4T4R railway 5G vehicle-mounted repeater system based on MIMO technology and control method thereof

Abstract

The invention relates to the technical field of mobile communication, and discloses a 4T4R railway 5G vehicle-mounted repeater system based on an MIMO technology and a control method thereof, and the system comprises a roof 4T4R donor array antenna, a distributed carriage coverage 4T4R antenna, a near-end host unit, a cascade expansion unit, a far-end slave unit and a Beidou and inertial navigation positioning module. The units form a digital transmission link through optical fibers; according to the control method, a line electronic map and a scene-mode mapping table are loaded, train position information and adjacent cell measurement parameters are obtained, switching among spatial multiplexing, transmit diversity and beam forming is carried out under the scenes of stability, high quality, shielding, multipath, deep fading, multi-bend hills and the like, 4T4R and 2T2R self-adaption is achieved under the transmit diversity, and the method has the advantages of being simple in structure, low in cost and high in reliability. And when entering a strong interference area, forming null suppression interference based on synchronous signal block decoding and spatial domain and frequency domain filtering, and triggering soft / hard switching according to a measurement condition to improve continuous coverage and stability.

Description

Technical Field

[0001] This invention relates to the field of railway mobile communication technology, specifically to a 4T4R railway 5G vehicle-mounted repeater system based on MIMO technology and its control method. Background Technology

[0002] As an important part of railway transportation, conventional railways typically traverse various complex terrains such as mountains, hills, and cities. The distribution of 5G base stations along these lines is uneven, and trains frequently pass through different base station coverage areas during operation, which can easily lead to problems such as frequent signal switching, signal interruption, and dropped calls.

[0003] Existing vehicle-mounted repeaters mostly employ single-antenna configurations and 2T2R MIMO configurations. Single antennas are susceptible to multipath effects and interference, leading to unstable quality. While 2T2R improves speed and capacity, it still struggles to meet the high-speed and stable requirements of the complex wireless environment of conventional railways, and lacks scenario-based optimization designs for signal fading and rapid handover. Furthermore, 5G high-frequency signals are easily affected by obstacles and attenuate faster. The train body shields wireless signals, and the propagation path along the line is variable, making stable coverage and efficient transmission even more challenging. Additionally, typical scenarios on conventional railways include severe fading caused by non-line-of-sight propagation, rapid "on-off-on" fluctuations caused by tunnel clusters, and co-channel or adjacent-channel interference from urban-rural fringe areas and industrial zones. Existing repeaters generally employ fixed strategies, making it difficult to adapt to these rapidly changing and complex scenarios.

[0004] To address this issue, a 4T4R railway 5G vehicle-mounted repeater system and its control method based on MIMO technology are proposed, which solves the aforementioned problems. Summary of the Invention

[0005] The purpose of this invention is to provide a 4T4R railway 5G vehicle-mounted repeater system and its control method based on MIMO technology, so as to solve the problems mentioned in the background art.

[0006] To address the aforementioned technical problems, this invention provides the following technical solution: a 4T4R railway 5G vehicle-mounted repeater system based on MIMO technology, comprising: a dedicated four-transmitter-four-receiver (4T4R) vehicle-mounted donor antenna, a distributed carriage coverage 4T4R antenna, a near-end host unit, a cascaded expansion unit, a far-end slave unit, and a positioning module integrating BeiDou and inertial navigation. The dedicated 4T4R vehicle-mounted donor antenna is installed on the roof of the train and is used to establish a 4T4R wireless transceiver link with an external public 5G base station. The dedicated 4T4R vehicle-mounted donor antenna is an array antenna configured to adjust the beam shape and direction according to the phase weight to support beamforming. Its radio frequency front end integrates a phase shifter and a switching network to control the phase weight and transceiver channel configuration of the antenna array elements. The distributed carriage coverage 4T4R antennas are deployed inside each carriage to provide 5G signal coverage inside the carriage; The near-end host unit and the cascaded expansion unit are installed in the train equipment compartment. The far-end slave unit is distributedly installed inside each carriage and electrically connected to the distributed carriage coverage 4T4R antenna. The positioning module integrating Beidou and inertial navigation is installed on the train and is communicatively connected to the near-end host unit. The near-end host unit, the cascaded expansion unit and the far-end slave unit form a digital signal transmission link through optical fiber. The near-end host unit includes an RF front-end module, a scene recognition and MIMO mode dynamic switching module, an intelligent anti-interference processing module, a baseband processing module, an optical module, a power supply module, and a control and monitoring module. The scene recognition and MIMO mode dynamic switching module includes a positioning and analysis submodule, a scene perception submodule, and a MIMO algorithm submodule. The scene recognition and MIMO mode dynamic switching module is used to identify communication scenes based on the positioning and analysis submodule, the scene perception submodule, and the MIMO algorithm submodule, and to control the system to switch between spatial multiplexing mode, transmit diversity mode, and beamforming mode according to the scene-mode mapping table stored internally. The near-end host unit is used to control the dedicated 4T4R vehicle-mounted donor antenna to adaptively switch between 4T4R working mode and two-transmit two-receive (2T2R) working mode in transmit diversity mode. When 2T2R cannot meet the preset link quality lower limit, it switches to 4T4R. When it is detected that it has entered a strong external interference area, it triggers the intelligent anti-interference processing module to perform anti-interference processing. In beamforming mode, the near-end host unit outputs antenna beam and phase adjustment commands to adjust the beam direction and phase weight of the dedicated 4T4R vehicle-mounted donor antenna.

[0007] According to the above technical solution, the intelligent anti-interference processing module includes: a synchronization signal block decoding submodule, a primary physical cell identifier selection submodule, a spatial filtering submodule, and a frequency filtering submodule. The synchronization signal block decoding submodule is used to decode the synchronization signal blocks in the received signal to obtain the frequency point, physical cell identifier, reference signal received power, and signal-to-interference-plus-noise ratio. The primary physical cell identifier selection submodule is used to filter the synchronization signal blocks corresponding to the primary physical cell identifier and suppress non-primary synchronization signal blocks. When entering the strong external interference zone, the spatial filtering submodule is used to form a beam null in the interference direction, and the frequency filtering submodule is used to filter out unwanted synchronization signal frequencies.

[0008] According to the above technical solution, the cascaded expansion unit is used to receive the digital baseband signal from the near-end host unit and drive the remote slave unit after completing signal regeneration, clock recovery and format conversion.

[0009] According to the above technical solution, the remote slave unit is used as an end-coverage device. It receives digital signals from the cascaded expansion unit through optical fiber, performs digital-to-analog conversion and radio frequency processing, and then radiates mobile communication signals through the distributed carriage coverage 4T4R antenna. The uplink signal is then amplified by low noise and digitized before being transmitted back.

[0010] According to the above technical solution, the positioning module integrating BeiDou and inertial navigation includes a BeiDou receiving antenna, an inertial measurement unit, and a positioning calculation unit. The BeiDou receiving antenna is installed on the roof of the train, and the inertial measurement unit and the positioning calculation unit are installed in the train equipment compartment or driver's cab. The positioning calculation unit is used to fuse the positioning information output by the BeiDou receiving antenna and the inertial navigation information output by the inertial measurement unit to obtain the train position information, the speed information, and the running direction information, and send them to the near-end host unit.

