# Feasibility of LoRa for Smart Home Indoor Localization
## 1 Introduction  
A smart home is a dwelling that interconnects and manages intelligent devices to provide mutual functions of omnidirectional information to occupants [1]. Some applications of the smart home (e.g., health and sleep monitoring, surveillance, security) require a real-time indoor positioning of users, which is specifically important for Edlers and physically disabled people [2]. Furthermore, the localization allows intelligent devices not only to carry out basic tasks (e.g., home service robots) but also to execute complex commands, flexibly interacting with residents [3]. Thus, accurate indoor localization is an essential prerequisite of implementing an automated and convenient smart home environment. To select an appropriate localization technology for a smart home, the stakeholders should consider four aspects. First, indoor settings often reflect, diffract, and scatter the signals during the transmission and such signals decrease the accuracy of localization [4; 5]. Thus, the localization systems should be able to obtain the device locations under bothline-of-sight (LOS) and non-line-of-sight (NLOS) conditions accurately. Second, stakeholders for a smart home should consider the ranges of the signals of localization technologies. Technology with a broader range has better adaptability for various scenarios, and the broader reception range also reduces the number of anchor points [6]. The third aspect is the cost of localization technology. Since the consumers of the smart home are sensitive to prices, an affordable localization system increases the feasibility of smart home implementation [7]. The last aspect is energy efficiency [8; 9]. The property of high energy efficiency extends device battery life, reduces the cost, and more accessible for end-users. Tag-based localization techniques rely on at least three static anchors to estimate the position of a dynamically moving tag. However, due to walls, furniture, and heavy electronic devices (e.g., refrigerator, television) blocking the signals, it is highly challenging to ensure the minimum number of anchors continuously communicates with tags in a smart home. Several technologies have been applied in the indoor localization of smart homes. The Global Positioning System (GPS) [10] is the most pervasive outdoor localization system, while it is unavailable for smart home localization. Since the surface in the building blocks and reflects GPS signals, this phenomenon makes the GPS signal too weak to work accurately inside of buildings [11]. Several tag-based localization technologies have been applied in the indoor localization of smart homes including passive radio-frequency identification (RFID), active RFID, ultra-wideband (UWB), Bluetooth low energy (BLE), and low range (LoRa). With the introduction of radio communication technologies, various affordable sensing techniques, such as RFID system, have provided a good opportunity for indoor localization services [12; 13; 14; 15; 16; 17]. The existing RFID localization techniques can be categorized into two types: tag and antenna localization. The tag is attached to tracked objects in the tag localization technique, while multiple antennas are installed at known locations in the indoor environment [12; 18]. Moreover, the antenna localization technique tracks RFID antennas' position, which is equipped to moving objects, and tags are installed in the underlying place. In both cases, dynamically moving objects' locations can be estimated based on received signal strength between tags and antennas converted to distance [19]. However, the RFID positioning systems with a high-level accuracy require installing a significant number of tags or antennas in the room [15]. Compared with the RFID system, the UWB system, which transmits ultra-short pulses over a large bandwidth (>500 MHz), could correct to a few centimeters [20]. However, the limitation of UWB localization systems is its poor performance under NLOS conditions that commonly exist in residential buildings with walls and furniture [21].