Optimizing room division unit electrical component integration system

Abstract

This invention relates to the field of radio navigation technology and discloses an optimized indoor distributed antenna unit (DAS) electrical component integration system, comprising: a main working path, a static calibration reference path, and a signal sampling module. The system calibrates internal electronic drift by comparing the signal differences between the main working path and the static calibration reference path, and compensates for additional phase drift introduced by external environmental coupling by analyzing the reflected signals at the antenna port. Furthermore, it superimposes the two drifts to generate a full-link compensation command to pre-adjust the signal. This invention combines internal electronic calibration with external physical environment perception, constructing an end-to-end calibration closed loop from the electronic link to the physical transmission aperture, enabling the system to proactively adapt to dynamic changes in its deployment environment, thereby transforming a communication unit into a reliable spatiotemporal navigation reference point.

Description

Technical Field

[0001] This invention relates to an optimized indoor distributed antenna system (DAS) electrical component integration system, belonging to the field of radio navigation technology. Background Technology

[0002] Currently, providing high-precision location services using widely deployed terrestrial wireless communication networks has become an important technological direction in radio navigation applications. Among these, the dense signal coverage of 5G indoor distributed antenna systems (DAS) provides the physical layer foundation for high-precision indoor positioning. However, when these DAS, designed to ensure communication quality, are directly applied to radio navigation tasks with high requirements for signal timing characteristics, an inherent technical constraint in their design begins to limit their application. As a mass-produced communication product, the design goal of DAS is to meet the requirements of communication protocols... To achieve a balance between cost and performance, the electrical components on the internal radio frequency link have manufacturing tolerances. Furthermore, during long-term operation, their electrical characteristics dynamically drift due to changes in operating temperature, power supply, and component aging. For communication services, the system can compensate for this through channel coding or retransmission mechanisms. However, in high-precision positioning applications, each indoor distributed array (DAS) unit needs to serve as a stable spatiotemporal reference point. Nanosecond-level delays in the signal on the radio frequency link can directly cause errors in the positioning results. This transforms the aforementioned physical layer characteristic fluctuations, acceptable in the communication field, into a source of error that must be addressed in positioning applications.

[0003] However, existing technologies not only suffer from the aforementioned uncertainties in physical characteristics at the hardware level, but also have inherent limitations in the control methods for signal fusion and error processing. They are difficult to adapt to complex and ever-changing actual deployment environments. For example, Chinese invention patent CN118131292B discloses a positioning system that uses 5G and BeiDou signal fusion. After positioning with BeiDou, it uses a fixed threshold parameter based on the coverage range of 5G base station signals to eliminate fuzzy solutions that do not conform to geographical common sense. The fundamental flaw of this method is that the threshold parameter it uses is a fixed, preset static value, which cannot dynamically adapt to the actual distribution density of 5G base stations and the real-time changes in signal coverage in different areas. When the positioning terminal is on the edge of the base station coverage or in an area with complex signals, this one-size-fits-all filtering method based on static parameters is prone to incorrect judgments. It not only makes it difficult to achieve effective fusion of BeiDou and 5G signals, but may even lose 5G signals by incorrectly excluding valid positioning points, thus reducing positioning accuracy.

[0004] To address this issue, a direct technical approach is to require all indoor distributed antenna system (DAS) units to use highly stable precision components and undergo rigorous factory calibration. However, this would significantly increase the cost of a single DAS unit, making it economically unfeasible in high-density deployment scenarios and deviating from the original technical purpose of using existing communication facilities for positioning. In engineering practice, this field faces a difficult technical choice: on the one hand, high-precision positioning demands near-instrument-level electrical performance consistency from a large number of network endpoints; on the other hand, large-scale deployment economically necessitates the use of low-cost, non-precision communication-grade components. In this regard, existing technologies have the following shortcomings: 1. They lack a technical method to ensure that low-cost DAS units from different production batches deployed on a large scale exhibit uniform electrical performance during operation, avoiding unpredictable fluctuations in the overall positioning system performance; 2. At the level of a single DAS unit, there is a lack of an internal system mechanism capable of real-time measurement and proactive compensation for dynamic drift caused by changes in operating conditions in its own radio frequency link, making it impossible to guarantee the stability of its own measurement reference point. Therefore, the technical problem to be solved by this invention is how to propose a new system integration method that enables each independent, large-scale deployed indoor distribution unit to actively calibrate and maintain the stability of its own radio frequency link electrical characteristics in real time without relying on high-cost precision components, thus transforming it from a communication signal transmission system with uncertain performance into a radio navigation reference point with accurate and reliable spatiotemporal reference. Summary of the Invention

[0005] This invention provides an optimized integrated system for electrical components of indoor distributed antenna systems (DAS) units. Its main purpose is to solve the problem of how to enable large-scale deployed indoor DAS units to perform active real-time self-calibration without relying on high-cost precision components, so as to maintain the stability of their radio frequency link electrical characteristics. This solves the problem of balancing positioning reference consistency and deployment economy in the prior art.

