A gateway and switching method for low-orbit satellite IoT-NTN and 4G cellular network fusion communication

Abstract

The application discloses a gateway and a switching method for low-orbit satellite IoT-NTN and 4G cellular network fusion communication, and the gateway comprises a main control module, a 4G communication module, a low-orbit satellite IoT-NTN communication module, a power management module and the like. The 4G module and the satellite module are independent of each other and are uniformly scheduled by the main control module. In the switching mode, the main control module constructs an adaptive switching decision model based on a double-link packet loss rate: when the 4G network packet loss rate exceeds a first threshold value, and the difference between the 4G and satellite network packet loss rates in a plurality of continuous detection periods is greater than a second threshold value, and the minimum switching interval is met, the satellite network is switched to; when the satellite network is working, if the 4G network quality is restored and the minimum network staying time is met, the 4G network is switched back. Through the double-link cooperation and the intelligent switching mechanism based on the packet loss rate difference and the time constraint, the application solves the problem that the communication continuity and the cost control are difficult to be considered in the Internet of Things scene, and realizes the low-power, low-frequency and high-reliable dual-mode communication.

Description

Technical Field

[0001] This invention relates to the fields of wireless communication, satellite communication and Internet of Things (IoT) technology, and specifically to a dual-mode switching gateway and switching method that integrates low-Earth orbit satellite IoT-NTN (Internet of Things-Non-Terrestrial Networks) and 4G cellular network. Background Technology

[0002] Existing wireless communication solutions struggle to simultaneously ensure continuous reliability of communication links and control communication costs over the long term in remote areas and special scenarios. A single 4G cellular network can lead to communication interruptions in areas with weak signals or no coverage; while satellite communication can achieve full coverage, it suffers from narrow bandwidth and high costs; existing dual-mode satellite and terrestrial network devices are mostly designed based on high-orbit broadband satellites, resulting in high power consumption and cost, and lacking intelligent switching mechanisms between low-orbit narrowband satellite IoT-NTN and cellular networks.

[0003] Therefore, how to achieve intelligent and adaptive switching between 4G cellular networks and low-orbit satellite IoT-NTN networks in IoT low-power, small data packet transmission scenarios has become an urgent technical problem to be solved.

[0004] Currently, achieving continuous access to communication links in remote areas and special operating environments remains a technical challenge in the fields of wireless communication and the Internet of Things (IoT). Due to the limited coverage of terrestrial mobile communication base stations, cellular networks suffer from weak signals, numerous blind spots, or even no coverage in some areas, making it difficult to guarantee the continuous online communication needs of IoT terminal devices.

[0005] To address the above problems, existing technologies mainly offer the following three types of solutions, but all of them have significant shortcomings: (a) Single 4G cellular network communication solution This solution relies on terrestrial mobile communication networks for data transmission, which can meet communication needs in areas with good signal coverage. However, in environments with weak signals, no coverage, or fluctuating networks, it can directly lead to communication interruptions. IoT terminals cannot reliably transmit data, and the management platform loses its ability to continuously monitor remote devices, making it difficult to meet the requirements for communication continuity in unattended scenarios.

[0006] (ii) Single satellite communication scheme This solution achieves full coverage via satellite networks, such as CN202320075329.9, which can solve the problem of blind spots in terrestrial networks. However, satellite communication generally suffers from narrow bandwidth and high costs, which significantly increases operating costs for the large number of small data packets and long-term online communication needs in IoT scenarios, hindering large-scale applications.

[0007] (III) Existing "Satellite + Terrestrial Network" Dual-Mode Communication Equipment Solution Existing dual-mode communication devices are mostly designed based on high-orbit satellite broadband communication architectures, such as CN201920824301.4. They are mainly designed for high-bandwidth internet access and satellite phone needs, and suffer from high power consumption and high hardware costs, which are incompatible with the low-power, small data packet communication characteristics of the Internet of Things (IoT). Furthermore, these devices lack dedicated optimization designs for the communication between low-orbit narrowband satellite IoT-NTN and cellular networks, especially lacking intelligent handover control mechanisms based on link quality, making it difficult to achieve low-frequency, low-jitter, and low-cost automatic handover between 4G networks and low-orbit satellite networks.

