WalkAround: Multipath-assisted Indoor Localization and Mapping Using a Single Receiver

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Multipath signals, which are suppressed in conventional localization algorithms, usually relate target location and structure of indoor environment through geometry parameters such as Angle of arrival (AOA) and Time of Flight (TOF). Thus, they can be exploited to locate the target and construct maps, which describe the structure topology of indoor environment. In this paper, we propose WalkAround, a multipath-assisted indoor localization and mapping system using the commodity WiFi signals, which contain phase errors caused by imperfect hardware and non-synchronized clocks. To realize accurate localization without interference of phase errors, we firstly construct a geometry model for jointly estimating the locations of target and scatterers which can be regarded as objects such as wall and furniture, by using TOF differences between the reflection paths and direct path. Then, with the help of AOAs we develop a locations searching algorithm based on Particle Swarm optimization (PSO). After that, we propose a density-based mapping algorithm with the locations of the scatterers and target, which does not need any anchor nodes or landmarks. We have implemented WalkAround in actual indoor environments by using the commodity WiFi devices. Based on the experiment results, the median location error of the target is 1. 49m and the constructed map matches the real structure topology of indoor environment well using only one receiver.