0 Introduction In recent years, China has actively promoted the development of the Internet of Vehicles (IoV) industry. As of December 2023, over 8,500 roadside units (Road Side Units, RSUs) have been deployed in the country, with several road sections equipped with millimeter-wave radars, laser radars, cameras, and edge computing servers to support the verification and promotion of new technologies such as vehicle-road collaboration and intelligent driving[1]. According to the “Summary Report of the Pilot Application Activities of C-V2X IoV (2022)” and the experiences of various regions in testing IoV infrastructure, it has been found that several areas still face issues such as inconsistencies between actual construction and standards, and insufficient accuracy of roadside information[2]. Additionally, there is a general lack of operational maintenance systems for infrastructure in various regions, leading to insufficient guarantees for the continuous availability of facilities. This article attempts to propose an industry-level system for testing and evaluating IoV infrastructure, aiming to assist the industry in conducting inspection tests on IoV infrastructure, maintaining efficient, stable, and long-term operation of the infrastructure, and ensuring the effectiveness of IoV infrastructure in enhancing road traffic safety and efficiency[3].1 Research on Testing and Operation Maintenance System of IoV InfrastructureThe IoV infrastructure testing and evaluation system mainly involves two stages: first, acceptance testing during the construction phase, which primarily tests the performance and service capabilities of the equipment after the system is built, to verify whether the IoV infrastructure has stable and efficient service capabilities; and second, operational monitoring during the operation phase, to continuously verify whether the IoV infrastructure can provide stable services.1.1 Testing System During Construction PhaseDuring the construction phase, performance and standard compliance testing should be conducted on key devices and systems within the infrastructure. The testing subjects should at least include IoV roadside infrastructure, IoV communication networks, IoV platforms, and IoV communication security certificates.IoV roadside infrastructure mainly includes roadside information and roadside perception systems. Protocol consistency testing and application message accuracy testing should be conducted on roadside information; target perception performance testing and traffic detection performance testing should be conducted on roadside perception systems.For the IoV communication network, coverage testing and radio frequency protocol consistency testing should be conducted on the Cellular Vehicle to Everything (C-V2X) communication network, and network performance testing should be conducted on 5G cellular networks, backbone networks, and bearer networks.The IoV platform mainly conducts interface protocol consistency testing between the platform and RSUs, as well as testing the basic service capabilities regarding device access, event processing, data analysis, etc., and operational management capabilities regarding device management and alarm management.IoV communication security certificates mainly include testing in areas such as certificate management mechanisms, security protocol consistency, security privacy protection, and secure communication performance. The framework of the IoV infrastructure testing and evaluation system is shown in Figure 1.
Figure 1 Framework of IoV Infrastructure Testing and Evaluation System1.2 Monitoring System During Operation PhaseAfter the IoV infrastructure is put into use, it is necessary to conduct regular monitoring and daily inspections of the IoV infrastructure, establishing an abnormal response mechanism to ensure the long-term stable operation of roadside facilities. The operational monitoring system of IoV infrastructure mainly includes: establishing a regular monitoring mechanism, relying on real-time indicators from the IoV platform to monitor the operational status of the infrastructure at all times; establishing a daily inspection mechanism, following current standards and data specifications, using professional testing equipment to regularly test roadside infrastructure, IoV communication networks, and communication security certificates to ensure the reliability and stability of roadside infrastructure data; establishing an abnormal response mechanism to promptly respond to abnormal data detected through regular monitoring and road inspections, ensuring that equipment continues to operate normally and that data meets the application needs of various scenarios. The framework of the IoV infrastructure operation and maintenance testing system is shown in Figure 2. 
