Final Year Project
LYU0301
Using GSM Cell Information on
Mobile Phone
Mok Ming Fai CEG mfmok1@cse
Lee Kwok Chau CEG leekc1@cse
Agenda
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Symbian OS
Location-based services (LBS)
Connectivity of GSM base stations and
mobile phones
Using GSM cell information
Example application: MTRTravaller
Future Work
Symbian and Symbian OS
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Symbian:
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a software licensing company owned by Ericsson,
Nokia, Panasonic, Psion, Samsung Electronics
Siemens and Sony Ericsson.
Symbian OS:
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standard operating system for data-enabled
mobile devices
Symbian OS
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Currently supported mobile phones
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Nokia 6600, 7650, 3650, N-Gage and 9210 Communicator
Sony Ericsson P800, P900
Motorola A920
Fujitsu F2051, F2102V
New mobile phones supporting Symbian OS
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Samsung SGH-D700
Siemens SX1
Sendo X
BenQ P30
Characteristics of Symbian OS
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Integrated multimode mobile telephony
Open application environment
Open standards and interoperability
Multi-tasking
Fully object-oriented and component based
Flexible user interface design
Special Features in Symbian
OS
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Error Handling
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Cleanup Stack
Two-phase Constructions
Active Object
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implements multi-tasking without using multithread
One active scheduler per thread cooperating with one or
mor active objects
Non-preemptive, no mutual exclusion codes are needed
Programs Written for Symbian
OS
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Robot Hello World
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Illustrations of the use of GUI
components and basic APIs
Nokia Square
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Illustrations of the basic APIs
and the structure of Symbianbased applications
Location-Based Services (LBS)
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Services are provided based on user’s current
location.
Applicable on different fields:
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Driving
Billing
Shopping Guides
Security
Games and Entertainment
......
Each of them requires different accuracy and latency.
Current Technologies on LBS
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1) Global Positioning System (GPS)
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2) 3rd Generation GSM (3G)
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Need time to replace current mobile network
3) Modified SIM Card
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Good Accuracy: 30-100m
Poor indoor and urban-area capabilities
Generally high power consumption
Expensive hardware
Cooperation with telco
4) Global System for Mobile Communications (GSM)
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Common regular mobile phone network standard
Available on ordinary cell phones
Operation of Mobile Phone
Connectivity
Location: [50]
Cell ID: [2]
Location: [50]
Cell ID: [4]
Location: [50]
Cell ID: [3]
Location: [50]
Cell ID: [1]
Using GSM Cell Information
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Main idea: each base station may somehow
indicate certain ‘information’ about location or
region
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Cell information includes:
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Location ID
Cell ID
Received Signal Strength
Traditional Cell Information
Collection Methods
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1) Communicating with GSM modem
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Using AT command
AT+CREG?
+CREG: <n>,<stat>[,50,7474]
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Location: [50]
Cell ID: [7474]
Require different kinds of hardware
Traditional Cell Information
Collection Methods
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2) Phone engineering mode
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Tell you a list of cell information
Need to record them manually
Getting Cell Information via
Symbian API
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Problem:
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Solution:
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Current Nokia SDK doesn’t provide any method
for retrieving GSM cell information
The internal library of the phone actually contains
such API
Use header file from other Symbian SDK
GSMStatus
Integrate current cell information and
application
Cell Information for LBS
Accuracy depends on:
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Base station deployment
Cell size
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Pico-cell: 10-1000m
Micro-cell: 100-1000m
Small Macro-cell: 1000-3000m
Large Macro-cell: 3000-30km
Not accurate enough telling where you are
How can we make use of such information?
Problem of Pure Cell ID
Detection
Location: [50]
Cell ID: [2]
Location: [50]
Cell ID: [4]
Location: [50]
Cell ID: [3]
Location: [50]
Cell ID: [1]
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Different registered cell in a particular location each
time
Pure Cell Detection VS Cell
Change Event
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Event of Entering / Leaving a boundary
Provide transition Information (from 1 cell to another)
Cell IDs in the 2D Space
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Initiatives
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To locate the approximate location of a mobile phone uses
with a program run on Symbian OS
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Determining GSM cells coverage and their distribution
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Plot a cell ID-to-location map
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Locate current position of
a mobile device
Cell ID Data Collection
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Collected location ID and cell ID pairs for two
telcos in the CU campus.
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Data Collection method:
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Static Method for SmarTone
Cell Change Method for Peoples
Principle of the two data
collection methods
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Static Method
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Wait for a sufficiently long period of time at a
specific point in the 2D map to see the strength
and stability of a cell strength.
