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IEEE TRANSACTIONS ON MULTIMEDIA 2004. Multiple Sender Distributed Video Streaming. Thinh Nguyen and Avideh Zakhor Presented by Huang Wendong. Introduction. Multiple sender distributed video streaming Multiple senders and single receiver Independent routes from senders to the receiver
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IEEE TRANSACTIONS ON MULTIMEDIA 2004 Multiple Sender Distributed Video Streaming Thinh Nguyen and Avideh Zakhor Presented by Huang Wendong
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 Packet Partition algorithm Estimate available bandwidth Control ACK Sender 1 Data Estimate RTT Rate Allocation algorithm Receiver Estimate RTT Data Sender 2 Estimate loss rate Packet Partition algorithm Control ACK
Receiver-driven Transport Control • Receiver • Calculate the optimal sending rate using RAAbased 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 lossunder 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 • istheinterval between the successive transmitted FEC blocks in seconds
Rate Allocation Algorithm(3) • Implementation • Search over all possible values of and • For M senders, the exhaustive search has complexity of
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
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
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.
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