A distributed digital overlay system

Abstract

The application discloses a distributed digital coverage system, comprising an access unit, an extension unit MEU and a remote unit; the access unit comprises 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 master control module. The technical scheme of the application does not blindly amplify the signals of the whole bandwidth, and does not require any prior information, and can detect and analyze the signal system, frequency band, frequency point, bandwidth and carrier number feature information of the signal actually working in real time and adaptively.

Description

Technical Field

[0001] This invention belongs to the field of mobile communication technology, and in particular relates to a distributed digital coverage system. Background Technology

[0002] The distributed digital coverage system consists of a radio frequency access unit (MAU), an expansion unit (MEU), and a remote unit (MRU). The MAU receives downlink radio frequency signals from sources such as 2G, 3G, 4G LTE, and 5G NR via wired coupling. After being converted into digital signals, these signals are then converted to optical signals via optoelectronic conversion and transmitted to the expansion unit (MEU). The MEU, through protocol conversion and integrated PoE power supply capabilities, connects to the MRU via a composite optical cable. The MRU performs digital up-conversion and radio frequency conversion on the digital signals transmitted through the composite optical cable, outputting a radio frequency signal. Simultaneously, the remote unit (MRU) restores the PoE power from the composite optical cable to power itself. Furthermore, the MAU converts the digital signals uploaded by the remote unit into uplink radio frequency signals and transmits them back to the source via wired connection. The MAU must support remote monitoring and management functions as well as centralized upgrade functions for its expansion units and remote units. The remote unit converts the digital signals sent by the extension unit (MEU) into radio frequency signals, enabling wireless coverage for 2G, 3G, 4G LTE, and 5G NR. Simultaneously, it converts the received uplink radio frequency signals into digital signals and transmits them to the access unit (MAU). Distributed digital coverage systems are a low-cost indoor coverage solution, particularly suitable for scenarios with low capacity requirements but high signal coverage needs, such as basements, office buildings with few users, tunnels, and small retail stores. This expands the service area and eliminates coverage blind spots.

[0003] The traditional signal processing method for distributed digital coverage systems involves obtaining some prior information about the distributed digital coverage system, assuming the operator (such as China Mobile) is known in advance.

[0004] 1. Which standards need to be supported, such as single 5G, or dual-mode 4G and 5G;

[0005] 2. Specific frequency band, such as: 2300MHz;

[0006] 3. In the case of a single carrier, the maximum carrier configuration bandwidth, such as 20MHz for a single-carrier 4G LTE, will no longer distinguish between configurations with signal bandwidths below 20MHz, and will uniformly process the signal using the maximum carrier configuration bandwidth of 20MHz; if the single-carrier 5G NR has a bandwidth of 100MHz, within the frequency band, the maximum carrier configuration bandwidth of 100MHz will uniformly process the signal.

[0007] 4. Under the same standard, with a multi-carrier (M carriers) configuration, the maximum carrier configuration bandwidth (Max_BW) is: M*Max_BW. Under the same standard, the maximum bandwidth that needs to be processed is: M*Max_BW.

[0008] In terms of maximizing frequency band configuration, China Mobile's 2600MHz band has a total bandwidth of 160MHz. Among them, 2515-2615MHz is commonly used for 100MHz 5G NR; and from 2615MHz to 2675MHz, there is a total of 60MHz, which can support up to three 20MHz LTE carriers.

[0009] Therefore, traditional signal processing methods for 5G NR, regardless of the actual operating bandwidth or the configured bandwidth, uniformly amplify the 100MHz bandwidth. This is because, in practice, to reduce interference, the actual configured 5G NR bandwidth might be 80MHz out of the total 100MHz bandwidth (2515-2615MHz). On one hand, energy cannot be concentrated within the useful signal bandwidth (80MHz bandwidth) for signal amplification; on the other hand, the excess 20MHz of invalid signal is amplified, wasting useful energy. Simultaneously, noise signals in non-working bandwidths (such as the non-working 20MHz bandwidth) are amplified, interfering with the actual operating signal. For 4G LTE, regardless of the number of carriers or the configured bandwidth, uniformly amplify the 60MHz bandwidth. Again, energy cannot be concentrated within the useful signal bandwidth; on the other hand, energy is wasted, and noise signals in non-working bandwidths (such as the non-working 20MHz bandwidth) are amplified, interfering with the actual operating signal. Especially for a bandwidth of 60MHz, it's rare to configure LTE with three carriers. Moreover, even with dual LTE carriers, not every carrier is necessarily configured at 20MHz; the LTE operating bandwidth needs to be adjusted appropriately based on the actual application scenario. Therefore, directly amplifying the signal within a 60MHz bandwidth results in a significant waste of energy and also amplifies noise signals outside the operating bandwidth. Summary of the Invention

[0010] The technical problem this invention aims to solve is to provide a distributed digital coverage system that does not blindly amplify the signal across the entire bandwidth, nor does it require any prior information (communication standard, frequency band, bandwidth, number of carriers, etc.). This is achieved by adding an intelligent analysis module—a signal feature analysis module—to the system. This module detects and analyzes the current signal's standard, frequency band, frequency point, bandwidth, and number of carriers in real time and adaptively. Combining this detected signal feature information with the system's efficient uplink and downlink signal amplification for specific standards, frequencies, bandwidths, and carrier numbers, it reduces energy waste and significantly lowers costs. Furthermore, for FDD (Frequency Division Duplexing) signals, only the signal feature analysis module needs to be added. For TDD (Time Division Duplexing) signals, the time-domain synchronization function can be integrated into the signal feature analysis module, performing two different functions and further reducing costs.

