Method and system for evaluating eCall function based on cellular simulation network and GNSS signal simulation

Abstract

The present application relates to the technical field of vehicle testing, and discloses an eCall function evaluation method and system based on a cellular simulation network and GNSS signal simulation, which comprises a darkroom in which a measured piece with an emergency call terminal is placed; a test antenna is arranged in the darkroom; a test management unit, a simulation network subsystem and a GNSS signal simulation subsystem connected between the test management unit and the test antenna are arranged outside the darkroom; the test management unit comprises a control module, an emergency call conversation test module and a public safety answering point simulation module, and is used for completing test parameter configuration, evaluation process control, monitoring signaling interaction and test data collection, and establishing a voice conversation link with the measured piece through the simulation network subsystem, receiving an eCall voice call and MSD data of the measured piece. Through deep integration of the cellular simulation network and the GNSS signal simulation and in combination with a flexible parameter configuration mechanism, the present application realizes comprehensive, accurate and reproducible performance evaluation of the eCall system in a complex communication environment.

Description

Technical Field

[0001] This invention relates to the field of vehicle testing technology, and more specifically to an eCall function evaluation method and system based on cellular analog networks and GNSS signal simulation. Background Technology

[0002] The eCall function of the Automotive Accident Emergency Call System (AECS) serves as the last line of defense in the field of vehicle passive safety, and its importance has gained widespread consensus globally. This system can automatically or manually trigger an emergency call after a collision, establish a voice communication link with the Emergency Service Center (PSAP) through the public mobile communication network, and transmit the Minimum Data Set (MSD), which includes the vehicle's precise location coordinates, vehicle identification number, and timestamp, to the PSAP. This significantly shortens the golden rescue time and substantially reduces the accident casualty rate.

[0003] Traditional AECS terminal testing primarily relies on integrated testing equipment to simulate base station testing. The basic principle is to trigger the eCall (emergency call) function in a vehicle equipped with the AECS terminal under test through actual collisions (e.g., at a crash test track) or simulated collisions (e.g., by triggering collision sensors). The terminal then searches for and registers with the simulated base station system based on the integrated testing equipment, initiates a call to the PSAP, and transmits MSD data. Testers evaluate the eCall function's functionality by monitoring the call and analyzing the MSD data. The main problems with this method are: the network signal simulated by the integrated testing equipment is too idealistic, differing from the uneven network coverage and frequent handovers in real-world environments; it struggles to simulate the interference of complex environments such as urban canyons and tunnels on network signals; and the communication signal differs significantly from real-world scenarios. Summary of the Invention

[0004] The present invention aims to provide an eCall function evaluation method and system based on cellular simulated network and GNSS signal simulation, so as to simulate the complex network signals in real traffic, and solve the technical problems of the existing comprehensive test instrument eCall test method, such as idealized test network, single scenario, and difficulty in reproducing real-world scenarios.

[0005] The basic solution provided by this invention is: an eCall functional evaluation system based on cellular analog network and GNSS signal simulation, which simulates a real complex network environment to conduct comprehensive functional testing on emergency call terminals; the system includes an anechoic chamber for placing the device under test with an emergency call terminal; a test antenna is provided inside the anechoic chamber; a test management unit is provided outside the anechoic chamber, as well as an analog network subsystem and a GNSS signal simulation subsystem connected between the test management unit and the test antenna; The test management unit includes a control module, an emergency call test module, and a public safety answering point simulation module; The control module is used to control the operation of the analog network subsystem and the GNSS signal analog subsystem according to different test parameters to simulate communication signals under different complex traffic and different network state switching in the dark room, control the triggering of the eCall function of the device under test, and collect and process the signaling interaction information and transmitted MSD data between the device under test and the analog network subsystem. The emergency call test module is used to establish a voice call link with the device under test through the simulated network subsystem after the device under test's eCall function is triggered. The Public Safety Answering Point Simulation Module is used to receive eCall voice calls and MSD data from the device under test (DUT) via the simulated network subsystem after the eCall function of the DUT is triggered.