Figure 2 Framework of IoV Infrastructure Operation and Maintenance Testing System2 Testing Methods During Construction Phase of IoV InfrastructureDuring the construction phase of IoV infrastructure, testing of roadside infrastructure, communication networks, platforms, and communication security can verify the standard compliance and construction quality of the infrastructure, ensuring that the infrastructure meets design operational conditions.2.1 Testing of IoV Roadside Infrastructure2.1.1 Testing of IoV Roadside InformationAs an important communication unit of IoV infrastructure, RSUs are the main carriers of demonstration activities and pilot applications in the IoV industry, responsible for continuously broadcasting roadside information. Therefore, protocol consistency and application message accuracy testing should be conducted on IoV roadside information.Protocol consistency testing is based on the Long Term Evolution Vehicle-to-Everything (LTE-V2X) network layer, security layer, and message layer (Phase 1 and Phase 2) in China, ensuring the standard compliance and interoperability of RSUs. The network layer protocol testing includes sending Dedicated Short Messages (DSMs) by the tested entity, parsing DSMs by the tested entity; application registration, and maintaining the information database. Security layer protocol testing includes issuing Secure Protocol Data Units (SPDUs) by the tested entity, verifying SPDU signatures, and testing secure message validation. Message layer protocol testing includes: Phase 1 basic safety messages for assisted driving scenarios, map messages, traffic signal messages, roadside traffic messages, roadside unit messages, etc.; Phase 2 cooperative driving enhanced scenario vehicle intention and request messages, roadside coordination messages, perception sharing messages, etc.Application message accuracy testing is based on YD/T 3709-2020 “Technical Requirements for Message Layer of Wireless Communication Technology for IoV Based on LTE” and CSAE 159-2020 “Technical Requirements for Roadside Units of Direct Communication Systems for IoV Based on LTE”, verifying the accuracy of real road information, real-time traffic events, and data sent by RSUs at various points within the pilot and demonstration areas, ensuring that onboard terminals can correctly trigger applications.2.1.2 Performance Testing of IoV Roadside Perception SystemThe IoV roadside perception system is an important infrastructure that provides information on traffic participants and traffic flow statistics to vehicle users and urban cloud platforms. On one hand, it uses sensors such as cameras, laser radars, and millimeter-wave radars to generate structured data through roadside edge computing units and sends structured data to vehicle users and urban cloud platforms via LTE-V2X, 5G networks, etc., assisting vehicles in achieving beyond-visual-range perception and blind spot warning applications; on the other hand, it empowers urban digital traffic, supporting the construction of a real-time, highly accurate traffic monitoring system.
Figure 3 Architecture of IoV Roadside Perception SystemPerformance testing of the IoV roadside perception system mainly focuses on four dimensions: roadside system performance, traffic participant perception performance, traffic flow statistics performance, and traffic event detection performance. By evaluating the perception level, it ensures that the roadside perception system in the IoV pilot and demonstration areas can support the application scenarios corresponding to the construction goals[4]. The architecture of the IoV roadside perception system is shown in Figure 3.2.2 Testing of IoV Communication NetworkThe IoV communication network includes 5G cellular networks, C-V2X direct communication networks, and wired networks such as backbone networks and bearer networks. This article mainly introduces testing methods for the C-V2X communication network, including radio frequency protocol consistency and network coverage testing. Ensuring that RSUs meet relevant technical standards from the communication radio frequency layer guarantees interoperability among devices of different brands and models, effectively supporting real-vehicle application verification in the field, and ensures that the network coverage and quality meet the requirements for LTE-V2X applications through network coverage testing.Radio frequency protocol consistency testing should be conducted according to the physical layer standards of C-V2X established by the 3rd Generation Partnership Project (3GPP) and the China Communications Standards Association (CCSA), verifying the compliance of the transmitter and receiver of terminal devices with radio frequency standards and their anti-interference capabilities, ensuring that roadside devices meet standard requirements for radio frequency performance.Network coverage testing should be conducted according to communication industry standards YD/T 3709-2020 “Technical Requirements for Message Layer of Wireless Communication Technology for IoV Based on LTE” and CSAE 159-2020 “Technical Requirements for Roadside Units of Direct Communication Systems for IoV Based on LTE”, testing the signal strength at different locations on the road and conducting coverage range tests in all directions at intersections to ensure that the network coverage quality meets the requirements for LTE-V2X applications[5]. The testing methods for V2X communication networks are shown in Figure 4.
