# Robust Bluetooth AoA Estimation for Indoor Localization Using Particle Filter Fusion
## 5 Conclusions  
Some of the attractive advantages of PF include its generality and ability to handle multimodal probability distributions and nonlinear functions. The system incorporates  
Figure 8: Variation in RMSE with signal-to-noise ratio and with the number of snapshots. (**a**) Variation in RMSE with signal-to-noise ratio. (**b**) Variation in RMSE with the number of snapshots.  
Figure 9: The cumulative error distribution curves of three algorithms.  
mvdr, a robust AoA estimation algorithm with a priori knowledge of the target's motion model, into the probabilistic framework of the PF to achieve localization of a moving target. The system is first modeled from the target's state equations as well as the observation equations. Through the system model, the target object's behavioral information and the signal source's transient information are combined to overcome the defects of the traditional DoA algorithm that only localizes the fixed signal source. Then, to reasonably calculate the weights of the particles and reduce the particle scarcity, a particle filtering weight calculation function based on the Gaussian function is designed to resample the function. The effectiveness of the algorithm is verified through simulation. It is verified that the algorithm can realize the tracking navigation of the target and is strongly robust to the nonlinear model of the moving target.  
Although the algorithm's feasibility is demonstrated through MATLAB simulation in this article, there are still several shortcomings in the algorithm's research when compared to real-world conditions. There are numerous issues that need to be addressed in the future. The article outlines the future research directions as follows:  
(1) In this paper, a particle filter-based algorithm for mobile target Bluetooth AoA navigation and tracking is proposed to address the challenge of tracking the movable trajectory of the target. It recognizes that coherent signal sources can interfere with Bluetooth AoA navigation and tracking technology. Therefore, it suggests that future work should consider the impact of coherent signals on the algorithm and propose effective methods to address this issue.  
(2) Additionally, the paper examines the relationship between the spatial coordinates of the target object and its directional angle in space. It constructs a typical motion navigation trajectory for the target object and verifies the navigation and tracking algorithm through simulations in typical scenarios. Although the results demonstrate basic navigation and tracking of the target trajectory, the algorithm's performance is less than satisfactory when the directional trajectory of the target object undergoes significant changes.  
(3) When designing the particle filter-based mobile target Bluetooth AoA navigation tracking algorithm, it is assumed that the signal of a single target object exists. However, there is insufficient research on effectively extracting valid data when there are multiple targets, and real experimental verification is lacking. Real-world scenarios present more influencing factors compared to simulation scenarios, thus potentially affecting the algorithm in unexplored ways. To enhance the algorithm's robustness, it is essential to incorporate more influencing factors and carry out real experimental tests.  
Conceptualization, R.C.; methodology, K.Q.; software, K.Q.; validation, R.C.; formal analysis, K.Q.; investigation, W.L.; resources, G.G.; data curation, K.Q.; writing--original draft preparation, K.Q.; writing--review and editing, Y.W.; visualization, Y.W.; supervision, G.G.; project administration, G.G.; funding acquisition, R.C. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the NSFC (grant no. 42201460) and the National Key Research and Development Program of China (grant nos. 2023 YFB3906600).  
Not applicable.  
Data Availability Statement: Data is unavailable due to privacy.  
The authors declare no conflicts of interest.