[0006] This invention also provides an eCall function evaluation method based on cellular analog network and GNSS signal simulation. The method utilizes an eCall function evaluation system based on cellular analog network and GNSS signal simulation, and includes: S1, Place the device under test with an emergency call terminal in an anechoic chamber and ensure that its emergency call terminal is within the analog signal coverage area; S2, configure test parameters using the test management unit; S3 controls the operation of the simulation network subsystem and the GNSS signal simulation subsystem according to different test parameters to simulate communication signals under different complex traffic and different network state switching in the dark room; S4. Trigger the eCall function of the device under test according to the configured test parameters. After triggering, the device under test initiates an eCall voice call to the public safety answering point simulation module through the analog network subsystem and transmits MSD data. S5 utilizes the test management unit to collect signaling interaction information and transmitted MSD data between the device under test and the analog network subsystem in real time, and performs result analysis.

[0007] The working principle and advantages of this invention are as follows: Cellular network simulation testing utilizes commercial equipment to construct an end-to-end test environment in the laboratory with the same architecture as a commercial network. This environment is used to verify the functionality, performance, and adaptability of vehicle communication in a real-world network. GNSS signal simulation systems support the generation of multi-mode, multi-constellation satellite navigation signals and support comprehensive testing under various conditions. The laboratory can simulate mobile reception at any location and time, along any route, to verify the functionality and performance of the vehicle's emergency call system.

[0008] This invention achieves comprehensive, accurate, and reproducible performance evaluation of eCall systems in complex communication environments through deep fusion of cellular analog networks and GNSS signal simulation, combined with a flexible parameter configuration mechanism. Its specific advantages include: First, by dynamically configuring cellular network parameters and GNSS signal parameters, various extreme geographical scenarios and network conditions, such as weak tunnel coverage, base station switching, and multipath effects in urban canyons, can be accurately reproduced in a laboratory environment. The parameterized configuration of test scenarios not only ensures that the test conditions are fully controllable, reproducible, and iteratively optimized, but also significantly reduces the test cycle and resource investment, breaking through the limitations of traditional test scenarios that are single, idealized, and difficult to reproduce. More importantly, functions such as automatic switching of multiple network standards, weak signal retry mechanism, and automatic collision triggering of the eCall system can be accurately triggered and verified through parameterized configuration, so as to comprehensively evaluate the reliability of the system in real driving environments. Secondly, the test management unit deeply integrates configuration parameters, real-time data collection, and a comparative analysis mechanism with standard data. It can dynamically capture key performance indicators during the testing process and, based on relevant standard requirements (GB 45672-2025 Appendix A, EN 17184:2024 Figure 5), view signaling interaction and check the accuracy of MSD data. This achieves closed-loop management of the entire process from signal excitation and data collection to result evaluation, expanding the evaluation dimensions to core functions such as call setup success rate, MSD data transmission integrity, impact of positioning accuracy changes, retry mechanism under weak signals, and voice quality assessment. This enables a comprehensive performance evaluation of the eCall function under real-world conditions. Third, in addition to eCall function testing (MSD information and audio voice), the test management unit can also view the entire process of signaling interaction (whether AL-ACK application layer confirmation signaling, etc., is correct); through data comparison and analysis results, it can quickly locate and close the loop of faults, significantly improving test efficiency; Fourth, the anechoic chamber creates a test space that isolates external interference, effectively eliminating the influence of signals from the external environment on the terminal. This improves the accuracy and confidence of the test data, providing quantifiable and comparable objective evidence for the performance of the eCall system under different operating conditions. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the eCall function evaluation system based on cellular analog network and GNSS signal simulation provided in an embodiment of the present invention. Figure 2 This is a flowchart illustrating the eCall function evaluation method based on cellular analog network and GNSS signal simulation provided in an embodiment of the present invention. Detailed Implementation

