Distributed Multimedia Streaming over Peer-to-Peer Network

Jin B. Kwon, Heon Y. Yeom

Euro-Par 2003, 9th International Conference on Parallel and Distributed Computing, August 2003, (Klagenfurt, Austria)

(Also published in LNCS 2790, Euro-Par 2003 Parallel Processing, pp. 851-858)

Agenda

IntroductionDefinitions and assumptionsTransmission SchedulingFast DistributionSimulations and Performance StudiesConclusion

Introduction

Existing multimedia streaming Client-sever model

-> server network bandwidth limitations…

Possible solutions Multicast

->scalability Peer-to-Peer model

->in early stage

Introduction

The authors focus on1)Transmission scheduling of the media data for

a multi-supplier P2P streaming session Supplying peers with heterogeneous out-bound

bandwidth The problem is to schedule the segments of media

data so as to minimize the buffering delay Propose Fixed-length slotted scheduling (FSS),

better than OTS.

Introduction

The authors focus on2)Fast distribution of media contents

P2P system is self-growing. Important to convert requesting peer to supplying

peers as soon as possible Propose FAST : aims at accelerating the speed at

which the P2P system capacity increases

Definitions

Candidate Set : Set of supplying peers Requesting peer

selects the supplying peers from the set, opens a channel with each selected supplying

peer, requests the data segment from them according

to a scheduling mechanism After receiving, stores and becomes a

candidate of the media content

Assumptions

Appropriate searching algorithm γ : playback rate of the media dataPr : requesting peer

Rin(r) : in-bound bandwidth Pr

Rout(r) : out-bound bandwidth Pr

0 < Rin(r) ≤ γ Rout > 0

: buffering delay

Transmission Schedule

The goal : minimize buffering delay while ensure continuous playback

Determine the data segments to be transmitted over each channel and the transmission order of the segments.

To ensure continuous playback

p(t) Amount of data being played for t seconds since beginning of playback

d(t) Amount of consecutive data from the beginning of the media file received for t seconds

OTS

Consider 4 channels with bandwidth of

8842

8

L3

Fixed Length Slotted Scheduling (FSS)

Variable-length segments are assigned to the channels in round-robin fashion

Define slot length w

i-th channel bandwidth Bi

segment length wBi

Use previous example,

8

L

4

Lw

Fixed Length Slotted Scheduling (FSS)

w B 1

• notice the overhead transmission!

Fast Distribution - definition

Requesting PeerCandidate PeerMature Peer : holding

the whole media fileImmature Peer : being

download the media data

Fast Distribution

Xi(t, r) : when Pi is assumed to be selected as a supplying peer of a request peer Pr, the position within the media file of the data to be requested to transmit at t.

Rate of increase

)r(Bi

peer immature is P when }L,w

w

tB*Bt

Bmin{

peer mature is P when L)t(d

i11

i

For a immature peer to be a supplying peer of Pr (called semi-mature peer)

Fast Distribution

Xi(t, r) can not be determined until Pr select its supplying peers

use upper bound function xr(t)

ww/)tt()r(R)t(x 0inr

However, not satisfying it does not mean that Pi is not a semi-mature peer

Peer requesting video : procedure

Select from mature and semi-mature peers

Since FSS depends on B1, the maximum outbound bandwidth peer will be chosen. The procedure is repeated until B*(r) = Rin(r)

Peer requesting video : procedure

If the P2P system is beyond capacity Start download with the acquired channels and

buffering (FAST1) Withdraw the request and retry after a

randomized second.(FAST2) Start download with the acquired channels and

retry to acquire the remainder after T minutes.(FAST3)

Simulation

Parameters 50,100 peers, 100 seed peers

initial Request arrival rate follows P

oisson distribution with mean 1/Θ

Video length = 60min Inbound bandwidth = γ Outbound bandwidth :

Seed peers : γ/2 Others : γ/2, γ/4, γ/8 γ/16 : 1

0%, 10%, 40%, 40%

Performance Study

Assume Channel bandwidth has one of γ/2, γ/4, γ/8 γ/1

6 … γ/2n

B*(r) = γ

Time to transmit a segment

=>

Conclusion

Variable length segment for Transmission Scheduling FSS

Define semi-mature peer for fast Distribution

Performance evaluation over OTS and FSS

~ End ~