View
215
Download
0
Tags:
Embed Size (px)
Citation preview
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
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
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