[0006] To achieve the above objectives, the present invention provides an optimized indoor distribution unit electrical component integration system, the system comprising:

[0007] A digital baseband processing unit;

[0008] A main working path is connected to the digital baseband processing unit, which contains components whose electrical characteristics change dynamically with operating conditions;

[0009] A static calibration reference path whose electrical characteristics remain stable under varying operating conditions;

[0010] A signal switching module is configured to selectively send the probe signal output from the digital baseband processing unit into the main working path and the static calibration reference path;

[0011] A signal sampling module, located before the antenna port of the main working path, is configured to sample the probe signal propagating forward to the antenna port and to sample the probe signal reflected back from the antenna port;

[0012] The digital baseband processing unit is configured to: compare the electrical characteristics of the probe signals propagating forward through the main operating path and the static calibration reference path to determine the real-time drift error, which is the first error source, caused by the dynamically changing components of the main operating path; analyze the characteristics of the reflected probe signal and compare it with a reference reflection characteristic predetermined in a standard environment to determine the additional phase drift, which is the second error source, caused by the coupling effect between the antenna port and the external physical environment; superimpose the additional phase drift with the real-time drift error to generate a full-link compensation command; and apply the full-link compensation command to pre-adjust the RF signal when transmitting the RF signal.

[0013] Preferably, the digital baseband processing unit is further configured to perform a digital source self-calibration before determining the real-time drift error of the main working path. The digital source self-calibration includes the following rules: within the digital baseband processing unit, the probe signal is looped back before being sent to the digital-to-analog converter to form a pure digital loop; the digital zero-point drift of the digital signal processing link itself is determined by analyzing the probe signal passing through the pure digital loop; and the digital zero-point drift is applied to pre-compensate the signal generation process when generating the probe signal.

[0014] Preferably, the digital baseband processing unit is further configured to: periodically generate a two-tone detection signal consisting of at least two single-tone signals of different frequencies, and send it to the main working path via a signal switching module; perform spectral analysis on the two-tone detection signal sampled by the signal sampling module after passing through the main working path to detect intermodulation distortion components generated by the nonlinear characteristics of the main working path; determine the nonlinear distortion index of the main working path based on the characteristics of the intermodulation distortion components; and use the nonlinear distortion index as an input parameter when generating the full-link compensation command to adjust the generation algorithm of the full-link compensation command.

[0015] Preferably, when determining the real-time drift error of the main operating path, the digital baseband processing unit is further configured to: generate and, via a signal switching module, send a probe sequence consisting of at least two probe signals of different power levels into the main operating path; measure the drift error of each probe signal in the probe sequence after passing through the main operating path; and, based on the measured drift error related to the power level, construct a power-drift mapping model characterizing the main operating path, which is used to determine the instantaneous power of the RF signal. The output is a power-dependent compensation value; and when the digital baseband processing unit generates the end-to-end compensation command, it superimposes the real-time drift error with the phase drift and the power-dependent compensation value output from the power-drift mapping model based on the instantaneous power of the RF signal.

[0016] Preferably, the digital baseband processing unit is configured to analyze the characteristics of the reflected probe signal by: extracting the frequency response curve of the group delay of the reflected probe signal as a real-time reflection characteristic of the coupling effect between the antenna port and the external physical environment; the reference reflection characteristic is a reference group delay frequency response curve calibrated under a preset standard environment; the digital baseband processing unit determines the additional phase drift by calculating the difference vector between the real-time reflection characteristic and the reference reflection characteristic, and inputting the difference vector into a model that converts the difference vector into an additional phase drift before factory calibration.

[0017] Preferably, the digital baseband processing unit is further configured to: record historical real-time drift error and additional phase drift time series data; establish a time series model based on the time series data to characterize the aging trend of components or the changing trend of the external physical environment; calculate a quantitative index characterizing the rate of trend change based on the time series model; and output predictive maintenance alarm information when the quantitative index exceeds a preset alarm threshold.

[0018] Preferably, the static calibration reference path is a microstrip line made of a highly stable dielectric material laid on a circuit board, whose physical length and dielectric constant remain constant when the operating conditions change.

[0019] Preferably, the digital baseband processing unit applies the full-link compensation command to pre-adjust the radio frequency signal in the following manner: inside the digital baseband processing unit, digital predistortion technology is used to apply a phase and delay pre-adjustment to the baseband digital signal that is about to enter the main working path. The magnitude of the pre-adjustment is equal to the magnitude of the full-link compensation command but opposite in direction.

[0020] Preferably, the detection signal is a broadband detection signal whose spectral width covers the entire frequency band in which the system operates.

[0021] Preferably, the pure digital loop includes a first digital loop and a second digital loop that are physically mirror-symmetric; the digital baseband processing unit is further configured to: measure the differential delay of the signal as it passes through the first digital loop and the second digital loop to determine the non-uniform delay caused by the thermal gradient on the chip; determine a thermally induced error compensation value based on the non-uniform delay; and subtract the thermally induced error compensation value from the analysis results of the probe signal passing through the first digital loop when determining the digital zero-point drift.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. By combining digital source self-calibration with analog link drift measurement, a traceable end-to-end spatiotemporal reference stabilization mechanism is established. Before the system measures the electrical characteristics of the main working path, the probe signal itself is pre-calibrated within the digital baseband processing unit using a pure digital loop. This isolates the digital signal source drift caused by changes in chip operating conditions, obtaining a stable digital probe signal that can be used as a reference. Subsequently, this calibrated probe signal is sent to the main working path and the static calibration reference path. By comparing the differences in the electrical characteristics of the two outputs, the obtained real-time drift error purely reflects the physical changes of the analog link. This two-step method of calibrating the measurement tool first and then performing physical measurement avoids the industry technical problem of confusing digital source error with analog link error and performing incorrect compensation. This ensures that the final compensation command corrects the precisely locked analog physical link, thereby giving the signal transmission timing reference of the entire indoor distribution unit both logical and physical stability.

