AT Commands Reference Manual - wireless netcontrol GmbH

A-GPS
A-GPS
Overview
gpsOne technology merges global positioning system (GPS) satellite and network information to
provide a high-availability solution that offers industry-leading accuracy and performance. This
solution performs well, even in very challenging environmental conditions where conventional
GPS receivers fail, and provides a platform to enable wireless operators to address both
location-based services and emergency mandates such as the United States Federal
Communications Commission (FCC) E911 mandate.
In mobile-assisted mode, when a request for position location is issued, available network
information is provided to the location server (e.g., cell-ID) and assistance is requested from the
location server. The location server sends the assistance information to the handset. The
module/mobile unit measures the GPS observables and provides the GPS measurements along
with available network data (that is appropriate for the given air interface technology) to the
location server. The location server then calculates the position location and returns results to the
requesting entity.
In mobile-based mode, the assistance data provided by the location server encompasses not only
the information required to assist the module in measuring the satellite signals, but also the
information required to calculate the module's position. Therefore, rather than provide the GPS
measurements and available network data back to the location server, the mobile calculates the
location on the module and passes the result to the requesting entity.
In standalone (autonomous) mode, the module demodulates the data directly from the GPS
satellites. This mode has some reduced cold-start sensitivity, and a longer time to first fix as
compared to the assisted modes. However, it requires no server interaction and works out of
network coverage.
Getting Location (position fix information) can be acquired in two different formations
• Application level location requests and reports. See “Application Level Location Request
and Report” on page 3-361.
• Streaming output of GPS NMEA messages over serial connection. See “NMEA Streaming
Output” on page 3-365.
1-18 H24 - AT Commands Reference Manual April 15, 2010