Analysis and Modelling GPS NLOS effect in Highly Urbanized Area | IPNL — Intelligent Positioning and Navigation Laboratory

Hsu L. T.

GPS Solutions (2018)

journal Q1

Aerial views distinguishing multipath — a reflected copy interfering with a received direct signal — from NLOS, where only the reflection arrives because the direct path is blocked.

Key idea. Multipath and NLOS are different errors (figure): multipath is a reflection interfering with a direct signal that still arrives; NLOS means only the reflection arrives. The paper analyzes and models the NLOS pseudorange error observed in a highly urbanized area.

Why it matters. NLOS is the dominant and hardest-to-fix GNSS error in dense cities. Understanding and modeling it — rather than lumping it in with multipath — is the prerequisite for correcting it. (GPS Solutions, 2018, Q1.)