1. Reduced TCP Window Size and Adaptive Playout for Legacy LAN VoIP Niko Färber, Yi Liang November 29, 2000

2. Outline Buffer Delay vs. Late Loss Load = 20, 40 % TCP window size = 1, 2, 4, 8, 16, 32, 64 packets Adaptive/Fixed playout Adaptive playout over time Load = 10, 40% TCP window size = 32 packets Analysis/Modeling of queuing delay F d (d) (CDF of delay) n(t), d(t) (n = number of simultaneous transmissions) f n (n) (PDF of simultaneous transmissions) F d (d | n) (conditional PDF of delay)

3. Simulation conditions Balanced N-N communication, N=16 hosts, 1 switch File size PDF: Log-Normal Idle time ~ file size 70 KB buffer 10 Mbps Full duplex Drop tail

4. Load = 20% buffer delay [ms] late loss [%] W = {1, 2, 4, 8, 16, 32, 64} fixed playout adaptive playout

5. Load = 40% buffer delay [ms] late loss [%] W = {1, 2, 4, 8, 16, 32, 64} fixed playout adaptive playout

6. Adaptive Playout, Load = 10%

9. Adaptive Playout, Load = 40%

12. Delay CDF At load link is not used with prob. 1- With 1- prob. voice packets see empty queue (and therefore experience zero queuing delay) Empirical model for significant delay range (99 % of packet delays are less than d 99 ) 1- 1 dd 99 F d (d) d max

13. Delay CDF, Load = 10% d [ms] F d (d)

14. Delay CDF, Load = 20% d [ms] F d (d)

15. Delay CDF, Load = 30% d [ms] F d (d)

16. Delay CDF, Load = 40% d [ms] F d (d)

17. Delay CDF, Load = 50% d [ms] F d (d)

18. Delay and Simultaneous Txs t [s] d(t) [ms] n(t) 1 2 3

19. PDF of Simultaneous Txs n f n (n) Binominal (f n (0) matched)  = 10%, W=32

20. Cond. Delay PDF, 0 simult. Tx d [ms] f d (d | n=0)

21. Cond. Delay PDF, 1 simult. Tx d [ms] f d (d | n=1)

22. Cond. Delay PDF, 2 simult. Txs d [ms] f d (d | n=2)

23. Cond. Delay PDF, 3 simult. Txs d [ms] f d (d | n=3)

24. Mean and Std of Cond. Delay PDF n d [ms] dd dd