Distributed digital coverage system

Abstract

The invention discloses a distributed digital coverage system, which comprises an access unit, an expansion unit MEU and a far-end 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 Transceiver subsystem, an FPGA processing subsystem, a signal coupler, a signal feature analysis and / or time domain synchronization module and an MCU core main control module. By adopting the technical scheme of the invention, the signal of the whole bandwidth is not blindly amplified, any prior information is not needed, and the characteristic information of the signal system, the frequency band, the frequency point, the bandwidth and the carrier number which are actually working at present can be detected and analyzed in real time and adaptively.

Description

Technical Field

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

[0002] The distributed digital coverage system consists of a radio access unit MAU, an extension unit MEU, and a remote unit MRU. The radio access unit converts the downlink radio frequency signals of 2G, 3G, 4G LTE, 5G NR and other sources into digital signals through wired coupling, and then transmits them to the extension unit MEU after photoelectric conversion into optical signals. The MEU is connected to the remote unit MRU through a composite optical cable through protocol conversion and integrated PoE power supply capability. The MRU performs digital up-conversion and radio frequency conversion on the digital signals transmitted by the composite optical cable and outputs radio frequency signals. At the same time, the remote unit MRU restores the PoE power supply of the composite optical cable to the MRU for power supply. At the same time, the digital signals uploaded by the remote unit are converted into uplink radio frequency signals and transmitted back to the source through wired means. The radio access unit must support remote monitoring and management functions and centralized upgrade functions for its extension units and remote units. The remote unit converts the digital signal sent by the extension unit MEU into a radio frequency signal to achieve wireless coverage of 2G, 3G, 4G LTE, and 5G NR; at the same time, it converts the uplink radio frequency signal received by the wireless into a digital signal and transmits it to the access unit MAU. The distributed digital coverage system is a low-cost indoor coverage solution, which is particularly suitable for scenarios with low capacity requirements and high signal coverage requirements, such as basements, office buildings with a small number of users, tunnels, small stores, etc. It can expand the service range and eliminate coverage blind spots.

[0003] The signal processing method of the traditional distributed digital coverage system is: when the operator (such as China Mobile) is known in advance, some prior information of the distributed digital coverage system needs to be obtained:

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

[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 bandwidth for single-carrier 4G LTE, will no longer distinguish between configurations with signal bandwidths below 20MHz, and uniformly process signals for the maximum carrier configuration bandwidth of 20MHz; if the single-carrier 5G NR has a bandwidth of 100MHz, within the frequency band, uniformly process signals for the maximum carrier configuration bandwidth of 100MHz;

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

[0008] From the perspective of maximum frequency band configuration, China Mobile's 2600MHz band has a total bandwidth of 160MHz, of which 2515-2615MHz is commonly used for the 100MHz 5G NR band; from 2615MHz to 2675MHz, there is a total of 60MHz, which can support a maximum of 3 20MHz LTE carriers.

[0009] Therefore, for 5G NR, the traditional signal processing method is: regardless of the actual work, no matter how much bandwidth 5G NR is configured, the signal amplification processing is uniformly performed on the 100MHz bandwidth, because in actual work, in order to reduce interference, the actual configuration may be 80MHz bandwidth of 5G NR bandwidth in the total bandwidth of 100MHz between 2515-2615MHz. On the one hand, the energy cannot be concentrated in the bandwidth of the useful signal (80MHz bandwidth) for signal amplification; on the other hand, the redundant 20MHz invalid signal is amplified, the useful energy is wasted, and at the same time, the noise signal in the non-working bandwidth (such as the non-working 20MHz bandwidth) is amplified, which also causes interference to the actual working signal. For 4G LTE: regardless of the actual work, no matter how many carriers 4G LTE is configured, no matter how much bandwidth LTE is configured, the signal amplification processing is uniformly performed on 60MHz. On the one hand, the energy cannot be concentrated in the bandwidth of the useful signal for signal amplification; on the other hand, the energy is wasted, and the noise signal in the non-working bandwidth (such as the non-working 20MHz bandwidth) is amplified, which also causes interference to the actual working signal. Especially for the 60MHz bandwidth, it is rare to configure 3 carriers of LTE. Moreover, even if there are two LTE carriers, each carrier is not necessarily configured to 20MHz. It is also necessary to combine the actual application scenario and appropriately change the configuration of LTE working bandwidth. Therefore, directly amplifying the signal of 60MHz bandwidth brings a lot of energy waste and also amplifies the noise signal in the non-working bandwidth. Summary of the invention

