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A Method for P2P Streaming System Join Latency Reduction Using Preferred Peer Lists. Jeonghun Noh Sachin Deshpande* Information Systems Laboratory Stanford University * Sharp Laboratories of America. Toward Low Latency P2P Video Streaming. Real-time video streaming is time-sensitive.

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a method for p2p streaming system join latency reduction using preferred peer lists

A Method for P2P Streaming System Join Latency Reduction Using Preferred Peer Lists

Jeonghun Noh

Sachin Deshpande*

Information Systems Laboratory

Stanford University

* Sharp Laboratories of America

toward low latency p2p video streaming
Toward Low Latency P2P Video Streaming
  • Real-time video streaming is time-sensitive.
    • Users prefer quick video play-back.
    • Channel surfing benefits from a short join latency.
  • Join latency in P2P systems
    • During join procedure, new peers connect to peers in the system to receive video.
    • Existing P2P networks: new peers blindly probe for parents at random.

GOAL: Design a P2P network that provides

a small join latency

overview
Overview
  • Preferred Peers List System
    • Overview
    • Preferred Peer Cache/List
    • Parent switching
    • Soft Handover
  • Experimental Results
  • Conclusions
overview preferred peer list system
Overview: Preferred Peer List System
  • Preferred Peer Cache (PPC)
    • Caches information about available peers (preferred peers) in the overlay.
    • Maintained by the source peer
  • Preferred peers have a high probability of being available to other peers
  • Using PPC for peer recommendations
    • New incoming peers contact the source peer.
    • The source peer sends a Preferred PeerList (PPL) containing preferred peers.
    • The new peers directly contact the preferred peersto connect to.
partial learning of the overlay

PX

PY

Partial Learning of the Overlay
  • Source peer partially learns about the overlay from the peer’s join / leave reports

S

X

Y

JOIN Report

LEAVE Report

using the knowledge about the overlay
Using the Knowledge about the Overlay
  • A list of peers, PPL, is created when a recommendation is requested from new peers.
  • Among the most recently updated peers, peers recommended less often are chosen.

Peer address | Use-count | Update time (in secs)

PPC

(at the source)

Selected peers

join p rocedure using ppl

Video stream

Join Procedure Using PPL

Initial join request

  • Contact video source
  • Receive number of trees, video rate
  • Receive flat list, preferred peer list (PPL)

Direct connection and peer probe

  • Contact preferred peers on PPL
  • Probe peers on flat list

Use probe replies;

if preferred peer attempt fails.

  • Selects best parent from probe replies
  • Parent selection factor
    • Available bandwidth
    • Minimize tree height
parent switching
Parent Switching
  • Preferred peer recommendations do not guarantee the best parents
  • One method to choose better parents
    • Utilize collected probe replies
    • Perform the probe-based join process
distribution tree at time 71s
Distribution Tree at time 71s

No Parent Switch

: video source

: peer in the session

: peer that left the session

Average Tree Height : 3.76

Average PSNR : 39.71dB

distribution tree at time 71s1
Distribution Tree at time 71s

Parent Switch

: video source

: peer in the session

: peer that left the session

Average Tree Height : 2.67

Average PSNR : 40.13dB

soft handover
Soft Handover
  • Parent switching may cause video discontinuity.
  • Using Soft Handover
    • Keep old and new parents simultaneously so that both parents forward video packets.
    • As soon as duplicate packets are detected, send leave message to old parent.
experimental s etup
Experimental Setup
  • Network simulation in ns-2
    • 75 / 300 active peers
    • Random peer arrival/departure average: ON (90 sec)/OFF (10 sec)
    • Peer uplink: typical access bandwidth / uniform bandwidth
  • Video streaming
    • Mother & Daughter sequence encoded with H.264/AVC @ 281 Kb/s (CIF quality)
    • 15-minute live multicast
  • System constructs 4 complimentary multicast trees.
distribution of join latency
Distribution of Join Latency
  • Comparison of join time distribution
    • PPL system versus a probe-based system
    • Influence of peer uplink bandwidth: heterogeneous / uniform distributions

First tree join time

Full connection time

effects of parent switching
Effects of Parent Switching
  • Simulation setup: 500 secs, uniform bandwidth distribution for peer uplink
  • PSNR averaged over 10 simulations and 75 peers
effects of soft handover
Effects of Soft Handover
  • Observations

(+) Up to 55% of redundant packet forwarding is reduced

(-) Slight PSNR drop may occur

conclusions
Conclusions
  • PPC keeps partial information about the P2P overlay system.
  • Preferred peers are selected from incomplete PPC.
  • One step closer to low-latency P2P video streaming:
    • New peers can join faster.
    • By switching parent after PPL-based direct attach, overlay quality is improved.
    • By Soft Handover, up to 55% of redundant video packet transmission can be avoided.
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