1. RELIABLE MULTIMEDIA TRANSMISSION OVER COGNITIVE RADIO NETWORKS USING FOUNTAIN CODES Proceedings of the IEEE | Vol. 96, No. 1, January 2008 Harikeshwar Kushwaha, Student Member IEEE, Yiping Xing, Student Member IEEE, Rajarathnam Chandramouli, Senior Member IEEE, and Harry Heffes, Fellow IEEE 1

2. Outline 2

3. Introduction 3  Wireless multimedia applications require  significant bandwidth and  satisfying relatively tight delay constraints.  Radio spectrum is a scarce resource.  spectrum has already been allocated.  Secondary spectrum access(FCC)  dynamic access to the unused parts of the spectrum owned by the primary license holder  facilitated by Cognitive radios

4. Introduction 4

5. Spectrum Pooling Concept 5

6. 6  A link is composed of multiple different SCs at different frequencies.  achieving distributed streaming  Reliable  But, the coordination required between the SCs.

7. Digital Fountain Codes 7  No need of coordination required between the SCs.  Robust against the packet loss caused by the PU interference and other channel conditions.

8. Primary User Arrival Model 8

9. 9

10. Coding Scheme for Scalable Multimedia Applications 10

11. Problem description 11 How many?

12. Problem description 12

13. Subchannel Selection 13

14. 14

15. 15

16. 16

17. 17

18. 18

19. 19

20. Simulation Result 20

21. Simulation Result - Parameterization 21  1) Estimation of Number of Required Subchannels:

22. Simulation Result - Parameterization 22

23. Simulation Result - Parameterization 23  2) LT Codes(ideal case) ： robust soliton distribution

24. Simulation Result - Parameterization 24  3) Delay and Other Requirements:

25. Simulation Result - Parameterization 25

26. Simulation Result - Parameterization 26

27. Simulation Result – Performance Analysis 27  Observation in Figs. 12-14 ： 1) Dependence on X For each value of S, attains a maximum value at a specific value of X. 2) Dependence on S η attains another maximum at a specific value of S. 3) Dependence on λ η decreases as λ increases

28. Conclusion 28  Propose a scheme for the transmission of distributed multimedia applications over cognitive radio networks with the help of digital fountain codes.  For a given λ and number of original packets K, we can find out the value of the optimum number of SCs and the overhead X that give maximum spectral efficiency.