# A Method for Managing ADS-B Data Based on a 4D Airspace-Temporal Grid (GeoSOT-AS)
## 3 A 4D Airspace-Temporal Grid Framework (GeoSOT-AS) for ADS-B Data Organization  
The 2\({}^{\text{n}}\) one-dimensional integer global subdivision grid with one-dimension-integer on two to \(n\)th power (GeoSOT) [39] proposed by the Peking University team is a latitude and longitude subdivision grid system. GeoSOT subdivision grids and codes are advantageous for their global uniqueness, multiscale, and flexible extension, etc. The grid codes are controlled by the number of bits [40], which are sufficient to accurately represent spatial information of arbitrary location and size, while maintaining characteristics of small deformation, multiscale, simple subdivision, rapid computational processing, etc., and are used in a variety of spatial information organization fields [41].  
This section investigates the application of the earth segmentation principle corresponding to the Chinese specification of civil aeronautical charting. Meanwhile we try to reshape the airspace grid coding model and establish the airspace spatial location coding identification system and aims to form a discrete grid framework designed for air traffic management, ADS-B, and other kinds of flight information elements. The redesigned airspace grid segmentation and coding methods must adhere to the following requirements:  
1. Partial grid flattening: For large aircraft with fast flight speeds in the horizontal direction and slow climbing speeds, the grid must be switched flexibly according to the specific application requirements and cannot be strictly polygonal. Therefore, during design, the height and planar dimensional grids are decoupled and treated independently;
2. Code identification uniqueness: One identification code corresponds to only one grid under the same hierarchy;
3. The height required to reach adjacent space.  
In response to the above constraints, based on the original GeoSOT geo-profile method, and in line with the Chinese specification of civil aeronautical charting, the profile method was redrawn to make it applicable to airspace element information management, while accounting for the temporal dimension. The airspace grid coding model was defined in the airspace based on latitude and longitude coordinates by treating the plane and altitude dimensions, as well as the time dimension separately in an approach termed here as GeoSOT-AS (airspace), a multi-level 4D airspace-temporal grid framework for the ADS-B data organization.  
GeoSOT-AS has been designed with a spatial plane, altitude, and a temporal dimension, resulting in a decadal dissection in the latitude and longitude directions, extending from degree to second level regions, a multiscale division in the altitude direction from a base 150 m stratification to the adjacent space (covering the base flight altitude stratification), and a temporal dimension (days to seconds), with each of these three elements described by specific codes. In the GeoSOT-AS architecture, any moment in time in the Earth's airspace can be expressed by the following Equation (1):  
\[\begin{split} G=&<P,H,T>_{code}\\ s.t.& P=f_{i}(Lat,Lon)\,\\ & H=f_{j}(h)\,\\ & T=f_{k}(t),\end{split} \tag{1}\]where \(P\), \(H\), and \(T\) represent discrete codes in profile form; and \(f_{i}\), \(f_{j}\),\(f_{k}\) correspond to the specific conversion forms and coding methods for latitude, longitude, altitude and time of the plane, respectively. The specific coding design conversion and coding methods are described below.