[0010] The technical problem to be solved by the present invention is to provide a distributed digital coverage system, which does not blindly amplify the signal of the entire bandwidth and does not require any prior information (communication standard, frequency band, bandwidth, number of carriers, etc.). By adding an intelligent analysis module in the system: a signal feature analysis module, the feature information of the signal standard, frequency band, frequency point, bandwidth, number of carriers, etc. that is actually working at present can be detected and analyzed in real time and adaptively. Combined with the signal feature information obtained by the detection, the uplink and downlink signals are efficiently amplified and processed for a specific standard, a specific frequency point, a specific bandwidth, and a specific number of carriers, thereby reducing energy waste and greatly reducing costs. In addition, for FDD standard (FDD: Frequency Division Duplexing) signals, only the signal feature analysis module needs to be added. For TDD standard (TDD: Time Division Duplexing) signals, the time domain synchronization function can be integrated into the signal feature analysis module to complete two different functions, thereby further reducing costs.

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

[0012] A distributed digital coverage system, which is a distributed digital coverage system of FDD standard, includes: an access unit MAU, an extension unit MEU and a remote unit MRU; wherein the access unit MAU includes: an uplink and downlink radio frequency signal processing subsystem, a radio frequency transceiver Transceiver subsystem, an FPGA processing subsystem, a signal coupler, a signal feature analysis module and an MCU core main control module; the extension unit MEU includes: an FPGA processing subsystem, a PoE power supply subsystem and an MCU main control module; the remote unit includes: an FPGA processing subsystem, a radio frequency transceiver Transceiver subsystem, an uplink and downlink radio frequency signal processing subsystem, a PoE power supply subsystem and an MCU core main control module.

[0013] Preferably, the uplink and downlink RF signal processing subsystems, the RF transceiver subsystem, and the FPGA processing subsystem are connected in sequence to form the main link of the uplink and downlink signal processing of the access unit; the access unit and the base station signal source of the distributed digital coverage system realize signal transmission and reception communication with 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 of optical fiber link synchronization and data conversion, and the control word of signal characteristics, which are input into the expansion unit of the distributed digital coverage system to realize signal transmission and communication; wherein, the control word of signal characteristics is: the MCU core main control module of the access unit processes data on the format, frequency band, frequency point, bandwidth, and number of carriers of the effective working signal to obtain the specific frequency band, frequency point, center frequency point, and bandwidth required to amplify the effective working signal.

[0015] Preferably, the FPGA processing subsystem of the remote unit receives the baseband IQ signal, the control word of the optical fiber link synchronization and data conversion, and the control word of the signal characteristics from the extension unit, performs CPRI decapsulation processing, encodes the IQ data into a format adapted to the RF transceiver subsystem, and inputs it to the RF transceiver subsystem; at the same time, the FPGA processing subsystem transmits the control word of the signal characteristics obtained by decapsulation to the MCU core main control module of the remote unit, and the MCU core main control module performs appropriate parameter configuration on the FPGA processing subsystem, the RF transceiver subsystem, and the uplink and downlink RF signal processing subsystems of the remote unit, and performs signal filtering and amplification processing on the effective working signal.

[0016] Preferably, the signal characteristic analysis module couples the RF signal from the RRU source through a coupler, performs RF down-conversion, analog conversion, digital down-conversion and baseband signal processing, and obtains the characteristics of the baseband signal, including: the communication standard of the signal, RSRP, SINR, the frequency point information of the signal, the frequency band information of the signal, the bandwidth of the signal, and the number of carriers;

[0017] Among them, 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 restore the original baseband data;

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

[0022] The signal feature analysis module determines the valid 4G LTE signal including:

[0023] Perform baseband demodulation on the full-band 4G LTE signals to obtain the signal characteristics of the corresponding signals: frequency band, frequency point, bandwidth, number of carriers, RSRP, and SINR. Among them, only the demodulated signals can obtain RSRP and SINR information;

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

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

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

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

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

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

[0030] The present invention also provides a distributed digital coverage system, which is a TDD-standard distributed digital coverage system, comprising: an access unit MAU, an extension unit MEU and a remote unit MRU; wherein the access unit comprises: an uplink and downlink radio frequency signal processing subsystem, a radio frequency transceiver Transceiver subsystem, an FPGA processing subsystem, a signal coupler, a signal feature analysis and time domain synchronization module and an MCU core main control module; the extension unit MEU comprises: an FPGA processing subsystem, a PoE power supply subsystem and an MCU main control module; the remote unit comprises: an FPGA processing subsystem, a radio frequency transceiver Transceiver subsystem, an uplink and downlink radio frequency signal processing subsystem, a PoE power supply subsystem and an MCU core main control module.

