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!