# A Heterogeneous Battlefield Situation Information Sharing Method Based on Content
## Sharing Framework of Heterogeneous Battlefield Situation Information
### Heterogeneous Information Sharing Framework Based on Unified Information Space  
As shown in Figure 3, at any time \(t\), each instance of the entity space, consisting of information from combat systems, can be viewed as a local battlefield information space (BSIS). Each BSIS describes a portion of the entire battlefield space, and they have both overlaps and differences with respect to the scope, as well as the content of the battlefield space described. On this condition, take entities as the basic units of information organization; the decentralized information transmitted in different systems can be organized and integrated. Meanwhile, a more comprehensive and complete information collection describing battlefield information, which is called the unified battlefield situation information space (UBSIS), can be obtained.  
Based on UBSIS, a single system can capture more battlefield situation information than before, so that the system functions can be more effectively performed and more effective information services can be provided for combat units within the system. For example, the misjudgment of friend or foe, which is caused by possible errors in the identification algorithm and incomplete target information in a single system, can be reduced. Besides, commanders and other combat units can form a consistent understanding and cognition of the current battlefield situation based on the unified information space, which is conducive to provide better information support for distributed decision-making and to improve the effectiveness of joint operations. For example, when a commander makes a decision to attack a target, every combat unit in different systems can exactly know what and where the target is just as the commander knows and take corresponding action, which will improve the efficiency of the operation.  
Figure 3: Flow of information based on the unified information space.  
Moreover, different combat units may need information about different aspects of the same target when they execute different missions. For example, when the senior commander makes a decision to attack a target, e.g., a command post, he/she may just need to know where the command post is; while the subordinate commander and combat units executing this mission need to know more detailed information, such as what is the surrounding environment near the command post, how many troops there are and their combat capability, etc. As the UBSIS can be viewed as a complete collection of information that describes the battlefield situation at a given moment, each combat unit can obtain the information on demand, which will be useful for realizing the distribution of information according to needs.  
Based on the above analysis, we designed a layered heterogeneous information sharing framework, which is shown in Figure 4. The information transmission layer is mainly used to complete the generation and transmission of messages in each combat information system. It is the main body to realize transmission access, link control and data control, which provides control support and data transfer services to the upper level. The information presentation layer is used to realize the mapping between the proprietary message encoding format and the general information description format. The information sharing layer is mainly used to maintain the unified battlefield situation information space, which is shared by all combat units, and realize information query and information distribution.  
To realize effective information sharing based on the proposed framework, we focused on the general description of heterogeneous information, the construction method of the unified battlefield situation information space, and the content based query mechanism.