[0031] Preferably, the uplink and downlink RF signal processing subsystems, the RF transceiver subsystem, and the FPGA processing subsystem are connected in sequence to form the main link of the uplink and downlink signal processing of the access unit; the access unit and the RRU 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 the control word for baseband IQ signal optical fiber link synchronization and data conversion after protocol conversion, the control word for signal characteristics and the control word for time domain synchronization, which are input into the remote unit of the distributed digital coverage system to realize signal transmission and communication; wherein, the control word for signal characteristics is: the MCU core main control module of the access unit processes data on the format, frequency band, frequency point, bandwidth and number of carriers of the effective working signal to obtain the specific frequency band, frequency point, center frequency point and bandwidth required for amplifying the effective working signal; the time domain synchronization control word is the control word information for time domain synchronization - time slot switching information.

[0033] Preferably, the control words for data conversion, signal feature control words and time domain synchronization control words are encapsulated through the CPRI protocol in the access unit, decapsulated through the CPRI protocol in the extension unit and the remote unit, and output to the MCU core main control module; the MCU core main control module performs parameter configuration and time slot switching operations on the FPGA processing subsystem, the RF transceiver subsystem and the uplink and downlink RF signal processing subsystems, as well as filtering and amplifying the effective working signals.

[0034] Preferably, the signal characteristic analysis and time domain synchronization module couples the RF signal from the RRU source through a coupler, performs RF down-conversion, analog conversion, digital down-conversion and baseband signal processing, and obtains the characteristics of the baseband signal, including: the communication standard of the signal, RSRP, SINR, the frequency point information of the signal, the frequency band information of the signal, the bandwidth of the signal, and the number of carriers;

[0035] Among them, 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 restore the original baseband data;

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

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

[0041] Perform baseband demodulation on the full-band 4G LTE signals to obtain the signal characteristics of the corresponding signals: frequency band, frequency point, bandwidth, number of carriers, RSRP, and SINR. Among them, only the demodulated signals can obtain RSRP and SINR information;

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

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

[0044] The valid signal of 5G NR is judged, including the following processing steps:

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

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

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

[0048] The present invention introduces a signal characteristic analysis module, which does not blindly amplify the signal of the entire bandwidth, nor does it require any prior information (standard, frequency band, bandwidth, number of carriers, etc.), and can detect and analyze the characteristic information of the actual working signal standard, frequency band, frequency point, bandwidth, number of carriers, etc. in real time and adaptively, and then for a specific standard, specific frequency point, specific bandwidth, specific number of carriers, efficient uplink and downlink signal amplification processing is carried out, which reduces energy waste and greatly reduces costs. The same set of circuits supports full-band, multi-standard signal processing, covering 4G LTE and 5GNR, and can also be expanded upward to 6G, and derived downward to 3G and 2G, and can be expanded and derived as needed to adapt to more application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[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 structure of an extension unit of a distributed digital coverage system according to Embodiment 1 of the present invention;

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

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

[0056] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0057] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0058] Embodiment 1:

[0059] The embodiment of the present invention provides a distributed digital coverage system, which is extended to support FDD and TDD multiple standards and multiple frequency bands at the same time, and includes: an access unit, an extension unit MEU, and a remote unit.

[0060] like Figure 1 As shown, the access unit includes: a TDD RF signal processing subsystem, an FDD RF signal processing subsystem, a multi-channel RF 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 uses a multi-channel RF transceiver. These channels can process TDD and FDD in parallel, or all of them can be used for TDD signal processing, or all of them can be used for FDD signal processing. The TDD RF signal processing subsystem specializes in filtering and amplifying RF signals of the TDD standard, and the FDD RF signal processing subsystem specializes in filtering and amplifying RF signals of the FDD standard. The FPGA processing subsystem uniformly encapsulates the FDD and TDD IQ data output by the multi-channel RF transceiver subsystem, the time domain synchronization information output by the signal feature analysis and time domain synchronization module, and the frequency and bandwidth information of the effective working signal output by the MCU core main control module, and transmits them to the remote unit of the distributed digital coverage system. The FPGA processing subsystem performs protocol encapsulation and needs to process three types of data: the digital IQ signal of the multi-channel RF transceiver subsystem (including TDD and FDD IQ signals), the frequency band and bandwidth information of the effective working signal calculated by the MCU core control module, and the signal feature analysis and time slot switching information output by the time domain synchronization module.

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

[0063] Since the access unit MAU frames and transmits the baseband IQ data and control word information of TDD and FDD (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), the extension unit MEU will uniformly deframe and parse these data, and distribute and frame the data in combination with the topology structure. 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: FPGA processing subsystem, multi-channel RF transceiver subsystem, TDD RF signal processing subsystem, FDD RF signal processing subsystem, PoE power supply subsystem and MCU core main 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 FPGA processing subsystem decapsulates the control word obtained: the specific frequency, bandwidth and time slot switching information of the effective working signal, etc., and transmits this information to the MCU core 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 filter, amplify, and switch time slots of the effective working signal.

