# UWB-Based Real-Time Indoor Positioning Systems: A Comprehensive Review  
[PERSON]  
1 Center for Life Science Automation (Celisca), University of Rostock, 18119 Rostock, Germany; [EMAIL_ADDRESS] or [EMAIL_ADDRESS] (M.F.R.A.-O. ); [EMAIL_ADDRESS] (K.T. )1 Center for Life Science Automation (Celisca), University of Rostock, 18119 Rostock, Germany; thomas.roddelkopf@uni-rostock.de1 Center for Life Science Automation (Celisca), University of Rostock, 18119 Rostock, Germany; [EMAIL_ADDRESS] or [EMAIL_ADDRESS]u.iq (M.F.R.A.-O. ); [EMAIL_ADDRESS] (K.T. )1 Center for Life Science Automation (Celisca), University of Rostock, 18119 Rostock, Germany; thomas.roddelkopf@uni-rostock.de1 Center for Life Science Automation (Celisca), University of Rostock, 18119 Rostock, Germany; thomas. The concept of indoor positioning systems, which represent the second type of positioning systems, has evolved with the development of devices and equipment operating with Internet of Things technologies. IoT solutions have provided the possibility of carrying out these complex tasks with high efficiency and reliability. The idea of developing indoor positioning systems emerged due to the inability of the Global Navigation Satellite System to track and determine the location of objects inside buildings. This results from the attenuation of signals sent and received, due to the walls of buildings, as well as the large margin of error of several meters. This makes the use of these techniques impractical due to low accuracy, as some applications inside buildings require high accuracy and an error rate that does not exceed several centimeters [1]. The attractiveness of the topic of developing indoor positioning systems has prompted many researchers and companies to develop different feasible solutions to achieve this goal. The proposed solutions rely on the use of available IoT-based technologies such as Bluetooth Low Energy [2], Wi-Fi [3], ultra-wideband technology [4], vision-based techniques [5], acoustic waves [6], radio frequency identification (RFID) [7], and others. Choosing the appropriate IPS for determining object locations in indoor environments depends primarily on the nature of the place to be covered, in terms of area, and the presence of obstacles such as walls and furniture. The nature of an open space such as a warehouse or stadium differs from that of inhabited buildings such as laboratories and residences, which contain narrow corridors and large amounts of furniture (obstacles). The choice also depends on the type of application, the required accuracy, the speed of updating data, and the cost allocated for implementation. In this work, a deep and focused search was conducted in the literature to review research articles, conference papers, book chapters, and studies carried out practically for finding the positioning and tracking the motion of objects using ultra-wideband technology, as this is considered to be one of the best solutions currently available. Unlike other radio frequency waves (RF), Wi-Fi, and Bluetooth, the ultra-wideband waves are characterized by enabling accurate measurement of the time of flight between its units and, thus, the possibility of accurate measurement of distance, direction, and location determination with a relatively small margin of error compared to other RF waves. Ultra-wideband waves have a much larger bandwidth than narrowband waves. This results in ultra-wideband waves having a very short wavelength, enabling the temporal accuracy to be very high, which is reflected in high accuracy in measuring time of flight and also contributes to improving the resistance to multipath interferences and fading. Furthermore, the large bandwidth and low propagation time make the use of ultra-wideband waves ideal for real-time systems, especially those that require a quicker response time, as they are about 50 times faster than GPS systems and hundreds of times faster than traditional Bluetooth systems.