[0008] Therefore, existing technologies are not yet able to simultaneously achieve continuous reliability of communication links and effective control of communication costs in IoT scenarios with low power consumption and small data packet transmission. Summary of the Invention

[0009] The purpose of this invention is to overcome the technical defects of existing technologies, such as the difficulty in ensuring communication continuity with a single 4G cellular network, the high operating cost of a single satellite communication, and the incompatibility between existing dual-mode communication devices and the low power consumption and small data packet transmission characteristics of the Internet of Things, as well as the lack of intelligent switching mechanisms. This invention provides a gateway and switching method for the converged communication of low-orbit satellite IoT-NTN and 4G cellular networks.

[0010] To achieve the above objectives, the present invention provides a gateway, comprising a housing, an antenna assembly, a core circuit board, and an industrial interface assembly. The core circuit board integrates: a main control module; a 4G communication module; a low-Earth orbit satellite IoT-NTN communication module; an Ethernet communication interface; an industrial serial communication module; a power management module; and a level conversion module. The 4G communication module and the low-Earth orbit satellite IoT-NTN communication module are independently configured, each with its own independent antenna and SIM card circuit. They share only the power management module, with the main control module handling unified communication control and data scheduling.

[0011] The main control module establishes serial communication and power-on / wake-up control connections with the 4G communication module and the low-orbit satellite IoT-NTN communication module respectively through a level conversion module; the main control module connects to the Ethernet communication interface through the RMII interface to realize Ethernet data communication; the main control module connects to the industrial serial communication module for data interaction with external industrial equipment; the power management module adopts a wide voltage input, and outputs multiple stable voltages to power each functional module through multi-stage DC-DC step-down and LDO regulation; an electrostatic discharge protection circuit is set at the SIM card interface of the 4G communication module and the low-orbit satellite IoT-NTN communication module.

[0012] Furthermore, the main control module establishes serial communication and power-on / wake-up control connections with the 4G communication module and the low-orbit satellite IoT-NTN communication module respectively through a level conversion circuit; the main control module connects to the Ethernet PHY chip through the RMII interface; the main control module connects to multiple RS485 communication interfaces. The circuit board adopts a separate design for digital ground and RF ground, and achieves single-point common ground through ferrite beads; an electrostatic discharge protection circuit is set at the SIM card interface; an impedance matching network and a filtering network are set in the RF path.

[0013] Furthermore, the power management module adopts a hierarchical power supply architecture, including: the first stage wide-voltage DC input is synchronously stepped down to an intermediate bus voltage; the second stage further steps down the bus voltage to obtain a second-stage stable voltage; and the third stage outputs the operating voltage of the core digital circuit through a linear voltage regulator chip.

[0014] A switching method for a converged communication gateway based on low-Earth orbit satellite IoT-NTN and 4G cellular network includes: Step A: By default, 4G cellular network is the preferred communication link, and the main control module calculates the 4G network packet loss rate PLR4G in real time; Step B: When PLR4G exceeds the first threshold, the IoT-NTN network detection mechanism is activated to calculate the IoT-NTN network packet loss rate PLR_NTN at fixed intervals; Step C: When multiple consecutive detection cycles satisfy PLR4G When PLR_NTN > the second threshold and the time interval between the current time and the last handover is greater than the minimum handover interval, the main control module controls the gateway to switch from the 4G network to the IoT-NTN network. Step D: Periodically probe the 4G network quality during IoT-NTN network operation; Step E: When PLR4G is continuously lower than PLR_NTN and lower than the first threshold for multiple consecutive detection cycles, and the IoT-NTN network camping time reaches the minimum camping time, the main control module controls the gateway to switch back from the IoT-NTN network to the 4G network.

[0015] A computer-readable storage medium having a computer program stored thereon that, when executed by a processor, implements the switching method of the present invention.

[0016] This invention constructs a dual-mode communication hardware architecture adapted to the characteristics of IoT applications and designs an adaptive switching control method based on link quality assessment to achieve intelligent, low-frequency, and low-jitter automatic switching between 4G cellular networks and low-orbit satellite IoT-NTN networks. While ensuring the continuous and reliable communication link, it prioritizes the use of low-cost 4G networks for data transmission, thereby effectively reducing the frequency of satellite communication usage and long-term operating costs.

[0017] This invention further solves the problems of high power consumption, poor adaptability, and frequent disconnections caused by simple switching strategies in existing dual-mode devices, enabling the communication system to meet the application requirements of uninterrupted, low-cost, and highly reliable communication in remote areas and special operating scenarios.