[0024] 2. This invention combines the calibration of the electronic characteristics inside the RF link with the real-time sensing of the coupling effect of the antenna port to the external environment, realizing an end-to-end calibration closed loop from the inside of the unit to the physical transmission aperture of the signal. While the system uses the embedded static calibration reference loop to determine the real-time drift error inside the main working path, its signal sampling module also samples the detection signal reflected back from the antenna port. The digital baseband processing unit analyzes the characteristic changes of the reflected signal to invert the additional phase drift caused by changes in the external environment such as aging of the antenna cover and attachments. Finally, the compensation command generated by the system is the superposition of two independently measured variables with different physical causes: the internal electronic link drift and the additional drift of the external physical aperture. This method enables the system not only to correct the state changes of its internal components, but also to actively adapt to the dynamic changes of its external physical environment, extending the calibration boundary from the circuit board to the actual wireless signal transmission origin.

[0025] 3. In the process of linear delay phase calibration of the RF link, a synchronous diagnostic capability for the nonlinear characteristics of the link is incorporated, expanding the system's function from simple error correction to long-term monitoring of the link's health status. In addition to periodically generating broadband probe signals for measuring linear drift, the system further generates probe signals composed of at least two single-tone signals of different frequencies and sends them to the main working path. The digital baseband processing unit performs spectral analysis on the sampled signal to detect the intermodulation distortion component generated by the nonlinearity of components such as power amplifiers. The characteristics of this intermodulation distortion component are used to determine a quantization index characterizing the degree of link nonlinearity. This index exists in parallel with the linear drift compensation value. The former is used to correct the instantaneous spatiotemporal reference of the signal, while the latter serves as a long-term health status indicator reflecting the aging trend of key components, providing a new dimension for the stability and maintainability of the entire positioning system. Attached Figure Description

[0026] Figure 1 This is a flowchart of the end-to-end self-calibration process of the system of the present invention;

[0027] Figure 2 This is a schematic diagram illustrating the system functions and interaction use cases of the present invention;

[0028] Figure 3 This is a block diagram of the hardware structure for the self-calibration system of the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below. 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.

[0030] An optimized indoor distributed antenna system (DAS) unit electrical component integration system, serving as a spatiotemporal reference point in a radio navigation network, integrates a digital baseband processing unit, a main working path, a static calibration reference path, a signal switching module, and a signal sampling module. This system establishes an end-to-end calibration closed loop from the digital signal source to the physical transmitting aperture through a periodic self-calibration process, compensating for signal timing errors introduced by the combined effects of internal component dynamic drift and external environmental coupling, thereby ensuring the reference stability of the transmitted navigation and positioning signals. In radio navigation applications, the stability of each indoor DAS unit as a measurement reference point in a large-scale deployed indoor positioning network is difficult to guarantee. To address this, this system is configured to first perform a digital source self-calibration to isolate digital signal source drift caused by changes in chip operating conditions. Specifically, within the digital baseband processing unit, a broadband detection signal generated by its digital oscillator is processed before being sent to the digital-to-analog converter. The digital signal stream is copied and looped back through a pure digital loop, which includes a first digital loop and a second digital loop physically mirror-symmetrically arranged on the chip. The digital baseband processing unit determines the non-uniform delay caused by the thermal gradient resulting from the uneven power consumption of different functional modules on the chip by measuring the nanosecond-level differential delay of a test pulse signal passing through the first and second digital loops. Subsequently, based on a thermal delay model calibrated by thermal simulation before leaving the factory, this differential delay is converted into a thermally induced error compensation value. The system analyzes the loopback signal of the first digital loop carrying the broadband probe signal to determine a total digital drift including thermal effects, and subtracts the thermally induced error compensation value from it to obtain a pure digital zero-point drift that can be used as a reference for subsequent analog link calibration. Thereafter, when generating all signals for external link probes, this digital zero-point drift is applied to pre-compensate the signal generation process, thus obtaining a digital probe signal that can be used as a reference.

[0031] After calibrating the measuring tools, the system then performs real-time measurements of the drift of the analog physical link. Given that the electrical components on the indoor distributed antenna system's RF link dynamically drift with changes in operating temperature, power supply, and component aging, the system utilizes a signal switching module to selectively send the broadband probe signal, calibrated by the digital source, to the main working path and the static calibration reference path. The main working path includes components such as power amplifiers and filters whose electrical characteristics dynamically change with operating conditions, while the static calibration reference path is a section laid out on a circuit board, composed of components with a dielectric constant temperature coefficient less than [missing information]. The microstrip line is composed of a highly stable dielectric material, whose physical length and dielectric constant remain constant under varying operating conditions. A signal sampling module, configured as a directional coupler, is located before the antenna port on the main operating path. It samples the probe signal propagating forward to the antenna port. When the probe signal flows through the main operating path, the signal sampling module performs a first sampling. Subsequently, the signal switching module sends the probe signal to the static calibration reference path, where the signal sampling module performs a second sampling. The digital baseband processing unit directly calculates the real-time drift error, the first error source, caused by the dynamically changing components of the main operating path, by comparing the phase and group delay differences between these two sampled signals. To extend the calibration boundary from the circuit board to the actual wireless signal transmission origin and compensate for additional phase drift caused by external environmental changes such as radome aging and deposits, the signal sampling module is also configured to sample the probe signal reflected from the antenna port. The digital baseband processing unit extracts the frequency response curve of the group delay of the reflected broadband probe signal as a real-time reflection characteristic characterizing the coupling effect between the antenna port and the external physical environment. This real-time reflection characteristic is compared with a standard environment, i.e., temperature 25°C. The frequency response curves of the reference group, calibrated in an anechoic chamber with a relative humidity of 50% and no reflectors within 1 meter in front of the antenna, are compared. The difference vector between the real-time reflection characteristics and the reference reflection characteristics is calculated, and this difference vector is input into a lookup table model established by multiphysics simulation before leaving the factory, which converts the difference vector into additional phase drift, to determine the additional phase drift caused by the coupling effect of the external physical environment as the second error source.

