# An Overview of Indoor Positioning and Mapping Technology Standards
## 2 Related Work
### Indoor Positioning Technologies  
Since there are numerous indoor positioning techniques and technologies, it is hard to present a complete survey covering all existing and emerging technologies. Numerous surveys on indoor positioning principals, approaches, methods, systems, solutions, platforms, classifications, evaluations, comparisons, challenges, and future potential directions can found in the literature [5, 6, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23]. [PERSON] et al. [14] present an attractive survey of indoor positioning and navigation systems observed from literature, and they propose an overview of positioning algorithms, techniques, and technologies as shown in Figure 1. The technologies discussed include infrared (IR), ultrasound/ultrasonic, audible sound, magnetic, optical and vision, radio frequency (RF), visible light, pedestrian dead reckoning (PDR)/inertial navigation system (INS) and hybrid. The RF technologies discussed include Bluetooth, ultra-wideband (UWB), wireless sensor network (WSN), wireless local area network (WLAN), radio-frequency identification (RFID), and near field communication (NFC). The authors analyzed the pros and cons of the positioning technologies according to metrics such as accuracy, complexity, cost, privacy, scalability, and usability. However, the survey needs to be updated to cover the most recent and relevant technologies since IPSs are a rapidly evolving area. For example, the arrival of 5G, IoT, and AI as well as big data have taken indoor positioning to a new level. Therefore, we reference their classification of indoor positioning technologies as an overview of existing technologies and a guidance for indoor positioning related applications. Indoor positioning technologies can be classified in different ways. According to [12], localization systems are roughly divided into active and passive systems, where active systems require tracked persons to participate actively, i.e., a person needs to carry an electronic device which sends information to a positioning system helping it to infer that person's position. In contrast, passive systems use passive localization, that is, the position is estimated based on the variance of a measured signal or video process, which means the tracked person is not carrying any electronic devices to infer the user's position. Based on previous surveys on indoor positioning systems, [PERSON] et al. [15] provide a comparison of nearly 28 technologies, which are categorized into optical (infrared, visible light communication), sound-based (ultrasound, audible sound), radio frequency (Wi-Fi, Bluetooth, ZigBee, RFID, UWB), passive/without embedded information (magnetic field, inertial, passive sound-based, passive visible light, computer vision), and hybrid technologies. The paper aims to present the evolution and trends of indoor positioning fields. Most of the technologies are partly discussed in [14] from a different viewpoint. [PERSON] et al. [16] present a classification of localization methods based on positioning algorithms and measurement techniques. [PERSON] et al. [17] propose a hierarchical classification of indoor navigation systems; and, the first level is grouped into computer vision-based, communication-based,  
Figure 1: Classification of indoor positioning techniques and technologies [14]. and PDR-based navigation systems, where communication-based wayfinding systems are sub-grouped into RFID, Wi-Fi, visible light communication (VLC), UWB, and Bluetooth technologies. Most surveys present limitations and strengths analyses, performance evaluations, comparisons of various heterogenous technologies and systems, as well as challenges, opportunities and future research directions in this field. From the indoor positioning device perspective, [PERSON] et al.