US 7,064,706 B2 · Method and apparatus for assisted GPS

Abstract

A cellular network protocol that maintains the reliability of assisted GPS based positioning is taught. An Integrity Monitor (IM) informs mobile stations, their users, or networks of measurement quality and it warns them of failing and failed GPS satellites by isolating them from the effects of these failures. Whenever an unhealthy satellite is detected, its corresponding assistance data will be excluded for delivery or for position determination. In other words, there are two specific aspects to the Integrity Monitor (IM). For DGPS users, it predicts the reliability or quality of the DGPS corrections. For all users, it isolates the mobile position calculation from the effects of GPS satellite failures. The UDRE parameter, nominally output by a reference DGPS receiver, is used to communicate the DGPS quality information, and DGPS corrections are simply excluded for failed satellites. For autonomous GPS users, a special integrity message is required and defined to communicate the satellite failure status information.

Claims23

Dependent claims

A method for maintaining the integrity of a mobile handset's location determination in a system comprising the mobile handset, radio communication infrastructure and a Differential Global Positioning System (DGPS) reference receiver coupled to the radio communication infrastructure and installed at a predetermined location, the DGPS reference receiver receiving GPS information from a plurality of GPS satellites, the method comprising:

said radio communication infrastructure receiving DGPS information, from which differential correction data may be obtained, from the DGPS reference receiver;
determining whether one or more of said plurality of GPS satellites have failed/are failing based on differential correction data within a specified time after failure;
generating a failed satellite message when it is determined that one or more of said plurality of GPS satellites have failed/are failing, said failed satellite message identifying the one or more of said plurality of GPS satellites that have failed/are failing;
and
transmitting the failed satellite message identifying the one or more of said plurality of GPS satellites that have failed/are failing when it is determined that the one or more of said plurality of GPS satellites has failed/are failing.

2 more elements

Dependencies are inferred from the claim text.

Method and apparatus for assisted GPS

Life of this patent

Method and apparatus for assisted GPS

Life of this patent

Abstract

Claims23