Method and apparatus for a portable communication device to identify its own location
US5900838A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 7, 1997 |
| Grant date | May 4, 1999 |
| Priority date | — |
| Expiry date | Jul 7, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01Q3/22
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method and apparatus for a portable communication device, such as a mobile radio terminal in a CDMA network, to identify its geographic location. A communication network comprises multiple base stations which transmit pilot signals, where the pilot signals of one base station are offset from the pilot signals of other base stations by integral multiples of a substantially fixed duration. Associated sync channel messages are also transmitted from which the geographic location of the base stations may be extracted. A portable communication device identifies its location by calculating the delay between the arrival time of a pilot signal from a primary base station and the arrival times of pilot signals from at least two other base stations. For each pair of base stations corresponding to one of the calculated delays, the portable communication device initially specifies its location as being on a selected one of three curves. The current location of the portable communication device is identified based upon points of intersection of the selected curves. The identified location may be stored in, transmitted from, or displayed at the portable communication device.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.