Information Technology Reference
In-Depth Information
MED
C,A
Time
A
A Speaks
C Heard
MED
A,B
MED
C,B
HRD
B
B
A Heard
C Heard
HRD
C
MED
A,C
C
C Speaks
A Heard
MED
A,D
MED
C,D
D
C Heard
A Heard
Conversation unit: A to C
Conversation unit: C to B
Figure 2.4
A four-party conversation.
2500
Skype system
2000
1500
1000
1
2
3 4 5
Conversation turn index (between one speech segment and the next)
6
7
8
9
10
11
12
Person A
Person B
Person C
Person D
Person E
Figure 2.5
MSs in a simulated Skype conversation.
four-party conversation. Each listener experiences different asymmetric MSs
across the speakers: some appear to be more distant than others or some
respond slower than others.
Figure 2.5 illustrates the disparities in MSs perceived by five participants
in 13 CUs when we simulate a multi-party Skype (Version 3.5.0.214) conver-
sation (with HRD of 750 ms) using UDP traces of five sites (three in North
America and two in Asia) collected in PlanetLab [10]. Since all traffic in Skype
is routed through a common client, there are large disparities in MSs from
one CU to the next.