Figure 4 Testing Methods for V2X Communication Network 2.3 Testing of IoV Platform2.3.1 Interface Protocol Consistency Testing of IoV PlatformThe IoV platform is a key node connecting roadside infrastructure and urban cloud platforms. It realizes real-time access and exit of various dynamic/static information related to the real-time status of LTE-V2X roadside devices, road perception data, IoV terminal users (including data from pre-installed and retrofitted smart connected vehicle terminal users), and other cloud platforms.T/CCSA 455 “Data Interface Communication Protocol Requirements between IoV Platform and Roadside Devices”[6] and T/CCSA 456 “Technical Requirements for Operation and Maintenance Management Platform for Roadside Communication Devices (RSU)”[7] specify the technical requirements and interface protocol specifications for the business data interface and operation and maintenance management between the IoV platform and RSUs, roadside edge computing units (RSCU)[8]. Among them, the business data interface is responsible for transmitting business-related upstream and downstream messages between RSUs, RSCUs, and the IoV platform, while the operation and maintenance management interface is responsible for transmitting operation and maintenance management messages of RSUs, roadside perception, and computing devices. Therefore, it is necessary to conduct compliance verification of the communication interface between RSUs and the IoV platform, ensuring that the communication protocols and data transmission content between roadside devices and the IoV platform meet standard requirements. The testing environment for IoV platform interface protocol is shown in Figure 5.
Figure 5 Testing Environment for IoV Platform Interface Protocol2.3.2 Basic Service and Operation Management Capability Testing of IoV PlatformTesting of the basic service capabilities of the IoV platform is conducted. Testing is performed on device access and management to ensure that the platform can accurately access and manage RSUs, RSCUs, roadside perception devices, and C-V2X business terminals; testing is conducted on event processing and management to ensure the platform’s event type classification, event operation, and event processing capabilities; testing is conducted on data analysis and management to ensure that the platform can perform data analysis processing, data operations, data type operations, and data usage, as well as ensuring the technical and application levels of the IoV platform; testing is conducted on support capabilities to ensure that the platform has capabilities for edge application management, security platforms, resource dynamic allocation, and business monitoring[9].Operation and maintenance management capability testing of the IoV platform is conducted. Relevant functional testing is carried out in areas such as device management, alarm management, configuration management, performance management, security management, remote upgrades, fault diagnosis, and data statistics, ensuring the unified operation and maintenance capabilities of the IoV platform across manufacturers and types of devices.2.4 Testing of IoV Communication Security CertificatesRoadside infrastructure and testing vehicles that access C-V2X need to install and use digital certificates that comply with national standards to ensure the authenticity and integrity of the V2X communication process. To prevent personal privacy and confidential data leakage, and to prevent attackers from spreading false information without verification, after the RSU starts providing roadside data, security certificate testing for C-V2X messages is necessary. The security testing of C-V2X devices includes testing the certificate management mechanism, security protocol consistency testing, security privacy protection testing, and secure communication performance testing. By testing security certificates, it can be ensured that the C-V2X security certificate permissions are correct, updated in a timely manner, devices have security protection mechanisms, and performance meets requirements[10]. The architecture of the IoV identity authentication and security trust system is shown in Figure 6.
