A reactive location-based service for
geo-referenced individual data collection and analysis
Xiujun Ma
Department of Machine Intelligence, Peking University
Zhongya Wei
Department of Electrical Engineering, Tsinghua University
Yanwei Chai
Department of Urban and Regional Planning, Peking University
Kunqing Xie
Department of Machine Intelligence, Peking University
Contents
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Introduction
Methodology
The reactive LBS architecture
Scenario and prototype testing in Beijing city
Conclusion
Introduction
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Importance of data about human activities and
movements in space-time
Data collection methods
– surveys, samples and synthetic data
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New possibility using mobile phone
– location of mobile phones can be precisely tracked
– the massive spread of mobile phones
Introduction
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Location based services: LBS
– A Location Based Service is any product, service, or
application that uses knowledge of a mobile subscriber’s
location to offer value to the mobile subscriber or to a third
party
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Difficulties of space-time data collection using LBS
– personal privacy
– LBS can not record what the user is doing at a particular
time, the purpose of the activity or trip, and other
activities…….
Introduction
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LBS taxonomy
– Proactive LBS: passive and high privacy
– Reactive LBS: active and low privacy
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Objectives of our work
– reactive LBS to collect individual space-time data with other
information about activities and movements
– (1) to collect the actual location and movement of people;
– (2) to improve both the quality and precision of this data;
– (3) it makes possible to work in real time.
Methodology
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Assembly of the Online Map Services
– Google Maps, Yahoo Maps, MAP24, MapQuest, Microsoft
TerraServer and Google Earth;
– go2map, 51ditu, mapabc, mapbar
Common features of Online Map Services
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Mapping: powerful interactive maps and high quality
map
Geocoding: to calculate a location’s latitude and
longitude coordinates, including street addresses and
intersections, street blocks, postal codes, centers of
administrative areas.
Routing: to calculate driving directions between two
locations
POI searching: a very detail business and landmark
database.
Geotagging: to add map annotations using shapes or
text.
Combination with mobile positioning services
Combination with mobile positioning services
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Mobile positioning technology
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CELL-ID
E-OTD
OTDOA
A-GPS
Mobile positioning technology
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X,Y
Cell-ID
Cell Size
Mobile positioning technology
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AOA (Angle of Arrival)
1
2
Mobile positioning technology
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TOA (Time of Arrival)
Base Station 1
Mobile
T1 =distance 1
Base Station 3
T2 =distance 2
T3
=distance 3
Base Station 2
Mobile positioning technology
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AGPS (Network Assisted GPS)
AGPS(1)
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AGPS (Network Assisted GPS)
– Assisted-GPS means that a Location Server assists a
wireless device client to produce location fixes
– TO IMPROVE PERFORMANCE AND REDUCE COST!
– More accurate location fixes
– Higher yield
– Faster Time to Fix
– Lower Battery consumption
– Lower terminal device costs
AGPS（2）
AGPS（3）- GPSone Phone
The reactive LBS architecture
Mobile
user
Web users
Data Collection Server
SMS
M
ob
da
ta
ile
P
os
PI
iti
on
A
S
ap
SM
M
Space-Time
Datasets
Mobile Positioning
Provider
Maps
Map Service Provider
Scenario and prototype testing in Beijing city
Service
Gateway
WML
China Mobile
Network
WML/HTML
SMS, GPRS,
Wireless Internet
AGPS
BS
AGPS
API
Data Collection
Server
BS
API
Online Map Services
API
Data validation
Server
API
Scenario and prototype testing in Beijing city
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Geotagging daily trips on web map
– to tag their home, work place and favourite shopping and
entertainment sites
– To tag their daily trips ( including trip route and information
about trip purpose, time departure, origin and destination
locations.
Scenario and prototype testing in Beijing city
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Blogging daily real time activities by SMS
Similar to Self-Reporting
– Users tell the system where they are and what they are doing
– a blog consists of one real time activity entry including
information about a user’s on-going activity in a place.
– Using mobile positioning and map geocoding to get the
accurate location data
Conclusion
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Technical feasibility
– save great cost to build a map base
– be accessed to millions of web users
– to collect real time activity of mobile phone owners
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To combine web map service API and mobile
positioning service, it is possible to collect large scale
space-time samples about millions users in big cities
with lower data collection cost.
Conclusion
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the advantages of proposed LBS approach
– (1) geotagging and mobile positioning approach get the
actual location and movement of people;
– (2) the data quantity and the precision are higher than
traditional survey method;
– (3) data collection using mobile phone makes it possible to
collect people’s real time activities.
Future Works
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we call collaboration to develop more attractive
services and to cover most of main cities in China
We continue to complete our LBS enabling new
analysis and visualizing method for the collected large
space-time datasets
Thank you!
LBS
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By Siemens
LBS Application Mode
LBS Applications