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Innovative Replication Technique for Continuous Media Placement in Wireless Peer-to-Peer Networks

This paper presents a novel approach for the placement and replication of continuous media in wireless peer-to-peer networks, focusing on the H2O framework. The method enhances on-demand access to continuous media while minimizing storage requirements. By dividing video clips into manageable blocks, the paper proposes effective strategies for placing replicas across devices, ensuring efficient delivery and reduced retrieval delays. Assumptions related to bandwidth and network topology are addressed, leading to significant storage savings compared to traditional full replication methods.

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Innovative Replication Technique for Continuous Media Placement in Wireless Peer-to-Peer Networks

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  1. Placement of Continuous Media in Wireless Peer-to-Peer Network Shahramram Ghandeharizadeh, Bhaskar Krishnamachari, and Shanshan Song IEEE Transactions on Multimedia, April 2004

  2. Home-to-Home Online (H2O) devices collaborate to deliver continuous media H2O may act as: A producer of data An active client A router H2O Framework

  3. Motivation • A new replication technique that • Provide on-demand access to continuous media • Minimize the total storage space required

  4. Assumptions • CBR continuous data • Total size of available clips exceeds the storage capacity of one device • Bandwidth between two H2O devices exceeds the bandwidth required to display a clip • One hop distance is a constant

  5. Hi: the Farthest Number of Hops a Block Can be Located • Cycle: period to display a block • D=Sb/BDisplay • The farthest number of hops that the block i can be located: • Hi=((i-1)D)/h block size playback rate time to retrieve a block from one hop away

  6. Data Placement and Replication • For each video clip X: • Divide X into equal-sized blocks with size Sb • Place first block, b1 on each node. • For each block bi, 1<i<=z, compute delay tolerance Hi • Compute ri based on Hi • Construct ri replicas of bi and place them • ri is a topology dependent computation

  7. Topology I: Worst Case Linear Topology • Block i should be replicated ri times: • Hi=(i-1)D/h • ri=N-Hi • Reset ri to one if ri is zero or negative • Total storage space (SC,R) occupied by a clip with z blocks: … 1 2 3 8 9

  8. Percentage Saving Compared with Full Replication in Linear Topology • N=1000, h=0.5, • BDisplay = 4Mbps • y: 100x(1-SC,R)/(SCxN)

  9. Topology II: Grid Topology • Organize N nodes in a square area • At least one copy of bi must be placed within Hi hops • There are nodes within Hi hops of every node • Total storage required:

  10. Total Storage Space Required as a Function of Block Size (1/2) • h=0.75s • 2 min clip (total 60MB)

  11. Total Storage Space Required as a Function of Block Size (2/2) • h=0.75s • 2 hour clip (total 3600MB)

  12. Topology III: Average Case Topology (1/2) • Network connectivity depends on radio range R • N nodes are scattered in area A • There are on average between and nodes within Hi nodes.

  13. Topology III: Average Case Topology (2/2) • Using the upper boundary, the H number of replicas ri required by bi is: • Total storage required for a clip:S

  14. Percentage Saving Comparison

  15. Distributed Implementation • H2Op: publish a clip X • Compute block size Sb, number of blocks z, and Hi for each block • Flood the network to query which H2O will host a copy of which block of X • H2Oj: each recipient of the message • Compute a binary array Aj that consists of z elements whose values are 0 or 1 • Two computation methods: TIMER or ZONE

  16. Technique I: TIMER • When H2Oj receives query message • Perform z rounds of elections • Pick a random timer value between 1 and M then count down • The one first count down to zero stores a copy and send suppress message within Hi hops • May generate more than one copies of a block within Hi hops

  17. Technique II: ZONE • Assume each node is aware of its (x, y) coordinate • Place each copy in a separate square zone whose size is such that all nodes can be reached within Hi hops

  18. Simulation: TIMER vs. ZONE • N=300, R=100m, A=1km2, z=60

  19. Simulation: Comparison of Analytical Models for Graph Topology with 2 Implementations • SC=60MB • R=100m • A=1km2

  20. Simulation: How Many Blocks a H2O Device Have When Using TIMER • N=300, R=100m, A=1km2 • Average # of blocks per node for a clip is marked as dashed line

  21. Conclusion • Provide a novel replication technique for on-demand clips • Minimize startup delay • Storage saving compared with full replication • Provide two distributed implementations

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