Assessment of Direct Position Estimation Performance in Multipath Channels

Multipath signal is the satellite signal that is delayed due to the reflection or diffraction off various obstacles or surfaces and thus endangers the leverage of signal under Line-of-Sight model. Multipath error is one of the most important error sources in Global navigation satellite system and many advanced tracking, filtering and classifying techniques are developed in past decades to better understand and mitigate the multipath effect. Direct Position Estimation (DPE), which is a novel positioning technique, has its potential to resist the multipath due to its early combination of the satellite information and operation in the navigation domain without estimating intermediate variables. This paper analyzes and assesses the DPE positioning performance under multipath environments. The multipath error envelope, as an important tool to understand the multipath error functioning, is computed and plotted to appeal the relation between the multipath error and positioning error. The multipath channel model, developed by the German Aerospace Center (DLR) in the ITU-R P.681 recommendation, is used to simulate realistic multipath scenarios and evaluate the DPE positioning performance. It is shown that in all simulations of multipath environments, the DPE approach outperforms the traditional two-step method in terms of precision.