Congestion-Distortion Optimized Peer-to-Peer Video Streaming Eric Setton*, Jeonghun Noh and Bernd Girod Information Systems Laboratory Stanford University * Recently joined HP Labs

2 E. Setton, J. Noh, and B. Girod: Congestion-Distortion Optimized Peer-to-Peer Video Streaming Motivation Optimized scheduling for peer-to-peer (CoDiO P2P) 1.Prioritization algorithm: sender  receivers 2.Retransmission scheduler: receiver  senders Experimental Results –Comparison to state-of-the-art schedulers –Benefits of adaptive scheduling on P2P streaming Outline

3 E. Setton, J. Noh, and B. Girod: Congestion-Distortion Optimized Peer-to-Peer Video Streaming Prior Work TCP-friendly rate-control –Indicates average rate as a function of collected statistics –Does not indicate any particular schedule Rate-Distortion optimized scheduling (RaDiO) –Formalization of the multimedia scheduling problem –Adapted the framework to video streaming Congestion-Distortion optimized scheduling (CoDiO) –Congestion defined as end-to-end delay –Designed for throughput-limited streaming –Same R-D performance as RaDiO and ~40% less congestion [Chou and Miao, 2001] [Floyd et al., 1997] [Kalman and Girod, 2003] [Setton and Girod, ]

4 E. Setton, J. Noh, and B. Girod: Congestion-Distortion Optimized Peer-to-Peer Video Streaming Video Multicast over P2P Networks Challenges Limited bandwidth Delay due to multi-hop transmission Unreliability of peers Related work [Chu, Rao, Zhang, 2000] [Padmanabhan, Wang and Chou, 2003] [Guo, Suh, Kurose, Towsley, 2003] [Cui, Li, Nahrstedt, 2004] [Do, Hua, Tantaoui, 2004] [Hefeeda, Bhargava, Yau, 2004] [Zhang, Liu, Li and Yum, 2005] [Zhou, Liu, 2005] [Chi, Zhang, 2006] Our Approach Build and maintain complementary multicast trees Adapt media scheduling to network conditions and to content Error resilience through retransmission requests … … Video stream

5 E. Setton, J. Noh, and B. Girod: Congestion-Distortion Optimized Peer-to-Peer Video Streaming Specificities of P2P Multicast Many-to-many transmission Little or no feedback Limited content information Low complexity constraint Routing not imposed

6 E. Setton, J. Noh, and B. Girod: Congestion-Distortion Optimized Peer-to-Peer Video Streaming Principles of CoDiO P2P Scheduler which combines 1.optimized prioritization algorithm Decide which packets to send, when and to which peer, to maximize performance while limiting incurred congestion Receiving peer Sending peer

7 E. Setton, J. Noh, and B. Girod: Congestion-Distortion Optimized Peer-to-Peer Video Streaming Scheduler which combines 1.optimized prioritization algorithm 2.optimized retransmission requests Decide which missing packets to request, when and from which peer, to maximize performance while limiting incurred congestion Principles of CoDiO P2P Sending peer Receiving peer Sending peer

8 E. Setton, J. Noh, and B. Girod: Congestion-Distortion Optimized Peer-to-Peer Video Streaming Scheduler iteratively selects Intervals between transmission sufficient to –Mitigate any congestion of the uplink –Reserve rate for control traffic CoDiO Prioritization Sender PI BP B P B

9 E. Setton, J. Noh, and B. Girod: Congestion-Distortion Optimized Peer-to-Peer Video Streaming Parent on multicast tree 2 PPIBBBP … … Distortion-Optimized Retransmission Requests Determine missing packets Iteratively request most important packet Limit number of unacknowledged retransmissions PPIBBBP … … Parent on multicast tree 1

10 E. Setton, J. Noh, and B. Girod: Congestion-Distortion Optimized Peer-to-Peer Video Streaming Server-Client Scheduler Performance Simulations over ns-2 2-hop network path, ACKs from receiver Throughput: 400 kb/s, delay 50 ms, packet losses 2% H.264 encoding Simulations over ns-2 2-hop network path, ACKs from receiver Throughput: 400 kb/s, delay 50 ms, packet losses 2% H.264 encoding 365 kb/s 290 kb/s

11 E. Setton, J. Noh, and B. Girod: Congestion-Distortion Optimized Peer-to-Peer Video Streaming Experimental Setup Network/protocol simulation in ns-2 –300 active peers –Random peer arrival/departure average: ON (4.5 min) / OFF (30 sec) –Typical access bandwidth distribution –Over-provisioned backbone –Delay: 5 ms/link + congestion Video streaming –H.264/AVC encoder –15 minute live multicast –CIF resolution –16-frame GOP I-B-B-B-P … Downlink UplinkPercentage 512 Kb/s256 Kb/s 56% 3 Mb/s384 Kb/s 21% 1.5 Mb/s896 Kb/s 9% 20 Mb/s 2 Mb/s 3% 20 Mb/s 5 Mb/s 11% Downlink UplinkPercentage 512 Kb/s256 Kb/s 56% 3 Mb/s384 Kb/s 21% 1.5 Mb/s896 Kb/s 9% 20 Mb/s 2 Mb/s 3% 20 Mb/s 5 Mb/s 11%

12 E. Setton, J. Noh, and B. Girod: Congestion-Distortion Optimized Peer-to-Peer Video Streaming Benefits of Optimized Scheduling (I) Salesman Foreman Simulations over ns-2, 300 peers Number of trees: 4 Retransmissions enabled Simulations over ns-2, 300 peers Number of trees: 4 Retransmissions enabled 2 dB 1 dB

13 E. Setton, J. Noh, and B. Girod: Congestion-Distortion Optimized Peer-to-Peer Video Streaming Benefits of Optimized Scheduling (II) 320 kb/s 290 kb/s Simulations over ns-2, 300 peers Number of trees: 4 Retransmissions enabled Simulations over ns-2, 300 peers Number of trees: 4 Retransmissions enabled 4 dB 5 dB

14 E. Setton, J. Noh, and B. Girod: Congestion-Distortion Optimized Peer-to-Peer Video Streaming CoDiO P2P dB No prioritization dB 0.8 second latency for all peers Average Video Sequence for 64 Peers

15 E. Setton, J. Noh, and B. Girod: Congestion-Distortion Optimized Peer-to-Peer Video Streaming P2P Video Multicast: 36 of the Peers 0.8 second latency for all streams CoDiO P2P dB No prioritization dB

16 E. Setton, J. Noh, and B. Girod: Congestion-Distortion Optimized Peer-to-Peer Video Streaming Conclusions Summary –Congestion-distortion optimized scheduling for P2P 1. Prioritization adapts to the content and to the network conditions 2.Distortion-optimized retransmission scheduler –Largest gains when streaming with short playout deadlines (up to 4-5 dB) close to throughput limit (up to 1-2 dB) Future work –Study P2P scheduling of scalable video –Release of a peer-to-peer streaming client