[0010] The following detailed explanation illustrates the specific implementation methods: The basic implementation examples are as follows: Figure 1As shown: The eCall functional evaluation system based on cellular analog network and GNSS signal simulation simulates a real complex network environment to conduct comprehensive functional testing on the Emergency Call Terminal (AECS). The system includes an anechoic chamber for placing the device under test with the emergency call terminal; a test antenna is installed inside the anechoic chamber; a test management unit is installed outside the anechoic chamber, as well as an analog network subsystem and a GNSS signal simulation subsystem connected between the test management unit and the test antenna. The test management unit includes a control module, an emergency call test module, and a public safety answering point simulation module; The control module is used to control the operation of the analog network subsystem and the GNSS signal analog subsystem according to different test parameters to simulate communication signals under different complex traffic and different network state switching in the dark room, control the triggering of the eCall function of the device under test, and collect and process the signaling interaction information and transmitted MSD data between the device under test and the analog network subsystem. The emergency call test module is used to establish a voice call link with the device under test through the simulated network subsystem after the device under test's eCall function is triggered. The Public Safety Answering Point Simulation Module is used to receive eCall voice calls and MSD data from the device under test (DUT) via the simulated network subsystem after the eCall function of the DUT is triggered.

[0011] Specifically: In this embodiment, the device under test is the vehicle under test; in other embodiments, it can be any carrier with an emergency call terminal.

[0012] The simulated network subsystem includes a simulated core network and simulated base stations, a first programmable attenuator, and a first channel simulator connected to the simulated core network, thereby constructing an end-to-end test network environment consistent with the commercial mobile network architecture. The simulated core network provides network registration, session management, and voice call functions; the simulated base stations provide wireless signal coverage and establish wireless connections with the vehicle under test; the first programmable attenuator enables fast, accurate, and repeatable attenuation control of signal power; and the first channel simulator simulates a real wireless channel environment, including the reproduction of channel characteristics such as delay spread, multipath fading, and dynamic environment simulation.

[0013] In this embodiment, the test management unit is connected to the simulated core network; the simulated core network is connected to the simulated base station through an SFP fiber optic interface to transmit network core control signals and support high-speed signaling interaction; the RF output port of the simulated base station is connected to the input of the first programmable attenuator through an RF feeder, the output of the first programmable attenuator is connected to the input of the first channel simulator, and the output of the first channel simulator is connected to the test antenna through a signal amplifier.

[0014] In this embodiment, the simulated core network uses the IKMME300 model, supporting multiple network standards including LTE / 5G, providing network registration, session management, and voice call (VoLTE) functions, and is compatible with the eCall protocol (EN 17184, GB 45672); the simulated base station uses the DBS5900 model, supporting multiple 3GPP standard spectrums such as 700MHz, 800MHz, and 850MHz for FDD, and supporting industry spectrums such as 400MHz and 1.8GHz for TDD; the first programmable attenuator uses the Keysight J7204B model, with a frequency range of 18GHz, an attenuation range of 0~121dB, a 1dB step, and supports precise and repeatable signal power control; the first channel emulator uses the Keysight F8820A model, with signal bandwidths of 5, 10, 15, 20, 25, 30, 40, 50, 60, 80, 90, 100, 200, and 400MHz, with a maximum signal bandwidth of 400MHz, supporting 5G... The NR carrier aggregation (CA) scheme can reach up to 1.2GHz, with 5G NR frequency range 1 and frequency range 2; the RF feeder adopts the LU7-C1862-10000 model product, with a characteristic impedance of 50Ω, operating frequency band of 0~6GHz, and attenuation ≤0.5dB / m@2GHz.

[0015] The GNSS signal simulation subsystem includes a GNSS signal simulator, a second programmable attenuator connected to the GNSS signal simulator, and a second channel simulator connected to the second programmable attenuator. It is used to simulate various complex scenarios and precise geographical locations at different latitudes, longitudes, and altitudes. The GNSS signal simulator generates and radiates simulated GNSS signals to simulate the arbitrary geographical location, motion state, and satellite signal environment of the vehicle under test. The second programmable attenuator and the second channel simulator are identical to the first programmable attenuator and the first channel simulator.

