# An Overview of Indoor Positioning and Mapping Technology Standards
## 2 Related Work
### Standards for Indoor Positioning, Mapping and Navigation
#### 2.3.2 ISO TC204 ITS  
According to Mordor Intelligence [73], ITS is the application of sensing, analysis, control, and communications technologies in transportation in order to improve safety, mobility, and efficiency, and it refers to the advanced technologies that are being applied to vehicles, infrastructure, and operating systems, which make the vehicles intelligent. The intelligent transport systems market was valued at USD 22.88 billion in 2020, and it is expected to reach a value of USD 30.65 billion by 2026, at a CAGR of 5.11% over the forecast period (2021-2026) [73]. Thus, many ITS standards were developed by SDOs to satisfy the fast-growing ITS application and service requirements. Early in 2000, the Joint Program Office (JPO) of the U.S. Department of Transportation (DOT) asked the National Research Council's (NRC's) Transportation Research Board to undertake a review of JPO's ITS Standards Program [74] and the reviewers presented their views and shared their experiences with the ITS Standards Program.  
Since ITS is a very complicated ecosystem that comprises humans, vehicles, and the backbone network, many standardization bodies are continuously working on the development of standards and protocols that define how ITS components must communicate with one another [75]. [PERSON] [76] presented a detailed list of ITS standards that were developed before 2008, and his book can be used as a reference of standards in the ITS sector. Nevertheless, none of standards in the list was intended for the indoor space. With the spread of mobile devices such as smart phones, and consequently the massive demands of various indoor navigation-based applications, several indoor navigation standards for ITS have been published, including ISO 17438.  
The ISO 17438 standard provided the documents and the references required to support the implementation of indoor navigation, consisting of four parts under the general title Intelligent transport systems--Indoor navigation for personal and vehicle ITS station.  
The ISO 17438 Part 1 standard [77] specified the indoor navigation system architecture, use cases, and requirements in providing indoor navigation to various types of users. The architecture follows the existing ITS communication architecture with four additional components. The indoor data server component generates and provides indoor map data and indoor positioning reference data, the indoor data server registry component in the central ITS station manages metadata for indoor map data; the indoor positioning infrastructure component facilitates indoor localization; and the indoor navigation function module component in the P/V ITS station provides navigation functionality. Applications supporting indoor navigation for personal and vehicle ITS stations need to obtain indoor map data and positioning reference data.  
Parts 2 and 3 of ISO 17438 are under development. Part 2 is planned to specify requirements and specification for indoor map data format and Part 3 is to specify requirements and specification for indoor positioning references data format. Part 4 of ISO 17438 [13] defined use cases, requirements, and message specifications for supporting indoor navigation in intelligent transport systems.  
Besides ISO 17438, several ITS standards can also be used as a reference for indoor navigation applications and services. The ISO 17267:2009 standard [78] specified an application programming interface (API) for ITS navigation, including a set of function calls, access interface, the data that may be retrieved from the map database, and application examples. The ISO 14825:2011 standard [79], which specified the conceptual and logical data model and physical encoding formats for geographic databases for ITS applications and services, has been replaced by ISO 20524-1:2020 [80] and ISO 20524-2:2020 [81]. The GDF5.1 is an evolution of GDF5.0 that introduces the concept of sharable features, cooperative ITS and public transport. The data model and encoding formats may be adapted for indoor map data representation.