[0011] A control method for controlling the vehicle-mounted repeater system according to any one of claims 1-5, comprising: Step S100: Establish fiber optic link communication between the near-end host unit, the cascaded expansion unit and the remote slave unit, and load the line electronic map and scene-mode mapping table; Step S200: Obtain the train location information, and obtain the reference signal received power and signal-to-interference-plus-noise ratio of the serving cell and neighboring cells. Calculate the reference signal received power fluctuation amplitude and the reference signal received power peak-to-valley difference according to a preset time window. The reference signal received power fluctuation amplitude is the average absolute value of the difference in reference signal received power between adjacent sampling points within the preset time window, and the reference signal received power peak-to-valley difference is the difference between the maximum and minimum reference signal received power within the preset time window. Generate an operation information set. The preset values ​​are: the first power threshold is -95dBm to -85dBm, the first signal-to-interference-plus-noise ratio threshold is 8dB to 12dB, the first time window is 0.5s to 2s, and the first fluctuation threshold is 3dB to 6dB. The second power threshold range is -115dBm to -95dBm, the second signal-to-interference-plus-noise ratio threshold range is 0dB to 8dB, the second time window is 0.5s to 2s, and the second fluctuation threshold is 6dB to 12dB. The third power threshold is -110dBm to -100dBm, and the third signal-to-interference-plus-noise ratio threshold is 2dB to 6dB. The fourth power threshold is -120dBm to -110dBm, the fourth signal-to-interference-plus-noise ratio threshold is -2dB to 2dB, the third time window is 0.2s to 1s, and the third fluctuation threshold is 12dB to 20dB. Step S300: Based on the operation information set, query the electronic map of the line and output the scene recognition results of the current and recent communication scenarios of the train; Step S400: Based on the scene recognition result and combined with the reference signal received power, the signal-to-interference-plus-noise ratio, the reference signal received power fluctuation amplitude, and the reference signal received power peak-to-valley difference, query the scene-mode mapping table, output the target MIMO working mode, control the system to switch to the target MIMO working mode, and control the dedicated 4T4R vehicle-mounted donor antenna to switch between 4T4R working mode and 2T2R working mode in transmit diversity mode; When the received power of the reference signal is not lower than the first power threshold, the signal-to-interference-plus-noise ratio is not lower than the first signal-to-interference-plus-noise ratio threshold, and the fluctuation amplitude of the received power of the reference signal within the first time window is not greater than the first fluctuation threshold, it is determined to be a stable high-quality scenario, the spatial multiplexing mode is selected, and the dedicated 4T4R vehicle-mounted donor antenna is controlled to work in 4T4R working mode. When the received power of the reference signal is within the second power threshold range, or the signal-to-interference-plus-noise ratio (SIR) is within the second SIR threshold range, or the fluctuation amplitude of the received power of the reference signal within the second time window is not less than the second fluctuation threshold, it is determined to be an obstruction or multipath fluctuation scenario. The transmit diversity mode is selected, and in the transmit diversity mode, when the received power of the reference signal is not lower than the third power threshold and the SIR is not lower than the third SIR threshold, the dedicated 4T4R vehicle-mounted donor antenna is controlled to work in 2T2R mode. When the received power of the reference signal is lower than the third power threshold, or the signal-to-interference-plus-noise ratio is lower than the third signal-to-interference-plus-noise ratio threshold, it is determined that 2T2R cannot meet the lower limit of link quality and the dedicated 4T4R vehicle-mounted donor antenna is switched to 4T4R working mode. When the received power of the reference signal is lower than the fourth power threshold, or the signal-to-interference-plus-noise ratio is lower than the fourth signal-to-interference-plus-noise ratio threshold, and the peak-to-valley difference of the received power of the reference signal is not less than the third fluctuation threshold within the third time window, it is determined to be a deep fading scenario, the transmit diversity mode is selected, and the dedicated 4T4R vehicle-mounted donor antenna is controlled to work in 4T4R working mode. When the electronic map of the line indicates that there are continuous curves within the current and preset distance range of the train, the preset distance range is the line distance of 200m to 1500m along the direction of train operation, or equivalent to the predicted travel distance range of 5s to 30s calculated according to the train speed, and the fluctuation amplitude of the reference signal received power is not less than the second fluctuation threshold within the second time window, it is determined to be a multi-curve hilly scene. Beamforming mode is selected, and antenna beam and phase adjustment commands are output to point the main lobe of the dedicated 4T4R vehicle-mounted donor antenna to the predicted base station incoming wave direction. The predicted base station incoming wave direction is the azimuth direction calculated based on the train position information and the base station position information in the electronic map of the line. Step S500: Determine whether the strong external interference zone has been entered based on the interference detection result. When the strong external interference zone is entered, the intelligent anti-interference processing module is triggered to perform anti-interference processing and output antenna beam and phase adjustment commands to form beam nulls in the interference direction and adjust the phase weight of the dedicated 4T4R vehicle-mounted donor antenna. Step S600: Monitor the signal strength of neighboring cells in real time and initiate a handover process when the handover conditions are met. The handover process includes a soft handover process and a hard handover process.

[0012] According to the above technical solution, step S300 includes: step S301, querying the electronic map of the line based on the train location information and the running direction information to obtain key point information of the corresponding line segment; Step S302: Based on the key point information, determine whether there is a tunnel area, continuous curve area or interference area within the current and preset distance range of the train; Step S303: Encode the judgment results of steps S301 and S302 into a communication scene tag, and output it as the scene recognition result to step S400.

[0013] According to the above technical solution, step S400 includes: Step S401: Based on the reference signal received power, the signal-to-interference-plus-noise ratio, and the fluctuation amplitude of the reference signal received power, determine whether a stable high-quality scenario is met and output the spatial multiplexing mode. Step S402: Based on the received power of the reference signal, the signal-to-interference-plus-noise ratio, and the fluctuation amplitude of the received power of the reference signal, determine whether the blockage or multipath fluctuation scenario is met and output the transmit diversity mode. Step S403: Based on the received power of the reference signal, the signal-to-interference-plus-noise ratio, and the peak-to-valley difference of the received power of the reference signal, determine whether the deep fading scenario is met and output the transmit diversity mode, and simultaneously output the channel configuration command of the 4T4R working mode or the 2T2R working mode.

[0014] Step S404: Based on the continuous curve area judgment result obtained in step S302, and combined with the reference signal received power fluctuation amplitude, determine whether the multi-curve hilly scenario is satisfied; if satisfied, output the beamforming mode and output antenna beam and phase adjustment command.

[0015] According to the above technical solution, step S500 includes: Step S501: Decode the synchronization signal blocks in the received signal to obtain the frequency point, physical cell identifier, reference signal received power and signal-to-interference-plus-noise ratio of each synchronization signal block; Step S502: Filter the synchronization signal blocks corresponding to the primary physical cell identifier from the decoding results and suppress non-primary synchronization signal blocks; Step S503: The phase weight of the dedicated 4T4R vehicle-mounted donor antenna is controlled by the interference incident direction obtained by array antenna beam scanning or direction finding algorithm, so that the spatial filtering submodule forms a beam null in the interference direction. Step S504: Execute the frequency domain filtering submodule to filter out unwanted synchronization signal frequency points; Step S505: Output antenna beam and phase adjustment commands and amplify and forward the processed signal through the vehicle-mounted repeater system.