[0066] The PoE power supply subsystem adjusts and allocates the DC power transmitted by the expansion unit MEU through the composite optical cable to provide working power for the FPGA processing subsystem, the RF transceiver subsystem, the uplink and downlink RF signal processing subsystems and the MCU core control module.

[0067] The functions of the multi-channel RF transceiver subsystem, TDD RF signal processing subsystem, and FDD RF signal processing subsystem of the remote unit of the distributed digital coverage system are the same as those of the access unit and will not be repeated here.

[0068] The distributed digital coverage system of the embodiment of the present invention supports multi-mode, covering 4G LTE and 5G NR. Of course, it can also be expanded to 6G and derived to 3G and 2G. It can be expanded and derived as needed to adapt to more 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 and re-farming to 5G NR, 1800MHz 4G LTE, 2300MHz 4G LTE, 2600MHz 4G LTE and 5G NR, and 5G NR expanded to 4.9GHz, etc.

[0069] Embodiment 2:

[0070] The embodiment of the present invention further provides a distributed digital coverage system, including: an access unit MAU, an extension unit MEU and a remote unit MRU.

[0071] For FDD distributed digital coverage systems, such as Figure 4 As shown, the access unit MAU includes: uplink and downlink RF signal processing subsystems, RF transceiver subsystems, FPGA processing subsystems, signal couplers, signal feature analysis modules and MCU core main control modules.

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

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

[0074] Among them, the control word of the signal characteristic refers to: the MCU core main control module of the access unit processes data on the standard, frequency band, frequency point, bandwidth, number of carriers and other information of the effective working signal, and obtains the specific frequency band, frequency point, center frequency point and bandwidth required to amplify the effective working signal.

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

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

[0077] Among them, 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 decoding of error correction coding 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 restore the original baseband data.

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

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

[0083] Among them, the signal feature analysis module determines the valid signal. The specific process includes the processing process of 4G LTE:

[0084] 1. Demodulate 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;

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

[0086] 3. Combined with the specific operator (for example, if the application scenario is China Mobile, the effective working signal of China Mobile is recorded), determine the final effective working signal and its signal characteristics: frequency band, frequency point, bandwidth, and number of carriers;

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

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

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

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

[0091] 3. Combined with the specific operator (for example, if the application scenario is China Mobile, the effective working signal of China Mobile is recorded), determine the final effective working signal and its signal characteristics: frequency band, frequency point, bandwidth, and number of carriers;

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

[0093] The MCU core main control module obtains the effective signal and its signal characteristics: frequency band, frequency point, bandwidth, number of carriers, calculates the frequency band and bandwidth of the signal to be processed, and the signal processing requirements (such as signal filtering requirements, power amplification requirements, delay requirements, etc.), and sends instructions to the uplink and downlink RF signal processing subsystems, RF transceiver subsystems, and FPGA processing subsystems, so as to process the effective working signal frequency band and bandwidth in a targeted manner, including: signal filtering, signal amplification, etc.

[0094] Among them, the uplink and downlink RF signal processing subsystem includes the following two key functions, one of which is: the uplink and downlink RF signal processing subsystem receives the RF signal from the duplexer at the donor end, which is generally a high-frequency band, such as China Mobile's 2600MHz RF signal, and obtains a moderately filtered and amplified high-frequency signal through a low-noise amplifier LNA, which is convenient for the subsequent RF transceiver subsystem to process. This solution directly adopts a zero intermediate frequency RF transceiver solution.

[0095] The traditional solution uses a digital intermediate frequency transceiver solution. The high-frequency RF signal passes through a low-noise amplifier (LNA) and then passes through an RF down-conversion module to perform RF down-conversion processing on the RF signal amplified by the LNA, outputting a zero intermediate frequency analog signal, and finally processing the signal through the RF transceiver transceiver subsystem.

[0096] Among them, the low noise amplifier LNA receives control instructions from the MCU core main control module and only amplifies the frequency band and bandwidth of the effective working signal, instead of using traditional signal processing methods to amplify the full-band signal.

