A positioning method and system for illegal terminals in a distributed terminal management and control system

Abstract

A positioning method of illegal terminal in a distributed terminal management and control system, applied to a distributed terminal management and control system comprising a baseband unit and multiple radio frequency units, assigns a unique gain modulation frequency to each radio frequency unit; the baseband unit controls the illegal terminal to report energy values to the radio frequency unit at a fixed period; each radio frequency unit performs gain modulation on the received energy values of the illegal terminal in parallel according to the gain modulation frequency assigned to itself, and reports the modulated energy values to the baseband unit; the baseband unit collects energy value data within a preset time length, performs frequency domain transformation to obtain an energy change spectrum, and identifies the coverage area of the radio frequency unit corresponding to the illegal terminal according to the gain modulation frequency corresponding to the energy change dominant frequency in the spectrum. The present application has higher processing efficiency, faster system response speed and better accuracy of illegal terminal positioning and identification.

Description

Technical Field

[0001] This invention relates to technology for locating unauthorized terminal devices in highly secure locations, specifically to a method and system for locating unauthorized terminals in a distributed terminal management system. Background Technology

[0002] A distributed terminal control system consists of a baseband unit and multiple radio frequency units (RRUs) connected via optical fiber communication. Each RRU covers a certain area via an antenna system. When an unauthorized terminal enters the coverage area of ​​a given RRU and is controlled, the RRU reports the energy value of the unauthorized terminal to the baseband unit. Existing technology uses a serial gain modulation method. When an unauthorized terminal is controlled, the uplink gain values ​​of all RRUs are changed sequentially within a specific time window. After modifying the uplink gain value of a particular RRU within the specified time window, the energy value detected by the baseband unit changes accordingly compared to the energy value before the gain modification, thus indicating that the unauthorized terminal is within the RRU coverage area. However, this scheme has the following drawbacks: it cannot accurately determine the unauthorized mobile terminal if its reported energy value fluctuates; and the serial modification of the uplink gain of the RRUs results in a long judgment period. Another approach in existing technologies is radio frequency fingerprinting (RFF). The core principle of this method is that the analog front-end components (such as power amplifiers, oscillators, and mixers) of each wireless device inevitably have manufacturing differences. These differences leave unique, difficult-to-replicate "fingerprint" features in the transmitted signal. These fingerprint features can be extracted and identified using deep learning models (such as convolutional neural networks and Transformers) to authenticate the transmitting device. However, this method's fingerprint features are sensitive to the environment; complex multipath effects and dynamic channel changes may mask the inherent hardware fingerprint. Furthermore, this method primarily identifies "which terminal device is transmitting a signal," rather than directly determining "which RRU reported the signal," resulting in high signal processing complexity. Therefore, a reliable and simple method for locating unauthorized terminals needs to be found within the existing distributed terminal management system hardware architecture to quickly pinpoint the RRU where the unauthorized terminal is located, facilitating subsequent processing. Summary of the Invention

[0003] In order to overcome at least one of the above-mentioned shortcomings of the prior art, the present invention proposes a method and system for locating illegal terminals in a distributed terminal management system.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: a method for locating unauthorized terminals in a distributed terminal management system, applied to a distributed terminal management system including one baseband unit and multiple radio frequency units, the method comprising:

[0005] Each radio frequency unit is assigned a unique gain modulation frequency;

[0006] The baseband unit controls unauthorized terminals to report their energy values ​​to the radio frequency unit corresponding to their physical area at fixed intervals.

[0007] Each radio frequency unit modulates the energy value of the received illegal terminal in parallel according to its assigned gain modulation frequency, and reports the modulated energy value to the baseband unit.

[0008] The baseband unit collects energy value data within a preset time period, performs frequency domain transformation to obtain the energy change spectrum, and identifies the coverage area of ​​the radio frequency unit corresponding to the illegal terminal based on the gain modulation frequency corresponding to the main frequency of energy change in the spectrum.