[0016] According to the above technical solution, step S600 includes: Step S601: When the difference between the received power of the neighboring cell reference signal and the received power of the serving cell reference signal is not less than the first hysteresis and the duration is not less than the first trigger time, and the signal-to-interference-plus-noise ratio of the serving cell is not lower than the first handover quality threshold, the soft handover process is executed. Step S602, the soft handover process includes target cell handover preparation, maintaining the original link connection while completing synchronous access to the target cell, and releasing the original link after access confirmation; Step S603: When the received power of the reference signal of the serving cell is lower than the second handover power threshold or the signal-to-interference-plus-noise ratio of the serving cell is lower than the second handover quality threshold, or when a connection failure or emergency handover condition occurs, the hard handover process is executed. Step S604, the hard handover process includes releasing the original link and completing access to the target cell within a preset handover timeout, and performing a backoff or reselection when access fails; Step S605: Set a hold time to suppress ping-pong switching; Wherein, the first hysteresis is 2dB to 5dB, the first trigger time is 0.5s to 2s, the first switching quality threshold is 3dB to 8dB; the second switching power threshold is -120dBm to -110dBm, the second switching quality threshold is -2dB to 2dB; the preset switching timeout is 50ms to 200ms, and the hold time is 1s to 5s.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) By integrating the positioning module of Beidou and inertial navigation with the scene recognition mechanism of the electronic map of the route, and combining the reference signal received power, signal-to-interference-plus-noise ratio and its fluctuation amplitude, peak-to-valley difference and other operating information, the system can dynamically switch between three MIMO modes of spatial reuse, transmit diversity and beamforming according to the "scene-mode mapping table". This enables the system to adjust its working strategy in real time for typical scenarios such as mountainous areas, hills, cities and other terrains, rapid fluctuations of "on-off-on" in tunnel groups, multipath blockage and deep fading, thereby improving the problem that the existing fixed strategy is difficult to adapt to rapidly changing scenarios and improving coverage continuity and service stability.

[0018] (2) A 4T4R donor-side array antenna is adopted and a phase shifter and a switching network are introduced. Beamforming and channel configuration control are achieved through phase weight control. In non-line-of-sight / variable propagation path scenarios such as continuous curves and multi-curved hills, the effective reception capability can be improved by beam pointing and gain allocation. In deep fading or strong fluctuation scenarios, robustness is enhanced by transmit diversity. Thus, compared with the existing single antenna and only 2T2R configuration, the impact of multipath effect and fading on link quality is reduced. It is more suitable for the coverage problem caused by the fast attenuation of 5G high frequency band and strong vehicle shielding.

[0019] (3) By decoding the synchronization signal block and selecting the primary physical cell identifier, combined with spatial filtering to form beam nulls and frequency filtering to suppress unwanted frequency points, and with soft handover, hard handover and hold time to suppress ping-pong handover, the anti-interference capability and handover stability under co-channel or adjacent channel interference scenarios are improved. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall deployment of the repeater system of the present invention on a conventional railway train.

[0021] Figure 2 This is a schematic diagram showing the deployment of the near-end host unit and cascaded expansion unit of the repeater system of the present invention.

[0022] Figure 3 This is a general principle block diagram of the repeater system of the present invention.

[0023] Figure 4 This is a block diagram of the near-end unit and cascaded expansion unit of the repeater system of the present invention.

[0024] Figure 5 This is a block diagram illustrating the principle of the remote unit of the repeater system of the present invention.

[0025] Figure 6 This is the main flowchart of the control method of the present invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be described below with reference to the accompanying drawings. The embodiments described below are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] For ease of understanding and implementation: 1. The preset distance range is the track distance of 200m to 1500m along the train's direction of travel, or equivalently, the predicted travel distance range of 5s to 30s calculated based on train speed; 2. The preset lower limit of link quality is defined as the reference signal received power not being lower than the third power threshold and the signal-to-interference-plus-noise ratio (SNR) not being lower than the third SNR threshold; 3. The fluctuation amplitude of the reference signal received power is the average absolute value of the difference in reference signal received power between adjacent sampling points within the preset time window, and the peak-to-valley difference of the reference signal received power is the reference signal received power within the preset time window. 4. The determination of strong external interference zone can be based on any of the following conditions: the number of non-primary synchronization signal blocks is not less than 2 and the reference signal received power of at least one non-primary synchronization signal block is not less than the reference signal received power of the primary synchronization signal block -6dB, or the signal-to-interference-plus-noise ratio of the primary synchronization signal block is continuously lower than the fourth signal-to-interference-plus-noise ratio threshold for not less than the third time window; 5. The interference direction is obtained by array antenna beam scanning or direction finding algorithm, preferably taking the direction corresponding to the non-primary synchronization signal block with the largest reference signal received power as the interference incident direction.

[0028] Please see Figures 1 to 5 This invention provides a technical solution: a 4T4R railway 5G vehicle-mounted repeater system based on MIMO technology, comprising: a dedicated four-transmitter-four-receiver (4T4R) vehicle-mounted donor antenna, a distributed carriage coverage 4T4R antenna, a near-end host unit, a cascaded expansion unit, a far-end slave unit, and a positioning module integrating BeiDou and inertial navigation. The dedicated 4T4R vehicle-mounted donor antenna is installed on the roof of the train and is used to establish a 4T4R wireless transceiver link with an external public 5G base station. The dedicated 4T4R vehicle-mounted donor antenna is an array antenna configured to adjust the beam shape and direction according to the phase weight to support beamforming. Its radio frequency front end integrates a phase shifter and a switching network to control the phase weight and transceiver channel configuration of the antenna array elements. The distributed carriage coverage 4T4R antennas are deployed inside each carriage to provide 5G signal coverage inside the carriage; The near-end host unit and the cascaded expansion unit are installed in the train equipment compartment. The far-end slave unit is distributedly installed inside each carriage and electrically connected to the distributed carriage coverage 4T4R antenna. The positioning module integrating Beidou and inertial navigation is installed on the train and is communicatively connected to the near-end host unit. The near-end host unit, the cascaded expansion unit and the far-end slave unit form a digital signal transmission link through optical fiber. The near-end host unit includes an RF front-end module, a scene recognition and MIMO mode dynamic switching module, an intelligent anti-interference processing module, a baseband processing module, an optical module, a power supply module, and a control and monitoring module. The scene recognition and MIMO mode dynamic switching module includes a positioning and analysis submodule, a scene perception submodule, and a MIMO algorithm submodule. The scene recognition and MIMO mode dynamic switching module is used to identify communication scenes based on the positioning and analysis submodule, the scene perception submodule, and the MIMO algorithm submodule, and to control the system to switch between spatial multiplexing mode, transmit diversity mode, and beamforming mode according to the scene-mode mapping table stored internally. The near-end host unit is used to control the dedicated 4T4R vehicle-mounted donor antenna to adaptively switch between 4T4R working mode and two-transmit two-receive (2T2R) working mode in transmit diversity mode. When 2T2R cannot meet the preset link quality lower limit, it switches to 4T4R. When it is detected that it has entered a strong external interference area, it triggers the intelligent anti-interference processing module to perform anti-interference processing. In beamforming mode, the near-end host unit outputs antenna beam and phase adjustment commands to adjust the beam direction and phase weight of the dedicated 4T4R vehicle-mounted donor antenna.

