## 1 Introduction
* Large-Scale The concept of \"large-scale\" pertains to congestion scenarios characterized by high vehicle density rather than vast road networks where multiple roads intersect and connect. * Field Testing Field testing involves simulating a high-density traffic environment for key vehicles by controlling the power (distance) of nodes and the Basic Safety Message (BSM) content (coordinates, vehicle speed, etc.) transmitted by these nodes, rather than using actual environmental vehicles. This method enables the assessment of application performance under complex traffic conditions. In our previous work [4], we developed an automated C-V2X large-scale testing system (LSTS), whose system architecture will be elaborated in Section 3.1. This system implements a field testing that is tailored to various communication scenarios using a density node array, enabling the automated testing of the Device Under Test's (DUT's) communication performance. The system's effectiveness can be cross-validated by comparing its results with those obtained from the simulation platform NS-3. However, integrating the application testing capability into this system presents significant challenges regarding the design of the test scheme, such as the following: the inclusion of application scenarios and communication scenarios, test message distribution and backhaul, and the collection and analysis of the test data. Furthermore, drawing on various field test cases, aspects such as data forwarding, processing, storage, real-time system monitoring, and the online automated Graphical User Interface (GUI) must also be considered. Given the large number of nodes that are involved and the need to ensure the effectiveness and authenticity of the tests, the realisation of the aforementioned functions is closely related to the software architecture of the TS. Therefore, this paper proposes a layered software architecture for the combined-scenario-oriented C-V2X automated LSTS. The core of the architecture is scenario encapsulation, which enables the testing of diverse applications and communication performances, facilitating repeatable and extreme-condition tests. The architecture introduces a node array that achieves a virtual-to-real mapping to construct unique scenarios, such as high-density congestion, while balancing the costs and complexity of the tests. This architecture allows for automated testing and web-supported visual online testing, enhancing the system's ease of use and user-friendliness. Additionally, the architecture investigates how to efficiently manage high-concurrency, high-load, and real-time data under conditions with many nodes. When benefiting from the proposed software architecture, our automated C-V2X LSTS can not only meet the requirements of On-Board Unit (OBU) testing and vehicle launch verification but can also accommodate diverse scenario demands, as outlined below:  
* Vehicle Testing: Autonomous Driving (AD), Advanced Driver Assistance Systems (ADAS), and overall vehicle performance;
* Road Infrastructure Testing: intelligent traffic signal control, Cooperative Vehicle Infrastructure System (CVIS), and smart parking;
* Pedestrian Testing: pedestrian safety warning and pedestrian priority;
* Other Scenarios: emergency management, data collection, and commercial applications. In addition, the LSTS achieved good application demonstration results. At the Jinfeng test field of China Merchants Testing Vehicle Technology Research Institute Co., Ltd. (Chongqing, China), the LSTS completed communication performance testing and warning function testing for 139 enterprises and 62 teams. At the AD closed field testing base authorised by the Ministry of Transport, the LSTS underwent C-V2X large-scale communication testing and application testing, including Line of Sight (LOS) communication capability, Non-Line of Sight (NLOS) communication capability, Forward Collision Warning (FCW), Abnormal Vehicle Warning (AVW), and Red Light Running Warning (RLVW).