[0009] Furthermore, the gain modulation specifically involves each radio frequency unit changing the gain value of the energy value through a gain change sequence according to the assigned gain modulation frequency. The gain change sequence is a preset sequence containing multiple step values. Each gain adjustment in the sequence is applied to the energy value of the illegal terminal in sequence, so that the energy value reported to the baseband unit exhibits a periodic envelope change corresponding to the gain change sequence.

[0010] Furthermore, the frequency domain transformation employs a fast Fourier transform.

[0011] Furthermore, when the baseband unit collects energy value data within a preset time period, the sampling frequency and collection time are set according to the frequency resolution requirements, so that the gain modulation frequency allocated to each radio frequency unit can be distinguished.

[0012] Furthermore, each radio frequency unit is assigned a corresponding identification number. The baseband unit reports the identification number of the identified radio frequency unit to the backend server to display the coverage area of ​​the radio frequency unit where the illegal terminal is located.

[0013] Furthermore, the illegal terminal is identified by the baseband unit: the baseband unit determines whether the currently accessed terminal is an illegal terminal. If not, the terminal is released; if yes, it is confirmed as an illegal terminal.

[0014] Furthermore, the baseband unit captures the terminal's IMSI, IMEI, or MAC address and compares it with a preset whitelist or blacklist. If the terminal is not in the whitelist or is in the blacklist, it is confirmed as an illegal terminal.

[0015] The present invention also proposes a positioning system for illegal terminals in a distributed terminal management system, comprising a baseband unit and multiple radio frequency units, wherein the baseband unit and each radio frequency unit are connected via optical fiber communication.

[0016] The baseband unit is used to: assign a unique gain modulation frequency to each radio frequency unit, control the illegal terminal to report energy values ​​to the radio frequency unit corresponding to its physical area at fixed intervals, collect energy value data within a preset time period, perform frequency domain transformation to obtain the energy change spectrum, and identify the coverage area of ​​the radio frequency unit corresponding to the illegal terminal based on the gain modulation frequency corresponding to the main frequency of energy change in the spectrum.

[0017] The radio frequency unit is used to: modulate the energy value of the received illegal terminal in parallel according to its assigned gain modulation frequency, and report the modulated energy value to the baseband unit.

[0018] Furthermore, gain modulation is implemented through a gain modulation unit, which is used to: change the gain value of the energy value through a gain change sequence, wherein the gain change sequence is a preset sequence containing multiple step values, and each gain adjustment amount in the sequence is applied to the energy value of the illegal terminal in sequence, so that the energy value reported to the baseband unit presents a periodic envelope change corresponding to the gain change sequence.

[0019] Furthermore, it also includes a backend server. The baseband unit assigns a corresponding number to each radio frequency unit. The baseband unit reports the identified radio frequency unit number to the backend server, which then displays the coverage area of ​​the radio frequency unit where the illegal terminal is located.

[0020] Compared with the prior art, the present invention has the following beneficial technical effects:

[0021] 1. After identifying an illegal terminal, the baseband unit takes over the terminal's transmission control by implementing management and control measures, thereby forcing the illegal terminal to report its energy value at a fixed period and keeping its transmission power relatively stable. This stable energy reporting mechanism provides a reliable data basis for subsequent accurate identification based on the frequency domain.

[0022] 2. This invention reports the gain-modulated energy value of an illegal mobile terminal to the baseband terminal via the radio frequency terminal. The frequency of the periodic envelope change of the energy value is used to determine which radio frequency terminal's coverage area the terminal is in. Through gain modulation and FFT operation, the terminal's random energy fluctuations and slow channel fading are averaged or separated in the frequency domain, avoiding misjudgments caused by energy value fluctuation interference, which is easily affected by traditional time-domain energy value comparison methods, and improving the accuracy of illegal terminal identification.