[0029] The 4T4R railway 5G vehicle-mounted repeater system based on MIMO technology is deployed on railway trains to achieve onboard relay, amplification, forwarding, and in-car coverage between the train and external public 5G base stations. 4T4R indicates a four-transmit, four-receive transceiver channel configuration, and 2T2R indicates a two-transmit, two-receive transceiver channel configuration. The onboard donor antenna is installed on the train roof facing the public base station to establish an external wireless transceiver link. This donor antenna is an array antenna, consisting of multiple antenna elements. Its phase weight is a phase control parameter applied to each element; changing the phase weight alters the shape and direction of the synthesized beam, thus achieving beamforming. To achieve this control, the donor antenna's RF front-end integrates a phase shifter and a switching network. The phase shifter adjusts the phase of the elements, and the switching network selects and configures the transceiver channels (including switching between 4T4R and 2T2R channel configurations). The distributed 4T4R antennas for carriage coverage are arranged inside each carriage to radiate 5G signals into the carriages to form carriage coverage. The near-end host unit and cascaded expansion unit are located in the train equipment compartment. The far-end slave units are distributed inside each carriage and electrically connected to the corresponding carriage coverage antenna. The near-end host unit, cascaded expansion unit, and far-end slave unit form a digital signal transmission link through optical fiber. Optical fiber is used to transmit digital signals between the above units to adapt to the carriage cascading distance and anti-interference requirements. The positioning module integrating Beidou and inertial navigation is installed on the train and communicates with the near-end host unit to output train-related location information and support scene recognition. The near-end host unit internally includes an RF front-end module, a baseband processing module, an optical module, a power supply module, and a control and monitoring module. It also includes a scene recognition and MIMO mode dynamic switching module and an intelligent anti-interference processing module. The scene recognition and MIMO mode dynamic switching module includes a positioning and parsing submodule, a scene perception submodule, and a MIMO algorithm submodule. The positioning and parsing submodule is used to parse the positioning output. The scene perception submodule is used to form communication scene information. The MIMO algorithm submodule controls the system to switch between spatial multiplexing mode, transmit diversity mode, and beamforming mode based on the scene-mode mapping table, which is a pre-stored rule table of scene and working mode correspondence. Among them, spatial multiplexing mode focuses on capacity, transmit diversity mode focuses on reliability, and beamforming mode focuses on redirection gain and direction control. In transmit diversity mode, the near-end host unit can adaptively switch between 4T4R and 2T2R operating modes. The preset link quality lower limit is the minimum acceptable link quality threshold set by the system. When 2T2R cannot meet this threshold, it switches to 4T4R. When entering a strong external interference area, the intelligent anti-interference processing module is triggered. In beamforming mode, the near-end host unit outputs antenna beam and phase adjustment commands. These commands are used to drive the donor antenna to perform beam direction adjustment and phase weight update, thereby completing beam control.

[0030] The strong external interference zone is defined as an area that meets any of the following conditions: the number of non-primary synchronization signal blocks is not less than two, and the received power of the reference signal of at least one non-primary synchronization signal block is not less than the received power of the reference signal of the primary synchronization signal block -6 dB; or the signal-to-interference-plus-noise ratio (SNR) of the primary synchronization signal block is continuously lower than the fourth SNR threshold for at least a third time window. The interference direction is obtained through array antenna beam scanning or direction-finding algorithms, preferably taking the direction corresponding to the non-primary synchronization signal block with the highest received reference signal power as the interference incident direction, so as to form a beam null in that direction.

[0031] Based on the above technical solution, please refer to Figure 4 The intelligent anti-interference processing module includes: a synchronization signal block decoding submodule, a primary physical cell identifier selection submodule, a spatial filtering submodule, and a frequency filtering submodule. The synchronization signal block decoding submodule is used to decode the synchronization signal blocks in the received signal to obtain the frequency point, physical cell identifier, reference signal received power, and signal-to-interference-plus-noise ratio. The primary physical cell identifier selection submodule is used to filter the synchronization signal blocks corresponding to the primary physical cell identifier and suppress non-primary synchronization signal blocks. When entering the strong external interference zone, the spatial filtering submodule is used to form a beam null in the interference direction, and the frequency filtering submodule is used to filter out unwanted synchronization signal frequencies.

[0032] To improve stability in multi-cell or strong interference environments with the same frequency, the intelligent anti-interference processing module is further composed of four sub-modules: 1. A synchronization signal block decoding sub-module, where the synchronization signal block refers to the synchronization signal resources in the received signal used for cell synchronization and measurement. After decoding, the frequency point (carrier frequency, frequency location), physical cell identifier (PCI) (used to distinguish different cells), reference signal received power (used to characterize received strength), and signal-to-interference-plus-noise ratio (used to characterize signal quality) are obtained. 2. A primary physical cell identifier selection sub-module, used to filter the primary physical cell identifier from the decoding results. The first part selects the synchronization signal block corresponding to the primary PCI and performs suppression processing on the non-primary synchronization signal block to avoid being pulled by non-target cells. The second part is the spatial filtering submodule. When it is determined that it has entered a strong external interference area, this submodule uses the phase weight control of the array antenna to form a beam null in the direction of interference. The beam null refers to the formation of a gain depression in the direction of interference to achieve spatial suppression. The third part is the frequency domain filtering submodule, which is used to filter out the frequency points of the unwanted synchronization signal to suppress unwanted interference components in the frequency dimension, thereby forming a joint anti-interference effect with the spatial null.

[0033] Based on the above technical solution, please refer to Figure 4 The cascaded expansion unit is used to receive digital baseband signals from the near-end host unit and drive the remote slave unit after completing signal regeneration, clock recovery and format conversion.

[0034] The cascaded expansion unit is used to realize the cascaded expansion from the on-board equipment compartment to the end coverage units of each carriage. It receives the digital baseband signal output from the near-end host unit, that is, the digital service and control signals after baseband processing, and performs signal regeneration, clock recovery, and format conversion on the digital baseband signal. Signal regeneration is used to reshape and restore the signal that may have attenuated or distorted after transmission. Clock recovery is used to recover the transmission clock from the received data stream and perform synchronization reshaping. Format conversion is used to convert between different interfaces and encapsulation formats so that the output signal meets the access requirements of the downstream remote slave unit, thereby enabling the remote slave unit to continue to complete the end coverage processing.

[0035] Based on the above technical solution, please refer to Figure 5 The remote slave unit is used as an end-coverage device. It receives digital signals from the cascaded expansion unit through optical fiber, performs digital-to-analog conversion and radio frequency processing, and then radiates mobile communication signals through the distributed carriage coverage 4T4R antenna. The uplink signal is then amplified with low noise and digitized before being transmitted back.

[0036] The remote slave unit is installed inside each carriage and serves as the end-point coverage device. It is directly connected to the carriage coverage antenna and completes the wireless coverage for terminals inside the carriage. The remote slave unit receives digital signals from the cascaded expansion unit through optical fiber, then performs digital-to-analog conversion to convert the digital baseband signal into an analog signal, and further performs radio frequency processing to obtain a radio frequency signal that can be radiated by the antenna. Finally, the distributed carriage coverage 4T4R antenna radiates mobile communication signals into the carriage to form downlink coverage. At the same time, the remote slave unit also receives uplink signals from terminals inside the carriage, improves the receiving sensitivity through low-noise amplification, and then digitizes them, i.e., performs analog-to-digital conversion, and transmits them back to the upper-level unit through the optical fiber link, thereby realizing the uplink backhaul closed loop.

[0037] Based on the above technical solution, please refer to Figure 3 The integrated BeiDou and inertial navigation positioning module includes a BeiDou receiving antenna, an inertial measurement unit, and a positioning calculation unit. The BeiDou receiving antenna is installed on the roof of the train, and the inertial measurement unit and the positioning calculation unit are installed in the train equipment compartment or driver's cab. The positioning calculation unit is used to fuse the positioning information output by the BeiDou receiving antenna and the inertial navigation information output by the inertial measurement unit to obtain the train position information, the speed information, and the running direction information, and send them to the near-end host unit.

[0038] The integrated BeiDou and inertial navigation positioning module consists of a BeiDou receiving antenna, an inertial measurement unit (IMU), and a positioning calculation unit. The BeiDou receiving antenna is mounted on the train roof to receive BeiDou satellite signals. The IMU is mounted in the equipment compartment or driver's cab and outputs inertial navigation information related to train motion. The positioning calculation unit, also mounted in the equipment compartment or driver's cab, fuses the positioning information output from the BeiDou receiving antenna with the inertial navigation information output from the IMU to obtain the train's position, speed, and direction of travel. The positioning calculation unit sends the calculation results to the near-end host unit, enabling the near-end host unit to use these positioning and motion state inputs during subsequent scene recognition and mode switching.