[0011] To achieve the above objectives, the present invention adopts the following technical solution:

[0012] A distributed digital coverage system, wherein the distributed digital coverage system is an FDD-compliant distributed digital coverage system, comprising: an access unit (MAU), an expansion unit (MEU), and a remote unit (MRU); wherein the access unit (MAU) includes: an uplink / downlink RF signal processing subsystem, an RF transceiver subsystem, an FPGA processing subsystem, a signal coupler, a signal feature analysis module, and an MCU core control module; the expansion unit (MEU) includes: an FPGA processing subsystem, a PoE power supply system, and an MCU core control module; the remote unit includes: an FPGA processing subsystem, an RF transceiver subsystem, an uplink / downlink RF signal processing subsystem, a PoE power supply system, and an MCU core control module.

[0013] Preferably, the uplink and downlink RF signal processing subsystem, the RF transceiver subsystem, and the FPGA processing subsystem are connected in sequence to form the main link for uplink and downlink signal processing of the access unit; the access unit of the distributed digital coverage system and the base station signal source realize signal transmission and reception communication between the access unit and the base station signal source through wired signal coupling.

[0014] Preferably, the FPGA processing subsystem outputs the baseband IQ signal after protocol conversion, the control word for fiber optic link synchronization and data conversion, and the control word for signal characteristics, which are then input to the expansion unit of the distributed digital coverage system to realize signal transmission and communication. Among them, the control word for signal characteristics is: the MCU core main control module of the access unit processes the data information of the effective working signal's system, frequency band, frequency point, bandwidth, and carrier number to obtain the specific frequency band, frequency point, center frequency point, and bandwidth that need to be amplified for the effective working signal.

[0015] Preferably, the FPGA processing subsystem of the remote unit receives the baseband IQ signal, fiber optic link synchronization and data conversion control words, and signal characteristic control words from the extension 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 decapsulated signal characteristics to the MCU core main control module of the remote unit. The MCU core main control module performs appropriate parameter configuration for the FPGA processing subsystem, the RF transceiver subsystem, and the uplink and downlink RF signal processing subsystem of the remote unit, and performs signal filtering and amplification processing on the effective working signals.

[0016] Preferably, the signal feature analysis module couples the radio frequency signal from the RRU signal source through a coupler, performs radio frequency downconversion, analog conversion, digital downconversion and baseband signal processing to obtain the characteristics of the baseband signal, including: the signal's communication standard, RSRP, SINR, signal frequency point information, signal frequency band information, signal bandwidth, and carrier number information.

[0017] Baseband signal processing includes:

[0018] (1) The digital signal processor performs digital filtering, synchronization and equalization on the converted digital signal;

[0019] (2) Channel estimation and decoding of error correction codes;

[0020] (3) The baseband demodulator demodulates the signal according to the modulation method. The demodulation process includes extracting the amplitude, frequency or phase information of the signal to recover the original baseband data.

[0021] (4) The demodulated baseband data is decoded to recover the original user information or control signals. The decoded data is output to the feature analysis module. The decoding process includes deinterleaving, descrambling, and decryption.

[0022] The signal feature analysis module determines the validity of 4G LTE signals by including:

[0023] Baseband demodulation processing is performed 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;

[0024] Set signal thresholds Th_RSRP_LTE and Th_SINR_LTE. For RSRP≥Th_RSRP_LTE and SINR≥Th_SINR_LTE, it is considered a valid working signal.

[0025] In conjunction with the operator, determine the final effective working signal and its signal characteristics;

[0026] The signal feature analysis module determines the validity of 5G NR signals, including the following processing steps:

[0027] Demodulate the 5G NR signal across the entire frequency band to obtain the signal characteristics of the corresponding signal: frequency band, frequency point, bandwidth, number of carriers, RSRP, and SINR;

[0028] Set signal thresholds Th_RSRP_NR and Th_SINR_NR. Only signals with RSRP ≥ Th_RSRP_NR and SINR ≥ Th_SINR_NR are considered valid working signals.

[0029] Then, by combining the specific operator, the final effective working signal and its signal characteristics are determined.

[0030] This invention also provides a distributed digital coverage system, which is a TDD-based distributed digital coverage system, comprising: an access unit (MAU), an expansion unit (MEU), and a remote unit (MRU); wherein the access unit includes: an uplink / downlink RF signal processing subsystem, an RF transceiver subsystem, an FPGA processing subsystem, a signal coupler, a signal feature analysis and time-domain synchronization module, and an MCU core control module; the expansion unit (MEU) includes: an FPGA processing subsystem, a PoE power supply system, and an MCU core control module; the remote unit includes: an FPGA processing subsystem, an RF transceiver subsystem, an uplink / downlink RF signal processing subsystem, a PoE power supply system, and an MCU core control module.

[0031] Preferably, the uplink and downlink RF signal processing subsystem, the RF transceiver subsystem, and the FPGA processing subsystem are connected in sequence to form the main link for uplink and downlink signal processing of the access unit; the access unit and the RRU signal source of the distributed digital coverage system realize signal transmission and reception communication with the RRU through wired signal coupling.

[0032] Preferably, the FPGA processing subsystem outputs control words for baseband IQ signal fiber optic link synchronization and data conversion, signal characteristic control words, and time-domain synchronization control words after protocol conversion. These are input to the remote unit of the distributed digital coverage system to realize signal transmission and communication. Among them, the signal characteristic control word is: the MCU core main control module of the access unit processes the data information of the effective working signal's system, frequency band, frequency point, bandwidth, and carrier number to obtain the specific frequency band, frequency point, center frequency point, and bandwidth that need to be amplified for the effective working signal; the time-domain synchronization control word is the time-domain synchronization control word information - time slot switching information.

