Differential received power measurements over off-body links for obstruction-resilient pedestrian navigation

Abstract

Abstract In this paper, we aim at improving pedestrian navigation experience based on standard narrow-band wireless technologies and simple radio metrics. The proposed solution takes benefits from body shadowing effects traditionally experienced at body-worn devices, for instance over off-body radio links with respect to fixed elements of infrastructure. The main idea is to infer relative angular information between the carrying body's heading and the received signal's direction of arrival. For this purpose, we consider differential received power measurements with judiciously placed on-body nodes. In comparison with related state-of-the-art contributions, a much lighter on-the-fly self-calibration procedure is made possible, based on the full-scale dynamics of the observed power measurements. We also describe a new algorithm that jointly estimates the body's absolute position and orientation, while benefiting from the body's movement continuity over time. The overall solution is validated by means of field experiments with IEEE 802.15.4-compliant devices operating at 2.4 GHz. Overall, the system is shown to be resilient, not only against self-shadowing effects generated by carrying bodies, but also against occasional obstructions caused by moving pedestrians in the vicinity (e.g., in crowded environments).