Mitigation of Ionospheric Effect on Multi-GNSS Positioning with Ionosphere Delay Estimation Using Single-Frequency Measurements of Selected Satellites

Abstract

Ionosphere delay is the largest source of positioning error for single point positioning using single-frequency receiver of global navigation satellite system (GNSS). To mitigate the effect of ionosphere which varies sometimes rapidly and locally due to the solar activity, we propose estimating the ionosphere delay in the process of positioning calculation by using the ionospheric thin shell model with single-frequency pseudorange measurement of single epoch. Since sufficient number of visible satellites is observable for multi-GNSS positioning, all those measurements are not necessarily used. We propose algorithm of selecting useful satellites by the residual ranging error of pseudorange measurement to mitigate the positioning error. The performance evaluation for proposed selection algorithm and ionosphere delay estimation was conducted by using L1 pseudorange measurements of global positioning system (GPS) and GLONASS on both quiet and disturbed ionospheric conditions. Proposed selection algorithm reduced the rms of horizontal positioning error by about 10% on disturbed condition. Proposed ionosphere delay estimation increased the average of horizontal error reduction by 30% in daytime on disturbed condition, compared with the conventional correction method using Klobuchar model.