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Presented by Jekkin Shah

Using Semantic Caching to Manage Location Dependent Data in Mobile Computing Qun Ren, Margaret H. Dunham. Presented by Jekkin Shah. Objective. Application of semantic caching to location dependent applications Eg. Mobile user, navigation system. Contributions.

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Presented by Jekkin Shah

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  1. Using Semantic Caching to Manage Location DependentData in Mobile ComputingQun Ren, Margaret H. Dunham Presented by Jekkin Shah

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

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

  4. Modeling mobility • L = (LX, ,LY) location of object in 2D ( lat-long ) • V = < VX, VY> velocity at any instant of time • Ldt = ( (VX * dt +LX, ) , (VY *dt ) + LY )

  5. Query model • (QR, QA, QP, QL, QC ) QL is the location QC is the result of the query

  6. Query predicate example (price < 100) ^ (LX – 20 < xposition < LX + 20 ) ^ (LY – 20 < xposition < LY + 20 ) • a operator ( LX + c ) • a = attribute , c = constant, LX = location variable

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

  8. LDD query processing • Query trimming • Probe query • Remainder query Coalesing partial results

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

  10. 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

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