[0018] Compared with existing technologies, the low-orbit satellite IoT-NTN and 4G cellular network converged communication gateway and handover method proposed in this invention have the following advantages: 1. Simultaneously resolve the technical contradiction between maintaining communication continuity and balancing communication costs. By constructing a dual-link collaborative communication mechanism between 4G cellular networks and low-orbit satellite IoT-NTN networks, low-cost cellular network communication is prioritized in areas with 4G signals, and automatically switched to satellite networks when there is no 4G coverage or network quality deteriorates. This avoids both the communication interruption problem caused by relying solely on 4G networks and the high cost associated with long-term use of satellite communication.

[0019] 2. Significantly improves network handover stability and avoids frequent jitter. By using a decision model based on the difference in packet loss rate, and combining the dual constraints of minimum handover interval and minimum network dwell time, the frequent handover phenomenon caused by instantaneous network fluctuations is effectively suppressed, so that the communication link remains stable in complex network environments.

[0020] 3. Ensure the continuity and integrity of data transmission during the handover process. During network switching, the main control module performs data caching and sequential forwarding to avoid data interruption and loss issues caused by link switching in existing devices, thus meeting the requirements of IoT monitoring data for reliable transmission.

[0021] 4. Highly adaptable to the low power consumption and small data packet communication characteristics of the Internet of Things Through a dedicated dual-mode hardware architecture design and a layered power supply structure, the overall power consumption of the device is significantly lower than that of existing dual-mode devices based on high-orbit satellite broadband architecture. At the same time, both communication links are adapted to the narrowband transmission requirements of the Internet of Things, improving the long-term economic efficiency of the system.

[0022] 5. Enhance anti-interference capabilities and operational reliability in harsh industrial environments. By separating digital ground and radio frequency ground, using a single-point common ground structure, radio frequency matching network, multi-level power supply filtering and interface electrostatic protection circuit, the communication stability of the equipment in complex electromagnetic environments is improved, and the probability of abnormal restart and communication interruption is reduced.

[0023] 6. Enhance the system's fault tolerance and maintainability. The dual communication modules adopt independent circuits, independent antennas, and independent SIM cards, sharing only the power supply module. This achieves module-level fault isolation, facilitates maintenance and upgrades, and improves the overall reliability of the system.

[0024] 7. Simplify deployment and peripheral device integration in industrial settings. By integrating Ethernet interfaces and multiple RS485 industrial interfaces, it can directly connect to various industrial IoT terminal devices without the need for additional adapters, reducing deployment complexity and construction costs. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the physical appearance and internal structure of the gateway. It includes: 1. Fiberglass amplifying antenna; 2. Sealing ring; 3. Circuit board; 4. Aviation connector female; 5. Aluminum alloy shell.

[0026] Figure 2 This is the circuit schematic of the power supply system. After three-stage conversion, it outputs stable voltages of 12V, 5V, and 3.3V to power each module, and also supports USB power supply.

[0027] Figure 3 This is the schematic diagram of the minimum system and peripheral circuits of the main control chip. The diagram shows an STM32F407, but other MCUs that support Ethernet MAC can also be used.

[0028] Figure 4 This is the schematic diagram of the core circuit of the BG95-S5 low-orbit satellite IoT-NTN communication module.

[0029] Figure 5 The schematic diagram of the circuit supporting the BG95-S5 satellite communication module includes SIM card circuit, dual antenna circuit, power supply circuit (shared with EC200), indicator light circuit, etc.

[0030] Figure 6 This diagram shows the level conversion and control circuit of the MCU and BG95-S5 module, the serial communication voltage conversion circuit between the MCU and BG95, and the MCU control circuit for BG95 power-on and wake-up.

[0031] Figure 7 This is a schematic diagram of the core circuit and dual-antenna circuit of the EC200 4G communication module.

[0032] Figure 8 The schematic diagram of the supporting circuit and level conversion circuit for the EC200 4G communication module includes the SIM card circuit, indicator circuit, serial communication voltage conversion circuit between MCU and EC200, and MCU control circuit for EC200 power-on and wake-up control, etc.

[0033] Figure 9 This is a schematic diagram of an Ethernet circuit, including the network port transformer and its connecting circuit, and the Ethernet PHY chip circuit.

[0034] Figure 10 This is a schematic diagram of a dual RS485 communication interface circuit. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0036] like Figure 1 As shown, a fiberglass amplifying antenna 1 and an aviation plug female 4 are respectively installed at both ends of the aluminum alloy shell 5 along its length; a circuit board 3 is installed inside the aluminum alloy shell 5; and a sealing ring 2 is installed between the circuit board 3 and the shell of the aluminum alloy shell 5.

