Final Year Project LYU0301

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Final Year ProjectLYU0301

• Using GSM Cell Information on Mobile Phone

Mok Ming Fai CEG mfmok1_at_cse Lee Kwok Chau CEG
leekc1_at_cse
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Agenda

• Symbian OS
• Location-based services (LBS)
• Connectivity of GSM base stations and mobile
  phones
• Using GSM cell information
• Example application MTRTravaller
• Future Work

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Symbian and Symbian OS

• Symbian
• a software licensing company owned by Ericsson,
  Nokia, Panasonic, Psion, Samsung Electronics
  Siemens and Sony Ericsson.
• Symbian OS
• standard operating system for data-enabled mobile
  devices

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Symbian OS

• Currently supported mobile phones
• Nokia 6600, 7650, 3650, N-Gage and 9210
  Communicator
• Sony Ericsson P800, P900
• Motorola A920
• Fujitsu F2051, F2102V
• New mobile phones supporting Symbian OS
• Samsung SGH-D700
• Siemens SX1
• Sendo X
• BenQ P30

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Characteristics of Symbian OS

• Integrated multimode mobile telephony
• Open application environment
• Open standards and interoperability
• Multi-tasking
• Fully object-oriented and component based
• Flexible user interface design

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Special Features in Symbian OS

• Error Handling
• Cleanup Stack
• Two-phase Constructions
• Active Object
• 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

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Programs Written for Symbian OS

• Robot Hello World
• Illustrations of the use of GUI components and
  basic APIs
• Nokia Square
• Illustrations of the basic APIs and the
  structure of Symbian-based applications

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Location-Based Services (LBS)

• Services are provided based on users current
  location.
• Applicable on different fields
• Driving
• Billing
• Shopping Guides
• Security
• Games and Entertainment
• ......
• Each of them requires different accuracy and
  latency.

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Current Technologies on LBS

• 1) Global Positioning System (GPS)
• Good Accuracy 30-100m
• Poor indoor and urban-area capabilities
• Generally high power consumption
• Expensive hardware
• 2) 3rd Generation GSM (3G)
• Need time to replace current mobile network
• 3) Modified SIM Card
• Cooperation with telco
• 4) Global System for Mobile Communications (GSM)
• Common regular mobile phone network standard
• Available on ordinary cell phones

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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
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Using GSM Cell Information

• Main idea each base station may somehow indicate
  certain information about location or region
• Cell information includes
• Location ID
• Cell ID
• Received Signal Strength

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Traditional Cell Information Collection Methods

• 1) Communicating with GSM modem
• Using AT command
• Require different kinds of hardware

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Traditional Cell Information Collection Methods

• 2) Phone engineering mode
• Tell you a list of cell information
• Need to record them manually

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Getting Cell Information via Symbian API

• Problem
• Current Nokia SDK doesnt provide any method for
  retrieving GSM cell information
• The internal library of the phone actually
  contains such API
• Solution
• Use header file from other Symbian SDK
• GSMStatus
• Integrate current cell information and application

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Cell Information for LBS

• Accuracy depends on
• Base station deployment
• Cell size
• 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?

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Problem of Pure Cell ID Detection
Location 50 Cell ID 2

• Different registered cell in a particular
  location each time

Location 50 Cell ID 4
Location 50 Cell ID 3
Location 50 Cell ID 1
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Pure Cell Detection VS Cell Change Event

• Event of Entering / Leaving a boundary
• Provide transition Information (from 1 cell to
  another)

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Cell IDs in the 2D Space

• Initiatives
• To locate the approximate location of a mobile
  phone uses with a program run on Symbian OS
• Determining GSM cells coverage and their
  distribution
• Plot a cell ID-to-location map
• Locate current position of a mobile device

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Cell ID Data Collection

• Collected location ID and cell ID pairs for two
  telcos in the CU campus.
• Data Collection method
• Static Method for SmarTone
• Cell Change Method for Peoples

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Principle of the two data collection methods

• Static Method
• 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.
• Determine the location ID and cell ID of that
  specific location after observing for a period of
  time

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Principle of the two data collection methods

• Cell Change Method
• Walk around the campus and find the boundaries
  of different cells
• When cell change occurs we note down the change
  and try to find out the boundaries of the cells

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Advantages and Disadvantages of the Two Methods

• Static Method
• 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

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Advantages and Disadvantages of the Two Methods

• Cell Change Method
• 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

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Expectations

• We expected
• 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.

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Experimental Result
For Peoples
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Experimental Result
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Experimental Result
For SmarTone
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Experimental Result
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Inconsistencies with Our Expectations

• 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

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Conclusion on the Experiment

• Potential difficulties in 2D Space
• 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

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The Idea of Cell IDs in 1D Space

• 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.

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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-gt2
Cell ID 2-gt3
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MTRTraveller for Stations in Subway

• Apply to traffic route
• MTRTraveller - tell user the station arrival
• Initial Observation
• 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 2
Station 1
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MTRTraveller for Stations in Open Area

• KCR Stations in open area
• Many cell IDs in between two stations
• A station platform may also involve multiple
  cells
• Transition pair gt in between S1 and S2
• Station cell gt in the station platform

Station 2
Station 1
Transition Pairs S1, S2, O, S1, S2, B, S1,
S2, P, S1, S2, G
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MTR Cell ID Data

• Peoples

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KCR Cell ID Data

• Peoples

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MTR Cell ID Data

• SmarTone

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KCR Cell ID Data

• SmarTone

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MTR Cell ID Data

• Sunday

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Statistics

• 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
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Demonstration

• Map data, station data, transition data
• Movie in actual stations
• Simulation

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Potential Problems

• All cell data depends on cell deployment
• 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
• Automatic cell information collection kit
• Users - update their data regularly
• Convenient update using SMS / GPRS

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More to Improve

• Personalize
• Informative
• Fancy user interface
• Distributed intelligence

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Other Possible Applications

• Bus route
• All bus stops are in open area
• Tram route for tourism
• Just tell tourists that they are in a particular
  district (e.g. Causeway Bay, Wan Chai)

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Other Possible Applications

• Detection of car speed detectors
• Make use of inaccuracy of GSM cell
• More data have to be stored

Oh, there is speed detector!
I am caught!
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Future Work

• Automatic cell information collection kit
• Improvement on MTRTraveller
• Personalization
• User Interface
• Informative
• Distributed intelligence
• Generic middleware/library for developers
• Other applications

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Conclusion

• Symbian OS for mobile phones
• GSM provides location-related information
• Using GSM cell information in Symbian program
• 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
• Other applications

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End of Presentation

• Thank you very much!