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Determine the location ID and cell ID of that
specific location after observing for a period of
time
Principle of the two data
collection methods
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Cell Change Method
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Walk around the campus and find the “boundaries”
of different cells
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When cell change occurs we note down the
change and try to find out the boundaries of the
cells
Advantages and Disadvantages of
the Two Methods
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Static Method:
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Accurate at those specific point
Experiment only done on a set of specific points
selected from the 2D map
Takes a longer time
Cannot figure out the cell boundary clearly unless
those sample points are dense enough
Advantages and Disadvantages of
the Two Methods
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Cell Change Method:
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Most of the cell boundaries can be detected
Can discover different overlapping of cells
Use less time
Boundaries detected are “regions” instead of
sharp lines
Expectations
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We expected:
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GSM Cells are of similar size
Only small overlapped region at the cell
boundaries
No large cell completely covering a smaller cell
Can be modeled as hexagonal shape covering
the area.
Experimental Result
For Peoples
Experimental Result
Experimental Result
For SmarTone
Experimental Result
Inconsistencies with Our
Expectations
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Cells vary greatly in size and shape
Large scale of cell overlap
Some marco-cell encapsulating smaller
micro-cells
Cells may change shapes under different
environment condition at different time
Cells in CU are too large to get an accurate
location of the mobile device
Conclusion on the Experiment
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Potential difficulties in 2D Space
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ID-to-location map drawn not accurate enough
Cannot locate the location of a mobile device to
an acceptable accuracy owing to the large size of
cells
Hierarchy of cells make it even harder to locate
your current position
The Idea of Cell IDs in 1D
Space
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Owing to the difficulties and inaccuracy of the
detection of cell ID in 2-dimensional space,
we turn to the 1-dimensional space
Only travel in one direction
Concentrate on the Entrance of a region
Limitation in 1D space helps to ease the
inaccuracy.
Cell IDs in 1D Space
Location: [50]
Cell ID: [2]
Location: [50]
Cell ID: [4]
Location: [50]
Cell ID: [3]
Location: [50]
Cell ID: [1]
Cell ID: [1->2]
Cell ID: [2->3]
MTRTraveller for Stations in
Subway
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Apply to traffic route
MTRTraveller - tell user the station arrival
Initial Observation:
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Between two stations in subway, there is exactly
one change
This event can tell user that you are going from
one station to another station
Due to the shape of antenna in these stations
Cell ID Changes Here
Station 1
Station 2
MTRTraveller for Stations in
Open Area
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KCR Stations in open area
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Many cell IDs in between two stations
A station platform may also involve multiple cells
Transition pair => in between S1 and S2
Station cell => in the station platform
Station 1
Transition Pairs:
Station Cells:
[S1, S2, O], [S1, S2, B],
[S1,[S1,
O], [S1,
O], [S1,
B], [S1,
B] P] [S1, S2, P], [S1, S2, G]
Station 2
MTR Cell ID Data
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Peoples
KCR Cell ID Data
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Peoples
MTR Cell ID Data
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SmarTone
KCR Cell ID Data
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SmarTone
MTR Cell ID Data
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Sunday
Statistics
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Time of ‘station arrival’ event occurrence
before entering that station
Should be enough for user to figure out the
change
Entering
station in
open area
Demonstration
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Map data, station data,
transition data
Movie in actual stations
Simulation
Potential Problems
All cell data depends on cell deployment
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Cannot control time to tell user the event of
station arrival
Problem occurred if two or more stations share
the same cell ID
Up-to-date cell information required
 Developers - collect data regularly
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Automatic cell information collection kit
Users - update their data regularly
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Convenient update using SMS / GPRS
More to Improve…
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Personalize
Informative
Fancy user interface
Distributed intelligence
Other Possible Applications
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Bus route
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All bus stops are in open area
Tram route for tourism
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Just tell tourists that they are in a particular district
(e.g. Causeway Bay, Wan Chai)
Other Possible Applications
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Detection of car speed detectors
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Make use of inaccuracy of GSM cell
More data have to be stored
Oh, there is
speed detector!
I am caught!
Future Work
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Automatic cell information collection kit
Improvement on MTRTraveller
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Personalization
User Interface
Informative
Distributed intelligence
Generic middleware/library for developers
Other applications
Conclusion
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Symbian OS for mobile phones
GSM provides location-related information
Using GSM cell information in Symbian program
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Not accurate enough for positioning
Easily available for ordinary mobile phones
Pure cell ID detection VS cell ID change event
Design special applications mastering these information
 MTRTraveller
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Other applications
End of Presentation
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Thank you very much!