ns-3 scalability iTETRIS project (ns-3 workshop Rome 09) · 1 ns-3 w o r k s h o p – R o m e M a...
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Transcript of ns-3 scalability iTETRIS project (ns-3 workshop Rome 09) · 1 ns-3 w o r k s h o p – R o m e M a...
Uwicore, Ubiquitous Wireless Communications Research Laboratory
Universidad Miguel Hernández, www.uwicore.umh.es
ns-3 workshopRome – March 2nd, 2009
ns-3 scalability constraints in heterogeneous wireless
simulations: iTETRIS a case study
Ramon Bauza ([email protected]), Javier Gozalvez ([email protected]) and
Miguel Sepulcre ([email protected])
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Contents
� iTETRIS project presentation
� WAVE/802.11p
� ns-3 scalability capabilities
� Impact of number of vehicles and vehicle density
� Reduction of physical layer accuracy
� Reduction of interference range and packet rate
� Conclusions
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iTETRIS presentation
� iTETRIS (an Integrated Wireless and Traffic Platform for Real-Time
Road Traffic Management Solutions)
� European project funded within the 7th Framework Programme
� Consortium of different research groups: THALES, CBT, City of Bologne,
DLR, Eurecom, Hitachi, Innovalia, Peek Traffic and UMH
� Main iTETRIS objectives
� Implement an open-source integrated wireless and traffic simulation
platform
� Estimate the impact of cooperative vehicular
communications on traffic management
� Test and optimize V2V and V2I
communications and networking protocols
� Test and optimize cooperative traffic
management policies
� Large scale trials (traffic data of the city of
Bologne)
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iTETRIS simulation platform
� Integration of two widely used open source platforms
� ns-3 (Network Simulator 3)
� SUMO (Simulation of Urban MObility)
� CTMC (Cooperative Traffic Management Centre)
� Decision on routing traffic
flows
� Inform vehicles using the
MxC functional block
� MxC (Message eXchange Communications)
� Also provides the CTMC with traffic condition estimates (derived from
V2X communication)
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iTETRIS wireless platform architecture
� The iTETRIS wireless platform will follow the European ITS communications architecture determined by COMeSafety.
� This architecture has many similarities with the CALM architecture developed under the ISO.
Applications
Management
Facilities
Transport & Network
Access Technologies
Road Safety Traffic EfficiencyValue-Added
Servicies
Application
SupportSession Support
Information
Support
ITS
Network
ITS Transport
Geo-
Routing
Other
Protocols
Ipv6 +
Mobility
TCP/UDP
NF-SAP
FA-SAP
MA-SAP
MF-SAP
MN-SAP
MI-SAP
IN-SAP
WAVE UMTS WiMAX DVB
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WAVE/802.11p
� Spectrum divided into three 10MHz sub-channels
� WAVE MAC/PHY for CCH and SCH
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ns-3 scalability capabilities
� ns-3 advantages over ns-2� Good scalability, modularity and multi-technology (from the beginning)
� ns-3 performance for large scale simulations� Capable to simulate large amount of nodes (20000 nodes or more)
� High execution times for large and dense scenarios
� Work needed to achieve feasible runtimes for iTETRIS� Paralellization techniques (planned for June 2009)
� Simplification of ns-3 communication modules
� Factors directly impacting on simulation performance� Total number of vehicles
� Traffic density
� Implementation accuracy
� Interference range
� Packet generation rate
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Impact of number of vehicles and vehicle density
40sSimulation time
6MbpsData rate
10 packets/second (default)Packet tx rate
700m (default) Interference range
LogDistancePropagationLossPropagation model
RandomWalk2dMobilityModelMobility model
70km/h (maximum)Nodes’ speed
ValueParameter
� Scenario under evaluation
� 802.11 one-hop periodic broadcast
� Influence of vehicle density on simulation performance
� Close related to number of neighbours (packets to be
processed)
� Simulations with different traffic densities
700m
Inte
rfere
nce
rang
e
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Impact of number of vehicles and vehicle density
� Impact of traffic density on execution time (40s 5000 nodes)
� Execution time linearly increases
with traffic density
0 500 1000 1500 20000
5
10
15
20
25
30
35
Execution tim
e [h]
Vehicle density [Veh/Km2]
0 0.5 1 1.5 2
x 104
0
20
40
60
80
100
120
Exe
cu
tio
n tim
e [h
]
Number of vehicles
D10 (High Density)
D100 (Low Density)
� Influence of traffic density and number of vehicles on simulation performance
� Unworkable execution times for 1h
simulation
� Improvements need to be introduced
into the simulator
170Low
397High
Execution time [days]Traffic density
1h 20000 nodes
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Reduction of physical layer accuracy
� ns-3 spends most of the time at the physical layer
� Packets processing and interference calculation
� Simplification of PHY models
� Removal of interference calculation
� Performance analysis
� Around 35% of reduction time
40s High Density (D100)
0 0.5 1 1.5 2
x 104
0
20
40
60
80
100
120
Exe
cu
tio
n tim
e [h
]
Number of vehicles
Default
Without Interference
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Reduction of interference range and packet rate
� Congestive scenarios
� Vehicles adapt transmission range and packet rate to reduce interference40s Default PHY model
100 200 300 400 500 600 7000
20
40
60
80
100
120
Exe
cu
tio
n tim
e [h
]
Interference range [m]
10000 nodes
20000 nodes
� Impact of interference range on simulation performance
� Execution times increases with interference range
� Impact of packet rate on simulation performance
� Simulations run 80% faster reducing transmission rate from 10 to 2 packets per second
� Realistic congestive scenario� High density (D10)
� Interference range of 100m
� 2 packets per second
� 1h simulation with 20000 nodes would take 30 days
� Execution time much more feasible for iTETRIS 100m
400m
700m
Interference range
149
245
397
Estimated execution
time [days]
1h Default PHY 20000 nodes High Density
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Conclusions
� iTETRIS presents demanding requirements in terms of simulation platformscalability
� Multi-technology platform
� Large-scale scenarios
� Long simulation times to obtain valid results
� ns-3 capable of simulating large scale scenarios and high traffic densities
� Default distribution takes considerable time
� Need for future enhancements for optimization
� More efficient scheduler
� Parallelization techniques
� Staged simulation techniques
� Grid-based decomposition
� Code performance improvement
� Further suggestions and proposals