[0032] Finally, the digital baseband processing unit vector-superimposes the real-time drift error (the first error source) with the additional phase drift (the second error source) to generate a full-link compensation command. When the system transmits normal 5G or BeiDou radio frequency signals, this command is applied to the digital predistortion module within the digital baseband processing unit. This module applies a pre-adjustment of phase and delay to the baseband digital signal about to enter the main working path. The magnitude of this pre-adjustment is equal to and opposite in direction to the magnitude of the full-link compensation command, thus pre-canceling the drift error that will be introduced into the full link before the signal enters the physical link. It should be noted that when the digital baseband processing unit performs the full-link self-calibration process, the transmission of its probe signal and the transmission of normal 5G service data are time-domain multiplexed. Specifically, this unit is configured to monitor downlink physical downlink sharing in real time. The channel is the resource block (RB) scheduling diagram of the PDSCH. When an idle RB not occupied by user data is identified within the current transmission time interval (TTI), the baseband data stream of the probe signal is sent only to the time-frequency positions corresponding to these idle RBs. Normal service data transmission of adjacent RBs is unaffected. The entire self-calibration measurement process is completed using one or more non-continuous TTI service idle gaps, thus periodically acquiring link status without interrupting the main communication service or reducing data throughput. To extend the system's function from simple error correction to long-term monitoring of link health, the digital baseband processing unit is also configured to periodically generate a sequence of frequencies... and The two single-tone signals constitute a dual-tone detection signal, which is then sent to the main working path; in addition, for the dual-tone detection signal used to monitor the nonlinear characteristics of the link, the frequency components of its two single-tone signals are... and The determination follows a set of engineering procedures to ensure the validity of the measurement. First, the interval between the two frequencies... It is set to be greater than the reciprocal of the signal sampling window duration so that the two signals can be clearly distinguished in the spectrum after processing by Fast Fourier Transform (FFT); secondly, The bandwidth was set to be less than one-tenth of the system channel coherence bandwidth, making the multipath fading characteristics experienced by the two signals highly correlated. This effectively eliminated the influence of channel frequency-selective fading when calculating the intermodulation distortion component. Finally, based on the technical specifications of the key components in the main working path, the third-order intermodulation distortion component was calculated. and The frequency of the signal sampling module is determined by constraints, ensuring it falls within the passband of the intermediate frequency filter. These constraints collectively define an effective frequency pair selection space, as given in the preceding embodiments. and The combination of these elements constitutes a specific technical implementation within that space. The signal sampling module samples the signal after it has passed through the main working path, and the digital baseband processing unit then performs spectral analysis on the sampled signal to detect... and Intermodulation distortion components generated by the nonlinear characteristics of the main working path at the frequency point; by calculating the ratio of the power of the intermodulation distortion components to the power of the original two-tone signal, a quantization index characterizing the degree of nonlinearity of the link is determined, namely the third-order intermodulation rejection ratio; this index serves as a long-term health indicator reflecting the aging trend of key components.

[0033] Simultaneously, the system records historical real-time drift error and additional phase drift time series data, and builds an autoregressive moving average time series model based on this data to characterize the aging trend of components or changes in the external environment. When the rate of change of the model's predicted value within a preset time window exceeds an alarm threshold, for example, if the phase drift rate is greater than a certain threshold... At that time, the system outputs predictive maintenance alarm information, providing a new dimension for the stability and maintainability of the positioning system. Considering the power dependence of the phase transmission characteristics of the power amplifier in the RF link, i.e., the AM-PM effect, in order to achieve instantaneous value compensation that accurately matches the real-time signal power, the digital baseband processing unit is also configured to generate and quickly send a probe sequence consisting of at least two probe signals with different power levels, for example, one with a power of 0dBm and the other with a power of 20dBm, when determining the real-time drift error of the main working path. The system measures the drift error of each probe signal in the probe sequence after passing through the main working path, and based on these discrete drift error measurement points related to the power level, constructs a power-drift mapping model characterizing the main working path through linear interpolation. This model is used to determine the instantaneous power of the RF signal. Output a power-dependent compensation value; when generating the full-link compensation command, the digital baseband processing unit superimposes the real-time drift error, the additional phase drift, and the power-dependent compensation value output from the power-drift mapping model based on the instantaneous power of the RF signal to be transmitted.

[0034] Example 1: In a large intelligent warehouse providing high-precision operation guidance for autonomous mobile robots (AMRs), the operational requirement is for the AMRs to complete material docking with an error of no more than 1 cm between dynamically changing shelves. However, the warehouse has hundreds of 5G indoor distribution units from different production batches. During peak midday communication hours, the performance of the entire positioning system becomes unstable, with frequent fluctuations in AMR positioning results in some areas, failing to meet operational requirements and leading to an increased docking failure rate. When the warehouse's operation and maintenance system detects a continuous decrease in positioning accuracy in a specific area exceeding a preset threshold, the technical solution of this invention... The system was triggered in one of the indoor distributed array units in the region. The system first entered the digital source self-calibration stage. Given that the digital baseband processing unit of this unit had a temperature gradient formed on its chip surface due to long-term high-load operation, the digital baseband processing unit determined the non-uniform delay caused by the thermal gradient by measuring the differential delay between the first and second digital loops arranged in a mirror-symmetric manner inside the test pulse signal. Based on this, it generated a thermal error compensation value to correct the total digital drift measured in the first digital loop, thereby obtaining a pure digital zero-point drift that is not affected by the current thermal conditions of the chip. This provides a stable reference for all subsequent measurements.

