Location Based Web Search on GSM/GPRS Mobile Devices

1
Location Based Web Searchon 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

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Agenda

• Introduction
• Solution Outline
• Steps Involved
• Open Issues

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Current search

• Obtained from http//mobilesearch.nokia.com

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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

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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

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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.

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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

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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)
• UserLeaveIfError(server.Connect())
• UserLeaveIfError(server.LoadPhoneModule(
  _L("phonetsy.tsy")))
• RTelServerTPhoneInfo info
• UserLeaveIfError(server.GetPhoneInfo(0,
  info))
• RBasicGsmPhone phone
• CleanupClosePushL(phone)
• UserLeaveIfError(phone.Open(server,
  info.iName))
• MBasicGsmPhoneNetworkTCurrentNetworkInfo
  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.iLocationAreaCod
  e //Location Area Code
• TInt cellId ni.iCellId
  //Cell ID

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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.

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Example Location Based Search for Chinese
Restaurant
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Example Location Based Search for Chinese
Restaurant
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Example Location Based Search for Chinese
Restaurant
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Example Location Based Search for Chinese
Restaurant
The above results are from a location in
India-Hyderabad- Banjara Hills
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MNC 013 Service Provider C
Service Provider A
Service Provider B
Service Provider C
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MCC 404 - India
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LAC 2711 Hyderabad
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CellID 04BE
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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.

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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

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Questions??

• Thank you