# Low-Altitude Sensing Model: Analysis Leveraging ISAC in Real-World Environments
## 1 Introduction
### Background  
Although progress has been made in the low-altitude ISAC networks, there are still many shortcomings. Current research mainly focuses on signal processing, algorithm optimization, network models, coverage models, and simulation verification. However, these studies often lack depth in model design or capability integration, or they have limitations in practical validation, failing to fully meet the requirements for accurate coverage, capability fusion, and real-world application in low-altitude ISAC networks. To address the challenge of seamless low-altitude sensing coverage in cellular networks, studies [6; 13] have focused on beamforming optimization for dual-base ISAC systems and multi-static systems with coordinated multi-point joint transmission (CoMP-JT), all using successive convex approximation (SCA) algorithms. However, these studiesfocus on signal processing and algorithm optimization and do not deeply explore network coverage model design. As a result, the sensing boundaries and coverage of a single base station in low-altitude scenarios remain unclear. [PERSON] et al. [14] proposed a radar sensing coverage model that comprehensively considers indicators such as range, field of view, and resolution. However, it only focuses on the radar independently and does not consider the integration of communication and sensing, making it difficult to support the complete coverage theory of low-altitude ISAC networks. [PERSON] et al. and [PERSON] et al. [6; 15] discussed the sensing coverage range and the general model in communication-sensing networks. However, their research focused on ground networks, and the feasibility and reliability of the model in low-altitude environments are questionable. In response to the abovementioned issues, our paper, through in-depth analysis of the vertical field of view (FOV) of base station antennas and the differences in cell radius and beam characteristics between communication and sensing, constructs a 3D sensing model for a single ISAC base station. This model accurately defines the sensing boundaries and range, provides a theoretical basis for the sensing capabilities of low-altitude networks, and fills the gap in the design of the key parameters for communication-sensing fusion. [PERSON] et al. [16] proposed a multi-base station (multi-BS) collaborative networking mode for UAV scenarios, but the content is insufficiently detailed, lacks specific modeling methods, and is unable to address the coverage issue at base station tower tops. [PERSON] et al. [17] designed a multi-BS integrated sensing and communication system for 6G macro-micro collaboration. Still, its coverage range calculation method is primarily targeted at ground networks and does not account for the specific characteristics of low-altitude environments. Several studies [18; 19; 20; 21; 22; 23; 24; 25; 26] analyzed low-altitude coverage issues from the communication perspective, such as by analyzing the impact of base station height, UAV altitude, and other parameters on coverage and validating the channel model through testing [18; 19]; by proposing 3D communication system models and new cellular structures [20; 21]; by improving cellular sector partitioning and 3D networking schemes [21; 22; 23; 24]; and by validating the feasibility of 5G low-altitude communication coverage [25; 26]. However, these studies do not consider the fusion of sensing capabilities, and their network solutions have low feasibility for large-scale commercialization. To address the coverage issue at base station tower tops, our paper proposes a multi-BS complementary coverage method and designs a 3D sensing-based cellular-like topology for low-altitude multi-BS networking, overcoming the limitations of traditional 2D network models. On the other hand, the existing research on the practical validation of ISAC fusion networks shows clear gaps, with most studies lacking real-world testing, leading to a disconnect between theory and actual application.