[0033] Preferably, the control word for data conversion, the control word for signal characteristics, and the time-domain synchronization control word are encapsulated via the CPRI protocol in the access unit, and decapsulated via the CPRI protocol in the extension unit and the remote unit before being output to the MCU core control module. The MCU core control module performs parameter configuration, time slot switching operations, and filtering and amplification of the valid working signals for the FPGA processing subsystem, the RF transceiver subsystem, and the uplink and downlink RF signal processing subsystem.

[0034] Preferably, the signal feature analysis and time-domain synchronization module couples the radio frequency signal from the RRU source through a coupler, performs radio frequency down-conversion, analog conversion, digital down-conversion and baseband signal processing to obtain the characteristics of the baseband signal, including: the signal's communication standard, RSRP, SINR, signal frequency point information, signal frequency band information, signal bandwidth, and carrier number information.

[0035] Baseband signal processing includes:

[0036] (1) The digital signal processor performs digital filtering, synchronization and equalization on the converted digital signal;

[0037] (2) Channel estimation and decoding of error correction codes;

[0038] (3) The baseband demodulator demodulates the signal according to the modulation method. The demodulation process includes extracting the amplitude, frequency or phase information of the signal to recover the original baseband data.

[0039] (4) The demodulated baseband data is decoded to recover the original user information or control signals. The decoded data is output to the feature analysis module. The decoding process includes deinterleaving, descrambling, and decryption.

[0040] The determination of a valid 4G LTE signal includes:

[0041] Baseband demodulation processing is performed 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;

[0042] Set signal thresholds Th_RSRP_LTE and Th_SINR_LTE. For RSRP≥Th_RSRP_LTE and SINR≥Th_SINR_LTE, it is considered a valid working signal.

[0043] In conjunction with the operator, determine the final effective working signal and its signal characteristics;

[0044] The process of determining the validity of 5G NR signals includes:

[0045] Demodulate the 5G NR signal across the entire frequency band to obtain the signal characteristics of the corresponding signal: frequency band, frequency point, bandwidth, number of carriers, RSRP, and SINR;

[0046] Set signal thresholds Th_RSRP_NR and Th_SINR_NR. Only signals with RSRP ≥ Th_RSRP_NR and SINR ≥ Th_SINR_NR are considered valid working signals.

[0047] Then, by combining the specific operator, the final effective working signal and its signal characteristics are determined.

[0048] This invention introduces a signal feature analysis module that avoids blindly amplifying the signal across the entire bandwidth without requiring any prior information (system, frequency band, bandwidth, number of carriers, etc.). It can detect and analyze the actual signal system's system, frequency band, frequency point, bandwidth, and number of carriers in real time and adaptively. Combining this detected signal feature information with targeted uplink and downlink signal amplification for specific systems, frequencies, bandwidths, and carrier numbers, it reduces energy waste and significantly lowers costs. The same circuitry supports full-band, multi-system signal processing, covering 4G LTE and 5G NR, and can be extended upwards to 6G and downwards to 3G and 2G, allowing for on-demand expansion and adaptation to various application scenarios. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0050] Figure 1 This is a schematic diagram of the access unit structure of the distributed digital coverage system according to Embodiment 1 of the present invention.

[0051] Figure 2 This is a schematic diagram of the extended unit structure of the distributed digital overlay system according to Embodiment 1 of the present invention;

[0052] Figure 3 This is a schematic diagram of the remote unit structure of the distributed digital coverage system according to Embodiment 1 of the present invention;

[0053] Figure 4 This is a schematic diagram of the access unit structure of the FDD-based distributed digital coverage system according to Embodiment 2 of the present invention;

[0054] Figure 5 This is a schematic diagram of the remote structure of the FDD-based distributed digital coverage system according to Embodiment 2 of the present invention;

[0055] Figure 6 This is a schematic diagram of the access unit structure of the TDD-based distributed digital coverage system according to Embodiment 2 of the present invention. Detailed Implementation

[0056] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments 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.

[0057] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0058] Example 1:

[0059] This invention provides a distributed digital coverage system that extends to simultaneously support multiple standards and frequency bands of FDD and TDD, including: an access unit, an extension unit (MEU), and a remote unit.

[0060] 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 time-domain synchronization module, and an MCU core main control module.

[0061] The RF transceiver subsystem employs a multi-channel RF transceiver. These channels can process TDD and FDD signals in parallel, or all channels can be used for TDD signal processing, or all channels can be used for FDD signal processing. The TDD RF signal processing subsystem is dedicated to filtering and amplifying TDD RF signals, while the FDD RF signal processing subsystem is dedicated to filtering and amplifying FDD RF signals. The FPGA processing subsystem encapsulates and processes the FDD and TDD IQ data output from the multi-channel RF transceiver subsystem, the time-domain synchronization information output from the signal feature analysis and time-domain synchronization modules, and the frequency and bandwidth information of the effective operating signals output from the MCU core control module, and transmits this data to the remote unit of the distributed digital coverage system. The FPGA processing subsystem encapsulates the protocol and needs to process three types of data: the digital IQ signal (including TDD and FDD IQ signals) of the multi-channel RF transceiver subsystem, the frequency band and bandwidth information of the effective working signal calculated by the MCU core main control module, and the time slot switching information output by the signal feature analysis and time domain synchronization module.