[0023] 3. By assigning a corresponding gain modulation frequency to each RF unit, it is equivalent to giving each RF unit a "fingerprint tag", enabling the baseband unit to directly determine the source of energy changes from the RF unit through spectrum analysis.

[0024] 4. In this invention, the gain changes of all radio frequency units are parallel. The baseband unit only needs to analyze the energy data reported by the radio frequency units once to accurately determine the location of the illegal mobile terminal. In contrast, traditional identification methods require serial modification of the gain of all radio frequency terminals and analysis of the energy data reported by all radio frequency terminals before a judgment can be made. Therefore, this application has the advantages of high processing efficiency and fast system response. Attached Figure Description

[0025] Figure 1 This is a flowchart of the method for locating illegal terminals in the distributed terminal management system of the present invention;

[0026] Figure 2 This is a timing diagram of the method for locating illegal terminals in the distributed terminal management system of the present invention;

[0027] Figure 3 The time-domain and frequency-domain signal diagrams and algorithm illustrations of the location process of illegal terminals in RRU0;

[0028] Figure 4 The time-domain and frequency-domain signal diagrams and algorithm illustrations of the location process of an illegal terminal in RRU3;

[0029] Figure 5 The time-domain and frequency-domain signal diagrams and algorithm illustrations are shown for the location process of an illegal terminal in RRU7. Detailed Implementation

[0030] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0031] Example 1

[0032] Example 1 describes the specific operation flow of the method for identifying the location of illegal terminals in the distributed mobile terminal management system of the present invention, combined with... Figure 1-5 To explain.

[0033] The distributed mobile terminal management system consists of a baseband unit connected to multiple radio frequency (RF) units via optical fiber. Signals are transmitted through the fiber, allowing for the direct superposition of multiple return signals, unlike wireless transmission which requires consideration of different spectrum resource allocations. This system supports a maximum of eight RF units, meaning one baseband unit connects to eight RF units, numbered RRU0 to RRU7.

[0034] First, initialization is performed, initializing the modulation signals of RRU0 to RRU7 and determining if there is an illegal terminal. Illegal terminals are identified by the baseband unit, which captures the terminal's IMSI, IMEI, or MAC address and compares it with a preset whitelist or blacklist. If it is not in the whitelist or is in the blacklist, it is confirmed as an illegal terminal. Only if an illegal terminal is confirmed to exist will the subsequent illegal terminal location process begin. If the baseband unit determines that the terminal is not an illegal terminal, it releases the terminal and waits for a signal from the illegal terminal to be received.

[0035] In distributed mobile terminal management scenarios, customers need to know which RRU (Radio Unit) coverage area an unauthorized mobile terminal is in order to quickly locate the specific target location. Currently, in a distributed management device with one baseband unit connecting eight radio units, the baseband side cannot accurately determine which radio unit detected the unauthorized mobile terminal. Therefore, each RRU is assigned a unique gain modulation frequency, and the frequency of energy value changes obtained by the baseband unit is used to identify which RRU reported the signal, thus identifying the unauthorized mobile terminal within the coverage area of ​​a specific RRU.

[0036] The distributed mobile terminal management system mainly consists of a baseband unit, a radio frequency (RF) unit, and an antenna feeder system. When an unauthorized terminal enters the coverage area of ​​an RRU (RF unit) antenna feeder system, the unauthorized terminal will be controlled by the management system. The baseband unit, through an algorithm, controls the unauthorized terminal to report its energy value at a fixed period of 10ms. After the RF unit of the management system collects the energy value of the unauthorized terminal, it transmits the energy value to the baseband unit. At this time, the uplink gain value of the RF unit is modified by different frequency modulation signals [0,-1,-2,-3,-2,-1]. Thus, the signal energy value received by the baseband unit will also change periodically with different gain modulation frequencies, forming a periodic envelope signal of the energy value. The modulation signal [0,-1,-2,-3,-2,-1] is a periodically changing step signal. The modulation signal 0 indicates that the original gain remains unchanged, -1 reduces the gain by 1dB, and so on.

