Location Based Web Search on GSM/GPRS Mobile Devices VVS. Naresh, Prasad Pingali, Vasudeva Varma International 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

Introduction Goal of this project : Provide a L ocation B ased S earch (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

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 – 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