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Use of a Software Simulator forModeling the ACTS Link
Roy Laurens
Parag Manihar
Ioannis Pavlidis
Satish Shetty Information Networking Institute
Carnegie Mellon University
ACTS Propagation Workshop
Oklahoma City, OK
October 22-23, 1998
Agenda
¥ CMU/NASA ACTS Experiment
¥ Network Simulator (ns)
¥ Error Modeling for the ACTS Link
¥ Data collection and analysis
¥ Conclusions and Future Research
Goals
¥ ACTS Error Modeling module for NS
¥ Performance analysis and Improvementof TCP behavior over ACTS
¥ Mobile IP performance over ACTS
CMU/NASA ACTS Experiment
LET
ACTS
EFData SDM9000 Comstream CM701
USAT
Comstream CM701 EFData SDM9000
Cisco 3640 Router Cisco 3640 Router
Cisco 1548Dual Speed Hub
NASA RouterCorrespondent
Node
100Mbps
RS449HSSI RS449 HSSI
Internet
NASA CMU45Mbps
6 Mbps
6 Mbps
45Mbps
Network BCMU ChaosNet
Network ANASA
FreeBSD Router
FreeBSD Router
Wean Hall
Hammershlag Hall
"Mobile Node"
Hub
Correspondent
Ethernet"Mobile Node" Ethernet
Network Simulator (ns)¥ Collaborative effort: USC/ISI, PARC,
LBNL & UCB
¥ Event based queue modeling
¥ Easily extendable modular framework
¥ Protocol definition and simulationconfiguration using scripting language
¥ Graphical tools for animation andconfiguration
ns Architecture
Traffic
Routing
Queues
Error Model
Application
Transport
Network
Link
Demux
Agent
Error modeling in ns
¥ Bit Error Rate
¥ Error inter-arrival time
0
2
4
6
8
10
12
14
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60
Time (sec.)
Fre
qu
ency
First Second Third Model
Experiment Data
¥ Eb/No, BER, Beacon Fade and TCP data
¥ Signal Degradation on a Rainy day
¥ Effect on the TCP tests performed
Fade data on Rainy Day from Beacon Signals at 20Ghz and 30Ghz
-35
-30
-25
-20
-15
-10
-5
0
10.00 10.50 11.00 11.50 12.00 12.50 13.00 13.50 14.00
Time (Hour of Day)
Fad
e L
evels
Co
mp
are
d t
o C
lear
Sky (
dB
)
TCP Test Near Fade Event
0.0E+00
1.0E+06
2.0E+06
3.0E+06
4.0E+06
5.0E+06
6.0E+06
7.0E+06
8.0E+06
9.0E+06
0 20 40 60 80 100 120 140
Time (seconds)
Receiv
er A
CK
Seq
Nu
ms
Simulation verification
¥ Modeling the Observed Link Conditions
¥ Model vs Observed Link Behavior
¥ Multiple Simulation Run Results
Multiple Simulation Run Results
0
2
4
6
8
10
12
14
16
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60
Time (sec.)
Fre
qu
en
cy
Conclusions
¥ BER and error inter-arrival time usedfor modeling
¥ NS : modular extendable tool formodeling propagation
¥ ACTS ns model can be used for researchof current and future protocols oversimilar links
Future Research
¥ ns in emulation mode
¥ Mapping of fade data and atmosphericconditions to predict expected Bit ErrorRate
Special Thanks
¥ Kul Bhasin
¥ Bob Bauer
¥ Mike Zernic
¥ Rich Reinhart
¥ Adesh Singhal
¥ ACTS Control Room Team at NASALewis
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