[0062] like Figure 2 As shown, the expansion unit MEU includes: an FPGA processing subsystem, a PoE power supply system, and an MCU main control module.

[0063] Since the access unit MAU frames and transmits the baseband IQ data and control word information (including the frequency band and bandwidth information of the effective working signal calculated by the MCU core main control module, signal feature analysis and time slot switching information output by the time domain synchronization module) of TDD and FDD, the extension unit MEU will uniformly perform frame parsing processing on these data, and perform data distribution and framing processing in combination with the topology. Therefore, the extension unit no longer distinguishes between TDD and FDD data and processes them uniformly.

[0064] like Figure 3 As shown, the remote unit includes: an FPGA processing subsystem, a multi-channel RF transceiver subsystem, a TDD RF signal processing subsystem, an FDD RF signal processing subsystem, a PoE power supply system, and an MCU core control module.

[0065] The FPGA processing subsystem of the remote unit of the distributed digital coverage system 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 control word obtained by the FPGA processing subsystem after decapsulation contains the specific frequency point, bandwidth, and time slot switching information of the valid working signal. This information is transmitted to the MCU core control module of the remote unit. 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 subsystems to perform signal filtering, amplification, and time slot switching on the valid working signal.

[0066] The PoE power supply system transmits DC power from the expansion unit (MEU) via a composite optical cable, and through appropriate adjustment and allocation, provides the operating power to the FPGA processing subsystem, the RF transceiver subsystem, the uplink and downlink RF signal processing subsystem, and the MCU core control module.

[0067] The multi-channel radio frequency transceiver subsystem, TDD radio frequency signal processing subsystem, and FDD radio frequency signal processing subsystem of the remote unit of the distributed digital coverage system have the same functions as the access unit, and will not be described in detail here.

[0068] This invention's distributed digital coverage system supports multiple modes, covering 4G LTE and 5G NR. It can also be extended upwards to 6G and downwards to 3G and 2G, allowing for on-demand expansion and adaptation to various application scenarios. The distributed digital coverage system supports multiple frequencies. Taking China Mobile as an example, it can support 700MHz 5G NR, 900MHz 4G LTE (refarmed to 5G NR), 1800MHz 4G LTE, 2300MHz 4G LTE, 2600MHz 4G LTE and 5G NR, and can even extend to 4.9GHz 5G NR.

[0069] Example 2:

[0070] This invention also provides a distributed digital coverage system, including: an access unit (MAU), an extension unit (MEU), and a remote unit (MRU).

[0071] For FDD-based distributed digital overlay systems, such as Figure 4 As shown, the Access Unit (MAU) includes: uplink and downlink RF signal processing subsystem, RF transceiver subsystem, FPGA processing subsystem, signal coupler, signal feature analysis module, and MCU core control module.

[0072] The uplink and downlink RF signal processing subsystems, the RF transceiver subsystem, and the FPGA processing subsystem are sequentially connected to form the main link for uplink and downlink signal processing in the access unit of the distributed digital coverage system. The access unit of the distributed digital coverage system and the base station signal source achieve signal transmission and reception communication through wired signal coupling.

[0073] The inputs and outputs of the uplink and downlink RF signal processing subsystems are both high-frequency RF signals, such as 2300MHz RF signals. The outputs of the FPGA processing subsystem are baseband IQ signals after protocol conversion, control words for fiber optic link synchronization and data conversion, and control words for signal characteristics, which are input to the expansion unit of the distributed digital coverage system to realize signal transmission and communication.

[0074] Among them, the control word for signal characteristics refers to the data processing performed by the MCU core main control module of the access unit on information such as the system, 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.

[0075] The signal coupler, signal feature analysis module, and MCU core control module are connected in sequence to form the core functions of the signal feature analysis link and the control signal processing main link.

[0076] The signal feature analysis module, through a coupler, couples the radio frequency signal from the base station signal source, performs radio frequency down-conversion, analog-to-digital conversion, digital down-conversion, and baseband signal processing to obtain some characteristics of the baseband signal, including: the signal's communication standard, RSRP (Reference Signal Receiving Power), SINR (Signal to Interference plus Noise Ratio), signal frequency point information, signal frequency band information, signal bandwidth, carrier number information, etc.

[0077] Baseband signal processing includes:

[0078] (1) The digital signal processor (DSP) further processes the converted digital signal, including digital filtering, synchronization, equalization, etc.

[0079] (2) It also includes channel estimation and error correction coding decoding to recover the original data.

[0080] (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 recover the original baseband data.

[0081] (4) Data Decoding and Output: The demodulated baseband data undergoes decoding to recover the original user information or control signals. Decoding includes steps such as deinterleaving, descrambling, and decryption. Finally, the decoded data is output to the feature analysis module.

[0082] Among them, the signal feature analysis module is full-band and full-standard, and can identify the signal features of all standards and all frequency bands.

[0083] The signal feature analysis module, which determines valid signals, specifically includes the 4G LTE processing procedures:

[0084] 1. Demodulate the signals of 4G LTE across the entire frequency band 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;

[0085] 2. Set signal thresholds Th_RSRP_LTE and Th_SINR_LTE. Only when RSRP ≥ Th_RSRP_LTE and SINR ≥ Th_SINR_LTE is it considered a valid working signal. The detection of whether it is a valid signal generally needs to be performed multiple times, such as 5-10 times. Only when the number of times that meets the requirements is greater than 80% is it considered a valid working signal.

