Jitter Control in QoS Networks
Yishay Mansour
Dept. of Computer Science
Tel-Aviv University and
AT&T Research Labs
Boaz Patt-Shamir
Dept. of Electrical Engineering
Tel-Aviv University and
Northeastern University
Hung, Kuo-En NTHU/CS, Visual Communication Lab.
Outline
• Introduction
• Model
• Delay-jitter control
– Off-line delay-jitter control
– On-line delay-jitter control
• Distribute delay-jitter control
Introduction
• Delay-jitter
– Bounds the maximum difference in the total delay of different packets.
Model
Jitter-control algorithm
Packet arrival sequence
Sequence of packet: 0, 1, 2…n : k
Arrival time: a(k)
Packet release sequence
Model (cont’d)
Algorithm A using a buffer of size B.
S
A
( k ) : Which packet k is released by A a ( k )
Time
S
A
( k ) sequence
a ( k
n i i
0
B ), 0
k
n
Inter arrival time of
is X
ave
t n
t
0 n
X min
X max
min max
t t i
1 i
1
t t i i
0
0
k k
n n
Delay-jitter control
•
Algorithm A: off-line delay-jitter control
1.
for
E k each
a ( k
0
)
k
n, define kX ave
, a ( k
Where we define a(k)
the
B )
interval kX ave
,
for k
n
2.
3 .
find find
S off
( a k ) minimal interval M whick intersects all intervals each packet k, let
P k
kX ave
P k
min( E k
M ), and define
E k
Delay-jitter control(cont’d)
• Algorithm B: on-line delay-jitter control
Define
*
S on
( k )
a ( B )
kX ave for all 0
k
n.
The release sequence is define by
S on
( k )
*
S on a a
( k
( k
( k
), if
), if
2 B ), a(k)
*
S on if
( k
)
*
S on
S
* on
( k
( k a ( k
)
) a
( k a (
k
2
B
2
)
)
B )
Delay-jitter control(cont’d)
X ave
Delay-jitter control(cont’d)
J
J
n k k
0
( k ) def
max
0
i
n
( k ) def
max
0
i
n t
i t
k
( 1 ) For all k, J
( k ) t k t i
( i
( k
k ) X i ) X
0 and J
ave
ave
( k )
(2) For all k, J
( k )
J
( k )
J
0
( 3 ) There and J exist
( k ' ) k and k' such that
0
J
( k )
0
Distributed delay-jitter control
•
Algorithm BD for each 1
j
m, node v j employs Algorithm B with buffer space 2B/m.
node j set S
* on
( k , j )
a ( B / m , j ) releases packet k as close as possible to S
* on
( k , j )