Ismo Halivaara

On the feasibility of adding carrier phase –assistance to cellular GNSS assistance standards

The 3GPP (Third Generation Partnership Project) Release 7 of GSM and UMTS cellular standards as well as SUPL2.0, used in IP networks, include major modifications as to how AGNSS (Assisted GNSS) assistance data is transferred from the network (cellular or IP) to the cellular terminal. Simultaneously position accuracy improvements may be introduced. One potential option is to use carrier phase -based positioning methods. This can be achieved integrally in the cellular network or by the use of Virtual Reference Stations and an IP network. The bulk of AGNSS devices will be singlefrequency due to additional cost associated with two RF front-ends. Hence, this study addresses the feasibility of single-frequency carrier phase-based positioning, making comparison with the dual-frequency case. The study shows that single-frequency carrier phase –based positioning is feasible with short baselines (<5 km) given that: 1) real-time ionospheric predictions are available and 2) there are enough satellites available. Namely, this requires hybrid-use of GPS and Galileo.