[0037] I. Gateway Overall Structure Technical Solution This invention provides a dual-mode gateway for converged communication between low-orbit satellite IoT-NTN and 4G cellular network. The gateway includes a shell, antenna assembly, core circuit board and industrial interface assembly.

[0038] The core circuit board integrates the following modules: main control module; 4G communication module; low-orbit satellite IoT-NTN communication module; Ethernet communication interface; industrial serial communication module; power management module; and level conversion module.

[0039] The 4G communication module and the low-orbit satellite IoT-NTN communication module are set up independently, each with its own independent antenna and SIM card circuit. They only share the power management module, and the main control module performs unified communication control and data scheduling.

[0040] II. Technical Solutions for Key Circuit Connections The main control module establishes serial communication and power-on / wake-up control connections with the 4G communication module and the low-orbit satellite IoT-NTN communication module respectively through a level conversion circuit; The main control module connects to the Ethernet communication interface (Ethernet PHY chip) via the RMII interface to achieve Ethernet data communication; The main control module is connected to an industrial serial communication module (multi-channel RS485 communication interface) for data interaction with external industrial equipment; The power management module adopts a wide voltage input, and after multi-stage DC-DC step-down and LDO regulation, it outputs multiple stable voltages to power each functional module. The circuit board adopts a design that separates digital ground and radio frequency ground, and uses ferrite beads to achieve a single-point common ground. An electrostatic discharge protection circuit is installed at the SIM card interface between the 4G communication module and the low-orbit satellite IoT-NTN communication module; Impedance matching networks and filtering networks are set up in the RF path to improve signal transmission stability.

[0041] III. Layered Power Supply Technology Solution The power management module adopts a layered power supply architecture, including: First stage: Wide voltage DC input is synchronously stepped down and converted to intermediate bus voltage; Second stage: The intermediate bus voltage is further stepped down to obtain a second stage stable voltage, which serves as the main load power supply voltage and supports external backup power supply access; The third stage: The operating voltage of the core digital circuit is output through a linear voltage regulator chip to reduce the impact of power supply ripple on signal integrity.

[0042] Meanwhile, filter circuits and energy storage capacitors are set at the power input terminal, module power supply terminal, and RF module power supply terminal to prevent voltage drop during communication module operation from causing restart or communication interruption.

[0043] IV. Network Intelligent Handover Control Method and Technical Solution The main control module constructs an adaptive handover decision model based on the dual-link packet loss rate to realize intelligent, low-frequency automatic handover between the 4G network and the low-orbit satellite IoT-NTN network.

[0044] (a) 4G network to IoT-NTN network switching mechanism The main control module calculates the 4G network packet loss rate (PLR4G) in real time. When the PLR4G exceeds the first threshold, the IoT-NTN network detection mechanism is activated; The packet loss rate PLR_NTN of the IoT-NTN network is calculated at a fixed period. When multiple consecutive detection cycles satisfy: PLR4G When PLR_NTN > the second threshold and the time interval between the current time and the last handover is greater than the minimum handover interval, the network will automatically switch to the IoT-NTN network.

[0045] (ii) Mechanism for switching back from IoT-NTN network to 4G network Periodically probe the 4G network quality during IoT-NTN network operation; When multiple consecutive detection cycles satisfy: When the PLR4G value remains below PLR_NTN and below the first threshold, and the IoT-NTN network dwell time reaches the minimum dwell time, the network will automatically switch back to the 4G network.

[0046] (III) Switching Inhibition Mechanisms Settings: First threshold (link availability threshold); Second threshold (link difference threshold); Minimum handover interval; Minimum network dwell time; Used to suppress frequent handovers caused by instantaneous network fluctuations and ensure communication stability.

[0047] This embodiment discloses a 4G / IoT-NTN dual-mode smart gateway based on STM32F407, which can realize automatic and smooth switching between 4G network and low-Earth orbit satellite IoT-NTN network. It is suitable for wide-area IoT, low-Earth orbit satellite access and industrial remote communication scenarios. The gateway is equipped with an aluminum alloy IP67 protection-rated shell, which has high stability, strong anti-interference, high protection and industrial-grade adaptability. It can be directly adapted to unattended scenarios with no ground network coverage or weak signal, such as desert and Gobi monitoring, intelligent management of photovoltaic power stations, ocean navigation and inland waterways. The specific hardware selection, circuit design and core logic are as follows: Main control chip: STM32F407VGT6 is used. This chip has a built-in Ethernet MAC controller, a high-performance ARM Cortex-M4 core, and supports a rich set of peripheral interfaces such as UART, RS485, and RMII. It can stably realize dual network control, data processing and peripheral management functions, and meet the core control requirements of the gateway. Its minimum system and peripheral circuit are shown in Figure 3. The main control chip performs full-function control of the BG95-S5 satellite communication module and EC200 4G communication module by sending standard AT command set.

