Configurable Multipath-Assisted Indoor Localization Using Active Relay

In this article, we use the principle of configurable multipath in the field of indoor localization. To validate it, we give a case study of a single AP-based indoor localization system. In the proposed system, we first model the wireless channel in the presence of the designed active relays. Then, we resolve multipaths using sparse recovery and then collaborate it with the maximum likelihood (ML). After that, a likelihood-based method is proposed to identify the paths that are used for assisting localization. We also propose a localization model with the hybrid measurements of the angle of arrival (AoA) and time of flight (ToF). Then, we give the design of the active relay, which has a simple all-analog circuit and is free of self-interference via creating isolation between transmitting and receiving channels. Finally, we implement the proposed system in various indoor environments with the designed AP and active relays. The experimental results show that the median errors of relative ranging and AoA are 0.5 m and 3.3°, respectively, and the median location error is 0.49 m with only one AP, which is comparable to the accuracy achieved by the systems using multiple APs.