[0097] The uplink and downlink RF signal processing subsystem has another function: the uplink and downlink RF signal processing subsystem receives the analog signal of the high frequency band from the RF transceiver subsystem, directly amplifies it through the uplink power amplifier, and outputs the amplified high frequency signal. Among them, the uplink power amplifier receives the control instruction from the MCU core main control module, and only amplifies the frequency band and bandwidth of the effective working signal, instead of using the traditional signal processing method to amplify the full-band signal, which reduces the index requirements for the uplink power amplifier. At the same time, it only amplifies the useful signal in the band, and does not amplify the noise signal outside the effective bandwidth, which greatly improves the system performance.

[0098] The traditional processing solution adopts the digital intermediate frequency transceiver solution. The analog intermediate frequency signal output by the RF transceiver subsystem is first processed by the RF up-conversion module to achieve the conversion from the analog intermediate frequency signal to the high-frequency RF signal, and then the signal is amplified by the uplink power amplifier and output to the donor-end duplexer.

[0099] Among them, the RF transceiver with zero intermediate frequency (Zero-IF) architecture includes the variant type of zero intermediate frequency, low intermediate frequency transceiver (Low-IF). Zero intermediate frequency is also called direct frequency conversion, that is, the RF signal does not need to go through the intermediate frequency stage to directly enter the I / Q demodulation and convert to the baseband signal. No intermediate frequency signal is generated in the middle, and there are no intermediate frequency amplifiers, intermediate frequency filters and other components. Therefore, the architecture is relatively simple, the system size is smaller, and the cost and power consumption are lower. The advantage of zero intermediate frequency is that fewer devices are needed, it is easy to integrate, and the performance is also good. Except that DC cannot be eliminated in principle, there are almost no disadvantages.

[0100] Among them, the RF transceiver subsystem adopts a zero intermediate frequency digital-analog processing solution, which further improves the system integration, reduces the system complexity, and reduces the system cost. The RF transceiver subsystem adopts a single-chip solution, which can use a nationally produced chip solution, integrating ADC module, digital up-conversion, digital down-conversion, peak clipping CFR, and DAC module. The input and output of the RF transceiver subsystem are both zero intermediate frequency RF signals.

[0101] Among them, due to the high integration of the RF transceiver subsystem, the requirements for the FPGA processing subsystem are greatly reduced. The FPGA processing subsystem is mainly responsible for the timing adjustment and encoding of the digital IQ signals of the RF transceiver subsystem, as well as the protocol encapsulation and decapsulation of IQ data, optical fiber link synchronization and data conversion control words, and signal feature control words, such as using the CPRI protocol (CPRI (Common Public Radio Interface): Common Public Radio Interface).

[0102] Among them, the signal characteristic control word transmitted by the CPRI protocol includes: the MCU core main control module of the access unit processes the standard, frequency band, frequency point, bandwidth, number of carriers and other information of the effective working signal to obtain the specific frequency band, frequency point, center frequency point and bandwidth required for amplification of the effective working signal. The signal characteristic control word is the basis for the technical requirements of signal processing of the remote unit of the distributed digital coverage system.

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

[0104] Among them, based on the effective working signal obtained by the signal feature analysis module and its signal characteristics: frequency band, frequency point, bandwidth, number of carriers, the MCU core main control module calculates the frequency band and bandwidth of the effective working signal to be processed, as well as other parameter requirements (filter parameters, delay parameters, etc.), and sends them to the RF transceiver Transceiver subsystem through instructions. The RF transceiver TRansceiver subsystem processes the effective signal in a targeted manner according to the issued instruction requirements.

[0105] Among them, FPGA needs to process two kinds of data for protocol encapsulation: the digital IQ signal of the RF transceiver subsystem and the frequency band and bandwidth information of the effective working signal calculated by the MCU core control module.

[0106] For the FDD distributed digital coverage system, the extension unit MEU includes: FPGA processing subsystem, PoE power supply subsystem and MCU main control module.

[0107] Among them, the FPFA processing subsystem of the extension unit MEU, combined with the protocol definition, deframes and parses the digital baseband IQ signal and control word information from the access unit MAU, and distributes and processes these data and control word logic according to the system topology, and performs framing processing according to the protocol definition and transmits them to each coverage unit MRU; FPGA performs protocol encapsulation and needs to process three types of data: the baseband IQ signal transmitted from MAU, the frequency band and bandwidth information of the effective working signal, and the data baseband IQ regenerated data according to the system topology.

[0108] Among them, the FPFA processing subsystem of the extension unit MEU, combined with the protocol definition, deframes and parses the digital baseband IQ signals and control word information from different remote units MRU, and merges and processes these data according to the system topology. The merged data is combined with various control words, and then framed and protocol encapsulated, and transmitted to the access unit MAU based on the CPRI protocol.

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

[0110] The expansion unit is also equipped with a PoE power supply subsystem, which integrates a PoE power supply to deliver DC power to each remote unit MRU. The DC power of the expansion unit is delivered to the remote unit through a composite optical cable to provide working power for the remote unit.