[0048] Communication Modules: The 4G network chip uses the EC200 series LTE module, which supports high-speed 4G data transmission and is compatible with multi-band communication. It serves as the main communication link for the gateway, and its core circuit and dual-antenna circuit are shown in Figure 7. The satellite communication chip uses the BG95-S5 low-orbit satellite communication module, which operates at a 1.8V logic level. It is dedicated to enabling IoT-NTN network access and serves as a backup link for the 4G network, ensuring communication continuity in extreme scenarios without a terrestrial network. Its core circuit is shown in Figure 4. Both communication modules are compatible with the standard AT command set and can receive AT commands issued by the main control chip and provide feedback on working status, link quality, and other data, realizing standardized communication interaction between the module and the main control chip.

[0049] Ethernet-related components: The LAN8720 is used as the external PHY chip, which connects to the STM32F407's built-in MAC controller via the RMII interface to achieve 10 / 100M Ethernet communication. The network transformer is an HR911105A (RJ45 integrated type), which integrates the network transformer and LED indicators, simplifying the circuit design while achieving signal isolation and impedance matching to ensure stable network communication. The overall circuit is shown in Figure 9. The gateway's network communication interface connects to external devices via an industrial aviation connector, adapting to the external cabling requirements of industrial scenarios.

[0050] Antenna: Two 10dBi fiberglass high-gain antennas are used, corresponding to the 4G communication module and the BG95-S5 satellite module respectively, to improve signal reception capability and adapt to complex communication scenarios such as outdoor and remote areas. The RF connection ends of the antenna and the module are shielded against interference. The antenna is encased in an aluminum alloy IP67 shell for external deployment, balancing protection and signal reception efficiency.

[0051] Level conversion chip: The TXS0104 level conversion chip is used, which supports conversion between multiple voltage nodes such as 1.8V and 3.3V. Alternatively, a transistor conversion circuit as shown in Figures 6 and 8 can be used to simultaneously realize UART communication and control signal level matching between the STM32F407 (3.3V logic level) and the BG95-S5 satellite module (1.8V logic level) and the EC200 4G module (1.8V logic level, some control signals require level matching). This prevents communication abnormalities or module damage caused by level mismatch, while ensuring stable transmission of the standard AT command set in dual links. The serial communication voltage conversion and power-on wake-up control circuit between the MCU and BG95 is shown in Figure 6, and the serial communication voltage conversion and power-on wake-up control circuit between the MCU and EC200 is shown in Figure 8.

[0052] SIM card circuit: A dual SIM card design is adopted, with independent SIM cards configured for the 4G communication module and the BG95-S5 satellite module. At the same time, an ESD electrostatic protection device (PESD5V0S1BA or a functionally equivalent device) is added at the SIM card interface to prevent electrostatic damage to the SIM card and module. The SIM card circuit of BG95-S5 is shown in Figure 5, and the SIM card circuit of EC200 is shown in Figure 8.

[0053] Grounding Design: Digital ground and RF ground need to be isolated. Therefore, a separate design for digital ground and RF ground is adopted. A single-point common ground is achieved through a ferrite bead, which reduces interference between RF signals and digital circuits, especially avoiding RF signal interference with digital circuits and power circuits, ensuring the overall stability of the gateway, and preventing signal interference during the transmission of standard AT command sets, thereby improving the accuracy of command issuance and feedback.

[0054] Filtering and anti-interference design: The power input terminal adopts a π-type LC filter circuit to filter out high-frequency interference in the power supply; the RF path is designed with an inductor and capacitor matching network to ensure the quality of antenna signal transmission; a capacitor is connected in parallel at the module power interface to prevent restarts or communication interruptions caused by voltage drop during module operation.

[0055] RS485 Communication Interface: The gateway is designed with dual RS485 communication interface circuits. The overall circuit is shown in Figure 10. The dual RS485 communication interfaces communicate with external industrial monitoring and control peripherals through industrial aviation plugs to achieve serial data interaction. It is compatible with the docking standards of industrial equipment in scenarios such as desert photovoltaics and ocean-going ships, and realizes stable acquisition of peripheral data and command issuance.

