Interference and Service Discovery in Multi-Hop Ad Hoc Networks Alex Varshavsky University of...
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Transcript of Interference and Service Discovery in Multi-Hop Ad Hoc Networks Alex Varshavsky University of...
Interference and Service Discovery in Multi-Hop Ad Hoc Networks
Alex VarshavskyUniversity of Toronto
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Multi-Hop Mobile Ad Hoc Networks (MANETs)
Wireless medium Mobile nodes No fixed infrastructure Each node acts as router Applications
Relief operations Battlefield
A
F
3
4
Multi-hop Networks No Spatial Reuse
AFB
C D E
5
Multi-hop NetworksSpatial Reuse
AFB
C D E
6
Throughput Measurement
Chains of different length
Traffic pattern Constant Bit Rate (CBR)
……
7
0
100
200
300
400
500
600
700
800
900
40 104 168 232 296 360 424 488 552 616 680 744 808 872 936
Sending Rate (Kb/s)
Ave
rag
e T
hro
ug
hp
ut
(Kb
/s)
2 3 4 5 6 11
CBR Throughput
55%
Drop
8
Wireless Transmission
A B CDATA DATA
Collision
Hidden terminal
CSMA/CD doesn’t work
Use CSMA/CA
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Interference Range
A B CDATA D
Interference Range = 550m
Transmission Range = 250m
10
The Hidden Terminal Problem
A B CDATA D E F
DATACollision
11
CBR Throughput
0
100
200
300
400
500
600
700
800
900
40 104
168
232
296
360
424
488
552
616
680
744
808
872
936
Sending Rate (Kb/s)
Ave
rag
e T
hro
ug
hp
ut (K
b/s
)
2 3 4 5 6 11
• Self-interference
• Throughput depends
• route length
• sending rate
12
13
MANET in Action
Gee…I wear a Video CameraCool !
I act as Video
Redirector
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MANET in Action
I still wear a Video Camera
Now I act as Video Redirecto
r
15
Service Location Protocol (SLP)
Discover services Two modes of operation
Centralized Distributed
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Service Location Protocol (SLP)Centralized Mode
User Agent
Service Agent
DirectoryAgent
Camera Video RedirectorFind “video redirector” !
Register “video redirector”
Find “video redirector” !
Register “video redirector”
C
D
S1
S2
17
Service Location Protocol (SLP)Centralized Mode
User Agent
Service Agent
DirectoryAgent
Camera Video RedirectorFind “video redirector” !
Register “video redirector”
Find “video redirector” !
Register “video redirector”
C
D
S2
S1
18
Service Location Protocol (SLP)Centralized Mode
User Agent
Service Agent
DirectoryAgent
Camera Video RedirectorFind “video redirector” !
Register “video redirector”
Find “video redirector” !
Register “video redirector”
C
D
I found the video redirecto
r
S2
S1
19
Service Location Protocol (SLP)Distributed Mode
User Agent
Service Agent
Camera Video RedirectorFind “video redirector” !
Register “video redirector”
Find “video redirector” !
C
S1
S2
20
Service Location Protocol (SLP) Distributed Mode
User Agent
Service Agent
Camera Video RedirectorFind “video redirector” !
Register “video redirector”
Find “video redirector” !
C
I found the video redirecto
r
S1
S2
21
Service Discovery in MANETs
Centralized Hard to maintain Easy to lose
Distributed Large overhead Large overhead
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