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Final Year ProjectLYU0301
Using GSM Cell Information on Mobile Phone
Mok Ming Fai CEG mfmok1@cseLee Kwok Chau CEG leekc1@cse
Agenda
Symbian OS Location-based services (LBS) Connectivity of GSM base stations and mobil
e phones Using GSM cell information Example application: MTRTravaller Future Work
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 mobil
e devices
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
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
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 m
or active objects Non-preemptive, no mutual exclusion codes are needed
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
Location-Based Services (LBS)
Services are provided based on user’s current location.
Applicable on different fields: Driving Billing Shopping Guides Security Games and Entertainment ......
Each of them requires different accuracy and latency.
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
Operation of Mobile Phone Connectivity
Location: [50]Cell ID: [1]
Location: [50]Cell ID: [2]
Location: [50]Cell ID: [3]
Location: [50]Cell ID: [4]
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
Traditional Cell Information Collection Methods
1) Communicating with GSM modem Using AT command
Require different kinds of hardware
AT+CREG?
+CREG: <n>,<stat>[,50,7474]
Location: [50]Cell ID: [7474]
Traditional Cell Information Collection Methods
2) Phone engineering mode Tell you a list of cell information Need to record them manually
Getting Cell Information via Symbian API
Problem: Current Nokia SDK doesn’t provide any method fo
r 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 applicat
ion
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?
Different registered cell in a particular location each time
Problem of Pure Cell ID Detection
Location: [50]Cell ID: [1]
Location: [50]Cell ID: [2]
Location: [50]Cell ID: [3]
Location: [50]Cell ID: [4]
Pure Cell Detection VS Cell Change Event
Event of Entering / Leaving a boundary Provide transition Information (from 1 cell to
another)
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
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
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
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
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
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
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.
Experimental Result
For Peoples
Experimental Result
For SmarTone
Experimental Result
Experimental Result
Inconsistencies with Our Expectations
Cells vary greatly in size and shape Large scale of cell overlap Some marco-cell encapsulating smaller micr
o-cells Cells may change shapes under different env
ironment condition at different time Cells in CU are too large to get an accurate lo
cation of the mobile device
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
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.
Cell IDs in 1D Space
Location: [50]Cell ID: [1]
Location: [50]Cell ID: [2]
Location: [50]Cell ID: [3]
Location: [50]Cell ID: [4]
Cell ID: [1->2] Cell ID: [2->3]
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
Station 2Station 1Cell ID Changes Here
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 => in between S1 and S2 Station cell => in the station platform
Station Cells:
[S1, O], [S1, B]
Transition Pairs:
[S1, S2, O], [S1, S2, B],
[S1, S2, P], [S1, S2, G]
Station 2Station 1
Station Cells:
[S1, O], [S1, B], [S1, P]
MTR Cell ID Data
Peoples
KCR Cell ID Data
Peoples
MTR Cell ID Data
SmarTone
KCR Cell ID Data
SmarTone
MTR Cell ID Data
Sunday
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
Demonstration
Map data, station data, transition data
Movie in actual stations Simulation
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
More to Improve…
Personalize Informative Fancy user interface Distributed intelligence
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)
Other Possible Applications
Detection of car speed detectors Make use of inaccuracy of GSM cell More data have to be stored
I am caught!
Oh, there is speed detector!
Future Work
Automatic cell information collection kit Improvement on MTRTraveller
Personalization User Interface Informative Distributed intelligence
Generic middleware/library for developers Other applications
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
End of Presentation
Thank you very much!