Location Based Web Search on GSM/GPRS Mobile Devices VVS. Naresh, Prasad Pingali, Vasudeva Varma International Institute of Information Technology, Hyderabad,

Location Based Web Searchon GSM/GPRS Mobile Devices

VVS. Naresh, Prasad Pingali, Vasudeva VarmaInternational Institute of Information Technology, Hyderabad, India

Murali Krishna Punaganti Venkata Nokia Research Center, Helsinki, Finland

Agenda

• Introduction

• Solution Outline

• Steps Involved

• Open Issues

Current search

• Obtained from http://mobilesearch.nokia.com

Introduction

• Goal of this project : Provide a Location Based Search (LBS) for GSM/GPRS based mobile devices.

• GSM is a dominant mobile phone system.• Mobile devices most suited for location based

services, because they are “mobile” • Location based services were tried on desktops

using IP addresses for anonymous users.– e.g. URL redirection based on user's IP address

Solution Outline

• The solution can be seen as two main steps– Obtain Mobile Device

Location– Web search using Location.

• Difficulties Involved– Obtaining the location string

database– Refining and re-ranking

results

• Open Issues– Standardization of location

parameters– Privacy Issues– Security Policies

Steps Involved

• Displayed location string not accessible for third-party applications

• Mobile Device Location needs to be inferred– Get Location Codes from Device– Lookup Location Codes to get Location Names

• Web Search Using Location – Query Expansion– Web Meta-Search– Merge and Rank Search Results using a

Weighted Ranking function.– Default Ranking is based on Granularity of

Location.

Obtain Mobile Device Location

International Mobile Subscriber Identity (IMSI) used for identifying a mobile phone subscriber Maximum length of code being 15 symbols Composed of three different parts

MCC (Mobile Country Code) 3 digits fixed length

MNC (Mobile Network Code) 1-2 digits, variable length

MSIN or MIN (Mobile Station Identification Number) maximum 10 digits , variable length

Location Parameters of Interest Totally 4 parameters Two from IMSI which are standardized by ITU-T (The International

Telecommunication Union – Telecommunication Standardization Sector):

Mobile Network Code (MNC) Mobile Country Code (MCC)

Two from Service Provider Specific Information Location Area Code (LAC) and Cell ID

Get Location Information

• The Symbian C++ (series 60 version-2.1) code snippet to get all four location parameters from a mobile device looks like this:

RTelServer server;

CleanupClosePushL(server);

User::LeaveIfError(server.Connect());

User::LeaveIfError(server.LoadPhoneModule(_L("phonetsy.tsy")));

RTelServer::TPhoneInfo info;

User::LeaveIfError(server.GetPhoneInfo(0, info));

RBasicGsmPhone phone;

CleanupClosePushL(phone);

User::LeaveIfError(phone.Open(server, info.iName));

MBasicGsmPhoneNetwork::TCurrentNetworkInfo ni ;

phone.GetCurrentNetworkInfo( ni ) ;

TInt MCC = ni.iNetworkInfo.iId.iMCC; //Mobile Country Code

TInt MNC = ni.iNetworkInfo.iId.iMNC; //Mobile Network Code

TInt locationareacode = ni.iLocationAreaCode; //Location Area Code

TInt cellId = ni.iCellId; //Cell ID

Query Expansion & Search

• Query Expansion for each Location Name Individually.

• Three types of expansion using – Country name (MCC)– City Name/ Region Name (LAC)– Region Name within City (CellID)

• Region being most granular, Country being least granular information

• Search Results merged, ranked using granularity of location.

• Ranking function weights are tunable.

Example Location Based Search for “Chinese Restaurant”

Example Location Based Search for “Chinese Restaurant”

Example Location Based Search for “Chinese Restaurant”

Example Location Based Search for “Chinese Restaurant”

The above results are from a location in India-Hyderabad- Banjara Hills

MNC – 013 –Service Provider “C”

Service Provider A

Service Provider C

Service Provider B

MCC – 404 - India

LAC – 2711 Hyderabad

Banjara Hills

CellID – 04BE

Obtaining the Location Database

• Difficulty in Obtaining Location Database because– Three of the four Location parameters vary

across service providers except MCC (Mobile Country Code).

• Used community effort to populate the

database.

• Application prompts user to identify any

unknown location codes. Users help

populating the database.

Issues

• Not all location parameters are standardized. Therefore makes the task much more complicated than IP address to Location mapping in desktops.

• Open issues– User Privacy– Security

Questions??

Thank you