Exploiting Phase Difference of Arrival of V2X Signals for Pedestrian Positioning

Position information plays an important role in preventing pedestrian accidents by pedestrian-to-vehicle communication. But the computation of pedestrian position, based on GPS, may fail in urban canyons due to the obstruction of roadside building. This problem can be solved by using vehicles and roadside units as anchors for pedestrian positioning, where trilateration is used to compute pedestrian position based on distances to anchors. But the performance is degraded by multipath propagation and limited by the time resolution. To address this problem, in this paper, we investigate how phase information of OFDM signals in V2X communications varies with the propagation distance, and exploit the phase difference of arrival to estimate the distance difference. We study how to deal with the inter-symbol interference in OFDM symbols and combine multiple estimations of distance difference to improve the accuracy. Simulation evaluations by 3D ray-tracing confirm the effectiveness of the proposed method.