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 )