[0111] For FDD distributed digital coverage systems, such as Figure 5 As shown, the remote unit structure includes: FPGA processing subsystem, RF transceiver subsystem, uplink and downlink RF signal processing subsystem, PoE power supply subsystem and MCU core main control module.

[0112] Among them, since the corresponding data information of the frequency and bandwidth information of the useful working signal has been obtained at the near end of the distributed digital coverage system, it is only necessary to transmit the data information from the access unit to the extension unit through the protocol and then to the remote unit. There is no need to add a signal feature analysis module, which further reduces the cost of the system.

[0113] Among them, the FPGA processing subsystem of the remote unit of the distributed digital coverage system receives the baseband IQ signal, the control word of the optical fiber link synchronization and data conversion, and the control word of the signal characteristics 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 decapsulates the obtained signal characteristic control word: the specific frequency and bandwidth of the effective working signal, and transmits this information to the MCU core main control module of the remote unit. The MCU core main control module configures appropriate parameters for the FPGA processing subsystem, the RF transceiver subsystem and the uplink and downlink RF signal processing subsystem of the remote unit to filter, amplify and other processes the effective working signal.

[0114] Among them, the PoE power supply subsystem, through appropriate adjustment and deployment, transmits the DC power of the expansion unit MEU through the composite optical cable to provide working power for the FPGA processing subsystem, the RF transceiver subsystem, the uplink and downlink RF signal processing subsystems and the MCU core main control module.

[0115] The functions of the RF transceiver subsystem and the uplink and downlink RF signal processing subsystem of the remote unit of the distributed digital coverage system are the same as those of the access unit and will not be described in detail here.

[0116] For TDD signals, an embodiment of the present invention proposes another distributed digital coverage system, which can integrate the time domain synchronization function into the signal feature analysis module in the access unit MAU to complete two different functions and further reduce costs.

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

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

[0119] The input and output of the uplink and downlink RF signal processing subsystems are both high-frequency RF signals, such as 2300MHz RF signals; the FPGA processing subsystem outputs the baseband IQ signal after protocol conversion, the control word for optical fiber link synchronization and data conversion, the control word for signal characteristics, the time domain synchronization control word, etc., which are input into the remote unit of the distributed digital coverage system to realize signal transmission and communication.

[0120] Among them, the control word of the signal characteristic refers to: the MCU core main control module of the access unit processes data on the standard, frequency band, frequency point, bandwidth, number of carriers and other information of the effective working signal, and obtains the specific frequency band, frequency point, center frequency point and bandwidth required to amplify the effective working signal.

[0121] The time domain synchronization control word refers to: time domain synchronization control word information-time slot switching information.

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

[0123] For time division duplex (TDD) systems, all systems need to process transmit and receive signals separately in different time slices. In the transmit time slice, the focus is on the coupling and transmission of the transmit signal; in the receive time slice, the focus is on the coupling and transmission of the receive signal.

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

[0125] Among them, for the time domain synchronization of the TDD system:

[0126] This is not enough for TDD systems, so in addition to clock synchronization technology, there is also a TDD uplink and downlink switch synchronization in the TDD system, which can also be called time domain synchronization. That is, find a point where the reference remains unchanged, and then the system resumes switching at this point.

[0127] The switch synchronization of the TDD standard is a step up from the frequency domain clock synchronization, and synchronization is also required in the time domain. For the TDD standard, if the uplink and downlink of the terminal and the base station are inconsistent, the signal quality will be affected, or even no signal will be present.

[0128] There are several ways to synchronize the time domain:

[0129] 1. Envelope detection: In TD-SCDMA of the 3G era, there is a constant envelope position as a reference point, so you only need to detect this point to use it as the reference for the system switch, and then generate the uplink and downlink switches of the repeater. This cost is relatively cheap.

[0130] 2. Coarse synchronization

[0131] Similar to the LTE standard, no matter how the TDD system configuration changes, there is a fixed frequency domain area in the PSS synchronization series, and this position can be found as a reference point. The autocorrelation characteristics of the ZC sequence are used for synchronization. Synchronization involves signal filtering, sampling, extraction and related calculations, which requires a corresponding hardware platform, which will also increase the corresponding cost. This cost requires ADC and FPGA, but if it is a digital system, it has ADC and FPGA chips, so there is actually no cost.

[0132] 3. Analyze baseband signal source

[0133] This is similar to mobile phone terminals, directly parsing the baseband signal source, which requires high-performance FPGA chips or DSP chips, which is the most expensive. But it also has advantages, which can obtain relevant information about the base station cell, such as Cell ID, RSRP, SINR, PLMN, etc., which is very convenient for engineers.

