# Feasibility of LoRa for Smart Home Indoor Localization
## 2 Literature Review
### Radio Frequency Identification Device (RFID)  
The passive RFID is a low-cost location-sensing technique. The passive tags reflect and modulate the radio frequency signal emitted from readers to realize the localization. Nevertheless, passive tags can run without a battery; simultaneously, it has a limited applicable range. [PERSON] et al. [48; 49; 50] tracked the localization of a mobile robot \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Technology** & **Applications** & **Pros** & **Cons** \\ \hline \multirow{4}{*}{Passive RFID} & Working location tracking [30] & & Short reception range \\  & Material tracking [31; 32] & Cheap tags & Low accuracy \\  & Mobile robot’s self-localization [33] & High energy efficiency & Need a great amount of tags \\  & Activity recognition and assistance [14] & & or antennas \\ \hline \multirow{4}{*}{Active RFID} & Material tracking [17] & & Expensive tags \\  & Robot interaction with smart objects [34] & & Low accuracy \\  & User position tracking [16] & & Lower portability \\  & Misplaced object positioning [35] & & \\ \hline \multirow{4}{*}{BLE} & Worker location tracking [36] & & \\  & Worker-equipment proximity detection & Long reception range & High susceptibility of other \\  & [37] & Low energy consumption & signals \\ \cline{1-1}  & Residential activity labelling [38] & High acceptance & High packet-drop rate \\ \cline{1-1}  & Indoor localization in the smart home & Low cost of infrastructure & High packet-drop rate \\ \cline{1-1}  & [39; 40] & & \\ \hline \multirow{4}{*}{UWB} & Worker location tracking [41; 42] & & \\ \cline{1-1}  & Equipment tracking [43] & High accuracy of & Short reception range \\ \cline{1-1}  & User location-based adjustment of & localizationImmune to & High cost of infrastructure \\ \cline{1-1}  & home-entertainment applications [44] & & \\ \cline{1-1}  & Accurate indoor localization [45] & & \\ \hline \multirow{4}{*}{LoRa} & Outdoor localization [33; 46; 47] & Long reception range & \\ \cline{1-1}  & Not applied in construction & Low cost & Unexplored \\ \cline{1-1}  & Not applied in construction & High energy efficiency & \\ \cline{1-1}  & Penetration & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Summary of sensing technologies applicable in smart home localization. with RFID antennas using an RSSI fingerprinting method. This study requires a training phase that involves the collection of RSSI data from tags and matching of the RSSI vectors to locations. Though centimeter-level accuracy was reported, this approach relies on RSSI-based training when the space configuration changes. In smart home applications, slight changes in configurations (e.g., moving furniture, tables) would lead to fingerprints changes and the need for frequent training. [PERSON] et al. [51] also introduced a learning-based localization method with passive RFID technology to provide a position for mobile robots. The RFID system used Support Vector Machine (SVM) to construct classifiers to model the features of localization problems. However, the experiment does not consider the signal blocking caused by general building elements. The improved experimental results were calculated under the LOS conditions, which cannot correctly reflect the accuracy of indoor localization for real-world implementation. [PERSON] et al. [16] constructed a prototype that uses the passive RFID system for localization and navigation of a light-weight robot in the smart home environment. In this prototype, most sensing tags can be installed in the environment, and the service robot is equipped with an RFID antenna for object recognition and object handling for localization. Although a smart environment was developed, lightweight robots' performance (e.g., accuracy, applicable range, reliability) has not been tested or validated in this study. Furthermore, tracking an antenna may not be a universal solution for smart home applications that need to track the locations of people or small objects. The active RFID consists of readers and active tags.