[0035] Subsequently, the system enters the synchronous calibration phase between the analog link and the external environment. A broadband probe signal calibrated by the aforementioned digital source is sequentially sent to the main working path and the static calibration reference path. The digital baseband processing unit determines the real-time drift error in the main working path caused by the temperature rise of the power amplifier by comparing the differences between the two sampled signals. At the same time, the signal sampling module captures the probe signal reflected from the antenna port. The digital baseband processing unit analyzes the group delay frequency response curve of the reflected signal and finds a small difference vector between it and the reference reflection characteristics. After the difference vector is input into the internal model, the additional phase drift caused by a thin layer of dust on the surface of the radome is calculated. The joint measurement of this additional phase drift and the aforementioned real-time drift error reveals that the error source of the indoor distribution unit at this moment is the superposition of internal electronic drift and external physical environmental pollution. Considering that the communication service is at its peak, the system further performs power-dependent calibration. A probe signal consisting of two different power levels, 0dBm and 20dBm, is used. The probe sequence is injected into the main working path; the system quickly constructs a power-drift mapping model characterizing the current power amplifier state by measuring the drift error of each probe. Finally, a full-link compensation command is generated by vector superposition of the real-time drift error, the additional phase drift, and the power dependence compensation value obtained from the power-drift mapping model based on the instantaneous transmit power under the current high service load. This command is then applied to the digital predistortion adjustment of all radio frequency signals to be transmitted. After the full-link compensation command is applied, the spatiotemporal reference of the positioning signal transmitted by the indoor unit stabilizes, the fluctuation phenomenon of the AMR positioning results covered by it disappears, and the material docking success rate returns to normal. The entire process transforms a dynamic multi-factor coupled performance drift problem into a static, separable measurable problem of path difference, environmental reflection characteristic difference, and power response characteristic difference. By synchronously measuring and compensating for these three differences, the contradiction between using low-cost communication-grade components and achieving high-precision navigation reference stability is resolved.

[0036] To further illustrate the fundamental improvement of the technical solution of the present invention compared to that achieved by using only conventional internal calibration techniques, the following comparative examples are provided.

[0037] Comparative Example 1: To verify the technical necessity of the end-to-end calibration method of this invention, which combines internal electronic link calibration with external physical environment sensing, a special test platform was built, and a comparative test system containing only a conventional internal calibration loop was prepared. In terms of hardware structure, this comparative system is basically the same as the system in the embodiment of this invention, both including a digital baseband processing unit, a main working path, a static calibration reference path, and a signal sampling module. The only essential difference between this system and the present invention is that this comparative system is configured to calculate and compensate for the real-time drift error caused by internal components by comparing the signal difference between the main working path and the static calibration reference path. However, it is not configured to analyze the reflected signal of the antenna port, and therefore does not have the ability to sense and compensate for the additional phase drift caused by the coupling effect of the external physical environment. The test was carried out in a programmable temperature chamber, and a vector network analyzer (phase measurement resolution 0.1 picosecond) was used to accurately monitor the signal phase change of the RF output port of the comparative system.

[0038] The test procedure is as follows: initial state calibration: at 25 Under standard ambient temperature, the comparison system was initially powered on and its internal calibration process was executed. The phase of the output signal measured by the vector network analyzer at this moment was recorded and defined as a zero-point reference of 0.0 picoseconds. Internal thermal drift simulation: the ambient temperature of the programmable chamber was increased from 25°C. Gradually rising to 65 This is used to simulate the thermal drift of internal components caused by long-term high-load operation of the system, with the temperature in the chamber stabilizing at 65°C. Then, the internal calibration procedure of the comparison system was executed again, and the phase drift was recorded at this point; external environment coupling simulation: the temperature in the chamber was maintained at 65°C. Under these conditions, a 2 mm thick polytetrafluoroethylene dielectric plate was tightly covered at the antenna port of the comparison system. This operation was intended to simulate the additional coupling effect caused by external environmental changes such as aging of the radome, dust accumulation, or icing in real deployment scenarios, which is not caused by the internal electronic links. The internal calibration process of the comparison system was then executed again, and the final cumulative phase drift was recorded. The key data during the test process are recorded in Table 1.

[0039] Table 1: Test data table for Comparative Example 1.

[0040]

[0041] Test data shows that, under conditions where only internal temperature changes (from 25... Rise to 65 The comparison system, through its internal static calibration reference path, can effectively suppress the thermally induced phase drift of internal components to within 2.3 picoseconds, demonstrating good internal compensation capability. However, when an external medium is introduced to simulate changes in the antenna port environment, the system cannot detect changes in the reflection characteristics of the antenna port due to its design principle. Therefore, its internal calibration mechanism is completely unable to compensate for the additional phase drift introduced externally, resulting in a dramatic increase in the final cumulative phase drift to 36.5 picoseconds. Experimental results show that while a calibration solution relying solely on the internal reference path can address the drift problem caused by changes in the operating conditions of internal components to some extent, it is completely powerless against signal timing errors caused by the coupling effect between the antenna port and the external physical environment.