[0134] The present invention adopts a TDD time domain synchronization solution for analyzing baseband information sources, and the signal feature analysis is also performed by analyzing the signal features through the solution of analyzing baseband information sources. In this way, the signal feature analysis module can integrate the function of time domain synchronization, and integrate the two functions into one module, thereby improving the module integration and reducing the system cost.

[0135] Among them, the FPGA processing subsystem performs protocol encapsulation and needs to process three types of data: the digital IQ signal of the RF transceiver subsystem, the frequency band and bandwidth information of the effective working signal calculated by the MCU core main control module, and the signal feature analysis and time slot switching information output by the time domain synchronization module.

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

[0137] For the TDD distributed digital coverage system extension unit and remote unit, the system structure is exactly the same as that of the FDD distributed digital coverage system extension unit and remote unit, except that the control word part of the FPGA processing subsystem is increased: time domain synchronized control word information - time slot switching information.

[0138] The control word information is encapsulated by the CPRI protocol in the access unit, decapsulated by the CPRI protocol in the extension unit and the remote unit, and output to the MCU core control module. The MCU core control module configures the parameters of the FPGA processing subsystem, the RF transceiver subsystem, and the uplink and downlink RF signal processing subsystem, and performs time slot switching operations to filter and amplify the effective working signal.

[0139] Among them, the signal feature analysis module detects and analyzes the actual working signal format, frequency band, frequency point, bandwidth, number of carriers and other characteristic information in real time and adaptively. Combined with the signal characteristic information obtained by the detection, the uplink and downlink signal processing circuits then amplify and process the uplink and downlink signals efficiently according to the specific format, specific frequency point, specific bandwidth and specific number of carriers, which reduces energy waste and greatly reduces costs.

[0140] The embodiments described above are only descriptions of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A distributed digital coverage system, characterized in that: The distributed digital coverage system is a distributed digital coverage system of FDD standard, including: an access unit MAU, an extension unit MEU and a remote unit MRU; wherein the access unit MAU includes: an uplink and downlink radio frequency signal processing subsystem, a radio frequency transceiver Transceiver subsystem, an FPGA processing subsystem, a signal coupler, a signal feature analysis module and an MCU core main control module; the extension unit MEU includes: an FPGA processing subsystem, a PoE power supply subsystem and an MCU main control module; the remote unit includes: an FPGA processing subsystem, a radio frequency transceiver Transceiver subsystem, an uplink and downlink radio frequency signal processing subsystem, a PoE power supply subsystem and an MCU core main control module.

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

3. The distributed digital coverage system as claimed in claim 2, characterized in that: The FPGA processing subsystem outputs the baseband IQ signal after protocol conversion, the control words for optical fiber link synchronization and data conversion, and the control words for signal characteristics, which are input into the expansion unit of the distributed digital coverage system to realize signal transmission and communication; among which, the control words for signal characteristics are: the MCU core main control module of the access unit processes data on the format, frequency band, frequency point, bandwidth, and number of carriers of the effective working signal to obtain the specific frequency band, frequency point, center frequency point, and bandwidth that need to be amplified for the effective working signal.

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

5. The distributed digital coverage system as claimed in claim 4, characterized in that: The signal characteristic analysis module couples the RF signal from the RRU source through a coupler, performs RF down-conversion, analog conversion, digital down-conversion and baseband signal processing to obtain the characteristics of the baseband signal, including: the communication standard of the signal, RSRP, SINR, the frequency point information of the signal, the frequency band information of the signal, the bandwidth of the signal, and the number of carriers; Among them, baseband signal processing includes: (1) The digital signal processor performs digital filtering, synchronization, and equalization on the converted digital signal; (2) Channel estimation and decoding of error correction codes; (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 restore the original baseband data; (4) The demodulated baseband data is decoded to restore the original user information or control signal, and the decoded data is output to the feature analysis module; wherein the decoding process includes deinterleaving, descrambling, and decryption; The signal feature analysis module determines the valid 4G LTE signal including: Perform baseband demodulation on the full-band 4G LTE signals to obtain the signal characteristics of the corresponding signals: frequency band, frequency point, bandwidth, number of carriers, RSRP, and SINR. Among them, only the demodulated signals can obtain RSRP and SINR information; Set the signal thresholds Th_RSRP_LTE and Th_SINR_LTE. If RSRP ≥ Th_RSRP_LTE and SINR ≥ Th_SINR_LTE, it is considered as a valid working signal. In conjunction with the operator, determine the final effective working signal and its signal characteristics; The signal feature analysis module determines the valid signal of 5G NR, including the following processing steps: Demodulate the 5G NR signals in the full frequency band to obtain the signal characteristics of the corresponding signals: frequency band, frequency point, bandwidth, number of carriers, RSRP, and SINR; Set the signal thresholds Th_RSRP_NR and Th_SINR_NR. RSRP ≥ Th_RSRP_NR and SINR ≥ Th_SINR_NR are considered valid working signals. Then, combined with the specific operator, the final effective working signal and its signal characteristics are determined.