[0016] In this embodiment, the test management unit is connected to the GNSS signal simulator; the RF output port of the GNSS signal simulator is connected to the input of the second programmable attenuator via an RF feeder, the output of the second programmable attenuator is connected to the input of the second channel simulator, and the output of the second channel simulator is directly connected to the test antenna via an RF feeder.

[0017] In this embodiment, the GNSS signal simulator supports multiple satellite navigation systems, including GPS, BeiDou, GLONASS, and Galileo, to simulate the latitude, longitude, and altitude of any location. The Spirent GSS7000 model can be used, with a positioning accuracy of ±0.1m. The selection of the second programmable attenuator and the second channel simulator is the same as that of the first programmable attenuator and the first channel simulator.

[0018] The test management unit can be a mobile workstation computer. The control module integrates test software within the test management unit to perform corresponding tasks. The test management unit (mobile workstation computer) is connected to the analog network subsystem (Ethernet port of the analog core network) and the GNSS signal simulation subsystem (LAN port of the GNSS signal simulator) via Cat6A network cables (unshielded twisted pair), adhering to the TCP / IP protocol, and is used at least for configuring test parameters, issuing start commands, and transmitting data back. In this embodiment, the mobile workstation computer uses a Core i9-13900H processor, 32GB of memory, 1TB SSD storage, and supports multiple network ports to meet the needs of real-time data acquisition and analysis; the Cat6A network cables (unshielded twisted pair) support Gigabit Ethernet transmission with a bandwidth of 250MHz and conform to the Cat.6A standard, used for wired communication between the test management unit and each subsystem.

[0019] The control module is used to configure test parameters, including: GNSS signal simulation subsystem operating parameters (GNSS location information (latitude, longitude, altitude), trajectory, signal strength, and number of visible satellites); simulation network subsystem operating parameters (network type, signal strength, cell ID, handover conditions, network anomaly conditions, traffic scenario channels, etc.); and expected eCall triggering conditions (automatic or manual triggering). It is also used to control the test process, issuing start and stop commands, i.e., controlling the operation of the simulation network subsystem and GNSS signal simulation subsystem based on the configured test parameters to output simulated communication signals under various traffic conditions and different network state transitions to the anechoic chamber via the test antenna. Furthermore, it is used to monitor network signaling, specifically monitoring and recording all signaling interactions between the vehicle under test and the simulated core network, including call setup, bearer setup, and MSD data transmission processes. Finally, it is used to collect test data, specifically MSD data fed back by the simulation network subsystem.

[0020] The emergency call test module can work with the analog network subsystem and test management unit to establish a voice call link with the vehicle under test after the emergency call terminal eCall function of the device under test is triggered. It is used for voice quality evaluation after the emergency call is established. The YT4211 model product can be used, which supports voice link establishment and call, and is compatible with AMR-NB / AMR-WB encoding formats.

[0021] The public safety answering point simulation module is used to receive eCall voice calls and MSD data from the device under test (DUT) via the simulation network subsystem after the eCall function of the DUT's emergency call terminal is triggered.

[0022] The test antenna can be the FPA-SET model, with a frequency of 0.80-6.00GHz, a gain of 4.5 dBiC Nom, and a right-hand circular polarization, suitable for wireless signal transmission and reception in anechoic rooms.

[0023] In this embodiment, the dimensions of the anechoic chamber are selected as 13.1m long x 10.9m wide x 7.4m high, which meets the requirements for placement of the entire vehicle. At the same time, the shielding effectiveness is (14k)>80dB and (100kHz-18GHz)>100dB, with no interference from external communication / positioning signals.

