired signal coupling; wherein, The output of the FPGA processing subsystem is the baseband IQ signal after protocol conversion, the control word of optical fiber link synchronization and data conversion, and the control word of signal characteristics, which are input to the remote unit to realize signal transmission and communication; among which, the control word of signal characteristics is: the MCU core main control module of the access unit processes the format, frequency band, frequency point, bandwidth, and carrier number information of the effective working signal to obtain the specific frequency band, frequency point, center frequency point, and bandwidth that need to be amplified for the effective working signal; The signal characteristic analysis module couples the RF signal from the RRU source through a coupler, performs RF down-conversion, analog conversion, digital down-conversion and baseband signal processing to obtain the characteristics of the baseband signal, including: the communication standard of the signal, RSRP, SINR, the frequency point information of the signal, the frequency band information of the signal, the bandwidth of the signal, and the number of carriers; Among them, baseband signal processing includes: (1) The digital signal processor (DSP) further processes the converted digital signal, including digital filtering, synchronization, equalization, etc. (2) It also includes channel estimation and decoding of error correction coding to recover the original data. (3) Baseband demodulation: In the digital signal processing stage, the baseband demodulator demodulates the signal according to the modulation method (such as QAM, PSK, etc.). The demodulation process includes extracting the amplitude, frequency or phase information of the signal to restore the original baseband data. (4) Data decoding and output: The demodulated baseband data is decoded to restore the original user information or control signal. Decoding includes steps such as deinterleaving, descrambling, and decryption. Finally, the decoded data is output to the feature analysis module.

2. The digital optical fiber repeater system according to claim 1, characterized in that: The signal feature analysis module determines the valid 4G LTE signal including:

1. Perform baseband demodulation on the full-band 4G LTE signals to obtain the signal characteristics of the corresponding signals: frequency band, frequency point, bandwidth, number of carriers, RSRP, and SINR. Among them, only the demodulated signals can obtain RSRP and SINR information; 2. Set the signal thresholds Th_RSRP_LTE and Th_SINR_LTE. If RSRP ≥ Th_RSRP_LTE and SINR ≥ Th_SINR_LTE, it is considered as a valid working signal.

3. In conjunction with the operator, determine the final effective working signal and its signal characteristics; The signal feature analysis module determines the valid signal of 5G NR, including the following processing steps:

1. Demodulate the 5G NR signals of the full frequency band to obtain the signal characteristics of the corresponding signals: frequency band, frequency point, bandwidth, number of carriers, RSRP, and SINR; 2. Set the signal thresholds Th_RSRP_NR and Th_SINR_NR. RSRP ≥ Th_RSRP_NR and SINR ≥ Th_SINR_NR are considered valid working signals.

3. Combined with the specific operator, determine the final effective working signal and its signal characteristics.

3. The digital optical fiber repeater system according to claim 2, characterized in that: The FPGA processing subsystem of the remote unit receives the control words of the baseband IQ signal optical fiber link synchronization and data conversion and the control words of the signal characteristics from the access unit, performs CPRI decapsulation processing, encodes the IQ data into a format adapted by the RF transceiver subsystem, and inputs it to the RF transceiver subsystem; at the same time, the FPGA processing subsystem transmits the control words of the signal characteristics obtained by decapsulation to the MCU core main control module of the remote unit, and the MCU core main control module configures the parameters of the FPGA processing subsystem, the RF transceiver subsystem and the uplink and downlink RF signal processing subsystems of the remote unit, and performs signal filtering and amplification processing on the effective working signals.

4. A digital optical fiber repeater system, characterized in that: The digital optical fiber repeater system is a TDD digital optical fiber repeater system, including: an access unit and a remote unit; wherein the access unit structure includes: an uplink and downlink radio frequency signal processing subsystem, a radio frequency transceiver subsystem, an FPGA processing subsystem, a signal coupler, a signal feature analysis and time domain synchronization module and an MCU core main control module; the remote unit includes: an FPGA processing subsystem, a radio frequency transceiver subsystem, an uplink and downlink radio frequency signal processing subsystem connected in sequence, the FPGA processing subsystem, the radio frequency transceiver subsystem, and the uplink and downlink radio frequency signal processing subsystems are connected to the MCU core main control module respectively; the uplink and downlink radio frequency signal processing subsystems, the radio frequency transceiver subsystem, the FPGA processing subsystem The processing subsystems are connected in sequence to form the main link of the uplink and downlink signal processing of the access unit; the access unit and the RRU source realize the signal receiving and sending communication with the RRU through wired signal coupling; the FPGA processing subsystem outputs the control words of the baseband IQ signal optical fiber link synchronization and data conversion after protocol conversion, the control words of the signal characteristics and the control words of the time domain synchronization, which are input to the remote unit of the digital repeater to realize signal transmission and communication; among which, the control words of the signal characteristics are: the MCU core main control module of the access unit processes the data of the format, frequency band, frequency point, bandwidth and number of carriers of the effective working signal to obtain the specific frequency band, frequency point, center frequency point and bandwidth that need to be amplified for the effective working signal; the control words of the time domain synchronization are: the control word information of the time domain synchronization-time slot switching information.

5. The digital optical fiber repeater system according to claim 4, characterized in that: The FPGA processing subsystem of the remote unit receives the control words for baseband IQ signal optical fiber link synchronization and data conversion, signal characteristic control words and time domain synchronization control words from the access unit, performs CPRI decapsulation processing, encodes the IQ data into a format adapted to the RF transceiver subsystem, and inputs it to the RF transceiver subsystem; at the same time, the FPGA processing subsystem transmits the signal characteristic control words and time domain synchronization control words obtained by decapsulation to the MCU core main control module of the remote unit, and the MCU core main control module performs parameter configuration, time slot switching operations, and signal filtering and amplification processing on the effective working signals for the FPGA processing subsystem, RF transceiver subsystem and uplink and downlink RF signal processing subsystem of the remote unit.

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