[0039] Please see Figure 6 The present invention provides a technical solution: a control method for controlling the vehicle-mounted repeater system according to any one of claims 1-5, comprising: Step S100: Establish fiber optic link communication between the near-end host unit, the cascaded expansion unit and the remote slave unit, and load the line electronic map and scene-mode mapping table; Step S200: Obtain the train location information, and obtain the reference signal received power and signal-to-interference-plus-noise ratio of the serving cell and neighboring cells. Calculate the reference signal received power fluctuation amplitude and the reference signal received power peak-to-valley difference according to a preset time window. The reference signal received power fluctuation amplitude is the average absolute value of the difference in reference signal received power between adjacent sampling points within the preset time window, and the reference signal received power peak-to-valley difference is the difference between the maximum and minimum reference signal received power within the preset time window. Generate an operation information set. The preset values ​​are: the first power threshold is -95dBm to -85dBm, the first signal-to-interference-plus-noise ratio threshold is 8dB to 12dB, the first time window is 0.5s to 2s, and the first fluctuation threshold is 3dB to 6dB. The second power threshold range is -115dBm to -95dBm, the second signal-to-interference-plus-noise ratio threshold range is 0dB to 8dB, the second time window is 0.5s to 2s, and the second fluctuation threshold is 6dB to 12dB. The third power threshold is -110dBm to -100dBm, and the third signal-to-interference-plus-noise ratio threshold is 2dB to 6dB. The fourth power threshold is -120dBm to -110dBm, the fourth signal-to-interference-plus-noise ratio threshold is -2dB to 2dB, the third time window is 0.2s to 1s, and the third fluctuation threshold is 12dB to 20dB. Step S300: Based on the operation information set, query the electronic map of the line and output the scene recognition results of the current and recent communication scenarios of the train; Step S400: Based on the scene recognition result and combined with the reference signal received power, the signal-to-interference-plus-noise ratio, the reference signal received power fluctuation amplitude, and the reference signal received power peak-to-valley difference, query the scene-mode mapping table, output the target MIMO working mode, control the system to switch to the target MIMO working mode, and control the dedicated 4T4R vehicle-mounted donor antenna to switch between 4T4R working mode and 2T2R working mode in transmit diversity mode; When the received power of the reference signal is not lower than the first power threshold, the signal-to-interference-plus-noise ratio is not lower than the first signal-to-interference-plus-noise ratio threshold, and the fluctuation amplitude of the received power of the reference signal within the first time window is not greater than the first fluctuation threshold, it is determined to be a stable high-quality scenario, the spatial multiplexing mode is selected, and the dedicated 4T4R vehicle-mounted donor antenna is controlled to work in 4T4R working mode. When the received power of the reference signal is within the second power threshold range, or the signal-to-interference-plus-noise ratio (SIR) is within the second SIR threshold range, or the fluctuation amplitude of the received power of the reference signal within the second time window is not less than the second fluctuation threshold, it is determined to be an obstruction or multipath fluctuation scenario. The transmit diversity mode is selected, and in the transmit diversity mode, when the received power of the reference signal is not lower than the third power threshold and the SIR is not lower than the third SIR threshold, the dedicated 4T4R vehicle-mounted donor antenna is controlled to work in 2T2R mode. When the received power of the reference signal is lower than the third power threshold, or the signal-to-interference-plus-noise ratio is lower than the third signal-to-interference-plus-noise ratio threshold, it is determined that 2T2R cannot meet the lower limit of link quality and the dedicated 4T4R vehicle-mounted donor antenna is switched to 4T4R working mode. When the received power of the reference signal is lower than the fourth power threshold, or the signal-to-interference-plus-noise ratio is lower than the fourth signal-to-interference-plus-noise ratio threshold, and the peak-to-valley difference of the received power of the reference signal is not less than the third fluctuation threshold within the third time window, it is determined to be a deep fading scenario, the transmit diversity mode is selected, and the dedicated 4T4R vehicle-mounted donor antenna is controlled to work in 4T4R working mode. When the electronic map of the line indicates that there are continuous curves within the current and preset distance range of the train, the preset distance range is the line distance of 200m to 1500m along the direction of train operation, or equivalent to the predicted travel distance range of 5s to 30s calculated according to the train speed, and the fluctuation amplitude of the reference signal received power is not less than the second fluctuation threshold within the second time window, it is determined to be a multi-curve hilly scene. Beamforming mode is selected, and antenna beam and phase adjustment commands are output to point the main lobe of the dedicated 4T4R vehicle-mounted donor antenna to the predicted base station incoming wave direction. The predicted base station incoming wave direction is the azimuth direction calculated based on the train position information and the base station position information in the electronic map of the line. Step S500: Determine whether the strong external interference zone has been entered based on the interference detection result. When the strong external interference zone is entered, the intelligent anti-interference processing module is triggered to perform anti-interference processing and output antenna beam and phase adjustment commands to form beam nulls in the interference direction and adjust the phase weight of the dedicated 4T4R vehicle-mounted donor antenna. Step S600: Monitor the signal strength of neighboring cells in real time and initiate a handover process when the handover conditions are met. The handover process includes a soft handover process and a hard handover process.

[0040] In step S100, the near-end host unit, cascaded expansion unit, and far-end slave unit establish fiber optic link communication to ensure stable transmission of digital signals between units. Simultaneously, the electronic map of the line and the scene-mode mapping table are loaded into the system. The electronic map provides information on key areas of the line, and the scene-mode mapping table provides the correspondence between communication scenes and target MIMO operating modes. In step S200, the system acquires train location information, speed information, and direction of travel information, and acquires the reference signal received power and signal-to-interference-plus-noise ratio (SNR) of the serving cell and neighboring cells. The serving cell is the currently connected cell, and neighboring cells are candidate cells. The reference signal received power characterizes the received signal strength, and the SNR characterizes the signal quality. Within a preset time window, the system calculates the fluctuation amplitude (reflecting the degree of intensity fluctuation) and peak-to-valley difference (reflecting the difference between the maximum and minimum values) of the reference signal received power to form an operational information set. The first to fourth power thresholds, the first to fourth SNR thresholds, and each time window and fluctuation threshold belong to the preset criterion range used to determine different scenarios. In step S300, the system queries the electronic map of the line based on the operating information set and outputs the scene recognition results of the current and recent communication scenarios of the train. In step S400, based on the scene recognition results and combined with the reference signal received power, signal-to-interference-plus-noise ratio, fluctuation amplitude, and peak-to-valley difference, the system queries the scene-mode mapping table, outputs the target MIMO operating mode, and controls the system to switch between them. When the intensity, quality, and fluctuation are high and meet the first set of criteria, it is determined to be a stable and high-quality scene and the spatial multiplexing mode is selected. The donor antenna is controlled to operate in 4T4R mode. When the second set of criteria is met, it is determined to be an obstruction or multipath fluctuation scene and the transmit diversity mode is selected. In this mode, if the received power and signal-to-interference-plus-noise ratio meet the third set of criteria, it switches to 2T2R. The system operates in either of the following modes: 1) If the threshold of the third set of criteria is lower than the minimum link quality, 2T2R is deemed insufficient and the system switches back to 4T4R. 2) If the fourth set of criteria is met and the peak-to-valley difference meets the third fluctuation threshold, the system is identified as a deep fading scenario, transmit diversity is selected, and 4T4R operation is maintained. 3) If the electronic map indicates a continuous curve area and the fluctuation amplitude meets the second fluctuation threshold, the system is identified as a multi-curve hilly scenario, beamforming mode is selected, and antenna beam and phase adjustment commands are output. The predicted base station arrival direction is calculated from the train location information and the base station location information in the electronic map. In step S500, the system determines whether the system has entered a strong external interference zone based on the interference detection results. If it does, the intelligent anti-interference processing module is triggered, and a beam null is formed in the interference direction through phase weight control.In step S600, the system monitors the signal strength of neighboring cells in real time and initiates a handover process when the handover conditions are met. The handover process includes a soft handover process and a hard handover process to adapt to the handover requirements under different link states. In areas with good signal quality, soft handover is used, and in areas with poor signal quality or in emergency situations, hard handover is used to ensure communication continuity. The fluctuation amplitude of the reference signal received power is preferably calculated as the average absolute value of the difference between adjacent sampling points within a preset time window; the peak-to-valley difference of the reference signal received power is preferably calculated as the difference between the maximum and minimum values ​​within a preset time window.

