“The network connection terminal equipment introduced in this article combines a cellular network mobile communication terminal and a C-V2X PC5 direct connection communication terminal. Both of them exchange information via Ethernet. Both are powered by the vehicle battery and connected to the vehicle bus. According to the vehicle bus message, they enter different Mobile communication terminal can provide vehicles with multiple services such as remote control, anti-theft, OTA, data routing, etc.; C-V2X communication terminal can interact with other vehicles, infrastructure, etc., and then make judgments based on the interactive message and its own state And provide early warning information to the driver.
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Abstract: The networked terminal equipment introduced in this article combines a cellular network mobile communication terminal and a C-V2X PC5 direct-connected communication terminal. The two exchange information via Ethernet. Both are powered by the vehicle battery and connected to the vehicle bus. According to the vehicle bus message Enter different working modes; mobile communication terminals can provide vehicles with multiple services such as remote control, anti-theft, OTA, and data routing; C-V2X communication terminals can interact with other vehicles, infrastructure, etc., and then based on interactive messages and their own status Make judgments and provide early warning information to the driver.
The Internet of Vehicles is a new industry that is highly integrated with automotive electronics, mobile communications, and transportation systems, and is the most important technological innovation and industrial direction of the automotive industry. At present, the Internet of Vehicles has gradually begun to spread, and the number of new cars installed with T-boxes to realize the network connection function is increasing.The T-box installed on the new car and the mobile communication network with very high coverage can provide car owners, car manufacturers and 4S shops with a variety of networked services, such as remote control of the car, anti-theft, and OTA upgrade of car ECU software, etc. Service, which can provide data routing for other equipment in the vehicle, and has functions such as automatic or manual calls in an emergency; car factories and 4S shops can obtain information such as vehicle status and failures, and push reminders of repairs and maintenance to car owners[1].
0 Preface
C-V2X (Cellular-Vehicle to Everything) is a wireless communication technology for vehicles. It is a new generation of information communication technology that connects the vehicle with everything. V stands for vehicle and X stands for any object that interacts with the vehicle. X mainly includes vehicle V, person P, roadside infrastructure I (such as roadside unit RSU) and mobile communication network N. The intelligent transportation system represented by C-V2X can effectively reduce traffic accidents and improve traffic efficiency. At present, C-V2X equipment (V-Box for short) has been assembled in new cars. It can interact with other vehicles, RSUs, etc. through PC5 direct communication to achieve information interaction, and interact with mobile communication networks through T-box to obtain more changes. Remote traffic information, so that the vehicle can use this information to determine the status of other vehicles, road conditions or pedestrian intentions, etc., so as to make predictions and remind the driver to take timely measures to avoid traffic accidents, or make the vehicle Pass traffic light intersections at the optimal speed, reduce vehicle waiting time and road congestion, and improve road traffic efficiency.
my country is currently vigorously promoting the interconnection, intelligence and electrification of automobiles. It is foreseeable that with the development of technology, the improvement of infrastructure, and the implementation of relevant regulations, the Internet of Vehicles and the intelligent transportation system with C-V2X as the core will Gradually popularized, to bring faster, more comfortable and safe driving experience to car owners.
1 System design
The system structure is shown in Figure 1.
Figure 1 System structure
2 System characteristics
This article introduces a solution of T-box plus V-Box. The solution is to divide T-box and V-Box into two separate modules. Information exchange through the network can not only realize the function of connecting with the mobile communication network, but also realize the PC5 direct connection communication of C-V2X; this can realize the function of Internet of Vehicles, and also realize the functions of C-V2X (such as V2V, V2I). , V2N).
This architecture can add a V-Box to models that already have a T-box for upgrades, and provide different functional configurations according to different vehicle levels.