[0024] like Figure 2 As shown, this embodiment also provides an eCall function evaluation method based on cellular analog network and GNSS signal simulation. Utilizing an eCall function evaluation system based on cellular analog network and GNSS signal simulation, the method includes: S1, Place the device under test with an emergency call terminal in an anechoic chamber and ensure that its emergency call terminal is within the analog signal coverage area; S2, configure test parameters using the test management unit; S3 controls the operation of the simulation network subsystem and the GNSS signal simulation subsystem according to different test parameters to simulate communication signals under different complex traffic and different network state switching in the dark room; S4. Trigger the eCall function of the device under test according to the configured test parameters. After triggering, the device under test initiates an eCall voice call to the public safety answering point simulation module through the analog network subsystem and transmits MSD data. S5 utilizes the test management unit to collect signaling interaction information and transmitted MSD data between the device under test and the analog network subsystem in real time, and performs result analysis.

[0025] Specifically: During the construction of the S1 system, the analog signal coverage area, such as... Figure 1 The dashed line inside the dark room indicates the wireless signal coverage area of ​​the simulated base station (signal coverage radius ≥ 3m inside the dark room) and the radiation range of the GNSS signal simulator.

[0026] The S2 test configuration includes GNSS signal simulation subsystem operating parameters, simulation network subsystem operating parameters, and the expected eCall triggering method. By configuring these parameters, it can simulate communication signals under various complex traffic conditions in reality (such as urban roads, urban overpasses, underground parking garages, densely populated urban areas, borders, tunnels, mountain roads, urban canyons, riverside roads, highways, and rural roads), achieving realistic indoor simulation and resolving the network idealization issue in existing eCall testing solutions. It can simulate communication signals during different network state transitions (such as cell handover, reselection, and redirection) during movement, enabling laboratory reproduction of real-world network state transitions. This addresses the previous solution's inability to test eCall functionality under changing communication mobility conditions, and further verifies the robustness of eCall functionality in scenarios such as network coverage edges and handover. It can accurately reproduce complex signal interference (such as multipath reflection in urban canyons, signal blockage in tunnels, and weak signal attenuation in underground parking garages), simulate signal delay of 0-500ms, multipath error of 0-10m, and reference signal receiving power as low as -110dBm, perfectly matching the real application environment of eCall function.

[0027] Specifically, different test scenarios are formed by configuring different test parameters. Individual applications of these test scenarios simulate single traffic communication scenarios, while combined applications simulate complex traffic communication scenarios by switching between multiple test scenarios. For example: (1) For abnormal scenario testing, such as "eCall triggered after GNSS signal loss", the GNSS signal can be configured to be interrupted 2 seconds before the eCall function is triggered in step S2. In step S5, it is verified whether the MSD data contains the "positioning invalid" flag or whether the last known valid position is used, thereby verifying the response logic of the AECS terminal of the vehicle under test in the case of positioning failure.

[0028] (2) For testing specific complex real-world traffic scenarios, such as testing the automatic eCall function of a certain vehicle model in an "urban canyon" scenario, the following steps can be performed: In the simulation network subsystem, the traffic scenario is set to an urban canyon, and a higher signal delay and multipath error are added to simulate the reflection and obstruction of signals by tall buildings. The reference signal receiving power is configured to -105dBm to simulate general signal strength; the eCall trigger condition is configured as automatic collision trigger. After completing the subsequent signal injection and network registration, test execution and data acquisition, the results are analyzed in step S5 to determine whether they meet expectations.

[0029] (3) For testing different network scenarios, such as testing the eCall function of a certain vehicle model under network switching scenarios, the following steps can be performed in step S2: Set up a large-signal simulated base station and a small-signal simulated base station in the simulated network subsystem; configure the device under test to register with the network through the large-signal simulated base station; configure the large-signal base station signal to decrease and the small-signal base station signal to increase to simulate network switching; and configure the eCall function to be triggered during the switching process. After completing the subsequent signal injection and network registration, test execution, and data acquisition, analyze in step S5 whether the results meet expectations.

