PPP Performance with Large TEC Gradient and Mitigation Methods

During high-level solar activity time, frequent ionospheric irregularities lead to large total electron content (TEC) gradient. precise point positioning (PPP) performance can be significantly degraded under the unfavorable ionosphere conditions. We analyze the causes and effects of the ionosphere potential impacts on uncombined PPP (UPPP) performance in terms of the ionospheric stochastic model, blunders, and frequent cycle slips. Results show that a large enough stochastic variance is beneficial for better positioning solutions; blunders detection could improve the accuracy; a proper threshold to detect cycle slips could improve the accuracy significantly. Taking these effects into consideration, we can achieve a centimeter accuracy at each direction under the disturbed ionosphere conditions.