3 Function and role of each module
3.1 In the above architecture diagram, T-box is mainly used to communicate with mobile communication networks
1) The network connection module interacts with the V-Box or other devices in the car (such as the infotainment system) with the uplink and downlink data communicated with the mobile communication network through the Ethernet. The network connection module is equipped with two external antennas, the main antenna and the auxiliary antenna. In order to detect and notify the car owner in time when the antenna fails, the T-box needs to have the antenna open and short-circuit diagnosis function; the network connection module and the microprocessor MCU carry out status interaction through UART and so on. In the standby mode, in order to wake up the T-box remotely and quickly, the network module is in DRX mode. When the standby time exceeds a certain time (such as 14 days), in order to reduce the consumption of the vehicle battery, the power supply of the network module will be cut off and enter the power failure. state.
2) The MCU receives and decodes vehicle bus messages through the bus transceiver. According to the bus messages sent by the vehicle (such as vehicle ignition, flameout, etc.), it controls the T-box machine to turn on and standby, and manage the power of each module , To achieve the correct power-on sequence of key modules and the low power consumption requirements of the whole machine in standby mode. The MCU also monitors itself and other modules to prevent the whole machine from entering infinite loops. For example, the network connection module sends a timing signal to the MCU. If the MCU does not receive this signal after timeout, the network connection module is considered to be unexpected and forced to Perform a reset.
3) The bus transceiver is a CAN transceiver, and high-speed CAN or CAN FD can be selected according to the vehicle bus network. Using CAN FD can determine whether to wake up the T-box according to the bus message in the T-box standby state, thereby reducing power consumption.
4) The design of the power supply module should consider several factors under the premise of taking into account the cost: the requirement of the peak current of the whole machine and each module, the requirement of low power consumption in standby mode, the power supply diagnosis of key modules, and the power supply test standards of the car factory or the national standard Requirements (such as ISO7637, conducted radiation test, conducted immunity test, etc.).
3.2 V-Box is used for PC5 direct connection communication (such as communication with other vehicles and RSU)
1) The C-V2X direct communication module is mainly used to directly exchange information with other objects, and make early warning and other judgments based on the received message and the status information of the vehicle; it has two V2X antennas.
2) In addition to receiving and decoding CAN messages for V-box switch control and power management of each module, MCU will also receive CAN messages related to vehicle status (such as vehicle speed, left and right turns, braking, double flashing status, etc.) ) After decoding, it is sent to the C-V2X direct communication module, which then sends these messages to surrounding vehicles; the MCU also monitors itself and other modules such as direct communication modules and application processors to avoid infinite loops, etc. problem.
3) Due to the large amount of C-V2X message data to be processed by V-Box, if there are 200 vehicles within 300 m of the surrounding area and each vehicle interacts with 10 messages per second, V-Box needs to process 2,000 messages per second. Messages require high computing power for the processor, so an additional application processor is required to process C-V2X messages.
4) Because C-V2X has high requirements for positioning accuracy and time accuracy, in addition to the built-in communication module for GNSS data reception, positioning and timing, an inertial measurement unit IMU (gyro + accelerometer) and special The algorithm is used for the positioning and timing of special scenes, such as tunnels, urban areas with high-rise buildings, etc.
5) The hardware security module HSM is mainly used for C-V2X message signature, verification, certificate verification and secret key storage, etc. It needs to support the corresponding national secret algorithm.
6) In addition to the exchange of mobile communication network information with the T-box, the Ethernet will also forward the forward collision warning and vehicle out-of-control warning information generated by the V-Box to other systems through the Ethernet gateway to provide the driver with timely graphics and text , Voice warning. If the vehicle is equipped with a driving assistance system, the V-Box can also be used as a sensor. The system integrates the inputs of the V-Box, radar, camera, ultrasound, etc. to make calculation decisions, and then controls the vehicle accordingly (such as braking, deceleration, etc.).
4 Practical application
The scheme introduced in this system has been applied to actual products, and can realize the safety and efficiency scenarios in the TCSAE-53-2017 standard, such as the warning of road hazards in the V2I scenario, red light warning and green wave speed guidance, and vulnerable traffic participants Collision warning, etc.; V2V scene forward collision warning, blind spot warning and faulty vehicle warning, etc., have achieved good application effects.
references:
[1] Chinese Society of Automotive Engineering. TCSAE-53-2017 Cooperative Intelligent Transportation System Vehicle Communication System Application Layer and Application Data Interaction Standard[S].
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