[0042] Example 2: To objectively verify the effectiveness of the present invention's technical solution in suppressing timing errors caused by the combined effects of internal component thermal drift and external antenna port environmental coupling, a dedicated test platform was built. This platform consists of a programmable temperature chamber, a vector network analyzer, and a standard 5G signal generator. The programmable temperature chamber is used to simulate the operating state of the indoor distribution unit under different ambient temperatures, with a temperature control accuracy of ±0.5°C. A vector network analyzer was used to measure the signal phase change at the RF output port of the indoor distribution unit, with a measurement resolution of 0.1 picoseconds. During the test, a sample group using the technical solution of this invention (i.e., the sample group of this invention) and three control sample groups were selected for comparative testing. Control group 1 was a standard indoor distribution unit without any self-calibration function; control group 2 was an indoor distribution unit with only internal real-time drift error compensation function; and control group 3 was an indoor distribution unit with only external additional phase drift compensation function. Before the test, all sample groups were tested at 25°C. Initial calibration was performed under standard conditions, and the phase of its output signal was used as the zero-point reference. In the first stage of the experiment, all sample groups were placed in a programmable temperature chamber, with the ambient temperature starting from 25°C. Gradually rising to 65 The experiment simulated the thermal drift of components caused by changes in operating conditions, and recorded the phase drift of the output signals of each sample group at multiple temperature points; in the second stage of the experiment, the temperature of the chamber was stabilized at 65°C. During the test, a 2 mm thick polytetrafluoroethylene dielectric plate was covered at the antenna port of each sample group to simulate the coupling effect introduced by external environmental changes such as aging of the antenna cover or dust accumulation. The phase drift of the output signal of each sample group was recorded again. The key data of the entire test process are recorded in Table 2.

[0043] Table 2: Phase drift test data for different groups under different test conditions.

[0044]

[0045] The experimental data in Table 2 show that, under the combined effects of increased temperature and external medium coverage, the phase drift of control group 1 reached a cumulative 98.6 ps, resulting in decreased timing reference stability. Control group 2, possessing internal real-time drift error compensation, could suppress phase drift to within 1.9 ps during simple temperature increases. However, after the introduction of external medium coverage, its phase drift increased to 35.1 ps due to the inability to sense changes in the external environment at the antenna port. Control group 3, possessing only external additional phase drift compensation, lacked the ability to correct thermal drift of internal components, and its drift data was basically consistent with that of control group 1. The prototype of this invention, through the coordinated work of its internal electronic link drift compensation and external physical aperture additional phase drift compensation, achieved a maximum phase drift of only 2.1 ps throughout the entire test process. The experimental results demonstrate that optimizing the integrated system of electrical components in the indoor distribution unit, by combining real-time calibration of internal electronic characteristics with synchronous sensing of the antenna port's coupling effect to the external environment, constructs an end-to-end calibration closed loop.

[0046] Example 3: This example combines Figures 1 to 3 This describes an optimized indoor distribution unit electrical component integration system, such as... Figure 1 As shown, the process begins with the baseband digital signal from an external service signal source. After being adjusted by the applied digital predistortion stage, one path serves as a probe signal entering the main working path and interacting with the antenna and the external physical environment. The other path is used to measure the internal electronic drift. The system executes two processing paths in parallel: first, by analyzing the physical reflection signal at the antenna port and comparing it with the reference reflection characteristics, the additional phase drift is determined; second, by processing the internally measured sampled signal, the real-time drift error is calculated. Finally, the real-time drift error and the additional phase drift are superimposed to generate a full-link compensation command. This command is fed back to the applied digital predistortion stage in a closed loop, and its generation process is also supported by the calibration model library. In addition, the system also monitors the link health status and analyzes historical time-series data to establish a trend model and output predictive maintenance alarms to the operation and maintenance system.

[0047] like Figure 2 As shown, the digital baseband processing unit, as the internal execution entity, initiates the core execution end-to-end self-calibration use case. This use case includes three sub-use cases: performing digital source self-calibration, measuring internal electronic drift, and compensating for external environmental coupling. It can also be extended to apply power dependency compensation. Its ultimate goal is to provide high-precision positioning signals to the positioning terminal (AMR). The test engineer, as an external role, interacts with the system to perform factory calibration and parameter configuration. The digital baseband processing unit also executes a use case for monitoring the link health status. This use case, through adaptively updating the trend model, ultimately outputs predictive maintenance alarms to the operation and maintenance system. Figure 3As shown, the system mainly consists of a digital baseband processing unit, a signal switching module, a main working path, a static calibration reference path, and a signal sampling module. During operation, the probe signal generated by the digital baseband processing unit is selectively sent to the main working path or the static calibration reference path via the signal switching module. The main working path includes dynamic components such as power amplifiers and filters, while the reference path is a highly stable dielectric microstrip line with constant electrical characteristics. The output signals of the two paths and the reflected signals from the antenna port are captured by the signal sampling module, which acts as a directional coupler. The collected sampling data is finally fed back to the compensation command generation unit of the digital baseband processing unit, thus forming a complete signal processing and calibration closed loop.