[0037] Since the illegal terminal, exemplified by a mobile phone, is under control, the mobile phone's transmission power is relatively stable. Therefore, the energy of the mobile phone's transmitted signal can be considered stable for a short period of time. The gain modulation frequency of the gain modulation signal of RRU0~RRU7 is 1Hz~8Hz, and the corresponding relationship is shown in Table 1.

[0038] Table 1: Mapping Table of RRU and Gain Modulation Frequency

[0039]

[0040] In practice, for example, if the energy reporting frequency is 100Hz, and 5.12 seconds of data (512 points) are captured for Fast Fourier Transform (FFT) spectral analysis, then the frequency resolution is... The sampling frequency and acquisition duration are set according to the frequency resolution requirements, based on 100 / 512 = 0.1953125Hz, so that the gain modulation frequency allocated to each RF unit can be distinguished. The index of the point where the maximum value is detected by FFT is used as the reference. for The dominant frequency of the detected energy change is... Furthermore, this frequency value is close to the gain modulation frequency, and the corresponding RRU_ID, i.e., the radio frequency unit number identifier, can be directly indexed based on this frequency value.

[0041] The baseband unit transmits the obtained RRU_ID value to the backend server, which can then visually display the coverage area of ​​the RRU where the illegal mobile terminal is located.

[0042] The following example illustrates the RRU_ID identification process.

[0043] Figure 3 , 4 5 and 6 represent three different recognition processes.

[0044] Figure 3 The simulation demonstrates the location process of an unauthorized terminal in RRU0, with a gain modulation frequency of 1Hz. When an unauthorized terminal enters the coverage area of ​​the RRU0 antenna system, it will be controlled, and the energy received by RRU0 will be modulated with a 1Hz modulation signal and sent to the baseband unit.

[0045] After receiving the data, the baseband unit performs FFT processing to obtain the frequency of energy change and maps it to the corresponding RRU_ID.

[0046] The results above show that the index of the maximum value point... The value is 5, and the maximum point frequency is The value is rounded to approximately 1 Hz, which corresponds to RRU0.

[0047] Figure 4 The simulation demonstrates the location process of an unauthorized terminal in the RRU3, with a gain modulation frequency of 4Hz. When an unauthorized terminal enters the coverage area of ​​the RRU3 antenna system, it will be controlled, and the energy received by the RRU3 will be modulated with a 4Hz signal and sent to the baseband unit.

[0048] After receiving the data, the baseband unit performs FFT processing to obtain the frequency of energy change and maps it to the corresponding RRU_ID.

[0049] The results above show that the index of the maximum value point... The value is 21, and the maximum point frequency is The value is rounded to approximately 4Hz, which corresponds to RRU3.

[0050] Figure 5 The simulation demonstrates the location process of an unauthorized terminal in the RRU7, with a gain modulation frequency of 8Hz. When an unauthorized terminal enters the coverage area of ​​the RRU7 antenna system, it will be controlled, and the energy received by the RRU7 will be modulated with an 8Hz signal and sent to the baseband unit.

[0051] After receiving the data, the baseband unit performs FFT processing to obtain the frequency of energy change and maps it to the corresponding RRU_ID.

[0052] from Figure 5 The results show that the index of the maximum value point The value is 43, and the maximum point frequency is The value is rounded to approximately 8Hz, which corresponds to RRU7.

[0053] RRU_ID is a physical partition space, such as different floors, locations, or partitions A / B / C. After obtaining the RRU_ID of the area where an unauthorized mobile terminal is located, intervention control can be performed on the unauthorized terminal through subsequent processing such as communication blocking, alarms, reporting, and logging. It is particularly suitable for occasions such as anti-cheating in examination rooms and highly confidential meetings.

