Improvement of positioning accuracy by rotating and switching GNSS antenna in multipath environment

Abstract

The use of GNSS(Global Navigation Satellite System) has become common worldwide. However, in urban environment, the positioning accuracy of GNSS is lowered by the effect of multipath. There are two types of multipath, LOS multipath and NLOS multipath, and effective countermeasures are required for both. We propose a method using a rotating antenna or antenna switching. The arrival direction of the satellite signal is obtained from the doppler shift generated with the movement of the antenna. Then, the direction of arrival of the signal and the arrangement of the satellite are compared to judge the NLOS, and reject from the positioning calculation. The effect of LOS multipath is averaged by moving the antenna. As an experimental equipment, in the rotating antenna technique, GNSS antenna and receiver are mounted on the rotating arm. In the antenna switching technique, multiple GNSS antennas are switched by elements. By using this technique, the positioning rate of the rotating antenna increased from 0.23% to 100%. In another test, the positioning rate increased from 40.74% to 93.86% using the switching antenna.