selection strategies for peer-to-peer 3d streaming
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Selection Strategies for Peer-to-Peer 3D Streaming. Wei-Lun Sung, Shun-Yun Hu, Jehn-Ruey Jiang National Central University, Taiwan 2008/05/29. Virtual environments (VE). VEs allow users to interact in synthetic worlds - PowerPoint PPT PresentationTRANSCRIPT
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Selection Strategies for Peer-to-Peer 3D Streaming
Wei-Lun Sung, Shun-Yun Hu, Jehn-Ruey Jiang
National Central University, Taiwan
2008/05/29
National Central University, Taiwan
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Virtual environments (VE) VEs allow users to interact in synthetic worlds Larger content & more worlds content streaming (i.
e., 3D streaming) becomes necessary
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3D streaming Continuous and real-time delivery of 3D content to
allow user interactions without a full download. Object streaming fragments mesh into base & refinements
Base 1 2 3Refinements
User
(Hoppe 96)
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Scene streaming multiple objects object selection & prioritization
[Teler &
Lischinski 2001]
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Comparison with media streaming
Highly interactive (latency-sensitive) Behavior-based (non-linear)
How to scale to millions of concurrent users?
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Imagine you start with a globe
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Zoom in…
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To a city
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and a building
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Right now it’s flat…
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But in the near future…
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Observation Limited & predictable area of interest (AOI) Overlapped visibility = shared content
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Benefits of peer-to-peer Scalable
Growing amount of total resources
Affordable Commodity PCs
Feasible Better client hardware (CPU, broadband networks) Availability of user-hosted machines
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Peer selection Choose suitable candidates so that content
retrieval can be done quickly and efficiently
Source discoveryWhich peers possess the needed data
Source selectionWhich peers to request the data
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Related Work: FLoD [Infocom 2008]
VE partitioned into cells with scene descriptions Assumes P2P overlay that provides AOI neighbors
star: self triangles: neighborscircle: AOI rectangles: objects
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Peer selection in FLoD Source discovery
Query-responseExtra delay due to queries
Source selectionRandom selectionRequests contention due to overlapping requests
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OBJ
Request contention problem
Overlapping requests create contentions
R1
R2R3
R4
R5
R6
R1,R2
R1,R2,R3
R1,R2,R3,R4,R5,R6
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Proposed Solutions
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Incremental Piece List Exchange Proactive notification of content availability Periodic incremental exchange of content
availability information with neighbors.
Msg_Type Obj_ID Max_PID Obj_ID Max_PID ‧‧‧‧
incremental content information
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Extended Candidate Buffer Non-AOI neighbors may still possess data Maintain extra list of non-AOI neighbors
RS Obj
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Multi-Level AOI Request Localized requests may prevent contentions Peers request from closer neighbors/levels first
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Simulation Environment Based on FLoD (available on SourceForge)
World size: 1000 x 1000 Simulation steps: 3000 Objects: 500 Nodes: 50 ~ 500 (50 nodes increase) AOI radius: 75
Server bandwidth: 10 Mbps / 10 Mbps Peer bandwidth: 1 Mbps / 256 Kbps
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Simulation Environments (cont.) Source discovery
(QR) query-response: 5 steps interval, 10 requests (EE) exchanged & extended: 150 radius
Source selection (RAND) random (ML) multi-level AOI request : 4 levels
Original FLoD: QR-RAND Proposed method: EE-ML
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Hit Ratio
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Base Latency
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Fill ratio
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Bandwidth (Server)
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Bandwidth (Clients source discovery)
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Conclusion New selection strategies for P2P 3D streaming
Availability info exchange & extended candidate buffer reduce both latency and bandwidth overhead
multi-level AOI requests obtain data from closer providers but improve only hit ratio
Future work More sources Physical topology Pre-fetching
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Q & A
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Neighbor discovery via VON
Boundary neighbors
New neighbors
Non-overlapped neighbors
[Hu et al. 06]
Voronoi diagrams identify boundary neighbors for neighbor discovery
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LODDT
‧ ‧‧
‧‧
Object Tree Node Aura
U
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LODDT (cont.) Discovery
Estimation Selection
Every peer samples the time-to-serve (TTS) of its neighbors
Requestors organize their data requests so as obtain tree nodes in the right order
Drawback: incorrect estimation, congestion
Requests Candidates
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Simulation Environments (cont.) System performance
Hit ratio: Ratio of successful requests peers have sent Latency: Duration between initial request and data arrival Fill ratio: Ratio of the possessed required data
Scalability metrics Bandwidth usage (consumption) Content discovery overhead