[0056] Power System: As shown in Figure 2, the system adopts a hierarchical power supply architecture of industrial-grade wide voltage input + multi-stage DC-DC synchronous buck + LDO linear regulator. Through graded voltage conversion, it provides a stable, low-ripple, and highly reliable power supply solution for the entire device. The gateway's power input port connects to external power supply equipment via an industrial aviation connector, adapting to the wide voltage power supply wiring requirements of industrial scenarios and improving the reliability of power connection in outdoor, ocean, and other scenarios. The specific power supply link and chip implementation are as follows: First stage: The wide-voltage DC-DC buck system supports DC 12~36V industrial-grade wide voltage input. After passing through reverse connection protection diodes, the voltage is fed into the first-stage synchronous buck chip LMR36520, which converts the wide-range input voltage into a stable 12V DC bus voltage, providing intermediate bus power supply for subsequent circuits. Filter capacitors are configured at the input end to suppress surges and input ripple, improving the reliability of the preceding power supply. The second stage: DC-DC step-down. The 12V bus voltage is fed into the second-stage synchronous step-down chip SGM61220, which further steps down the voltage to output a 5V DC voltage to power the system's 5V load. Ripple performance is optimized through an output filter network to meet the power supply stability requirements of communication devices. Simultaneously, this 5V node supports external USB power supply as a backup power source. The third stage: LDO linear regulator. The 5V voltage, after passing through an anti-reverse-current diode, is input to the LDO linear regulator chip RT9013-3.3, which accurately regulates the output to 3.3V DC voltage to power the system's core digital circuitry. Utilizing the low noise and high voltage regulation accuracy of the LDO, the impact of power supply ripple on signal integrity is effectively reduced, ensuring stable and reliable operation of the core module. Simultaneously, a dedicated voltage regulation branch is derived from the 3.3V voltage terminal to power the 1.8V logic level section of the BG95-S5 satellite module, achieving precise power supply for multi-level devices.

[0057] Network switching core logic: This gateway prioritizes the 4G cellular network as the primary communication link by default to reduce communication costs during long-term operation in industrial scenarios. The main control chip collects dual network link quality data in real time through the standard AT command set, using packet loss rate as the core criterion. Combined with a triple constraint mechanism of fixed threshold, minimum interval time, and minimum network dwell time, it achieves intelligent, seamless, and infrequent switching between the 4G network and the IoT-NTN network. The specific logic is as follows: 4G network to IoT-NTN network switching logic: When the gateway is in 4G network communication state, the main control chip continuously sends link detection commands to the EC200 module through the standard AT command set to obtain and calculate the real-time packet loss rate (PLR_4G) of the 4G network in real time. When PLR_4G is detected to be greater than 15% (it is generally believed that a packet loss rate greater than 15% will affect the use of the smart IoT system; engineers can modify this according to the actual situation), the IoT-NTN satellite network detection mechanism is immediately triggered. Detection commands are sent to the BG95-S5 module through the standard AT command set. The module sends short frame detection packets to the IoT-NTN network in a 5-second detection cycle. The main control chip synchronously receives the feedback data from the module and calculates the packet loss rate (PLR_NTN) of the IoT-NTN network in each detection cycle. When PLR_4G - PLR_NTN > switching threshold B for 3 or more consecutive detection cycles (B is usually 8%, when the 4G network and IoT-NTN...), the switching logic is activated. When the packet loss rates of the networks are similar, 4G networks are preferred to reduce costs and can also prevent network fluctuations from causing network switching to some extent. When the time interval between the current time and the last network switching point is greater than or equal to the minimum interval (the minimum interval is set to 1 minute), the main control chip sends a switching command to the dual communication modules through the standard AT command set. The gateway automatically and seamlessly switches from the 4G network to the IoT-NTN network. During the switching process, data caching and forwarding are maintained to ensure that the communication link is not interrupted.

[0058] The IoT-NTN network to 4G network switchback logic is as follows: When the gateway is in IoT-NTN network communication mode, the main control chip continuously sends probe commands to the EC200 module through the standard AT command set. The EC200 module sends short frame probe packets to the 4G network in a 5-second probe cycle. The main control chip simultaneously receives feedback and calculates the real-time packet loss rate (PLR_4G). Only when PLR_4G is consistently lower than PLR_NTN for 5 or more consecutive probe cycles, and PLR_4G is stably ≤15%, meeting the 4G link quality requirements, and the gateway's network dwell time in the IoT-NTN network is ≥ the minimum network dwell time (minimum network dwell time is set to 1 minute), the main control chip sends a switchback command to the dual communication module through the standard AT command set. The gateway automatically switches back from the IoT-NTN network to the 4G network, restoring the low-cost communication mode. Through the constraints of the minimum network dwell time and the switching threshold B, the frequent switching problem caused by short-term fluctuations in the 4G network is effectively suppressed, ensuring the continuity and stability of the communication system.