[0054] In the above method, after identifying an illegal terminal, the baseband unit takes over the terminal's transmission control by implementing management and control measures. This forces the illegal terminal to report its energy value at a fixed period and keeps its transmission power relatively stable, providing a reliable data basis for subsequent accurate identification based on the frequency domain. Based on this, each radio frequency (RF) unit reports the gain-modulated energy value of the illegal terminal to the baseband unit. The baseband unit determines the RF coverage area to which the terminal belongs based on the frequency of change in the periodic envelope of the energy value. Through gain modulation and FFT operations, the terminal's random energy fluctuations and the slow fading effect of the channel are effectively averaged or separated in the frequency domain, avoiding misjudgments caused by energy fluctuation interference, which is easily affected by traditional time-domain energy value comparison methods. This significantly improves the accuracy of illegal terminal identification. Simultaneously, assigning a unique gain modulation frequency to each RF unit is equivalent to giving each RF unit an identifiable "fingerprint tag," enabling the baseband unit to directly determine the source RF unit of the energy change through spectrum analysis. Furthermore, the gain changes of all radio frequency units are performed in parallel, and the baseband unit only needs to perform frequency domain analysis on the energy data collected once to accurately determine the location of the illegal terminal; while the traditional serial gain modulation method requires modifying the gain of each radio frequency unit sequentially and analyzing the reported data multiple times to complete the judgment. Therefore, this invention has higher processing efficiency, faster system response speed, and better identification accuracy.

[0055] Example 2

[0056] Example 2 is a system for identifying the location of unauthorized terminals in a distributed mobile terminal management system, corresponding to Example 1. The distributed mobile terminal management system mainly consists of a baseband unit, a radio frequency (RF) unit, and an antenna feeder system. The baseband unit and each RF unit are connected via optical fiber communication, transmitting signals through the fiber optic cable and allowing for the direct superposition of multiple return signals. This system supports a maximum of 8 RF units, meaning one baseband unit connects to 8 RF units, numbered RRU0 to RRU7.

[0057] When an unauthorized terminal enters the coverage area of ​​a certain RRU (Radio Unit) antenna feeder system, the unauthorized terminal will be controlled by the control system. The baseband unit will control the unauthorized terminal to report its energy value to the radio unit corresponding to its physical area at a fixed period of 10ms through the algorithm. After the radio unit of the control system collects the energy value of the unauthorized terminal, it will transmit the energy value to the baseband unit.

[0058] The baseband unit assigns a unique gain modulation frequency to each radio frequency unit (RF unit). The gain modulation frequencies corresponding to the eight RF units RRU0 to RRU7 are 1Hz to 8Hz, respectively. The baseband unit controls the captured illegal terminal to report its energy value to the RF unit at a fixed period of 10ms. Data is captured for 5.12 seconds, i.e., 512 points, and then subjected to Fast Fourier Transform (FFT) spectral analysis to obtain the energy change spectrum. The index of the point with the maximum value detected by the FFT is also provided. for The dominant frequency of the detected energy change is... Furthermore, this frequency value is close to the gain modulation frequency, and the corresponding RRU_ID, i.e., the radio frequency unit number identifier, can be directly indexed based on this frequency value.

[0059] The RF unit has a built-in gain modulation unit used to modify the uplink gain value of the RF unit by using modulation signals of different frequencies [0,-1,-2,-3,-2,-1]. This causes the signal energy value to periodically change at different gain modulation frequencies, forming a periodic envelope signal of the energy value. The modulation signal [0,-1,-2,-3,-2,-1] is a periodically changing step signal; modulation signal 0 indicates that the original gain remains unchanged, -1 reduces the gain by 1 dB, and so on. The RF unit reports this periodic envelope signal to the baseband unit.

[0060] It also includes a backend server. The baseband unit transmits the obtained RRU_ID value to the backend server, which can then visually display the coverage area of ​​the RRU where the unauthorized mobile terminal is located. After obtaining the RRU_ID of the area where the unauthorized mobile terminal is located, intervention control can be performed on the unauthorized terminal through subsequent processing such as communication blocking, alarms, reporting, and logging. This is particularly suitable for occasions such as anti-cheating in examination rooms and high-security meetings.