[0041] According to the above technical solution, step S300 includes: step S301, querying the electronic map of the line based on the train location information and the running direction information to obtain key point information of the corresponding line segment; Step S302: Based on the key point information, determine whether there is a tunnel area, continuous curve area or interference area within the current and preset distance range of the train; Step S303: Encode the judgment results of steps S301 and S302 into a communication scene tag, and output it as the scene recognition result to step S400.

[0042] Scene recognition step S300 is achieved through the combination of electronic map and positioning information. In step S301, the system retrieves the electronic map of the line based on the train's location information and direction of travel to obtain key point information for the corresponding line segment. This key point information is used to characterize the line area or geographical features that are significantly related to wireless propagation. In step S302, the system determines whether there are tunnel areas, continuous curve areas, or interference areas within the train's current location and a preset distance range based on the aforementioned key point information. The preset distance range is used for advance prediction so that strategic preparations can be made in advance before the train enters the corresponding area. In step S303, the system encodes the query results of S301 and the judgment results of S302 to form a communication scene label. This communication scene label is output as the scene recognition result to step S400 for subsequent table lookup to select the MIMO working mode and execute the switch. Preferably, the preset distance range is the line distance of 200m to 1500m along the train's direction of travel, or equivalently, the predicted travel distance range of 5s to 30s calculated based on the train speed.

[0043] According to the above technical solution, step S400 includes: Step S401: Based on the reference signal received power, the signal-to-interference-plus-noise ratio, and the fluctuation amplitude of the reference signal received power, determine whether a stable high-quality scenario is met and output the spatial multiplexing mode. Step S402: Based on the received power of the reference signal, the signal-to-interference-plus-noise ratio, and the fluctuation amplitude of the received power of the reference signal, determine whether the blockage or multipath fluctuation scenario is met and output the transmit diversity mode. Step S403: Based on the received power of the reference signal, the signal-to-interference-plus-noise ratio, and the peak-to-valley difference of the received power of the reference signal, determine whether the deep fading scenario is met and output the transmit diversity mode, and simultaneously output the channel configuration command of the 4T4R working mode or the 2T2R working mode.

[0044] Step S404: Based on the continuous curve area judgment result obtained in step S302, and combined with the reference signal received power fluctuation amplitude, determine whether the multi-curve hilly scenario is satisfied; if satisfied, output the beamforming mode and output antenna beam and phase adjustment command.

[0045] Step S400 is further broken down into four judgment and output sub-steps for ease of implementation and verification. Step S401 uses the reference signal received power, signal-to-interference-plus-noise ratio (SIR), and received power fluctuation amplitude as criteria. If the strength and quality meet the requirements and the fluctuation is small, it is judged as a stable high-quality scenario, and the spatial multiplexing mode is output. Step S402 also uses the reference signal received power, SIR, and received power fluctuation amplitude as criteria. If the strength and quality are relatively degraded or the fluctuation is increased, it indicates that there are fluctuations caused by obstruction or multipath, and it is judged as an obstruction or multipath fluctuation scenario, and the transmit diversity mode is output. Step S403 uses the reference signal received power... The signal-to-interference-plus-noise ratio (SINR) and the peak-to-valley difference of the received power are used as criteria. The peak-to-valley difference is used to reflect the amplitude of rapid fluctuations. If the deep fading criterion is met, it is determined to be a deep fading scenario. The transmit diversity mode is output, and the channel configuration command is also output to clarify whether the donor antenna adopts the 4T4R or 2T2R working mode. Step S404 introduces the map recognition results. Based on the continuous curve area judgment results output by S302, and combined with the received power fluctuation amplitude, it is determined whether it belongs to a multi-curve hilly scenario. When it is met, the beamforming mode is output, and the antenna beam and phase adjustment command is output to guide the array antenna to perform beam pointing and phase weight adjustment.

[0046] According to the above technical solution, step S500 includes: Step S501: Decode the synchronization signal blocks in the received signal to obtain the frequency point, physical cell identifier, reference signal received power and signal-to-interference-plus-noise ratio of each synchronization signal block; Step S502: Filter the synchronization signal blocks corresponding to the primary physical cell identifier from the decoding results and suppress non-primary synchronization signal blocks; Step S503: The phase weight of the dedicated 4T4R vehicle-mounted donor antenna is controlled by the interference incident direction obtained by array antenna beam scanning or direction finding algorithm, so that the spatial filtering submodule forms a beam null in the interference direction. Step S504: Execute the frequency domain filtering submodule to filter out unwanted synchronization signal frequency points; Step S505: Output antenna beam and phase adjustment commands and amplify and forward the processed signal through the vehicle-mounted repeater system.

[0047] Step S500 serves as the anti-interference processing procedure after entering a strong external interference zone. Step S501 decodes the synchronization signal blocks in the received signal to obtain the frequency point, physical cell identifier, reference signal received power, and signal-to-interference-plus-noise ratio of each synchronization signal block, which is used to characterize the current co-frequency cell and interference situation. Step S502 filters the synchronization signal blocks corresponding to the primary physical cell identifier based on the decoding results and suppresses the non-primary synchronization signal blocks to stabilize the primary cell selection. Step S503 controls the phase weight of the donor antenna array according to the interference direction, so that the spatial filtering submodule forms a beam null in the interference direction, thereby achieving spatial dimension interference suppression. Step S504 executes the frequency domain filtering submodule to filter out the unwanted synchronization signal frequency points to further suppress interference components in the frequency dimension. Step S505 outputs antenna beam and phase adjustment commands to implement the above weight and beam control, and amplifies and forwards the processed signal through the vehicle-mounted repeater system to ensure that coverage service can still be provided after anti-interference processing.

[0048] According to the above technical solution, step S600 includes: Step S601: When the difference between the received power of the neighboring cell reference signal and the received power of the serving cell reference signal is not less than the first hysteresis and the duration is not less than the first trigger time, and the signal-to-interference-plus-noise ratio of the serving cell is not lower than the first handover quality threshold, the soft handover process is executed. Step S602, the soft handover process includes target cell handover preparation, maintaining the original link connection while completing synchronous access to the target cell, and releasing the original link after access confirmation; Step S603: When the received power of the reference signal of the serving cell is lower than the second handover power threshold or the signal-to-interference-plus-noise ratio of the serving cell is lower than the second handover quality threshold, or when a connection failure or emergency handover condition occurs, the hard handover process is executed. Step S604, the hard handover process includes releasing the original link and completing access to the target cell within a preset handover timeout, and performing a backoff or reselection when access fails; Step S605: Set a hold time to suppress ping-pong switching; Wherein, the first hysteresis is 2dB to 5dB, the first trigger time is 0.5s to 2s, the first switching quality threshold is 3dB to 8dB; the second switching power threshold is -120dBm to -110dBm, the second switching quality threshold is -2dB to 2dB; the preset switching timeout is 50ms to 200ms, and the hold time is 1s to 5s.

