Beacon-assisted precision location of untethered client in packet networks
US7528776B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 22, 2007 |
| Grant date | May 5, 2009 |
| Priority date | — |
| Expiry date | Jul 4, 2027 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S5/06
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A novel beacon-based position location technique for efficient location discovery of untethered clients in packet networks is disclosed. The position location technique utilizes the time-difference-of-arrival (“TDOA”) of a first signal transmitted by a beacon of known location and a second signal transmitted by an untethered client. The TDOA of these two signals is measured locally by at least three non-collinear signal receivers. For each of the receivers, the TDOA is used to calculate a perceived distance to the client. A circle is then calculated for each receiver, centered on the receiver and having a radius equal to the perceived distance. At least two lines defined by points of intersection of the calculated circles are then calculated. The point of intersection of the lines represents the location of the client. To facilitate operation, the signal receivers may be arranged on vertices which define a convex polygon as viewed from above. The location system requires no time (time-of-day) synchronization of the signal receivers, and only the coarse frequency synchronization, on the order of, tens of parts-per-million (ppm). The technique even works for the case where the signal…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.