[0030] (4) For combined applications of multiple test scenarios, such as testing the automatic eCall function of a certain vehicle model under multiple traffic scenario changes during long-distance driving, multiple scenarios can be selected and time-series configured in step S2: for example, in the simulated network subsystem, traffic scenarios are set as a certain city canyon, border line, tunnel, and mountain road based on the road conditions during long-distance driving. Corresponding operating parameters are configured for each scenario, and scenario sorting and start-up time settings are performed. The eCall trigger condition is configured as automatic triggering when the scenario changes. After completing the subsequent signal injection and network registration, test execution and data collection, the results are analyzed in S5 to see if they meet expectations.

[0031] In the S3 signal injection and network registration process, the test management unit sends start commands to each subsystem to control its operation. This includes the GNSS signal simulation subsystem starting to radiate the configured satellite signals, the simulation network subsystem completing network initialization, and entering standby mode. After the vehicle under test is powered on, it can receive satellite signals and complete network registration through the simulation network subsystem.

[0032] During S4 eCall triggering and execution, automatic triggering includes sending messages, while manual triggering includes button operation. After the emergency call terminal eCall function of the vehicle under test is triggered, the emergency call terminal receives simulated location information provided by the GNSS signal simulation subsystem, performs positioning calculations, and outputs vehicle location information. The emergency call terminal (AECS) establishes a wireless connection with the simulated base station through the wireless air interface (compliant with 3GPP communication protocols), completes network registration through the simulated core network, and initiates an eCall voice call to the public safety answering point simulation module. Before establishing the call or during the call, it transmits MSD data including vehicle location information.

[0033] In S5 data acquisition, signaling interaction information includes voice call data, signaling logs (signaling process information such as network registration, attachment, and call establishment of the vehicle under test), and voice call link establishment status.

[0034] In the S5 results analysis, the analysis includes comparing the collected MSD data with the configured test parameters, comparing the collected signaling interaction information with the signaling interaction standard information, and outputting the judgment results. The judgment results include: whether the eCall call was successfully established; whether the MSD was successfully transmitted and the content was accurate (refer to Appendix A of GB 45672-2025 standard).

[0035] Based on the identified problems, troubleshooting begins with checking whether there are issues with the signaling interaction between the device under test (DUT) and the public safety response service point (PSAP). (Refer to the signaling interaction requirements in Figure 5 of EN 17184:2024, such as the application layer acknowledgment (AL-ACK) requirement (clause 7.6) and PSAP request for a new MSD (clause 7.7)). Next, check whether there are any functional problems with the DUT (e.g., whether the eCall trigger type is normal, whether the eCall call status is normal, whether the eCall system can successfully transmit the MSD to the PSAP test point via the mobile network, and whether the MSD information is normal).

[0036] The eCall function evaluation method and system based on cellular analog network and GNSS signal simulation provided in this embodiment can simulate communication and positioning signals in complex real traffic scenarios in a dark room, shielding external communication and positioning signal interference, realizing laboratory evaluation of the eCall function of Emergency Call Terminal (AECS), effectively identifying its eCall function problems and proposing rectification solutions.

[0037] The above descriptions are merely embodiments of the present invention. Commonly known structures and characteristics of the solutions are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are aware of all existing technologies in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, under the guidance of this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. An eCall function evaluation system based on cellular analog network and GNSS signal simulation, characterized in that, The system simulates a real, complex network environment to conduct comprehensive functional testing on emergency call terminals. It includes an anechoic chamber for housing the device under test (DUT) containing the emergency call terminal, and a test antenna is installed within the chamber. The anechoic chamber is equipped with a test management unit, as well as an analog network subsystem and a GNSS signal simulation subsystem connected between the test management unit and the test antenna; The test management unit includes a control module, an emergency call test module, and a public safety answering point simulation module; The control module is used to control the operation of the analog network subsystem and the GNSS signal analog subsystem according to different test parameters to simulate communication signals under different complex traffic and different network state switching in the dark room, control the triggering of the eCall function of the device under test, and collect and process the signaling interaction information and transmitted MSD data between the device under test and the analog network subsystem. The emergency call test module is used to establish a voice call link with the device under test through the simulated network subsystem after the device under test's eCall function is triggered. The Public Safety Answering Point Simulation Module is used to receive eCall voice calls and MSD data from the device under test (DUT) via the simulated network subsystem after the eCall function of the DUT is triggered.