[0086] 3. Then, in conjunction with the specific operator (e.g., if the application scenario involves China Mobile, record the effective working signals of China Mobile), determine the final effective working signal and its signal characteristics: frequency band, frequency point, bandwidth, and number of carriers;

[0087] 4. Output the signal characteristics to the MCU core control module, which will then control the subsequent signal processing.

[0088] The specific process includes the 5G NR processing procedure:

[0089] 1. Demodulate the 5G NR signal across the entire frequency band to obtain the signal characteristics of the corresponding signal: frequency band, frequency point, bandwidth, number of carriers, RSRP, and SINR; among them, only the demodulated signal can obtain RSRP and SINR information;

[0090] 2. Set signal thresholds Th_RSRP_NR and Th_SINR_NR. Only signals with RSRP ≥ Th_RSRP_NR and SINR ≥ Th_SINR_NR are considered valid working signals. The detection of whether a signal is valid generally needs to be performed multiple times, such as 5-10 times. A signal is considered valid only if the number of times it meets the requirements is greater than 80%.

[0091] 3. Then, in conjunction with the specific operator (e.g., if the application scenario involves China Mobile, record the effective working signals of China Mobile), determine the final effective working signal and its signal characteristics: frequency band, frequency point, bandwidth, and number of carriers;

[0092] 4. Output the signal characteristics to the MCU core control module, which will then control the subsequent signal processing.

[0093] The MCU core control module obtains the valid signal and its signal characteristics: frequency band, frequency point, bandwidth, and number of carriers. It calculates the frequency band and bandwidth of the signal to be processed, as well as the signal processing requirements (such as signal filtering requirements, power amplification requirements, and delay requirements). It then sends these to the uplink and downlink RF signal processing subsystems, the RF transceiver subsystem, and the FPGA processing subsystem via instructions. This allows for targeted processing of the valid working signal frequency band and bandwidth, including signal filtering and signal amplification.

[0094] The uplink and downlink RF signal processing subsystem includes the following two key functions. One of these functions is that the uplink and downlink RF signal processing subsystem receives RF signals from the donor duplexer, which are generally high-frequency signals, such as China Mobile's 2600MHz RF signals. After passing through a low-noise amplifier (LNA), the high-frequency signals are appropriately filtered and amplified, which facilitates processing by the subsequent RF transceiver subsystem. This solution directly adopts a zero-IF RF transceiver solution.

[0095] Traditional solutions employ a digital intermediate frequency (IF) transceiver approach. The high-frequency RF signal passes through a low-noise amplifier (LNA), then through an RF down-conversion module. The RF signal amplified by the LNA is then down-converted to output a zero-IF analog signal, which is finally processed by the RF transceiver subsystem.

[0096] The low-noise amplifier (LNA) receives control commands from the MCU core control module and amplifies only the frequency band and bandwidth of the valid working signal, instead of using traditional signal processing methods to amplify the full-band signal.

[0097] Another function of the uplink / downlink RF signal processing subsystem is to receive high-frequency analog signals from the RF transceiver subsystem, amplify them directly through the uplink power amplifier, and output the amplified high-frequency signal. Specifically, the uplink power amplifier receives control commands from the MCU core control module and amplifies only the effective operating signal's frequency band and bandwidth, instead of using traditional signal processing methods to amplify the entire frequency band. This reduces the performance requirements of the uplink power amplifier and, by amplifying only the useful in-band signal while avoiding noise signals outside the effective bandwidth, significantly improves system performance.

[0098] Traditional processing solutions employ a digital intermediate frequency (IF) transceiver approach. The analog IF signal output from the RF transceiver subsystem is first processed by an RF upconversion module to convert the analog IF signal into a high-frequency RF signal. Then, the signal is amplified by an uplink power amplifier before being output to the donor duplexer.

[0099] Among them, the zero-IF (Zero-IF) architecture RF transceiver includes its variant, the low-IF (Low-IF) transceiver. Zero-IF, also known as direct conversion, means that the RF signal does not need to pass through an intermediate frequency (IF) stage before directly entering I / Q demodulation and being converted to a baseband signal. No IF signal is generated in the process, thus eliminating the need for IF amplifiers, IF filters, and other components. Therefore, the architecture is relatively simple, the system size is smaller, and the cost and power consumption are lower. The advantages of zero-IF are that it requires fewer components, is easier to integrate, and offers good performance. Aside from the inherent limitations of DC, it has few disadvantages.

[0100] The RF transceiver subsystem employs a zero-IF (intermediate frequency) analog-to-digital (A / D) processing scheme, further enhancing system integration, reducing system complexity, and lowering system cost. The RF transceiver subsystem uses a single-chip solution, allowing for the use of fully domestically produced chips, integrating an ADC module, digital up-conversion, digital down-conversion, peak clipping CFR, and DAC module. Both the input and output of the RF transceiver subsystem are zero-IF RF signals.

[0101] 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 timing adjustment and encoding of the digital IQ signals of the RF transceiver subsystem, as well as protocol encapsulation and decapsulation of IQ data, fiber optic link synchronization and data conversion control words, and signal characteristic control words, such as using the CPRI protocol (CPRI (Common Public Radio Interface)).

[0102] The signal characteristic control word transmitted via the CPRI protocol includes: the MCU core control module of the access unit processes data such as the standard, frequency band, frequency point, bandwidth, and number of carriers of the valid working signal to obtain the specific frequency band, frequency point, center frequency point, and bandwidth that need to be amplified for the valid working signal. This signal characteristic control word serves as the basis for the technical requirements of signal processing in the remote unit of the distributed digital coverage system.

