Using Semantic Caching to Manage Location Dependent Data in Mobile Computing Qun Ren, Margaret H. Dunham

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Using Semantic Caching to Manage Location
DependentData in Mobile Computing Qun Ren,
Margaret H. Dunham

• Presented by
• Jekkin Shah

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Objective

• Application of semantic caching to location
  dependent applications
• Eg. Mobile user, navigation system .

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Contributions

• Mobility model to represent moving objects
• Formal definition of location dependent queries
• Strategies for query processing
• Cache management strategies

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Modeling mobility

• L (LX, ,LY) location of object in 2D
• ( lat-long )
• V lt VX, VYgt velocity at any instant of time
• Ldt ( (VX dt LX, ) , (VY dt ) LY )

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Query model

• (QR, QA, QP, QL, QC )
• QL is the location
• QC is the result of the query

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Query predicate example

• (price lt 100)
• (LX 20 lt xposition lt LX 20 )
• (LY 20 lt xposition lt LY 20 )
• a operator ( LX c )
• a attribute , c constant, LX location
  variable

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LDD Cache model

• Cache consists of LDD semantic segments
• Each segment starts with a new page
• Additional parameters like Timestamp is also
  stored

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LDD query processing

• Query trimming
• Probe query
• Remainder query
• Coalesing partial results

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LDD Cache Management

• FAR ( Farthest Away Replacement )
• Improvisation on existing technique
• Calculating Manhattan distance taking location
  and direction into account
• ( in-direction , out-direction )

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Performance study

• Performance of semantic caching scheme
• Cache replacement strategy
• Workload Design
• Database design with various parameters
• Query design ( select only queries )
• Moving path design
• One-way, return trip , random