Figure 6 Architecture of IoV Identity Authentication and Security Trust System3 Research on Monitoring System During Operation PhaseAs the IoV infrastructure enters the regular operation phase, it is necessary to establish a monitoring system aimed at the infrastructure and the services provided to promptly detect facility faults and service defects, ensuring that the IoV infrastructure continuously and accurately provides services to users[11].3.1 Regular Monitoring MechanismThe regular monitoring mechanism refers to the continuous automated data monitoring of cloud data from roadside infrastructure through the IoV platform, reducing fault response time and improving the efficiency and quality of operation and maintenance work. First, monitoring indicators should be established to monitor and analyze key indicators such as performance parameters, resource usage, and network connection status of roadside devices in real-time, and the effectiveness and accuracy of monitoring indicators should be regularly evaluated and adjusted according to actual operating conditions and business needs; secondly, by employing machine learning, deep learning, and other technical means, intelligent analysis and processing of monitoring data should be conducted, continuously upgrading anomaly detection algorithms to improve the accuracy and efficiency of anomaly detection; finally, based on the historical data and operating conditions of the devices, alarm thresholds should be dynamically adjusted to more accurately capture anomalies[12].3.2 Daily Inspection TestingFirst, confirm the content of the inspection testing work, mainly targeting four areas: roadside perception systems, IoV communication networks, IoV platforms, and IoV communication security certificates for road testing. Testing should employ more convenient and automated testing tools, using road test data as the main basis and IoV platform data as auxiliary to ensure consistency between roadside data and platform data.The focus of daily inspections on the C-V2X communication network testing is: confirming the operational status of RSUs on-site to ensure that devices are correctly powered, connected to the network, and sending messages comprehensively and accurately; verifying the accuracy of roadside information to ensure real-time and accuracy of data; checking the communication coverage range of RSUs to ensure that there are no weak coverage points within the road range. The focus of testing on the roadside perception system is: verifying the perception accuracy and perception delay indicators of the roadside perception system through testing true value data to ensure that the roadside perception system can accurately detect traffic participants within the perception range; simulating some traffic events with test vehicles to ensure that the roadside perception system can accurately recognize traffic events and report them through RSUs; testing vehicle traffic flow statistics to ensure that the roadside perception system correctly counts traffic-related data and uploads it to the cloud. The focus of testing on the IoV platform is: checking the consistency of platform-side data in conjunction with the results of V2X communication network testing and roadside perception testing to ensure that all functions of the IoV platform are normal. The focus of testing on IoV communication security certificates is: ensuring that security certificates are obtained and updated in a timely manner, ensuring the safety and reliability of roadside messages from the IoV.Secondly, plan inspection routes and cycles, focusing on core areas for inspection work, ensuring that each inspection cycle tests data from all points. Combine different device technical characteristics, determine inspection cycles based on device workload and lifespan, ensuring that sufficient inspection testing data is generated annually for analysis of device performance degradation trends and potential fault modes, providing a basis for the maintenance and repair of devices.3.3 Abnormal Response MechanismThe abnormal response mechanism mainly responds to anomalies detected during regular monitoring and daily inspections, promptly addressing fault issues to maintain efficient and accurate continuous operation of the infrastructure.When abnormal data is detected by regular monitoring, a first response is initiated to verify the source of the abnormal data. The operation and maintenance team analyzes and judges the situation based on the system fault conditions and, according to the actual situation of on-site sudden faults, urgency, technical difficulty, spare parts, etc., dispatches and confirms technical engineers and emergency materials based on experience. After fault handling is completed, based on the actual progress on-site, data and events are recorded, analyzing the reasons for device faults, providing feedback to regular monitoring and daily inspection testing, focusing on testing the points and reasons for fault occurrence to ensure the reduction of subsequent risk points. A summary of the emergency response process is conducted to continuously improve the efficiency of the abnormal response mechanism, enhancing the service level of IoV infrastructure.After analyzing daily inspection testing data, if performance degradation and potential faults of roadside devices are found, the current roadside devices and intersection points should have their inspection frequency increased, and detailed positioning of the causes of the problems should be conducted. The operation and maintenance team should take necessary preventive maintenance measures based on the causes of the problems, such as replacing vulnerable parts, optimizing software configurations, and cleaning devices.4 Existing Issues in Testing and Operation Maintenance of IoV Infrastructure4.1 System-Level Testing Evaluation Standards and Certification System Have Not Yet Been EstablishedThe “Reference Technical Guidelines for IoV Infrastructure 1.0” has proposed reference technical requirements for the construction of IoV infrastructure[13]. However, after