[0103] The MCU core control module can configure and manage parameters such as frequency band, bandwidth, filter parameters, delay parameters, chip startup and shutdown parameters, and timing control of the RF transceiver subsystem.

[0104] The effective working signal obtained by the signal feature analysis module, along with its signal characteristics (frequency band, frequency point, bandwidth, number of carriers), is used by the MCU core control module to calculate the frequency band and bandwidth of the effective working signal to be processed, as well as other parameter requirements (filter parameters, time delay parameters, etc.). These parameters are then sent to the RF transceiver subsystem via instructions. The RF transceiver subsystem processes the effective signal according to the instructions.

[0105] The FPGA performs protocol encapsulation and needs to process two types of data: 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.

[0106] For an FDD-based distributed digital overlay system, the extension unit (MEU) includes: an FPGA processing subsystem, a PoE power supply system, and an MCU main control module.

[0107] The FPFA processing subsystem of the extended unit MEU, in accordance with the protocol definition, performs frame de-framing and parsing of the digital baseband IQ signals and control word information from the access unit MAU, and distributes and processes these data and control word logic according to the system topology. It also performs frame assembly processing according to the protocol definition and transmits them to each coverage unit MRU. The FPGA performs protocol encapsulation and needs to process three aspects of data: the baseband IQ signals transmitted from the MAU, the frequency band and bandwidth information of the effective working signals, and the data regenerated from the data baseband IQ according to the system topology.

[0108] The FPFA processing subsystem of the extended unit MEU, in accordance with the protocol definition, performs frame de-framing and parsing of digital baseband IQ signals and control word information from various remote units MRU, and merges these data according to the system topology. The merged data, combined with each control word, is then framed and encapsulated according to the protocol, and transmitted to the access unit MAU based on the CPRI protocol.

[0109] Among them, the control word transmitted by the extension unit MEU is the frequency band and bandwidth information of the valid working signal. The valid working signal and its signal characteristics (frequency band, frequency point, bandwidth, and number of carriers) are obtained by the access unit MAU based on the signal feature analysis module. The MCU core main control module calculates the frequency band and bandwidth of the valid working signal that needs to be processed, transmits it to the extension unit through the protocol, and then transmits it to each remote unit MRU through the extension unit.

[0110] The expansion unit is also equipped with a PoE power supply system, which integrates PoE power to supply DC power to each remote unit (MRU). The DC power from the expansion unit is transmitted to the remote units via a composite optical cable to provide power for their operation.

[0111] For FDD-based distributed digital overlay systems, such as Figure 5 As shown, the remote unit structure includes: an FPGA processing subsystem, a radio frequency transceiver subsystem, an uplink and downlink radio frequency signal processing subsystem, a PoE power supply system, and an MCU core control module.

[0112] Since the frequency and bandwidth information of the useful operating signal has already been obtained at the near end of the distributed digital coverage system, it is only necessary to transmit this data from the access unit through the extension unit and then to the remote unit via a protocol. This eliminates the need for an additional signal feature analysis module, further reducing system costs.

[0113] In this distributed digital coverage system, the FPGA processing subsystem of the remote unit receives baseband IQ signals, fiber optic link synchronization and data conversion control words, and signal characteristic control words from the extension unit. It 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. Simultaneously, the FPGA processing subsystem obtains the signal characteristic control words from the decapsulated data, including the specific frequency and bandwidth of the effective working signal. This information is transmitted to the MCU core control module of the remote unit. The MCU core control module then configures the FPGA processing subsystem, the RF transceiver subsystem, and the uplink and downlink RF signal processing subsystem of the remote unit with appropriate parameters to perform signal filtering, amplification, and other processing on the effective working signal.

[0114] The PoE power supply system transmits DC power from the expansion unit MEU via a composite optical cable, and through appropriate adjustment and allocation, provides the operating power for the FPGA processing subsystem, the RF transceiver subsystem, the uplink and downlink RF signal processing subsystem, and the MCU core control module.

[0115] The radio frequency transceiver subsystem and uplink / downlink radio frequency signal processing subsystem of the remote unit of the distributed digital coverage system have the same functions as the access unit, and will not be described in detail here.

[0116] For TDD signals, this invention proposes another distributed digital coverage system that integrates the time-domain synchronization function into the signal feature analysis module in the access unit (MAU), thus performing two different functions and further reducing costs.

[0117] For TDD-based distributed digital coverage systems, such as Figure 6 As shown, the access unit includes: uplink and downlink radio frequency signal processing subsystem, radio frequency transceiver subsystem, FPGA processing subsystem, signal coupler, signal feature analysis and time domain synchronization module, and MCU core main control module.

[0118] The uplink and downlink RF signal processing subsystem, the RF transceiver subsystem, and the FPGA processing subsystem are sequentially connected to form the main link for uplink and downlink signal processing in the access unit of the distributed digital coverage system. The access unit of the distributed digital coverage system and the RRU signal source achieve signal transmission and reception communication with the RRU through wired signal coupling.

[0119] The inputs and outputs of the uplink and downlink RF signal processing subsystems are both high-frequency RF signals, such as 2300MHz RF signals. The outputs of the FPGA processing subsystem are control words for fiber optic link synchronization and data conversion, signal characteristic control words, and time-domain synchronization control words, which are converted from baseband IQ signals after protocol conversion. These are then input to the remote unit of the distributed digital coverage system to realize signal transmission and communication.