[0049] Step S600 is used to implement neighbor cell monitoring and handover control in a vehicle-mounted environment. In step S601, if the difference between the received power of the neighbor cell reference signal and the received power of the serving cell reference signal reaches or is not less than a first hysteresis, and the duration of this difference is not less than a first trigger time, and the signal-to-interference-plus-noise ratio (SNR) of the serving cell is not less than a first handover quality threshold, then a soft handover procedure is executed. The first hysteresis is used to introduce handover margin to avoid false triggering due to small fluctuations; the first trigger time is used to require the difference to persist to suppress instantaneous jitter; and the first handover quality threshold is used to ensure that soft handover is completed under controllable quality. In step S602, the soft handover procedure includes target cell handover preparation, synchronous access to the target cell while maintaining the original link connection, and releasing the original link after access confirmation to reduce the risk of handover interruption. In step S603, when the received power of the serving cell reference signal is lower than a second handover power threshold or the SNR of the serving cell is lower than a second handover quality threshold, or when a connection failure or emergency handover condition occurs, a hard handover procedure is executed. In step S604, the hard handover process includes releasing the original link and completing access to the target cell within a preset handover timeout. If access fails, a backoff or reselection is performed to improve recovery capability. In step S605, a hold time is set to suppress ping-pong handover, that is, to reduce the probability of reverse handover during the hold period after handover is completed, thereby improving connection stability. 2dB~5dB, 0.5s~2s, 3dB~8dB, -120dBm~-110dBm, -2dB~2dB, 50ms~200ms, and 1s~5s correspond to the value ranges of the aforementioned hysteresis, trigger time, handover quality threshold, handover power threshold, handover timeout, and hold time, respectively.

[0050] Under the same train, the same route, and the same base station coverage environment, the MIMO working mode was forcibly locked by the near-end host unit, and the number of donor-side transceiver channels was changed for comparative testing. The control group was locked in 2T2R working mode, and the test group was locked in 4T4R working mode. The scene recognition, mode switching and anti-interference control strategies of the present invention were enabled, and the above indicators were collected.

[0051] Comparison example: The comparison shows that, under the same wireless environment and line location conditions, the 4T4R working mode of this invention has significant improvements in key indicators such as reference signal received power, signal-to-interference-plus-noise ratio, fluctuation amplitude, peak-to-valley difference, and number of communication interruptions compared to the 2T2R working mode. In particular, it can maintain a stable connection and significantly improve the average throughput in scenarios with multipath obstruction, winding hills, and strong external interference, thus verifying the effectiveness of this invention in complex railway environments.

[0052] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A 4T4R railway 5G car-mounted repeater system based on MIMO technology, characterized in that, The application relates to a train 5G communication system, comprising: a dedicated four-transmitting-four-receiving (4T4R) vehicle-mounted donor antenna, a distributed vehicle compartment coverage 4T4R antenna, a near-end host unit, a cascaded expansion unit, a remote slave unit and a positioning module integrated with Beidou and inertial navigation, the dedicated 4T4R vehicle-mounted donor antenna is arranged on the roof of a train and is used for establishing a 4T4R wireless transceiving link with an external public network 5G base station, the dedicated 4T4R vehicle-mounted donor antenna is an array antenna and is configured to adjust the beam shape and direction according to the phase weight so as to support beamforming, and the radio frequency front end of the antenna is integrated with a phase shifter and a switch network and is used for controlling the phase weight and the transceiving channel configuration of the antenna array element; the distributed vehicle compartment coverage 4T4R antenna is arranged in each compartment and is used for providing 5G signal coverage in the compartment; the near-end host unit and the cascaded expansion unit are installed in a train equipment compartment, the remote slave unit is distributedly installed in each compartment and is electrically connected with the distributed vehicle compartment coverage 4T4R antenna, the positioning module integrated with Beidou and inertial navigation is installed on the train and is in communication connection with the near-end host unit, and the near-end host unit, the cascaded expansion unit and the remote slave unit are connected through an optical fiber to form a digital signal transmission link; the near-end host unit comprises a radio frequency front end module, a scene recognition and MIMO mode dynamic switching module, an intelligent anti-interference processing module, a baseband processing module, an optical module, a power module and a control monitoring module, the scene recognition and MIMO mode dynamic switching module comprises a positioning analysis sub-module, a scene sensing sub-module and a MIMO algorithm sub-module, the scene recognition and MIMO mode dynamic switching module is used for identifying a communication scene based on the positioning analysis sub-module, the scene sensing sub-module and the MIMO algorithm sub-module and switching the system between a spatial multiplexing mode, a transmitting diversity mode and a beamforming mode according to a scene-mode mapping table stored in the system; the near-end host unit is used for controlling the dedicated 4T4R vehicle-mounted donor antenna to adaptively switch between a 4T4R working mode and a two-transmitting-two-receiving (2T2R) working mode in the transmitting diversity mode, switching to the 4T4R working mode when the 2T2R working mode cannot meet a preset lower limit of link quality, triggering the intelligent anti-interference processing module to perform anti-interference processing when it is identified that a strong external interference area is entered, and outputting antenna beam and phase adjustment instructions of the near-end host unit in the beamforming mode, which are used for adjusting the beam direction and the phase weight of the dedicated 4T4R vehicle-mounted donor antenna.

2. The 4T4R railway 5G car-mounted repeater system based on MIMO technology according to claim 1, characterized in that, The intelligent anti-interference processing module includes: a synchronization signal block decoding submodule, a primary physical cell identifier selection submodule, a spatial filtering submodule, and a frequency filtering submodule. The synchronization signal block decoding submodule is used to decode the synchronization signal blocks in the received signal to obtain the frequency point, physical cell identifier, reference signal received power, and signal-to-interference-plus-noise ratio. The primary physical cell identifier selection submodule is used to filter the synchronization signal blocks corresponding to the primary physical cell identifier and suppress non-primary synchronization signal blocks. When entering the strong external interference zone, the spatial filtering submodule is used to form a beam null in the interference direction, and the frequency filtering submodule is used to filter out unwanted synchronization signal frequencies. 3.The 4T4R railway 5G car-mounted repeater system based on MIMO technology of claim 2, wherein: The cascaded expansion unit is used to receive digital baseband signals from the near-end host unit and drive the remote slave unit after completing signal regeneration, clock recovery and format conversion.

4. The 4T4R railway 5G car-mounted repeater system based on MIMO technology according to claim 3, characterized in that: The remote slave unit is used as an end-coverage device. It receives digital signals from the cascaded expansion unit through optical fiber, performs digital-to-analog conversion and radio frequency processing, and then radiates mobile communication signals through the distributed carriage coverage 4T4R antenna. The uplink signal is then amplified with low noise and digitized before being transmitted back. 5.The 4T4R MIMO technology based 5G truck-mounted repeater system for railway application according to claim 4, characterized in that: The integrated BeiDou and inertial navigation positioning module includes a BeiDou receiving antenna, an inertial measurement unit, and a positioning calculation unit. The BeiDou receiving antenna is installed on the roof of the train, and the inertial measurement unit and the positioning calculation unit are installed in the train equipment compartment or driver's cab. The positioning calculation unit is used to fuse the positioning information output by the BeiDou receiving antenna and the inertial navigation information output by the inertial measurement unit to obtain the train position information, the speed information, and the direction of travel information, and then send them to the near-end host unit.

