With the advancement of low-power and low-cost wireless technologies in the past few years, the Internet of Things (IoT) has been growing rapidly in numerous areas of Industry 4.0 and smart homes. With the development of many applications for the IoT, indoor localization, i.e., the capability to determine the physical location of people or devices, has become an important component of smart homes. Various wireless technologies have been used for indoor localization including WiFi, ultra-wideband (UWB), Bluetooth low energy (BLE), radio-frequency identification (RFID), and LoRa. The ability of low-cost long range (LoRa) radios for low-power and long-range communication has made this radio technology a suitable candidate for many indoor and outdoor IoT applications. Additionally, research studies have shown the feasibility of localization with LoRa radios. However, indoor localization with LoRa is not adequately explored at the home level, where the localization area is relatively smaller than offices and corporate buildings. In this study, we first explore the feasibility of ranging with LoRa. Then, we conduct experiments to demonstrate the capability of LoRa for accurate and precise indoor localization in a typical apartment setting. Our experimental results show that LoRa-based indoor localization has an accuracy better than 1.6 m in line-of-sight scenario and 3.2 m in extreme non-line-of-sight scenario with a precision better than 25 cm in all cases, without using any data filtering on the location estimates.

Off-site prefabrication is becoming widespread in the construction industry owing to quality, safety, and schedule benefits, but logistical costs are still among the largest barriers to adopting it. This study focuses on stacking plans, which encapsulate information on logistical processes, for prefabricated interior wall panels to identify logistical problems and their potential solutions. Due to the scarcity of reports on logistical problems in the construction industry, the authors studied operations research and defined two metrics, stability and reshuffling effort. From two case projects, the authors found that the stability and reshuffling effort of stacks were 47% and 44% on average, respectively, where it is desirable to achieve high stability and low reshuffling effort. The authors also identified three causes of the problems associated with unstable stacks and reshuffling effort: (1) inherent difficulty avoiding unstable stacks and reshuffling effort simultaneously due to the panel designs and their installation sequences; (2) ad hoc adjustments of priority between stack stability and reshuffling effort; and (3) incapability of consistently creating stacking plans on a Pareto optimal surface. Interviews showed that the problem related to unstable stacks and reshuffling effort and their causes are commonly found in construction projects that use prefabricated interior wall panels. To address these problems, one of the potential solutions identified is to develop a methodology to generate stacking plans on a Pareto optimal surface considering stack stability and reshuffling effort.