[0120] Among them, the control word for signal characteristics refers to the data processing performed by the MCU core main control module of the access unit on information such as the system, 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.

[0121] The time-domain synchronization control word refers to the control word information for time-domain synchronization, which is the time slot switching information.

[0122] The signal coupler, signal feature analysis and time-domain synchronization module, and MCU core control module are connected in sequence to form the core functions of the signal feature analysis link and the control signal processing main link.

[0123] In Time Division Duplex (TDD) systems, all systems need to process transmit and receive signals separately in different time slots. During the transmit time slot, the main focus is on the coupling and transmission of the transmit signal; during the receive time slot, the main focus is on the coupling and transmission of the receive signal.

[0124] Among them, since it involves the control of the TDD time slot switching function, the MCU core main control module is also connected to the donor end RF switch, uplink and downlink RF signal processing subsystem A, RF transceiver subsystem, uplink and downlink RF signal processing subsystem B, and retransmission end RF switch to control these modules.

[0125] Specifically, for time-domain synchronization in TDD systems:

[0126] This is still insufficient for TDD systems. Therefore, in addition to clock synchronization technology, TDD systems also require synchronization of the TDD uplink / downlink switching switch, which can also be called time-domain synchronization. This involves finding a reference point that remains constant, and then resuming the switching at that point.

[0127] TDD switching synchronization goes a step further than frequency-domain clock synchronization, requiring synchronization in the time domain as well. For TDD, if the uplink and downlink speeds of the terminal and base station are inconsistent, it will affect signal quality, or even result in no signal at all.

[0128] There are several ways to synchronize time domains:

[0129] 1. Envelope detection: In 3G-era TD-SCDMA, there is a constant envelope position as a reference point. Therefore, only this point needs to be detected to serve as the reference for system switching, and then the uplink and downlink switches of the repeater can be generated. This method is relatively inexpensive.

[0130] 2. Coarse synchronization

[0131] Similar to the LTE standard, regardless of changes in the TDD system configuration, there is a fixed frequency domain region within the PSS synchronization series, which can be used as a reference point. Synchronization is achieved using the autocorrelation characteristics of the ZC sequence. Synchronization involves signal filtering, sampling, decimation, and related calculations, requiring a corresponding hardware platform, which increases costs. This cost requires an ADC and an FPGA, but if it's a digital system, it already has ADC and FPGA chips, so the cost is minimal.

[0132] 3. Analyze the baseband signal source

[0133] This method, similar to that of a mobile phone terminal, directly analyzes the baseband signal source, requiring high-performance FPGA or DSP chips, which is the most expensive. However, it also has advantages, as it allows access to relevant information about the base station cell, such as Cell ID, RSRP, SINR, PLMN, etc., which is very convenient for engineers.

[0134] This invention employs a TDD time-domain synchronization scheme that analyzes the baseband signal source, and the signal feature analysis is also performed using the same baseband signal source analysis method. In this way, the signal feature analysis module can integrate the time-domain synchronization function, combining both functions into one module, improving module integration and reducing system costs.

[0135] The FPGA processing subsystem encapsulates the protocol 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 time slot switching information output by the signal feature analysis and time domain synchronization module.

[0136] The specific functional implementation scheme of the TDD distributed digital coverage system access unit is the same as that of the FDD distributed digital coverage system access unit above, and will not be repeated here.

[0137] For the TDD-based distributed digital coverage system extension unit and remote unit, their system configuration is completely the same as that of the FDD-based distributed digital coverage system extension unit and remote unit. The only difference is that the control word part of the FPGA processing subsystem adds: time-domain synchronization control word information - time slot switching information.

[0138] The control word information is encapsulated using the CPRI protocol at the access unit, and decapsulated using the CPRI protocol at the extension unit and remote unit before being output to the MCU core control module. The MCU core control module then configures the parameters and performs time slot switching operations on the FPGA processing subsystem, the RF transceiver subsystem, and the uplink and downlink RF signal processing subsystems to perform filtering, amplification, and other processing on the valid working signals.

[0139] The signal feature analysis module detects and analyzes the signal type, frequency band, frequency point, bandwidth, number of carriers, and other feature information of the actual working signal in real time and adaptively. Combined with the detected signal feature information, the uplink and downlink signal processing circuits then perform efficient uplink and downlink signal amplification and processing for specific types, specific frequencies, specific bandwidths, and specific number of carriers, reducing energy waste and greatly reducing costs.

[0140] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A distributed digital overlay system, characterized in that, The distributed digital coverage system is an FDD-compliant distributed digital coverage system, comprising: an access unit (MAU), an expansion unit (MEU), and a remote unit (MRU). The access unit (MAU) includes: an uplink / downlink RF signal processing subsystem, an RF transceiver subsystem, an FPGA processing subsystem, a signal coupler, a signal feature analysis module, and an MCU core control module. The expansion unit (MEU) includes: an FPGA processing subsystem, a PoE power supply system, and an MCU core control module. The remote unit includes: an FPGA processing subsystem, an RF transceiver subsystem, an uplink / downlink RF signal processing subsystem, a PoE power supply system, and an MCU core control module. The signal feature analysis module couples the radio frequency signal from the base station signal source through a coupler, performs radio frequency down-conversion, analog conversion, digital down-conversion and baseband signal processing to obtain the characteristics of the baseband signal, including: the signal's communication standard, RSRP, SINR, signal frequency point information, signal frequency band information, signal bandwidth, and carrier number information. The signal feature analysis module determines the validity of 4G LTE signals by including: Baseband demodulation processing is performed 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; Set signal thresholds Th_RSRP_LTE and Th_SINR_LTE. For RSRP≥Th_RSRP_LTE and SINR≥Th_SINR_LTE, it is considered a valid working signal. In conjunction with the operator, determine the final effective working signal and its signal characteristics; The signal feature analysis module determines the validity of 5G NR signals, including the following processing steps: Demodulate the 5G NR signal across the entire frequency band to obtain the signal characteristics of the corresponding signal: frequency band, frequency point, bandwidth, number of carriers, RSRP, and SINR; Set signal thresholds Th_RSRP_NR and Th_SINR_NR. Only signals where RSRP≥Th_RSRP_NR and SINR≥Th_SINR_NR are considered valid working signals. Then, by combining the specific operator, the final effective working signal and its signal characteristics are determined; The MCU core control module of the access unit processes data on the system, 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.