[0059] This dual-mode smart gateway achieves high protection adaptability to harsh environments through an aluminum alloy IP67 protection-rated shell. It achieves standardized and highly reliable connection between the power supply, network port, RS485 interface and the outside world through an industrial aviation plug and socket. It achieves precise control of the dual communication modules by sending standard AT command sets. At the same time, through precise hardware circuit design and clear network switching logic, it achieves adaptive and seamless switching between 4G and low-orbit satellite IoT-NTN networks. While ensuring communication continuity in harsh environments such as deserts and oceans, it significantly reduces operating costs and can be directly and scalably applied to various industrial unattended scenarios.

[0060] The technical solution of the present invention has the following technical features: 1. Hardware isolation architecture with dual independent communication links The 4G cellular communication module and the low-orbit satellite IoT-NTN communication module are designed completely independently at the hardware level, including independent radio frequency circuits, independent antennas, and independent SIM card interfaces. They only share a power management module and are uniformly scheduled by the main control module to achieve link-level fault isolation and independent control.

[0061] 2. Dedicated dual-mode gateway architecture for narrowband communication characteristics of the Internet of Things Instead of adopting a high-power architecture designed for high-orbit satellite broadband, the hardware and system structure are specifically designed for the small data packet, low frequency, and low power consumption transmission characteristics of IoT, which significantly reduces the long-term power consumption of the device.

[0062] 3. Anti-interference circuit structure with separate digital ground and radio frequency ground and single-point common ground. By physically separating the digital ground and the radio frequency ground, and achieving a single-point common ground through ferrite beads, the electromagnetic interference of the radio frequency module to the main control and interface circuits is effectively reduced, and the communication stability in complex industrial environments is improved.

[0063] 4. Multi-level hierarchical voltage regulation power management architecture It adopts a three-level power supply structure that combines wide voltage input, DC-DC step-down and LDO regulation, and sets up filtering and energy storage capacitors at key power supply nodes to prevent voltage drops caused by instantaneous power consumption of communication modules from causing system abnormalities.

[0064] 5. Intelligent network handover algorithm based on packet loss rate difference judgment Instead of using traditional signal strength index (RSSI) as the basis for switching, the main control module calculates the packet loss rate of the 4G and IoT-NTN links in real time and uses the difference in packet loss rate as the core decision condition to improve the authenticity and stability of network quality assessment.

[0065] 6. Time constraint switching suppression mechanism Based on the packet loss rate judgment, a dual constraint of minimum handover interval time and minimum network dwell time is introduced to avoid frequent handovers caused by instantaneous network fluctuations and ensure communication continuity.

[0066] 7. Data caching and sequential forwarding mechanism during handover The main control module performs buffer management on the data to be sent during network switching and resends it in sequence after the new link is established to avoid data loss caused by link switching.

[0067] 8. Industrial-grade multi-interface integrated design It integrates an Ethernet interface and multiple RS485 industrial interfaces, which can be directly connected to various monitoring terminal devices in the field, reducing external conversion equipment and improving deployment efficiency.

[0068] 9. Dedicated protection and matching circuit for SIM card interface and RF path Electrostatic discharge protection circuits are installed in the SIM card interface, and impedance matching and filtering networks are set up in the radio frequency path to improve communication reliability and device safety.

[0069] 10. Highly reliable communication architecture suitable for unattended field and maritime scenarios Through dual-link complementarity, low-power design, and high anti-interference structure, the device can maintain stable communication in areas without public network coverage, such as deserts, Gobi, photovoltaic power stations, and ocean voyages.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A gateway for converged communication between low-orbit satellite IoT-NTN and 4G cellular network, characterized in that, The gateway includes a housing, an antenna assembly, a core circuit board, and an industrial interface assembly; the core circuit board integrates the following: Main control module, 4G communication module, low-orbit satellite IoT-NTN communication module, Ethernet communication interface, industrial serial communication module, power management module, level conversion module; The 4G communication module and the low-orbit satellite IoT-NTN communication module are set up independently, each with its own antenna and SIM card circuit. They only share the power management module, and the main control module performs communication control and data scheduling. The main control module establishes serial communication and power-on / wake-up control connections with the 4G communication module and the low-orbit satellite IoT-NTN communication module respectively through the level conversion module; The main control module connects to the Ethernet communication interface via the RMII interface to achieve Ethernet data communication; The main control module connects to the industrial serial communication module for data interaction with external industrial equipment. The power management module adopts a wide voltage input, and after multi-stage DC-DC step-down and LDO regulation, it outputs multiple stable voltages to power each functional module. An electrostatic discharge protection circuit is installed at the SIM card interface between the 4G communication module and the low-orbit satellite IoT-NTN communication module.

