1. Mohamed Hefeeda Cross-Layer Mac-Application Layer for Adaptive Retransmission and Packetization Using Langrangian Optimization Farid Molazem Cmpt 820 Fall 2010

2. Mohamed Hefeeda Introduction  We have seen that optimizing performance metrics separately in different layers might not result in the optimal solution for multimedia streaming applications  In this section, we design application-MAC layer optimization solution to minimize received video distortion  In order to do this, we find the optimal packet size and number of retransmissions necessary for the packets  We formulate the problem as an optimization function with constraint and solve it through lagrangian multipliers

3. Mohamed Hefeeda Modulation  Modulation: -Varying a property of a high Frequency signal (carrier signal) to convey another signal  Digital Modulation -Carries bit data in the form of symbols www.wikipedia.com

4. Mohamed Hefeeda Motivation for cross-layer optimization

5. Mohamed Hefeeda  Optimizing packetization in MAC layer does not consider characteristics of video streams Multimedia over IP and wireless networks – M. Van Der Schaar

6. Mohamed Hefeeda Formalizing Joint Cross-Layer Optimization  Organize video stream into layers according to delay deadlines of video frames -Data from different deadline layers are not jointly packetized Scalable Video Bitstream Multi-track hinting

7. Mohamed Hefeeda Formalizing Joint Cross-Layer Optimization

8. Mohamed Hefeeda Formalizing Joint Cross-Layer Optimization

9. Mohamed Hefeeda Formalizing Joint Cross-Layer Optimization

10. Mohamed Hefeeda Packetizing and transmitting data with common deadlines

11. Mohamed Hefeeda Packetizing and transmitting data with common deadlines

12. Mohamed Hefeeda Lagrangian formulation

13. Mohamed Hefeeda Lagrangian formulation www.wikipedia.com

14. Mohamed Hefeeda Lagrangian formulation

15. Mohamed Hefeeda Real time cross layer algorithm for video streaming

16. Mohamed Hefeeda Conclusions  Optimizing packet size and retransmission parameter based on MAC layer alone will be sub-optimal for video streaming applications  We can find and analytical optimal solution for packet size and retransmission parameter to minimize video distortion in the special case of all packets having the same decoding deadline  We can use this solution to design a greedy algorithm for the case we have different data with different decoding deadlines. This greedy algorithm is fast and real time and can use MAC layer feedback to determine the number of times current packets can be transmitted

17. Mohamed Hefeeda Thanks