Reduced TCP Window Size and Adaptive Playout for Legacy LAN VoIP Niko Färber, Yi Liang November 29,...
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Transcript of Reduced TCP Window Size and Adaptive Playout for Legacy LAN VoIP Niko Färber, Yi Liang November 29,...
Reduced TCP Window Size andAdaptive Playout for
Legacy LAN VoIP
Niko Färber, Yi LiangNovember 29, 2000
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 Fd(d) (CDF of delay) n(t), d(t) (n = number of simultaneous transmissions) fn(n) (PDF of simultaneous transmissions) Fd(d | n) (conditional PDF of delay)
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
Load = 20%
buffer delay [ms]
late
loss
[%
]
W = {1, 2, 4, 8, 16, 32, 64}
fixed playout
adaptive playout
Load = 40%
buffer delay [ms]
late
loss
[%
]
W = {1, 2, 4, 8, 16, 32, 64}
fixed playout
adaptive playout
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 d99)
99
W Nd
R
1-
1
dd99
Fd(d)
dmax