6. A distributed digital coverage system, characterized in that: The distributed digital coverage system is a TDD-standard distributed digital coverage system, including: an access unit MAU, an extension unit MEU and a remote unit MRU; wherein the access unit includes: an uplink and downlink RF signal processing subsystem, a RF transceiver subsystem, an FPGA processing subsystem, a signal coupler, a signal feature analysis and time domain synchronization module and an MCU core main control module; the extension unit MEU includes: an FPGA processing subsystem, a PoE power supply subsystem and an MCU main control module; the remote unit includes: an FPGA processing subsystem, a RF transceiver subsystem, an uplink and downlink RF signal processing subsystem, a PoE power supply subsystem and an MCU core main control module.

7. The distributed digital coverage system according to claim 6, characterized in that: The uplink and downlink RF signal processing subsystem, RF transceiver subsystem, and FPGA processing subsystem are connected in sequence to form the main link of the uplink and downlink signal processing of the access unit; the access unit and RRU signal source of the distributed digital coverage system realize signal transmission and reception communication with the RRU through wired signal coupling.

8. The distributed digital coverage system according to claim 7, characterized in that: The FPGA processing subsystem outputs the control words for the baseband IQ signal optical fiber link synchronization and data conversion after protocol conversion, the control words for signal characteristics, and the time domain synchronization control words, which are input into the remote unit of the distributed digital coverage system to realize signal transmission and communication; among which, the control words for signal characteristics are: the MCU core main control module of the access unit processes the data of the format, frequency band, frequency point, bandwidth, and number of carriers of the effective working signal to obtain the specific frequency band, frequency point, center frequency point, and bandwidth required for amplifying the effective working signal; the time domain synchronization control word is the control word information of time domain synchronization - time slot switching information.

9. The distributed digital coverage system as claimed in claim 8, characterized in that: The control words for data conversion, signal feature control words and time domain synchronization control words are encapsulated through the CPRI protocol in the access unit, decapsulated through the CPRI protocol in the extension unit and the remote unit, and output to the MCU core control module; the MCU core control module performs parameter configuration and time slot switching operations on the FPGA processing subsystem, the RF transceiver subsystem and the uplink and downlink RF signal processing subsystem, as well as filtering and amplifying the effective working signals.

10. The distributed digital coverage system according to claim 9, characterized in that: The signal feature analysis and time domain synchronization module couples the RF signal from the RRU source through a coupler, performs RF down-conversion, analog conversion, digital down-conversion and baseband signal processing, and obtains the characteristics of the baseband signal, including: the signal's communication standard, RSRP, SINR, signal frequency information, signal frequency band information, signal bandwidth, and carrier number information; Among them, baseband signal processing includes: (1) The digital signal processor performs digital filtering, synchronization, and equalization on the converted digital signal; (2) Channel estimation and decoding of error correction codes; (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 restore the original baseband data; (4) The demodulated baseband data is decoded to restore the original user information or control signal, and the decoded data is output to the feature analysis module; wherein the decoding process includes deinterleaving, descrambling, and decryption; Determining a valid 4G LTE signal includes: Perform baseband demodulation on the full-band 4G LTE signals to obtain the signal characteristics of the corresponding signals: frequency band, frequency point, bandwidth, number of carriers, RSRP, and SINR. Among them, only the demodulated signals can obtain RSRP and SINR information; Set the signal thresholds Th_RSRP_LTE and Th_SINR_LTE. If RSRP ≥ Th_RSRP_LTE and SINR ≥ Th_SINR_LTE, it is considered as a valid working signal. In conjunction with the operator, determine the final effective working signal and its signal characteristics; The valid signal of 5G NR is judged, including the following processing steps: Demodulate the 5G NR signals in the full frequency band to obtain the signal characteristics of the corresponding signals: frequency band, frequency point, bandwidth, number of carriers, RSRP, and SINR; Set the signal thresholds Th_RSRP_NR and Th_SINR_NR. RSRP ≥ Th_RSRP_NR and SINR ≥ Th_SINR_NR are considered valid working signals. Then, combined with the specific operator, the final effective working signal and its signal characteristics are determined.

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