2. The eCall function evaluation system based on cellular analog network and GNSS signal simulation according to claim 1, characterized in that, The analog network subsystem includes an analog core network connected to the test management unit, an analog base station connected to the analog core network, a first programmable attenuator connected to the analog base station, and a first channel simulator connected to the first programmable attenuator. Finally, the first channel simulator is connected to the test antenna via a signal amplifier.

3. The eCall function evaluation system based on cellular analog network and GNSS signal simulation according to claim 2, characterized in that, Analog base stations include large-signal analog base stations and small-signal analog base stations.

4. The eCall function evaluation system based on cellular analog network and GNSS signal simulation according to claim 1, characterized in that, The GNSS signal simulation subsystem includes a GNSS signal simulator connected to the test management unit, a second programmable attenuator connected to the GNSS signal simulator, and a second channel simulator connected to the second programmable attenuator. Finally, the second channel simulator is directly connected to the test antenna.

5. A method for evaluating eCall functionality based on cellular analog networks and GNSS signal simulation, characterized in that: The eCall function evaluation system based on cellular analog network and GNSS signal simulation as described in any one of claims 1-4; the method includes: S1, Place the device under test with an emergency call terminal in an anechoic chamber and ensure that its emergency call terminal is within the analog signal coverage area; S2, configure test parameters using the test management unit; S3 controls the operation of the simulation network subsystem and the GNSS signal simulation subsystem according to different test parameters to simulate communication signals under different complex traffic and different network state switching in the dark room; S4. Trigger the eCall function of the device under test according to the configured test parameters. After triggering, the device under test initiates an eCall voice call to the public safety answering point simulation module through the analog network subsystem and transmits MSD data. S5 utilizes the test management unit to collect signaling interaction information and transmitted MSD data between the device under test and the analog network subsystem in real time, and performs result analysis.

6. The eCall function evaluation method based on cellular analog network and GNSS signal simulation according to claim 5, characterized in that, In S2, the configured test parameters include GNSS location information, motion trajectory, signal strength and number of visible satellites of the GNSS signal simulation subsystem, network type, signal strength, cell ID, handover conditions and traffic scenario channel of the simulation network subsystem, and expected eCall triggering conditions.

7. The eCall function evaluation method based on cellular analog network and GNSS signal simulation according to claim 5, characterized in that, In S2, for the eCall function in the test network handover scenario, a large signal simulated base station and a small signal simulated base station are set up in the simulated network subsystem. The device under test is configured to register with the network through the large signal simulated base station. The large signal base station signal is configured to decrease and the small signal base station signal is configured to increase to simulate network handover. The eCall function is also configured to be triggered during the handover process.

8. The eCall function evaluation method based on cellular analog network and GNSS signal simulation according to claim 5, characterized in that, In S3, the test management unit sends start commands to each subsystem to control its operation, including the GNSS signal simulation subsystem starting to radiate the configured satellite signals, and the simulation network subsystem completing network initialization and entering standby mode. After being powered on, the device under test can receive satellite signals and complete network registration through the analog network subsystem.

9. The eCall function evaluation method based on cellular analog network and GNSS signal simulation according to claim 5, characterized in that, In S4, after the eCall function is triggered, the emergency call terminal receives the simulated location information provided by the GNSS signal simulation subsystem and performs positioning calculations to output vehicle location information. It also establishes a wireless connection with the simulation network subsystem, initiates an eCall voice call to the public safety answering point simulation module, and transmits MSD data, including vehicle location information, before or during the call.

10. The eCall function evaluation method based on cellular analog network and GNSS signal simulation according to claim 5, characterized in that, In S5, the result analysis includes comparing the collected MSD data with the configured test parameters, comparing the collected signaling interaction information with the signaling interaction standard information, and outputting the judgment result. The determination results include whether the eCall call was successfully established and whether the MSD data was successfully transmitted and its content was accurate.

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