# UWB-Based Real-Time Indoor Positioning Systems: A Comprehensive Review
## 6 Results  
The works selected for this review were investigated for several factors to ensure that they served the purpose of our work, which was to facilitate the study and selection of real-time indoor tracking and positioning systems operating with ultra-wideband technology. The first factor was suitability for the indoor environment. This point is essential because of the limited number of systems that operate efficiently in indoor environments, due to the difficulty of UWB wave transmission between IPS units without passing through the obstacles that are a feature of these places, such as walls, furniture, doors, windows, etc. The second factor that we emphasized was the possibility of using the selected works to track moving objects such as robots, drones, etc., as well as the ease of integrating them with these platforms. The third factor that we focused on was the ability of the selected works to display the location of the objects to be tracked, whether using user graphical interfaces, modeling software, or any programs that can be used to monitor moving objects in real time. We summarized the topology and ranging technique, the used UWB chip/module, the used sensors (hybrid), the used UWB frequency, the optimization algorithm/filter, the application, the performance improvement, the system positioning accuracy, the monitoring program/software, and the work reference number and year of the included IPSs/RTLSs, as shown in Table 3. \begin{table}
\begin{tabular}{p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt}} \hline \hline
**Topology** & **UWB Chip/Module** & **Multi-Sensor Channel** & **UWB Frequency/ Channel** & **Optimization Algorithm/Filter** & **Application Accuracy (cm)** & **Improvement Accuracy (cm)** & **Monitoring No, Year** \\ \hline SS-TWR & DW1000 & UWB & 5 GHz & KF, PF & IPS & 13 cm & MATLAB & [79], 2023 \\ \hline DS-TWR & DW3000 & UWB & 6.5 GHz, CH5 & Tilitation, LSM & IPS, Robotic & 50 cm & Python & [80], 2024 \\ \hline SS-TWR & DW1000 & UWB & 3.5-6.5 GHz & Tilitation & IPS & 14 cm & Custom & [81], 2020 \\ \hline DS-TWR & DW1000 & UWB & 3.5-6.5 GHz & KF & IPS & 8\% & Custom & [82], 2021 \\ \hline TWR & DW1000 & UWB+IMU & 3.5-6.5 GHz & DUKF, RMSE & IPS & 6 cm & MATLAB & [83], 2024 \\ \hline AltDS-TWR, TDA & DW-EVK1000 & UWB & 3.5-6.5 GHz & Multilateration & IPS & - & Custom & [84], 2020 \\ \hline SDS-TWR, AltDS-TWR & ElikoUWB-RTLS & UWB & 3.5-6.5 GHz & Active-passive method & RTTS & 20\% & R Language & [85], 2022 \\ \hline TWR & Wi-Pos UWB & UWB & CH5, 6.5 GHz & KF & IPS & 50\%, 15 cm & Custom & [86], 2024 \\ \hline TDA & DW1000 & UWB & 3.5-6.5 GHz & Tilitation & RTTS & 9 cm & Web-based application & [98], 2022 \\ \hline TDA & DW1000 & UWB & 3.5-6.5 GHz & Taylor algorithm & IPS & 10 cm & Custom & [99], 2022 \\ \hline TDA & DW1000 & UWB & 3.5-6.5 GHz & LSTM, DeepTAL & IPS & 20 cm & Custom & [100], 2019 \\ \hline TWR, TDA & DW3000 & UWB & CH5, 6.5 GHz & EKF & IPS & 38\%, 22 cm & Custom & [103], 2023 \\ \hline TDA & Custom & IR, UWB & 7.25 GHz & Multilateration, median, mean F. & RTLS & 10 cm & Custom & [104], 2021 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Summary of selected IPSs. \begin{table}
\begin{tabular}{p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt}} \hline \hline