RTT Positioning in WCDMA

The paper presents the details of a round trip time (RTT) positioning algorithm that provides a largely improved accuracy as compared to cell ID positioning - yet with an availability above 95% and a typical response time below 0.3 s. The algorithm fuses an RTT measurement with configured or computed cell polygon data, in order to determine an arc with left and right angles, and with the distance from the serving radio base station (RBS) determined by the RTT measurement. Reasons are given why this is an almost as accurate and a more cost efficient method, as compared to multi-leg RTT positioning. An overview of the obtained field performance is also provided.