personalized services using location based services (lbs) wei-meng lee ([email protected])...

Personalized Services Using Location Based Services (LBS)

Wei-Meng Lee ([email protected])

Technologist & Co-FounderActive Developer

http://www.activedevelop.com/

O’Reilly Emerging Technology ConferenceFebruary 9-12, 2004

Wei-Meng Lee, Active Developer

Agenda

• Motivation for LBS – E911

• Location-Based Services – the fundamentals

• Location-Based Services – the techniques

• Telcos adopting LBS in the US

• LBS Applications Model

• Some Case Studies in Singapore

• Issues of LBS


Singapore• Location: About 140

kilometres north of the equator

• It is 42 kilometers long and 23 kilometers across at its widest point

• Total area: 692.7 sq km (slightly more than 3.5 times the size of Washington, DC )

• Population 4,608,595 (July 2003 est.)

*


Motivation for LBS – E911

The wireless Enhanced 911 (E911) rules seek to improve the effectiveness and reliability of wireless 911 service by providing 911 dispatchers with additional information on wireless 911 calls.

• Phase I requires carriers, upon appropriate request by a local Public Safety Answering Point (PSAP), to report the telephone number of a wireless 911 caller and the location of the antenna that received the call.

• Phase II requires wireless carriers to provide far more precise location information, within 50 to 100 meters in most cases.


Triangulation – Locating the caller

• Triangulate from two angles – at least two reference points

• Triangulate from two points – at least three reference points

• Three-dimensional triangulation – at least four reference points


Triangulate from two angles

Two lines intersect at one point


Triangulate from two points

Two circles intersect at two points; a third circle is needed to remove the second point.


Three-dimensional Triangulation


Location Determination Technologies

• Satellite-based, Network-based

• Network centric, Handset centric


Cell of Origin

The tower transmitting the call is deemed to be the cell of origin.

Good for densely populated area where towers are close together.


Angle of Arrival (AOA)

Measures the angle at which a cell phone’s signal arrives at two or more towers

Useful for sparely populated area; less likelihood of interference.


Time Difference of Arrival (TDOA)

Vendors using TDOA:

• Cell-Loc (http://www.cell-loc.com)

• TruePosition (http://www.trueposition.com)

Measures the time at which a cell phone’s signal reaches at three or more towers


Enhanced Observed Time Difference (E-OTD)

Vendor supporting E-OTD:

• Cambridge Positioning Systems (CPS)

(http://www.cursor-system.com/cps/default.asp)

Measures the time at which signals from towers reaches the handset (requires changes to handsets and requires GSM).


Global Positioning SystemsUses 27 satellites (3 for backup) orbiting around the earth twice each day,

emitting low-power radio waves in the frequency range of 1500MHz.

Very costly to maintain – using GPS for LBS costs about $12 billion to build, staff, maintain and monitor. Lifespan: 7-15 years.


Three-dimensional Triangulation


Selective Availability• GPS was originally developed in the 1980s by the U.S.

Department of Defense for military use.

• The U.S. Department of Defense introduced Selective Availability (SA) to degrade the signal accuracy so that civilian usage could be restricted.

• In May 2000, President Clinton announced that the U.S. would no longer degrade the accuracy of GPS. With SA turned off, the accuracy of the GPS data could be within 5 meters.

• In the second Gulf war against Iraq in 2003, the United States reportedly degraded the GPS system so that Iraq could not make use of GPS against U.S. forces.

• While this is good news for the military, it certainly affected all those who rely on GPS for their daily activities. So, if you arrived at the wrong destination using a GPS navigational system, now you know why!


Assisted-GPS (A-GPS)

1. Handset broadcast request to towers

2. Location server tells handset which satellite to listen to

3. Handset listens to GPS satellite

4. Positional information combined with ranging information are sent back to the Location server

5. Location server calculates the actual position and returns the coordinates to the handset, or application server


Some A-GPS Phones


Comparing the different Location Determination Technologies

Cell-ID EOTD TDOA GPS AGPS

Consistency Poor Average Average Average Very good

Accuracy Poor100m – 20km2D Positioning

Average100m-500m2D Positioning

Average100m-500m2D Positioning

Good5m-100m3D Positioning

Excellent5m-50m3D Positioning

TTFF Excellent1s

Very Good5s

Very Good5s

Poor30s-15min

Very Good5-10s

Need to modify handset?

No Yes No Yes Yes

Network Efficiency

Excellent Poor Poor Excellent Excellent

Overall Cost Low High High Moderate Low

Summary Average Average Poor Average Very Good

* Source: SnapTrack (http://www.snaptrack.com)


Telcos adopting the various technologies

AT&T is adding GSM to its network as part of its migration to the third generation (3G), and implement E-OTD in its GSM network. VoiceStream, the largest GSM operator in

the U.S., is also supporting EOTD.

Sprint PCS, Alltel, U.S. Cellular, and Nextel Communications, have opted for a handset-based E-911

system using the satellite-based global positioning system (GPS).

Verizon and Western Wireless plan to use a network-based system, using a combination of TDOA and AOA.


Video - How LBS Works

http://www.trueposition.com


LBS Applications Model


Case Studies in Singapore

• * Send• Where am I?• What’s around me?• Weather forecast


Geo-Gaming

“Our game technology enables producers to place virtual representations of products in specific geo-graphic areas.

For example, a teen playing one of our games near a popular fast-food chain could find virtual “burgers” that could be consumed to provide extra energy or power to

their game avatar.”


Some Potential LBS applications

• Enhanced Shopping Experience– Sending promotional information to your cell phone

– Informing you on the discounts you are entitled to

• Mapping Applications

• Traffic Monitoring– Singapore has the Electronic Road Pricing (ERP)

• Warehousing

• Emergency services

• Tracking


Useful Links

• http://www.lbszone.com

• http://www.geoplace.com

• http://www.wirelessweek.com

• http://www.palowireless.com/lbs/devtools.asp

personalized services using location based services (lbs) wei-meng lee ([email protected])...

Documents

services lbs weimeng

active developer triangulation

active developer motivation

point slide

handset centric slide

singapore issues of

wireless carriers

precise location information