6. A control method for controlling the vehicle repeater system according to any one of claims 1 to 5, characterized by, include: Step S100: Establish fiber optic link communication between the near-end host unit, the cascaded expansion unit and the remote slave unit, and load the line electronic map and scene-mode mapping table; Step S200: Obtain the train location information, and obtain the reference signal received power and signal-to-interference-plus-noise ratio of the serving cell and neighboring cells. Calculate the reference signal received power fluctuation amplitude and the reference signal received power peak-to-valley difference according to a preset time window. The reference signal received power fluctuation amplitude is the average absolute value of the difference in reference signal received power between adjacent sampling points within the preset time window, and the reference signal received power peak-to-valley difference is the difference between the maximum and minimum reference signal received power within the preset time window. Generate an operation information set. The preset values ​​are: the first power threshold is -95dBm to -85dBm, the first signal-to-interference-plus-noise ratio threshold is 8dB to 12dB, the first time window is 0.5s to 2s, and the first fluctuation threshold is 3dB to 6dB. The second power threshold range is -115dBm to -95dBm, the second signal-to-interference-plus-noise ratio threshold range is 0dB to 8dB, the second time window is 0.5s to 2s, and the second fluctuation threshold is 6dB to 12dB. The third power threshold is -110dBm to -100dBm, and the third signal-to-interference-plus-noise ratio threshold is 2dB to 6dB. The fourth power threshold is -120dBm to -110dBm, the fourth signal-to-interference-plus-noise ratio threshold is -2dB to 2dB, the third time window is 0.2s to 1s, and the third fluctuation threshold is 12dB to 20dB. Step S300: Based on the operation information set, query the electronic map of the line and output the scene recognition results of the current and recent communication scenarios of the train; Step S400: Based on the scene recognition result and combined with the reference signal received power, the signal-to-interference-plus-noise ratio, the reference signal received power fluctuation amplitude, and the reference signal received power peak-to-valley difference, query the scene-mode mapping table, output the target MIMO working mode, control the system to switch to the target MIMO working mode, and control the dedicated 4T4R vehicle-mounted donor antenna to switch between 4T4R working mode and 2T2R working mode in transmit diversity mode; When the received power of the reference signal is not lower than the first power threshold, the signal-to-interference-plus-noise ratio is not lower than the first signal-to-interference-plus-noise ratio threshold, and the fluctuation amplitude of the received power of the reference signal within the first time window is not greater than the first fluctuation threshold, it is determined to be a stable high-quality scenario, the spatial multiplexing mode is selected, and the dedicated 4T4R vehicle-mounted donor antenna is controlled to work in 4T4R working mode. When the received power of the reference signal is within the second power threshold range, or the signal-to-interference-plus-noise ratio (SIR) is within the second SIR threshold range, or the fluctuation amplitude of the received power of the reference signal within the second time window is not less than the second fluctuation threshold, it is determined to be an obstruction or multipath fluctuation scenario. The transmit diversity mode is selected, and in the transmit diversity mode, when the received power of the reference signal is not lower than the third power threshold and the SIR is not lower than the third SIR threshold, the dedicated 4T4R vehicle-mounted donor antenna is controlled to work in 2T2R mode. When the received power of the reference signal is lower than the third power threshold, or the signal-to-interference-plus-noise ratio is lower than the third signal-to-interference-plus-noise ratio threshold, it is determined that 2T2R cannot meet the lower limit of link quality and the dedicated 4T4R vehicle-mounted donor antenna is switched to 4T4R working mode. When the received power of the reference signal is lower than the fourth power threshold, or the signal-to-interference-plus-noise ratio is lower than the fourth signal-to-interference-plus-noise ratio threshold, and the peak-to-valley difference of the received power of the reference signal is not less than the third fluctuation threshold within the third time window, it is determined to be a deep fading scenario, the transmit diversity mode is selected, and the dedicated 4T4R vehicle-mounted donor antenna is controlled to work in 4T4R working mode. When the electronic map of the line indicates that there are continuous curves within the current and preset distance range of the train, the preset distance range is the line distance of 200m to 1500m along the direction of train operation, or equivalent to the predicted travel distance range of 5s to 30s calculated according to the train speed, and the fluctuation amplitude of the reference signal received power is not less than the second fluctuation threshold within the second time window, it is determined to be a multi-curve hilly scene. Beamforming mode is selected, and antenna beam and phase adjustment commands are output to point the main lobe of the dedicated 4T4R vehicle-mounted donor antenna to the predicted base station incoming wave direction. The predicted base station incoming wave direction is the azimuth direction calculated based on the train position information and the base station position information in the electronic map of the line. Step S500: Determine whether the strong external interference zone has been entered based on the interference detection result. When the strong external interference zone is entered, the intelligent anti-interference processing module is triggered to perform anti-interference processing and output antenna beam and phase adjustment commands to form beam nulls in the interference direction and adjust the phase weight of the dedicated 4T4R vehicle-mounted donor antenna. Step S600: Monitor the signal strength of neighboring cells in real time and initiate a handover process when the handover conditions are met. The handover process includes a soft handover process and a hard handover process.

7. The control method of the car-mounted repeater system according to claim 6, wherein Step S300 includes: Step S301, querying the electronic map of the line based on the train location information and the running direction information to obtain key point information of the corresponding line segment; Step S302: Based on the key point information, determine whether there is a tunnel area, continuous curve area or interference area within the current and preset distance range of the train; Step S303: Encode the judgment results of steps S301 and S302 into a communication scene tag, and output it as the scene recognition result to step S400.

8. The control method of the car-mounted repeater system according to claim 7, wherein Step S400 includes: Step S401: Based on the reference signal received power, the signal-to-interference-plus-noise ratio, and the fluctuation amplitude of the reference signal received power, determine whether a stable high-quality scenario is met and output the spatial multiplexing mode. Step S402: Based on the received power of the reference signal, the signal-to-interference-plus-noise ratio, and the fluctuation amplitude of the received power of the reference signal, determine whether the blockage or multipath fluctuation scenario is met and output the transmit diversity mode. Step S403: Based on the received power of the reference signal, the signal-to-interference-plus-noise ratio, and the peak-to-valley difference of the received power of the reference signal, determine whether the deep fading scenario is met and output the transmit diversity mode, and simultaneously output the channel configuration command of the 4T4R working mode or the 2T2R working mode. Step S404: Based on the continuous curve area judgment result obtained in step S302, and combined with the reference signal received power fluctuation amplitude, determine whether the multi-curve hilly scenario is satisfied; if satisfied, output the beamforming mode and output antenna beam and phase adjustment command.

9. The control method of the car-mounted repeater system according to claim 8, wherein Step S500 includes: Step S501: Decode the synchronization signal blocks in the received signal to obtain the frequency point, physical cell identifier, reference signal received power and signal-to-interference-plus-noise ratio of each synchronization signal block; Step S502: Filter the synchronization signal blocks corresponding to the primary physical cell identifier from the decoding results and suppress non-primary synchronization signal blocks; Step S503: The phase weight of the dedicated 4T4R vehicle-mounted donor antenna is controlled by the interference incident direction obtained by array antenna beam scanning or direction finding algorithm, so that the spatial filtering submodule forms a beam null in the interference direction. Step S504: Execute the frequency domain filtering submodule to filter out unwanted synchronization signal frequency points; Step S505: Output antenna beam and phase adjustment commands and amplify and forward the processed signal through the vehicle-mounted repeater system.

10. The control method of the car-mounted repeater system according to claim 9, wherein Step S600 includes: Step S601: When the difference between the received power of the neighboring cell reference signal and the received power of the serving cell reference signal is not less than the first hysteresis and the duration is not less than the first trigger time, and the signal-to-interference-plus-noise ratio of the serving cell is not lower than the first handover quality threshold, the soft handover process is executed. Step S602, the soft handover process includes target cell handover preparation, maintaining the original link connection while completing synchronous access to the target cell, and releasing the original link after access confirmation; Step S603: When the received power of the reference signal of the serving cell is lower than the second handover power threshold or the signal-to-interference-plus-noise ratio of the serving cell is lower than the second handover quality threshold, or when a connection failure or emergency handover condition occurs, the hard handover process is executed. Step S604, the hard handover process includes releasing the original link and completing access to the target cell within a preset handover timeout, and performing a backoff or reselection when access fails; Step S605: Set a hold time to suppress ping-pong switching; Wherein, the first hysteresis is 2dB to 5dB, the first trigger time is 0.5s to 2s, the first switching quality threshold is 3dB to 8dB; the second switching power threshold is -120dBm to -110dBm, the second switching quality threshold is -2dB to 2dB; the preset switching timeout is 50ms to 200ms, and the hold time is 1s to 5s.

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