[0048] Example 4: This example aims to provide a standardized pre-shipment calibration procedure for models used to convert antenna port reflection characteristics into additional phase drift, thereby eliminating uncertainties in the model construction process. The initial state of the calibration work is defined as placing an integrated system of indoor distributed antenna unit electrical components that has completed internal link calibration in a standard electromagnetic anechoic chamber, where the ambient temperature is controlled at 25°C. ±1 The relative humidity is 50%±5%. In this environment, a vector network analyzer with a phase measurement accuracy better than 0.05 degrees is connected to the antenna port of the system to serve as an external high-precision phase change observation benchmark. The first step of the calibration process is to establish a zero-point benchmark. Under the condition that there are no reflectors within 3 meters in front of the antenna, the system first performs an internal measurement, records the frequency response curve of the reflected signal group delay at this moment, and stores it as the benchmark reflection characteristic. At the same time, the vector network analyzer is used to measure and record the phase of the transmitted signal at this moment as the phase zero point. The second step of the calibration process is to introduce a controllable environmental coupling disturbance. Multiple sets of standard dielectric plates with different dielectric constants and thicknesses, such as polytetrafluoroethylene plates with thicknesses of 1 mm, 2 mm and 3 mm, are attached tightly to the outer surface of the antenna radome of the system to simulate different degrees of external environmental changes such as dust accumulation or icing.

[0049] For each introduced standard dielectric substrate, the system performs a complete measurement and recording operation. First, the system's internal digital baseband processing unit, according to the method described in the specific implementation, captures and analyzes the probe signal reflected from the antenna port to obtain the current real-time reflection characteristics. By calculating the difference between these characteristics and the aforementioned reference reflection characteristics, a quantized difference vector is obtained. Simultaneously, an external vector network analyzer synchronously measures and records the change in the transmitted signal phase caused by the introduction of the standard dielectric substrate; this change is the true value of the additional phase drift corresponding to this disturbance. By repeating this process, a series of data pairs consisting of the difference vector and its corresponding true value of the additional phase drift can be obtained. Finally... All the obtained data pairs are used to populate a multidimensional lookup table, which is a model for converting the difference vector into an additional phase drift. The input address of the lookup table consists of the components of the difference vector, and the content stored at that address is the corresponding true value of the additional phase drift. Between two calibrated data points, the system uses a linear interpolation algorithm to calculate the output value. After this calibration is completed, the lookup table model is stored in the non-volatile memory of the digital baseband processing unit. This allows the system to determine the additional phase drift caused by the coupling effect of the external environment by looking up this table based solely on its internal measurement of the reflected signal at the antenna port during subsequent deployment, thus completing the deterministic construction of the core algorithm model.

[0050] Example 5: This example aims to provide a standardized adaptive adjustment procedure for determining the time series model used to output predictive maintenance alarm information and its alarm threshold. In an indoor positioning network that has been deployed and continuously operating for more than twelve months, when one of the indoor distributed unit electrical component integration systems is initially deployed, its internal autoregressive moving average time series model adopts a set of general factory preset parameters based on the aging data of similar devices, and its predictive maintenance alarm threshold is set to a phase drift rate greater than 0.1 ns / month.

[0051] After the system has been running for six months, it automatically initiates an adaptive reconstruction process for the model and thresholds. First, the digital baseband processing unit retrieves complete time-series data on real-time drift error and additional phase drift recorded and stored during the past six months of operation. Then, the system uses this historical data specific to the unit and its deployment environment to retrain its internal autoregressive moving average time-series model, generating a new set of model parameters that better reflects the aging trend of the unit. Based on this, the system further uses the new model to backtest the historical data from the past six months, calculates the residual sequence between the model's predicted values ​​and the actual measured values, and determines the standard deviation of the residual sequence. Finally, the system updates the predictive maintenance alarm threshold to the standard deviation of the residual sequence. Three times, that is Subsequently, the process of model reconstruction and threshold update is repeated every twelve months. Through this procedure, the predictive model and its alarm threshold used by the system are periodically recalibrated based on their own historical operating data.

[0052] Example 6: This example aims to provide a standardized offline optimization calibration procedure for determining the power level parameters of probe sequences used to construct power-drift mapping models. During the production testing phase of an indoor distributed antenna system (DAS) electrical component integration system, given the individual differences in power-dependent nonlinear phase shift characteristics of the power amplifiers used in its main operating path due to different batches, a preliminary probe sequence power level optimization is required to ensure that the power-dependent compensation value used in each independent system unit accurately matches its hardware characteristics. The calibration is performed on an RF test bench equipped with a vector network analyzer and a precision adjustable attenuator. The bit measurement resolution is better than 0.05 degrees to obtain a reference curve for the power-drift response. At the start of calibration, a system unit to be calibrated is placed on the test bench and operated in a special test mode in which its transmit power can only be controlled by an external test bench. The test bench controls the transmit power of the system unit, scanning from the lowest value of its rated operating range of -10dBm in 1dB steps to the highest value of +23dBm. At each power step point, the vector network analyzer measures and records the reference value of the phase drift generated by the main operating path at that moment, thereby obtaining a high-resolution power-drift mapping reference curve consisting of 34 data points covering the entire operating range.

[0053] Subsequently, the optimization algorithm within the digital baseband processing unit is activated. The objective function of this algorithm is to select a probe sequence consisting of detection signals from at least two different power levels from the aforementioned 34 power levels, for example, three power level points. , and Based on the phase drift values ​​corresponding to these three points, a piecewise linear interpolation model is constructed, ensuring that the maximum absolute error between this interpolation model and the reference curve over the entire working interval is minimized. To minimize; the optimization algorithm, through iterative calculation, ultimately determines the value that minimizes the objective function. The three minimized power levels, such as -5dBm, +15dBm, and +22dBm, correspond to the initial linear region, nonlinear inflection point, and near-saturation region of the power-drift mapping reference curve, respectively. This set of determined power level parameters is then stored in the non-volatile memory as probe sequence parameters specific to this system unit. In subsequent online self-calibration processes, the system will use only these three power points for measurement to construct its real-time simplified power-drift mapping model. This procedure transforms a general compensation method into a parameterized configuration for each individual hardware component.

