# Low-Altitude Sensing Model: Analysis Leveraging ISAC in Real-World Environments
## 1 Introduction
### Contributions  
Based on the current research, the existing network models in the low-altitude ISAC field show significant limitations in achieving \"wide-area, seamless, and 3D\" low-altitude network sensing based on the ISAC technology. The lack of theoretical network models has seriously hindered the practical deployment of ISAC networks. While a few studies on low-altitude coverage rely on simulations, they lack real-world testing and have not performed in-depth analysis from a holistic view of ISAC low-altitude networks. Therefore, this paper proposes an innovative low-altitude wide-area sensing model based on ISAC base stations, aiming to fill this critical gap. By overcoming the shortage of traditional 2D network models, this paper introduces a seamless coverage solution in 3D space, optimizing base station layout and functionality to address the differences between the communication and sensing requirements, thereby building a low-altitude network model with enhanced sensing capabilities that improve sensing efficiency and reliability in low-altitude environments. The results of this study not only provide theoretical support for the development of low-altitude networks, but also serve as a reference for other mobile network operators or countries, especially considering the expected continuous growth of the low-altitude economy in the coming years. Moreover, the proposed method is general and can be applied to 6G networks in the future. The main contributions of this paper are as follows:  
* This paper constructs a 3D sensing model for a single ISAC base station operating in a single base station responsible for both the transmission and reception nodes. It analyzes the influence on vertical FOV of base station antennas, and the differences in cell radius and beam characteristics between communication and sensing. Compared to previous studies, this model more precisely defines the sensing boundaries and range of a single base station, providing a more accurate theoretical basis for low-altitude network sensing capabilities. This achievement not only contributes to a deeper understanding of the basic characteristics of low-altitude ISAC networks, but also offers innovative ideas for designing the key parameters of ISAC fusion base stations, laying a theoretical foundation for the development of low-altitude ISAC networks. * To address the issue of base station tower top blind spots, this paper proposes a multi-BS complementary coverage method and designs a 3D sensing-based cellular-like topology for low-altitude multi-BS networking. Compared to traditional 2D network models, this topology overcomes the limitations in low-altitude 3D coverage. By optimizing base station layout and signal coverage, it achieves seamless 3D sensing in low-altitude environments, significantly improving the accuracy and reliability of wide-area low-altitude sensing. This innovative design provides a practical solution for the real-world application of low-altitude ISAC networks and lays the foundation for the widespread adoption of low-altitude sensing technology across various fields. * To validate the feasibility of the single base station model under ideal conditions, this paper conducts the first laboratory tests on the sensing boundary of a single base station in an mmW frequency far-field OTA anechoic chamber. Additionally, based on the world's first commercial mmW ISAC network, a real-world testing platform is set up in collaboration with leading equipment suppliers for outdoor field testing, successfully validating the effectiveness of the sensing network topology in actual scenarios. This combination of laboratory and real-world commercial network testing provides a comprehensive and reliable reference for the network deployment of low-altitude ISAC base stations, filling the gap in practical testing and verification in this field and providing crucial technical support and practical experience for future research and engineering practices. The remainder of this paper is structured as follows.