Use of GPS in Cellular Phone Industry

1
Use of GPS in Cellular Phone Industry

• September 11, 2001CGSIC Meeting
• Jari Syrjärinne Research and Technology
  AccessNokia Mobile Phones

2
In Telecom Industry GPS Is Needed for...

• Network synchronization

• Positioning of cellular phones

3
Network Synchronization

• US CDMA cellular network is inherently
  synchronized with GPS time.
• Synchronization is e.g. needed for call handovers.

• GSM and the coming 3G (UMTS) systems are
  asynchronous networks.
• Only time difference measurement is needed for
  call handovers.

4
Network Synchronization continued
Base station 2
Base station 1
E-OTD (GSM) IPDL-OTDOA (UMTS)
Cellular network based positioning methods
requirea synchronous network.
GPS is used to measure base station clock drifts
and real time differences.
Base station 3
5
Positioning of Cellular Phones

• Wireless Assisted GPS (WAG, AGPS)
• MS-Assisted NW-Based GPS
• MS-Based NW-Assisted GPS
• Network assistance includes e.g.
• navigation data
• DGPS corrections
• reference frequence
• reference position
• reference time
• Reductions in acquisition time and TTFF
• Sensitivity improvement app.. 20-25 dB

6
GPS Time Delivery over Asynchronous Cellular Link
Frame 12
Cellular phone
GPS
Base Station
GPS-time GPS-timestamp ?FN clockdrift(?FN)
RTD/2
7
Comparison of Global Positioning Technologies
Availability
Satellite-based technologies
remote
RTK GPS
2G
2G
rural
3G
CICITACIRx(CIRTT, 3G)
E-OTD,(TOA)
suburban
IPDL-OTDOA
WLANzone
urban/city
WLAN BT
BTzone
indoor
WLAN
1
3
10
30
100
300
1K
3K
10K
30K
0.1
0.3
Accuracy / m
8
Near Future Deployment of GPS in Telecom
Industry

• GPS is needed for implementing cellular network
  based methods
• rather small volume
• More than 400 million cellular phones sold
  annually in the world, but...
• Deployment of AGPS capable cellular phones
  depends on
• cost of technology
• maturity of technology
• competitiveness of AGPS
• emergence of location based services
• Synergism between cellular network based
  positioning and AGPS promotes both solutions!