Benefit of Joint DOA and Delay Estimation with Application to Indoor Localization in WiFi and 5G

Accurate indoor localization has long been a challenging problem due to the presence of multipath. Joint direction-of-arrival (DOA) and time delay (TD) estimation is a promising technique for accurate indoor Localization in next generation WiFi and 5G, as it has the capability of separating the line-of-sight (LOS) signal from multipath signals in the TD space. Although the benefit of joint DOA and TD estimation over DOA-only estimation has been empirically shown long ago, it has not been theoretically justified yet. In this paper, we provide a theoretical proof of the benefit of joint DOA and TD estimation over DOA-only estimation. Further, experimental results with simulated WiFi setting have been provided to demonstrate the theoretical finding. Matlab code is available at \textbf{https://github.com/FWen/JADE.git}.