GPS Technology Tech Talk April, 2008 Chad Halvarson

Agenda  Current GPS and Assisted GPS (AGPS) Overview  CDMA GPS Service  Conclusion  Q & A

GPS Review  A GPS receiver determines the travel time of a signal from a satellite – Synchronization A Travel Time x c (Speed of Light ~ 3 x 10 9 m/s) = Total Distance

GPS Requirements  GPS is good for open field.  Less accurate for blocked or indoor areas (urban locations).  Requires line of sight to at least 3 satellites.  GPS Receiver requires high processing power.  Expensive GPS hardware and Pre-loaded software.

AGPS Overview  Affordable solution  Uses an assistance server to calculate locations via Wireless Carrier Backbone  Commonly associated with Location Based Services (LBS) over cellular networks. Location Based Servicescellular networksLocation Based Servicescellular networks –E911 – Mandated by FCC to provide emergency service –Mobile Tracking –Navigation  Ability to download specific information dynamically in real-time

Assisted GPS Overview Wireless Carrier Internet Data Communication to cellular IP Assistance Server WEB for Operator or Customer

CDMA GPS Service  Replaces expensive typical GPS receivers with inexpensive Handset  Provides various mobile services –Location Base Service (i.e. E911, Weather, POI etc.) –Tracking –Navigation

CDMA Location Hierarchy Cell Sector Fix … indoors, edge coverage Cell Sector location reports the center of the cell sector as the current position. AFLT Fix … indoors AFLT is a “triangulation type” fix that requires contact with a minimum of three towers to establish a position. Hybrid Fix … partial view of sky CDMA pilot phase measurements can be used as a virtual GPS to determine position. AGPS Fix... open sky AGPS Fix requires a minimum of three GPS measurements. “Assisted” because network resources are still required. Advanced Forward Link Tri-lateration

CDMA StrengthWeakness CDMA  System delivers best fix available  Mid-level quality indoor fixes possible  Cell Sector fix, worst case  Network utilized for every initial fix  Network fixes take more time (non-GPS)  No off network capability

CDMA - Network Initiated Base Station Mobile Station Satellite Features: First fix in tens of seconds Very high accuracy Available during a voice call Fallback modes available Limitations: Each additional fix requires same time as initial fix Limited to specific devices Network resources needed for every location request Network does the math to calculate position 1 R 1 R 1 R Satellite Data No Ranging Location Application Satellite Acquisition and Sensitivity Assistance Data requested & passed Network HW Raw GPS data collected & passed

CDMA CDMA  Assigns dynamic IP address for each phone  Java not supported – Network dependent  Tracking is not supported directly by phone

Conclusion  Current GPS technology Overview –GPS vs. AGPS  CDMA GPS Service Offerings