multiple practical activities and field tests, it has been found that due to different construction periods in various pilot and demonstration areas, there are inconsistencies in adherence to standards regarding equipment interfaces, data consistency, etc., and no continuous service has been formed across the entire area. The industry has not yet proposed a system-level testing operation and maintenance system for the construction of IoV infrastructure, and various regions lack guidance on methods during construction verification and operation monitoring processes, with the certification system for facilities and services not being fully developed.4.2 Shortage of Automated Testing ToolsCurrently, IoV testing tools mainly refer to traditional cellular communication network testing tools for modification, with relatively insufficient investment in the development of testing tool products. Chip manufacturers, module manufacturers, and vehicle terminal manufacturers have developed some in-house tools from their own needs, but they generally have issues such as single testing capabilities and unguaranteed accuracy. It is necessary to strengthen investment in the development of relevant testing tools for various links such as communication networks, roadside perception, and system platforms, establish technical standards for testing tools, and create a testing product certification mechanism.4.3 General Lack of Professional Operation and Maintenance TeamsCurrently, the operation and maintenance testing of IoV infrastructure is generally carried out by construction units independently, lacking effective operational team support for IoV applications in practice. As an emerging industry crossing information, communication, and transportation fields, IoV requires a professional engineering team for support. When facing faults or abnormal incidents, it often requires coordination with external vendors for personnel scheduling, leading to untimely responses. In terms of funding, various pilot and demonstration areas are still exploring business models, with some regions facing insufficient funding guarantees for operation and maintenance.5 ConclusionPromoting the establishment of a testing operation and maintenance system for IoV infrastructure supports continuous and consistent cross-domain services. Guided by the “National Guidelines for the Construction of IoV Industry Standard System”, relevant units should jointly construct a system-level testing evaluation system for IoV infrastructure, increasing the effective supply of standards. Relying on IoV testing demonstration activities, organizations should conduct standard verification with upstream and downstream enterprises in the industry, deeply explore scenario application verification, promote unified roadside messaging across the country, and achieve continuous vehicle-side applications nationwide. Strengthen communication and cooperation between regions, combining typical application scenarios with characteristic application scenarios to promote the sharing of testing results across regions.Accelerate the research and development of automated testing tools for IoV infrastructure to improve operation and maintenance testing efficiency. Based on existing testing standards for roadside perception, IoV communication networks, and IoV communication security certificates, develop more convenient and automated testing tools. By designing standardized testing components, meet different testing needs, improve the flexibility and usability of testing tools, and approach automation in the operation and maintenance testing process, conducting daily inspection testing on a larger range of road infrastructure within a unit time, and promptly discovering potential faults in IoV infrastructure.Promote the construction of professional operation and maintenance service capabilities to ensure the continuous availability of IoV infrastructure. Support the construction of professional operation and maintenance service teams, assisting the main construction entities in conducting continuous operation monitoring, quickly responding to and addressing facility faults and service defects, ensuring the quality of service for the infrastructure. Encourage professional operation and maintenance service teams to explore business models in conjunction with construction entities, expanding user scale with high-quality services, exploring direct payment applications or indirect revenue services, achieving sustainable operation and maintenance.
Author Information
Li Boxiong
Engineer in the Research Department of IoV and Intelligent Transportation, China Academy of Information and Communications Technology, mainly engaged in research related to technology, standards, and testing in the fields of IoV and intelligent connected vehicles.
Yu Rundong
Senior Engineer in the Research Department of IoV and Intelligent Transportation, China Academy of Information and Communications Technology, mainly engaged in research related to policies, technologies, standards, security, and testing in the field of IoV.
Yu Shengbo
Engineer in the Research Department of IoV and Intelligent Transportation, China Academy of Information and Communications Technology, mainly engaged in research related to policies and regulations, technologies, standards, and testing in the field of IoV/intelligent connected vehicles.
Guo Meiying
Engineer in the Research Department of IoV and Intelligent Transportation, China Academy of Information and Communications Technology, mainly engaged in research on the construction of IoV C-V2X testing systems and testing certification systems.
Paper Citation Format:
Li Boxiong, Yu Rundong, Yu Shengbo, et al. Research on System-Level Testing and Operation Maintenance of IoV Infrastructure [J]. Information Communication Technology and Policy, 2024, 50(3): 66-72.
This article was published in “Information Communication Technology and Policy” 2024, Issue 3
Organized by: China Academy of Information and Communications Technology
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