# A Heterogeneous Battlefield Situation Information Sharing Method Based on Content
## Sharing Framework of Heterogeneous Battlefield Situation Information
### Entity Oriented Formal Representation of the Battlefield Situation  
To simulate combat units effectively, we adopted the entity oriented method, and entities were used to represent the independently identifiable, tangible geographical targets, combat units, and intangible concepts, such as mission or event, associated with combat operations. As shown in Figure 2, if we regard the physical space, i.e., the battlefield space, as a real space, and the information space composed of information describing the physical space as a virtual space, then we can take the entity in the virtual space as the mirror image of the corresponding target unit in the real space. A mapping relationship between entities and target units can be constructed. Then, the description information of entities in virtual space can correspondingly reflect the aspects such as the attributes or states of the target units in real space. Thus, we propose the concept of entity space, which is used to model the physical space. Figure 1: Multiple combat units with different information systems in the battlefield space. **Definition 1** (entity space). : _Suppose ES(t) = (E, \(C_{\text{EC}}\), \(A\), \(S\), \(R\), \(V\), F, t); where E represents the complete set of entities in the entity space; \(C_{\text{EC}}\) represents the collection of entity classes, which reflects the unary relationship of entities themselves in the entity space; \(A\) describes the attributes of entities; S describes the possible states of entities; R describes the possible semantic relationships, which can be viewed as binary relationships among entities; V represents the domain set of \(A\) and \(S\), while \(V=V_{A}\cup V_{S}\), and \(V_{A}=U_{a\in A}V_{a}\wedge V_{S}=U_{s\in S}V_{s}\) is satisfied, where \(V_{a}\) represents the domain of attribute a and \(V_{s}\) represents the domain of state s; F represents the set of unary or pluralistic relational mappings from \(A\) to \(S\)._  
Suppose that in system **A**, the number of attributes possessed by entity \(e_{i}\) is \(k\), and the number of state variables used to describe eis \(m\). Denote the value of the \(j\)th attribute variable at time \(t_{i}\) as \(a_{ij}(t_{i})\) and the value of the kth state variable at time \(t\) as \(s_{ik}(t_{i})\). Then, the state set of \(e_{i}\) at time \(t_{i}\) can be described as:  
\[S_{i}\left(t_{i}\right)=\left\{s_{i1}\left(t_{i}\right),s_{i1}\left(t_{i} \right)\ldots,s_{im}\left(t_{i}\right)\left|m\in\textbf{N}\right\}=f_{i}\left( a_{i1}\left(t_{i}\right),a_{i2}\left(t_{i}\right),\ldots,a_{ik}\left(t_{i} \right)\right) \tag{1}\]  
where \(f_{i}\) is a kind of relational mapping in \(F\). If the information of categories, attributes, and states of each entity in \(E\), as well as the information of relationships among entities are clarified, then an instance of \(ES\) can be obtained, which is denoted as \(IS_{A}(ES(t_{i}))\). It reflects the state of the real battlefield situation at time \(t_{i}\). At any time \(t\), the information in each information system describes an instance of the entity space respectively, where the instance of the entity space constructed based on the ith system is denoted as \(IS_{i}(ES(t_{i}))\). These instances correspondingly reflect an overall observable state of the battlefield space at that time, respectively. However, due to the different application requirements and information acquisition capabilities of different systems, the information of a single system usually describes some aspects of the physical space, but cannot describe the whole battlefield space; for example, as the reconnaissance scope and capability of reconnaissance equipment in a single system are limited, while various anti-reconnaissance means such as camouflage and interference are usually adopted by target combat units. Only partial attribute information of some external targets in a certain local area of the entire combat area can be obtained by the reconnaissance equipment.