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On Network Coding Based Multirate Video Streaming in Directed Networks

On Network Coding Based Multirate Video Streaming in Directed Networks. Chenguang Xu and Yinlong Xu University of Science and Technology of China. Outline. Multirate Video streaming About Network coding Related works Without network coding With network coding My work Future work.

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On Network Coding Based Multirate Video Streaming in Directed Networks

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  1. On Network Coding Based Multirate Video Streaming in Directed Networks Chenguang Xu and Yinlong Xu University of Science and Technology of China

  2. Outline • Multirate Video streaming • About Network coding • Related works • Without network coding • With network coding • My work • Future work

  3. Multirate Video Streaming • Property of Internet • Heterogeneity of Receivers • Approaches: • The replicated stream approach • Cumulative Layer approach, Such as MPEGx (Layered Coding) • Non-cumulative Layer approach, Such as MDC

  4. An example of Layer Coding

  5. What is Network Coding? • Transmission with network coding • Packet level encoding at intermediate nodes • Decoding at receivers • The common method of network coding • Linear Coding E.g. 2a+3b

  6. a a a b b b An example -Network Coding T1 F1 T2 ? S a+b F2 F3 T3

  7. The advantages of Network Coding in Multicasting cont Advantages: Throughput, Delay, Disadvantages: Packets Overhead(3%) Encoding/Decoding Time It depends…

  8. Related works-Streaming Without Network Coding • Layered multicast streaming without network coding Rate allocation for each layer Fairness Issues Adaptive layer receiving

  9. Related works-Streaming With Network Coding • Layered streaming with network coding “On multirate multicast streaming using network coding” Allerton05 Encode the packets of different layers Objective: Maximize the total rates of receivers Weakness: May cause ineffective transmission. Receiving higher layers while missing some lower layers .

  10. My work-The Unachievabilityof Network Coding for Streaming Layer1 {a, c} Layer2 {b, d} 2 time units as a generation {a, b, c, d} ? k1*a+k2*b+k3*c+k4*d m1*a+m2*b+m3*c+m4*d layer1 k1*a+k2*b+k3*c+k4*d m1*a+m2*b+m3*c+m4*d layer1 Streaming Conventional Content Distribution For T1 and T2

  11. Problem Descriptions The Model • Directed Networks G(V,E,c) • a set of layers {Layer 1, Layer 2,…Layer k} , with a fixed rate rm for layer m • R is the receivers’ set Objective : Maximizing the total layers received

  12. Basic Assumptions • Each encoding generation occupying Δ consecutivetime units. • The buffer is large enough and the link state is stable. • Acyclic network • Fixed rate for each layer

  13. The Coding Scheme- LSNC • Layered Separated Network Coding • The Advantages of LSNC The advantage of network coding Layer Separated for different priorities of layers Needn’t to pad the shorter packets with 0s

  14. The Coding Scheme- LSNC cont The remaining problems: • How to determine the layer for each receiver? • How to allocate bandwidth for each layer? • How to achieve the rate of each layer? By existed networkcoding algorithm

  15. Optimal Layer Separated Network Coding OLSNC: Jointly Solve 1 and 2.

  16. S is the source. T1 and T2 are receivers. The stream is consisted of 3 layers-L1, L2, L3, with rate of 1, 1, 1 respectively. {L3} {L1} {L2} {L2} {L1} OLSNC-An example By OLSNC, T1 can get 2 layers, and T2 can get 3 layers.

  17. OLSNC-An example Without Network Coding: Optimal Multicast Sub-graph: T1 : 2 layers T2 : 2 layers Optimal Multicast Tree: T1 : 1 layer T2 : 2 layers

  18. Discussion on OLSNC • Optimal result for LSNC • High Computing Complexity E.g. 15 receivers, 5 layers, worst cast execution time is over 1 hour • A time efficient algorithm is needed

  19. Sub-optimal Layer Separated Network Coding Main Idea: 1) Allocate the bandwidth for each layer from low to high, with the objective of maximizing the aggregated maxflows of receivers for rest higher layers. 2) Achieve the multicast rate for each layer with the bandwidth allocated by existed network coding algorithm.

  20. Performance Evaluation Simulation Environments V= {v0, v1,…v10}, R={v1, v2,…v10} Two topologies: E1={(vi,vj)| i < j }, E2=((vi,vj)| 0 < j−i ≤ 2 } Two layer rate allocation schemes: Flat and Exponential Scheme Performance metrics: AC(Vi) is the actual number of layers received by vi OL(vi) is the maximum number of layers permitted by maxflow

  21. Simulation Results E1, Exponential Scheme E1, Flat Scheme

  22. Simulation Results E2, Flat Scheme E2, Exponential Scheme The advantage is more obvious in E1, with Exponential Scheme.

  23. Simulation Results cont The comparison of LRR

  24. Future Works • In undirected networks • Distributed Network Coding Scheme • Fairness problem • Layered P2P Streaming Using Network Coding

  25. Thank You

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