Final Year ProjectLYU0301

Location-Based Services Using GSM Cell Information over

Symbian OS

Mok Ming Fai CEG mfmok1@cse.cuhk.edu.hk

Lee Kwok Chau CEG leekc1@cse.cuhk.edu.hk

Agenda

Project Motivation Work Review Middleware for Developers

LBS API Design Cell Snap Distance Mapper Cell Analyzer Reference Point Locator AppGen

Sample Application Improvement and Future Work

Motivation

Advanced positioning methods require: extra cost to existing network / synchronization between ba

se stations special hardware to end users telco-dependent

Not all LBSs need very accurate location information GSM cell information (e.g. cell ID) is available in ordi

nary GSM handset Symbian phone offers programming capability for ge

neral developers Location estimation by GSM cell ID is adopted in our

project

Overview of GSM Cell ID Location Estimation Each base station has unique (loc ID, cell ID) pair Main idea: each base station can somehow provide

certain ‘information’ about a particular location Advantages:

Simple implementation, only current registered cell stored locally in cell phone is required

Applicable on ordinary GSM phones Without any support from telco

Location: [50]Cell ID: [1001]

Location: [50]Cell ID: [1002]

Location: [50]Cell ID: [1003]

Location: [50]Cell ID: [1004]

Evolution of Our Positioning Methods

Pure GSM Cell

Information Location

Estimation(Region Based)

GSM Cell Change Method

(Boundary / Line Based)

GSM Cell Change Method in

1D Path(Point Based)Detect registered

cell change occurred at cell boundary

Concentrate on specific cell changes (intersections between the path and the boundary)

Work Review

Use of cell change events for getting more reliable information at cell coverage boundary

Symbian programming on retrieving current registered cell ID

Experiment on CU campus (2D space) Experiment on MTR / KCR route (1D path) MTR Traveller as sample application Cell Snap for facilitating cell data collection

Middleware

The proposed method is useful in different fields, but not just MTR / KCR route

To make the mechanism generic, middleware, including APIs and SDK, is provided for general LBS development

It reduces the development time and effort for both application developers and LBS content editors

Overview of Overall Development

LBS Application Programming Interface (API)

We define a set of APIs for LBS developers to make use of our mechanism through self-defined data structures and function calls

The interface should be platform-independent (i.e. applicable on any platforms with primitive data structures and not just limited to Symbian OS)

API Design

Helps developers in developing LBS applications

Encapsulates low level system calls so that developers can concentrate on logic implementation.

API Design

There are two major types of LBS: Performs a particular action upon entering a

specific location Searches the nearest reference point relative to

the current location

CNetWorkInfo

CLocationListener CProximity

API Design

CLocationListener Keeps track on the location transition Performs specific action when reaching selected l

ocations Allows developers to specify desired action to be t

aken by overriding a function

API Design

CProximity Reads a location definition file Determines the nearest reference point relative to cur

rent location

Some Definitions

Reference point: Place taken as a reference in Cell Snap for easy recognition during data processing after collection

Point of Interest (POI): Place that are interested in the application (e.g. railway station, bus stop, canteen)

Three Development Streams

Application developers who purely work on cell IDs with our APIs in a low-level manner

Application developers who want to save time on cell data collection and map distance measurement

LBS content builders who concern only and actions on cell changes (e.g. show a message if user enters/leaves a point of interest)

Three Development Streams(1)

Developers fromlow-level interfaces

Three Development Streams(2)

Application developers

Three Development Streams(3)

Content builders

Cell Snap

Cell Snap

Collection of cell data was done manually in the past Cell Snap - a tool for automated cell data collection Different reference points can also be captured by

phone camera

Cell Snap

Cell Snap can only produce raw cell change event log

03/03/2004 9:59:16 AM: Starting cell collection by CellSnap...

0 s: Starting at Location: [ 130 ], Cell ID: [ 30852 ]

4 s: < CellSnap0001.jpg > Location: [ 130 ], Cell ID: [ 30852 ]

12 s: Location: [ 130 -> 130 ], Cell ID: [ 30852 -> 26391 ]

49 s: Location: [ 130 -> 130 ], Cell ID: [ 26391 -> 33731 ]

.............

129 s: < CellSnap0002.jpg > Location: [ 130 ], Cell ID: [ 33731 ]

321 s: Location: [ 130 -> 130 ], Cell ID: [33731 -> 5812 ]

.............

03/03/2004 10:08:54 AM: Stopping cell collection by CellSnap...

Cell Analyzer

Cell Analyzer

Cell Analyzer is able to: transform data into locatio

n definition file rather than text description

edit collected data remove duplicates combine data from differe

nt telco into a single output through mapping

Distance Mapper

Distance Mapper

The above APIs need to read in location definition file in order to achieve their goal

The cell data file generated by Cell Analyzer alone is not enough for the above purpose

Distance Mapper allows developers to either manually or automatically maps collected location points

Distance Mapper

Reference Point Locator

Reference Point Locator

The usage is similar to Distance Mapper, but it is used to: locate reference points into a map, and; retrieve ref. points to x,y-coordinates mapping for

application generation. It is useful for application generation.

AppGen

LBS Application Generation

A typical LBS application have two types of functions: To keep track of interested cell changes and repo

rt to user (e.g. entering a new station for MTR Traveller), and;

To let user to specify a point of interest (POI) (e.g. engineering building) and acknowledge the user when he/she reaches a reference point containing that POI (e.g. central campus bus stop)

LBS Application Generation

AppGen is responsible to generate required source code with reference point list as input.

It allows develops to: specify POIs for corresponding ref. point browse the ref. points on an imported map add text and image when entering ref. point

Layered View of Overall Development

Reference Point Locator&

AppGenDistance Mapper

Cell Snap & Cell Analyzer

LBS Application Development Interface(API)

GSM Modem and NetworkAccess cell information

Work with low-level APIs

Generate LBS application (for

content builders)

Work with APIs convenient cell data processing

Flexibility

Convenience

Future Work and Improvement

Final implementation of AppGen Sample application built from AppGen with re

al data for different telcos: CU bus route

Conclusion

We have designed a set of APIs and toolkits for our positioning mechanism

Developers fromlow-level interfaces

Application developers

Content builders

Q&A Section

Thank you very much!