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 )

Agenda Introduction Definitions and assumptions Transmission Scheduling Fast Distribution Simulations and Performance Studies Conclusion

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 on 1)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 on 2)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 data P r : requesting peer R in (r) : in-bound bandwidth P r R out (r) : out-bound bandwidth P r 0 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

Fixed Length Slotted Scheduling (FSS) Variable-length segments are assigned to the channels in round-robin fashion Defineslot lengthw i-th channel bandwidthB i segment lengthwB i Use previous example,

Fixed Length Slotted Scheduling (FSS) notice the overhead transmission!

Fast Distribution - definition Requesting Peer Candidate Peer Mature Peer : holding the whole media file Immature Peer : being download the media data

Fast Distribution X i (t, r) : when P i is assumed to be selected as a supplying peer of a request peer P r, the position within the media file of the data to be requested to transmit at t. Rate of increase For a immature peer to be a supplying peer of P r (called semi-mature peer)

Fast Distribution X i (t, r) can not be determined until P r select its supplying peers use upper bound function x r (t) However, not satisfying it does not mean that P i is not a semi- mature peer

Peer requesting video : procedure Select from mature and semi-mature peers Since FSS depends on B 1, the maximum outbound bandwidth peer will be chosen. The procedure is repeated until B*(r) = R in (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 Poisson 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 : 10%, 10%, 40%, 40%

Performance Study Assume  Channel bandwidth has one of γ/2, γ/4, γ/8 γ/16 … γ/2 n  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

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