Method and system for determining the position of a mobile terminal in a CDMA mobile communications system

US6134228A · kind A · utility

Assignee

• Telefonaktiebolaget LM Ericsson (Publ) · SE

Inventors

• Mats Cedervall · Bissenkamp, SE
• Karim Jamal · Stockholm, SE

Key dates

• Filing date: Dec 12, 1997
• Grant date: Oct 17, 2000
• Expiry date: Dec 12, 2017

Classification

• Technology area (CPC G): Physics
• CPC primary: G01S5/02
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A method and system for use in determining the position of a mobile terminal in a CDMA mobile communications system is disclosed, whereby a different than usual spreading code is used when TOA measurements are being performed, but information is allowed to be transmitted while those TOA measurements are being performed. In one embodiment, the length of the different spreading codes used is equal to one symbol length. In a second embodiment, a mobile terminal uses a long spreading code and short spreading code prior to making TOA measurements. When TOA measurements are to be made, the serving base station orders the mobile terminal to change the spreading code by terminating the use of the long code and continuing use of the short code. Alternatively, when the TOA measurements are to be made, the serving base station orders the mobile terminal to substitute a second, predetermined short code for the long code being used, and to continue use of the first short code. The TOA measurements are then performed in at least three base stations, and the position of the mobile terminal is derived from this TOA information. The serving base station then orders the mobile terminal to resume nor…