2. The distributed digital overlay system as described in claim 1, characterized in that, The uplink and downlink RF signal processing subsystem, the RF transceiver subsystem, and the FPGA processing subsystem are connected in sequence to form the main link for uplink and downlink signal processing of the access unit; the access unit of the distributed digital coverage system and the base station signal source realize signal transmission and reception communication between the two through wired signal coupling.

3. The distributed digital coverage system as described in claim 2, characterized in that, The FPGA processing subsystem of the access unit (MAU) outputs the baseband IQ signal after protocol conversion, the control words for fiber optic link synchronization and data conversion, and the control words for signal characteristics. These are then input to the expansion unit of the distributed digital coverage system to realize signal transmission and communication. Among them, the control words for signal characteristics include frequency band, frequency point, bandwidth, and number of carriers.

4. The distributed digital overlay system as described in claim 3, characterized in that, The FPGA processing subsystem of the remote unit receives baseband IQ signals, fiber optic link synchronization and data conversion control words, and signal characteristic control words from the expansion unit. It 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 decapsulated signal characteristics to the MCU core main control module of the remote unit. The MCU core main control module performs appropriate parameter configuration for the FPGA processing subsystem, the RF transceiver subsystem, and the uplink and downlink RF signal processing subsystem of the remote unit, and performs signal filtering and amplification processing on the effective working signals.

5. A distributed digital overlay system, characterized in that, The distributed digital coverage system is a TDD-based distributed digital coverage system, comprising: an access unit (MAU), an expansion unit (MEU), and a remote unit (MRU). The access unit includes: an uplink / downlink RF signal processing subsystem, an RF transceiver subsystem, an FPGA processing subsystem, a signal coupler, a signal feature analysis and time-domain synchronization module, and an MCU core control module. The expansion unit (MEU) includes: an FPGA processing subsystem, a PoE power supply system, and an MCU core control module. The remote unit includes: an FPGA processing subsystem, an RF transceiver subsystem, an uplink / downlink RF signal processing subsystem, a PoE power supply system, and an MCU core control module. The signal feature analysis and time-domain synchronization module couples the radio frequency signal from the RRU source through a coupler, performs radio frequency down-conversion, analog-to-analog conversion, digital down-conversion, and baseband signal processing to obtain the characteristics of the baseband signal, including: the signal's communication standard, RSRP, SINR, signal frequency point information, signal frequency band information, signal bandwidth, and carrier number information. The determination of a valid 4G LTE signal includes: Baseband demodulation processing is performed 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; Set signal thresholds Th_RSRP_LTE and Th_SINR_LTE. For RSRP≥Th_RSRP_LTE and SINR≥Th_SINR_LTE, it is considered a valid working signal. In conjunction with the operator, determine the final effective working signal and its signal characteristics; The process of determining the validity of 5G NR signals includes: Demodulate the 5G NR signal across the entire frequency band to obtain the signal characteristics of the corresponding signal: frequency band, frequency point, bandwidth, number of carriers, RSRP, and SINR; Set signal thresholds Th_RSRP_NR and Th_SINR_NR. Only signals where RSRP≥Th_RSRP_NR and SINR≥Th_SINR_NR are considered valid working signals. Then, by combining the specific operator, the final effective working signal and its signal characteristics are determined; The MCU core control module of the access unit processes data on the system, 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 time domain synchronization control word is the control word information for time domain synchronization - time slot switching information.

6. The distributed digital overlay system as described in claim 5, characterized in that, The uplink and downlink radio frequency signal processing subsystem, the radio frequency transceiver subsystem, and the FPGA processing subsystem are connected in sequence to form the main link for uplink and downlink signal processing of the access unit; the access unit of the distributed digital coverage system and the RRU source realize signal transmission and reception communication with the RRU source through wired signal coupling.

7. The distributed digital overlay system as described in claim 6, characterized in that, The FPGA processing subsystem of the access unit (MAU) outputs control words for baseband IQ signal fiber optic link synchronization and data conversion, control words for signal characteristics, and time-domain synchronization after protocol conversion. These are then input to the remote unit of the distributed digital coverage system to realize signal transmission and communication. Among them, the control words for signal characteristics include frequency band, frequency point, bandwidth, and number of carriers.

8. The distributed digital overlay system as described in claim 7, characterized in that, The control words for data conversion, signal characteristics, and time-domain synchronization are encapsulated via the CPRI protocol in the access unit, and decapsulated via the CPRI protocol in the extension unit and remote unit before being output to the MCU core control module. The MCU core control module performs parameter configuration, time slot switching operations, and filtering and amplification of valid working signals for the FPGA processing subsystem, the RF transceiver subsystem, and the uplink and downlink RF signal processing subsystem.

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