[0061] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for locating unauthorized terminals in a distributed terminal management system, applied to a distributed terminal management system in a high-security environment comprising one baseband unit and multiple radio frequency units, characterized in that, The method includes: Each radio frequency unit is assigned a unique gain modulation frequency; The baseband unit controls unauthorized terminals to report their energy values ​​to the radio frequency unit corresponding to their physical area at fixed intervals. Each radio frequency unit modulates the energy value of the received illegal terminal in parallel according to its assigned gain modulation frequency, and reports the modulated energy value to the baseband unit. Specifically, the gain modulation is performed by each radio frequency unit changing the gain value of the energy value through a gain change sequence according to its assigned gain modulation frequency. The gain change sequence is a preset sequence containing multiple step values. Each gain adjustment in the sequence is applied to the energy value of the illegal terminal in sequence, so that the energy value reported to the baseband unit exhibits a periodic envelope change corresponding to the gain change sequence. The baseband unit collects energy value data within a preset time period, performs frequency domain transformation to obtain the energy change spectrum, and identifies the coverage area of ​​the radio frequency unit corresponding to the illegal terminal based on the gain modulation frequency corresponding to the main frequency of energy change in the spectrum.

2. The method according to claim 1, characterized in that, The frequency domain transformation employs the Fast Fourier Transform.

3. The method according to claim 2, characterized in that, When the baseband unit collects energy value data within a preset time period, the sampling frequency and collection time are set according to the frequency resolution requirements, so that the gain modulation frequency allocated to each radio frequency unit can be distinguished.

4. The method according to claim 1, characterized in that, Each radio frequency unit is assigned a corresponding identification number. The baseband unit reports the identification number of the identified radio frequency unit to the backend server to display the coverage area of ​​the radio frequency unit where the illegal terminal is located.

5. The method according to claim 1, characterized in that, The illegal terminal is identified by the baseband unit: the baseband unit determines whether the currently accessed terminal is an illegal terminal, and if not, the terminal is released; If yes, then it is confirmed as an illegal terminal.

6. The method according to claim 5, characterized in that, The baseband unit captures the terminal's IMSI, IMEI, or MAC address and compares it with a preset whitelist or blacklist. If the terminal is not in the whitelist or is in the blacklist, it is confirmed as an illegal terminal.

7. A system for locating unauthorized terminals in a distributed terminal management system, applied in high-security locations, comprising a baseband unit and multiple radio frequency units, wherein the baseband unit and each radio frequency unit are connected via optical fiber communication, characterized in that: The baseband unit is used to: assign a unique gain modulation frequency to each radio frequency unit, control the illegal terminal to report energy values ​​to the radio frequency unit corresponding to its physical area at fixed intervals, collect energy value data within a preset time period, perform frequency domain transformation to obtain the energy change spectrum, and identify the coverage area of ​​the radio frequency unit corresponding to the illegal terminal based on the gain modulation frequency corresponding to the main frequency of energy change in the spectrum. The radio frequency unit is used to: perform gain modulation on the energy value of the received illegal terminal in parallel according to its assigned gain modulation frequency, and report the modulated energy value to the baseband unit; In this process, gain modulation is achieved through a gain modulation unit, which is used to change the gain value of the energy value through a gain change sequence. The gain change sequence is a preset sequence containing multiple step values. Each gain adjustment in the sequence is applied to the energy value of the illegal terminal in sequence, so that the energy value reported to the baseband unit presents a periodic envelope change corresponding to the gain change sequence.

8. The system according to claim 7, characterized in that, It also includes a backend server. The baseband unit assigns a corresponding number to each radio frequency unit. The baseband unit reports the identified radio frequency unit number to the backend server, which then displays the coverage area of ​​the radio frequency unit where the illegal terminal is located.

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