[0054] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. An optimized indoor distribution unit electrical component integration system, characterized in that, The system includes: A digital baseband processing unit; A main working path is connected to the digital baseband processing unit, which contains components whose electrical characteristics change dynamically with operating conditions; A static calibration reference path whose electrical characteristics remain stable under varying operating conditions; A signal switching module is configured to selectively send the probe signal output from the digital baseband processing unit into the main working path and the static calibration reference path; A signal sampling module, located before the antenna port of the main working path, is configured to sample the probe signal propagating forward to the antenna port and to sample the probe signal reflected back from the antenna port; The digital baseband processing unit is configured to: compare the electrical characteristics of the probe signals propagating forward through the main operating path and the static calibration reference path to determine the real-time drift error, which is the first error source, caused by the dynamically changing components of the main operating path; analyze the characteristics of the reflected probe signal and compare it with a reference reflection characteristic predetermined in a standard environment to determine the additional phase drift, which is the second error source, caused by the coupling effect between the antenna port and the external physical environment; superimpose the additional phase drift with the real-time drift error to generate an end-link compensation command; and apply the end-link compensation command to pre-adjust the RF signal when transmitting the RF signal. Furthermore, the digital baseband processing unit is also configured to perform a digital source self-calibration before determining the real-time drift error of the main working path. The digital source self-calibration includes the following rules: within the digital baseband processing unit, the probe signal is looped back before being sent to the digital-to-analog converter to form a pure digital loop; the digital zero-point drift of the digital signal processing link itself is determined by analyzing the probe signal passing through the pure digital loop; and the digital zero-point drift is applied to pre-compensate the signal generation process when generating the probe signal. When determining the real-time drift error of the main operating path, the digital baseband processing unit is further configured to: generate and, via a signal switching module, send a probe sequence consisting of at least two probe signals of different power levels into the main operating path; measure the drift error of each probe signal in the probe sequence after passing through the main operating path; and, based on the measured drift error related to the power level, construct a power-drift mapping model characterizing the main operating path. This drift mapping model is used to determine the instantaneous power of the RF signal. Output a power-dependent compensation value; and when the digital baseband processing unit generates the end-to-end compensation command, it adds the phase drift to the real-time drift error and superimposes it with the power-dependent compensation value output from the power-drift mapping model based on the instantaneous power of the RF signal. The digital baseband processing unit is also configured to: record historical real-time drift error and additional phase drift time series data; establish a time series model based on the time series data to characterize the aging trend of components or the changing trend of the external physical environment; calculate a quantitative index characterizing the rate of trend change based on the time series model; and output predictive maintenance alarm information when the quantitative index exceeds a preset alarm threshold.

2. The optimized indoor distribution unit electrical component integration system according to claim 1, characterized in that, The digital baseband processing unit is also configured to periodically generate a dual-tone detection signal consisting of at least two single-tone signals of different frequencies, and send it to the main working path via a signal switching module. Spectral analysis is performed on the dual-tone detection signal after it passes through the main working path and is sampled by the signal sampling module to detect the intermodulation distortion component caused by the nonlinear characteristics of the main working path. Based on the characteristics of the intermodulation distortion components, the nonlinear distortion index of the main working path is determined. Furthermore, when generating end-to-end compensation instructions, the nonlinear distortion index is used as an input parameter to adjust the generation algorithm of end-to-end compensation instructions.

3. The optimized indoor distribution unit electrical component integration system according to claim 1, characterized in that, The digital baseband processing unit is configured to analyze the characteristics of the reflected probe signal by extracting the frequency response curve of the group delay of the reflected probe signal as a real-time reflection characteristic of the coupling effect between the antenna port and the external physical environment. The reference reflection characteristic is a reference group delay frequency response curve calibrated under a preset standard environment; the digital baseband processing unit calculates the difference vector between the real-time reflection characteristic and the reference reflection characteristic, and inputs the difference vector into a model that converts the difference vector into additional phase drift before leaving the factory to determine the additional phase drift.

4. The optimized indoor distribution unit electrical component integration system according to claim 1, characterized in that, The static calibration reference path is a microstrip line made of a highly stable dielectric material laid on a circuit board. Its physical length and dielectric constant remain constant when the operating conditions change.

5. The optimized indoor distribution unit electrical component integration system according to claim 1, characterized in that, The digital baseband processing unit applies the full-link compensation command to pre-adjust the radio frequency signal in the following way: inside the digital baseband processing unit, digital predistortion technology is used to apply a phase and delay pre-adjustment to the baseband digital signal that is about to enter the main working path. The magnitude of the pre-adjustment is equal to the magnitude of the full-link compensation command but opposite in direction.

6. The optimized indoor distribution unit electrical component integration system according to claim 1, characterized in that, The detection signal is a broadband detection signal, whose spectral width covers the entire frequency band in which the system operates.

7. The optimized indoor distribution unit electrical component integration system according to claim 1, characterized in that, The pure digital loop includes a first digital loop and a second digital loop that are physically mirror-symmetric; the digital baseband processing unit is also configured to: measure the differential delay of the signal as it passes through the first digital loop and the second digital loop to determine the non-uniform delay caused by the thermal gradient on the chip; and determine a thermal error compensation value based on the non-uniform delay. Furthermore, when determining the digital zero-point drift, the thermal error compensation value is subtracted from the analysis results of the detection signal passing through the first digital loop.

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