Post on 06-Jan-2016
description
Multiple Sender Distributed Video
Streaming
Thinh Nguyen and Avideh Zakhor
Presented by
Huang Wendong
IEEE TRANSACTIONS ON MULTIMEDIA 2004
Introduction Multiple sender distributed video streaming
Multiple senders and single receiver Independent routes from senders to the receiver Achieve higher throughput, increase tolerance to packet
loss and delay due to network congestion
Three main components in the proposed work
Rate allocation algorithm Packet partition algorithm Receiver-driven transport control
System Overview
Sender 1
Sender 2
Receiver
Data
Data
Control ACK
Control ACK
Packet Partition algorithm
Packet Partition algorithm
EstimateRTT
EstimateRTT
Rate Allocation algorithm
Estimate available
bandwidth
Estimate loss rate
Receiver-driven Transport Control
Receiver Calculate the optimal sending rate using RAA based
on the RTTs and estimated loss rates Monitor variations of each sender and readjust rate
distributions among senders accordingly Sender
Estimate and send its round-trip time to the receiver Run distributed PPA upon receiving the control packets
Control packet format Synchronization sequence number + RTT+ sending
rates
Rate Allocation Algorithm Objective
Minimize the irrecoverable loss under fixed FEC Be fair to existing TCP traffic
Setup of RAA Packet loss model: Two-state discrete Markov chain FEC scheme: RS(n, k), n and k are fixed for the entire
streaming process Bitstream model: single description and single layer
bitstream
Rate Allocation Algorithm(2) Mathematical model
Subject to
P(m,i,N) denotes the probability that i packets are lost out of N packets sent by m
is the interval between the successive transmitted FEC blocks in seconds
BA NN
KNj
j
iBABA NijBPNiAPNNKC
1 0
),,(),,(),,(
BB
AA
BA BN
BN
NNN
,,
Rate Allocation Algorithm(3)
},{ },{
),(),,(bgi bgj
mmij
mim NkNkmP
},{
))](1()1,()()1,1([),(bgl
lossm
mlj
mil
lossm
mlj
mil
mij jPpnkjPpnknk
)( 1MNO
Implementation Search over all possible values of and For M senders, the exhaustive search has
complexity of
AN BN
Packet Partition Algorithm Objectives
Run in distributed fashion All packets are sent by one and only one sender To minimize the startup delay
Mathematical model
Where the playback time of k-th packet with respect to
the estimated arrival time of the k-th packet sent by j
To maximize the time difference between arrival and playback time of the k-th packet
)(2)(,, jDjn kkj
( )kP k ),( kjAk , ,[ ( ) 2 ( )]j k kn j D j
( )kP k kT
Packet Partition Algorithm(2)
Distributed calculation Each sender effectively keeps track of all the values
of for all senders No need to synchronize all the sender’s clocks to a
global time
),( kjAk
10 14 13 12 11 15 18 17
18 16 14 12 10
17 15 13 11
Packet playback time
Sender 1
Sender 2
16
Sync
Packet Partition Algorithm(3)
The choice of the synchronization sequence number in the control packet
The lag among the senders needs to be as little as possible
The aggregate bit rate for all senders remains constant
where is the estimated sequence number for the latest packet sender j has just sent, before receiving the control packet.
min ( )jk k j
( )k j
Experiments Results Numerical Characteristics
Two common scenarios X and Y are considered FEC configuration: RS(30,27), RS(30,25), RS(30,23) irrecoverable loss probability change significantly
among various schemes Optimal packet partition scheme As the average bad time of route B increases, more
packets are sent by route A for all three levels of FEC protection;
At the same average bad time of route B, the number of packets sent on route A decreases with increased FEC level
Experiments Results(2) Single sender vs. multiple senders Irrecoverable packet loss is significantly reduced in
multiple sender scheme; Optimal RAA is more effective with stronger FEC
schemes Sensitivity Analysis of Optimal Sending
Rate Sensitivity of loss probability to deviations form
optimal sending rates In case of strong FEC protection,a slight variation in
the sending rate around the optimal value results in a smaller change in irrecoverable probability
Experiments Results(3) Internet Experimental Results Show
Multiple sender scheme can effectively combat burst packet loss In most cases, PPA provides interleaved packets with small lags
Conclusions The proposed work can effectively reduce
overall packet loss rate
Further work Adopt adaptive FEC schemes Employ scalable bitstream to accommodate the
additional data