1. Nuno Salta Supervisor: Manuel Ricardo Supervisor: Ricardo Morla
Towards the Optimization of Video P2P Streaming over Wireless Mesh Networks
Nuno Salta Supervisor: Manuel Ricardo
Supervisor: Ricardo Morla

2. Outline Introduction Context of the Work Video P2P Motivation
Tree based
Swarm based
Motivation
Related work
Solution approaches
Research topic
Conclusion

3. Introduction
In the past years we have assisted to a change of the Internet paradigm
WLANs are
Changing the way people access Internet
Contributing to the Always best connected concept
Ad-hoc networks enables further possibilities
Peer-to-Peer is playing a decisive role in Internet
P2P traffic produced is now dominant over the Internet
Server-less approach enables new services
Video P2P is an emerging research topic

4. Context of the Work: WMN
WMNs are dynamically self-organized and self-configured
WMNs features:
High reliability
Low deployment costs
Large coverage area
Can be deployed on:
Urban centres
Shopping areas
Public transportation systems
Some standards:
802.11s
802.16

5. Context of the Work: Video over IP
Video-over-IP rising in recent years
From professional content sites:
increased 50% in 2007 to 33.5 billion views
YouTube
2006  6.1 M videos
2008  83.4 M videos
Server-client model for streaming video has scalability issues
Good quality streams require high bandwidths
Servers may incur in significant costs or deadlocks
P2P Video can be an effective alternative

6. Video P2P Distribution types Can be classified as
Video-on-demand
Real-time
Can be classified as
Tree-based
Swarm-based
Important parameters:
Delay
Jitter
Chunk synchronization
Chunk received order
Rever

7. Tree-based Overlay structure is typically well defined
Each peer receives data through their parent
Tree-based systems are usually
Single-tree model
Multi-tree model
Single tree models are vulnerable to node departures
In multi-tree the stream is divided into the various sub-trees
Node has to join each sub-tree to retrieve information
Rever

8. Swarm based Similar with the traditional P2P file sharing
Each peer can receive for multiple parents
A peer can be parent or child in different times
Request-reply scheme
More flexible
More resilient to node departures
Allows better support for mobility
Rever

9. P2P Applications
P2P video distributions applications are focusing on swarm solutions
PPLive, PPStream, TVUPlayer, Sopcast
P2P-Next is an European Project (BBC, EBU and many universities and institutes)
Provide P2P video distribution
Uses BitTorrent-based protocol
Napa-Wine
France Telecom, NEC
Rever

10. Motivation P2P applications
Deployed over physical networks
Peers selected from those having the demanded contents
Closest path defined at the application layer
Application layer paths may be suboptimal
P2P video distribution brings additional problems
Not delay / jitter tolerant
Less original sources in real-time
Inefficiencies expected to increased

11. Motivation
In the the Internet is difficult to match the physical and the overlay topologies/paths
Multiple domains and types of routing
Not all nodes support applications
Usually only the edge nodes are in the overlay network
In Wireless Mesh Networks, these limitations may not apply
WMNs have features that may improve P2P performance:
Routing behaviour similar to P2P applications
Nodes often appear/disappear/move, as in P2P applications
Most of the nodes may contain P2P application layer
WMN topology and overlay topology can mapped in more effective way
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12. Related Work Cross-layer solutions Locality awareness
A Cross-Layer Optimization of Gnutella for mobile Ad hoc networks
MADPastry: a DHT substrate for practicably sized manets
Locality awareness
HIERAS: A DHT Based Hierarchical P2P Routing Algorithm
LDHT: Locality-aware Distributed Hash Tables
Content awareness
Content-aware Distortion-fair Video Streaming in Networks
Distributed Optimization of Media Flows in Peer-to-Peer Overlay Networks
Maximum Utility Selection for P2P Streaming in Wireless Ad Hoc Networks
Specific problems
A novel hotspot algorithm for P2P streaming distribution networking
An Empirical Study of Flash Crowd Dynamics in P2P-based Live Video Streaming System
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13. Research topic In real-time more than one node may need the same chunk
Duplicated content
Wasted bandwidth
Minimize requests for the same chunk
Define routes (dynamic trees)
Defined at requesting node or provider node?
Avoid nodes using other streams
Opportunistic capture
How to handle multiple streams
Unicast traffic
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14. Locality Awareness Swarm model uses request-reply scheme
Can lead to flooding
Use locality awareness
Allows the selection of neighbors based on physical proximity
L3 Neighbors tend to have the same delay
Limit the request propagation
How to detect proximity
How to decide when a request is not relayed
Initial seeder
Explore broadcast
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15. Mobility Evaluate the impact of moving nodes Priority schemes
Moving away or towards the seeders
Distant nodes will have older content
Closer nodes should keep older content?
Priority schemes
Node remaining buffer
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16. Conclusions
Video P2P streaming is an effective alternative to the traditional server-client model
Wireless Mesh Networks are emerging
Video P2P can be optimized for WMN scenarios
Cross-layer
Locality awareness
Content awareness
Minimize requests for the same chunk (duplicated content)
Create dynamic trees
Evaluate request flood
Evaluate the impact of moving nodes

17. The End
Questions?