2. The gateway according to claim 1, characterized in that, The main control module constructs an adaptive handover decision model based on the dual-link packet loss rate to realize automatic handover between the 4G network and the low-orbit satellite IoT-NTN network, which includes: 4G network to IoT-NTN network switching mechanism: The main control module calculates the 4G network packet loss rate PLR4G in real time; when PLR4G exceeds the first threshold, the IoT-NTN network detection mechanism is activated to calculate the IoT-NTN network packet loss rate PLR_NTN; when PLR4G is satisfied for multiple consecutive detection cycles... When PLR_NTN > the second threshold and the time interval between the current time and the last handover is greater than the minimum handover interval, the network will automatically switch to the IoT-NTN network. IoT-NTN network to 4G network switchover mechanism: During the operation of IoT-NTN network, the quality of 4G network is periodically detected; when PLR4G is continuously lower than PLR_NTN and lower than the first threshold for multiple consecutive detection cycles, and the IoT-NTN network camping time reaches the minimum camping time, the network automatically switches back to 4G network. Handover suppression mechanism: Set the first threshold, the second threshold, the minimum handover interval, and the minimum network dwell time to suppress frequent handovers caused by instantaneous network fluctuations.

3. The gateway according to claim 2, characterized in that, The first threshold is the link availability threshold, and the second threshold is the link difference threshold; the handover suppression mechanism also includes: during the handover process, the main control module performs data caching and sequential forwarding.

4. The gateway according to claim 1, characterized in that, The power management module adopts a layered power supply architecture, including: First stage: Wide voltage DC input is synchronously stepped down and converted to intermediate bus voltage; Second stage: The bus voltage is further stepped down to obtain a second stage stable voltage, which serves as the main load power supply voltage and supports external backup power supply access; The third stage: outputs the operating voltage of the core digital circuit through a linear voltage regulator chip.

5. The gateway according to claim 1, characterized in that, The core circuit board adopts a design that separates digital ground and radio frequency ground, and achieves a single-point common ground through ferrite beads; the SIM card interface of the 4G communication module and the low-orbit satellite IoT-NTN communication module is equipped with an electrostatic protection circuit; the radio frequency path is equipped with an impedance matching network and a filtering network.

6. The gateway according to claim 1, characterized in that, The main control module establishes serial communication and power-on / wake-up control connections with the 4G communication module and the low-orbit satellite IoT-NTN communication module respectively through a level conversion circuit; the main control module is connected to the Ethernet PHY chip through the RMII interface; the main control module is connected to multiple RS485 communication interfaces.

7. A switching method based on the gateway according to any one of claims 1 to 6, characterized in that, include: Step A: By default, 4G cellular network is the preferred communication link, and the main control module calculates the 4G network packet loss rate PLR4G in real time; Step B: When PLR4G exceeds the first threshold, the IoT-NTN network detection mechanism is activated to calculate the IoT-NTN network packet loss rate PLR_NTN at fixed intervals; Step C: When multiple consecutive detection cycles satisfy PLR4G When PLR_NTN > the second threshold and the time interval between the current time and the last handover is greater than the minimum handover interval, the main control module controls the gateway to switch from the 4G network to the IoT-NTN network. Step D: Periodically probe the 4G network quality during IoT-NTN network operation; Step E: When PLR4G is continuously lower than PLR_NTN and lower than the first threshold for multiple consecutive detection cycles, and the IoT-NTN network camping time reaches the minimum camping time, the main control module controls the gateway to switch back from the IoT-NTN network to the 4G network.

8. The switching method according to claim 7, characterized in that, The first threshold is 15%, the second threshold is 8%, the detection period is 5 seconds, the consecutive multiple detection periods are 3 or more consecutive periods, the minimum switching interval is 1 minute, and the minimum network stay time is 1 minute.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the switching method described in claim 7 or 8.

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