1. Accuracy and Efficiency in Simulating VANETs
Introduction and Motivation
VANETs Simulation
The CARLINK-UMA Scenario
Results
Conclusions and Future Work
Accuracy and Efficiency in Simulating VANETs
Enrique Alba, Sebastián Luna, and Jamal Toutouh
Universidad de Málaga

2. Outline Introduction and Motivation VANETs Simulation
The CARLINK-UMA Scenario
Results
Conclusions and Future Work
Outline 1
Introduction and Motivation
VANETs Simulation
The CARLINK-UMA Scenario
Results
Conclusions and Future Work 2 3
In this presentation we want to through light on the problem of simulating VANETs. For this reason, I will introduce the problem of the VANET simulation. I will show the results obtained over the CARLINK-UMA scenario. Finally, I will present the conclusions and the future work come from this work.
In the First Section I will introduce to the VANET simulation problem and the motivation of this presentation.
In the Second Section I will summarize the different alternatives for VANETs simulation, focusing in the simulators used during the CARLINK project
In the Third Section I will present the defined scenario, where both, simulations and real tests were carried out.
In the Fourth Section I will show the achieved results, comparing them.
Finally, in the Fifth Section I will present the conclusions and the future work come from this work 4 5 5
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3. Introduction and Motivation
VANETs Simulation
The CARLINK-UMA Scenario
Results
Conclusions and Future Work
Introduction and Motivation
The performance evaluation of the different VANET protocols and applications is done by using both outdoor experiments and simulations
The evaluation through outdoors experiments has several drawbacks:
neither easy nor cheap
difficult to analyze in an inherently distributed and complex environment
reproduction of all kinds of situations where they must act is not possible
The simulation avoid the previous drawbacks. Nevertheless it presents the following one:
the fidelity of the simulated results versus the real ones
Nowadays are appearing new protocols and applications for VANETs, the test of these new protocols and applications CAN BE DONE by BOTH outdoor experiments and simulations.
The VANETs evaluation through outdoor experiments is extremely difficult since:
It is NEITHER easy nor cheap to have a high number of vehicles and a real scenario for VANET designers
It is difficult to analyze the data generated during the real tests
It is not possible to reproduce all kinds of situations where the VANETs must act
The use of simulators avoids the previous drawbacks. However, it presents a new one, the fidelity of the simulated results versus the real ones.
In the following I will present a comparison between the simulations and real tests.
The goal is to better know the actual VANET used in CARLINK and the data/delay rates affecting the final applications.
We present here a comparison between simulations and real tests
The goal is to better know the actual VANET simulator used in CARLINK and the data/delay rates affecting the final applications
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4. Introduction and Motivation
VANETs Simulation
The CARLINK-UMA Scenario
Results
Conclusions and Future Work
VANET Simulation
Three kinds of approaches in VANET simulation have been initially considered:
Using an specially-designed VANET simulator
Alternatives: TraNS, MOVE, CARISMA, and STRAW
VanetMobiSim/Ns-2
Integrating a vehicular mobility model generator into an existing network (MANETs) simulator
Mobility model generator: SUDO and VanetMobiSim
Network simulators: Ns-2, GlomoSim, QualNet, and OpNet
Nowadays, we identify three different approaches trying to through light on the complex problem of simulating VANETs in a trustworthy manner.
The first one is using a specially-designed VANET simulators. As: TraNS, MOVE, CARISMA, and STRAW
The second approach integrates a vehicular mobility model generator (as SUDO or VMS) into a MANET simulator as (Ns-2, Glomosim, Qualnet or Opnet)
Finally, we found JANE, a MANET application programming framework which allows the developer to test the applications via simulations
Finally, we considered the use of VMS combined with Ns-2 and JANE for the CARLINK simulations
MANET applications programming framework which allows the developer to test the applications via simulations:
Alternative: JANE
JANE
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5. Vehicular Data Transfer Protocol (VDTP) has been added
Introduction and Motivation
VANETs Simulation
The CARLINK-UMA Scenario
Results
Conclusions and Future Work
VANET Simulation. VanetMobiSim/Ns-2
VanetMobiSim/Ns-2 [ mobility model generator + network simulator ]
VanetMobiSim:
Ns-2:
- Freely available
Different kind of outputs
Generates realistic models
Macro-mobility features
Micro-mobility features +
Freely available
Easily adding features
Widely used
Numerical output
VMS/Ns-2 is a combination of VMS/Ns-2 which is a vehicular mobility model generator and Ns-2 which is a well know network simulator.
We chose VanetMoviSim mainly because it s Freely available, the generated traces may have different outputs and it generates realistic models defined by different BOTH macro-mobility and micro-mobility features.
Ns-2 have been chosen because it s freely available, too. It offers the possibility of adding new features (we add the VDTP definition). it is widely USED and VERIFIED, and it offers different numerical and statistical outputs.
Vehicular Data Transfer Protocol (VDTP) has been added
TARGET: making precise simulations of the real systems
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6. VANET Simulation. JANE JANE: Java Ad hoc Network Environment
Introduction and Motivation
VANETs Simulation
The CARLINK-UMA Scenario
Results
Conclusions and Future Work
VANET Simulation. JANE
JANE: Java Ad hoc Network Environment
Open source Java-based middleware platform which is intended to assist ad-hoc network researchers in application and protocol design
Three different execution modes:
Simulation Mode: the complete environment is simulated
Hybrid Mode: the devices and the ad-hoc network are simulated, but real users can interact with the simulation
Platform Mode: the whole setting is real
Drawback: It is not specialized for VANETs
not provide realistic mobility models for the
simulation of vehicular networks
TARGET: programming high level applications
Open source Java-based middleware platform which assists ad-hoc network researchers in application and protocol design
It offers 3 different execution modes:
1.Simulation mode: The application is completely simulated
2.Hybrid mode: The user can interact with the simulator by using different defined interfaces
3.Platform mode: The application is executed over the real hardware platform
The main drawback is that it is specialized for MANETs, so it not provides the realistic vehicular mobility models
The main TARGET of JANE is to programming and test high level applications
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7. The CARLINK-UMA scenario
Introduction and Motivation
VANETs Simulation
The CARLINK-UMA Scenario
Results
Conclusions and Future Work
The CARLINK-UMA scenario
The scenarios are defined by their specific mobility models:
File transfers between two cars by using ad-hoc operation mode of the IEEE b MAC Layer Standard
PROXiM ORINOCO PCMCIA transceiver
Range extender antenna gain: 7 dBi
The CARLINK-UMA scenario defined to carry out the tests is defined as follows:
The Scenario A, the vehicles are located separated by 100m over the same lane and they move in the same sense with a velocity of 30 Km/h.
The Scenario B, the vehicles are in different lanes, separated by 500m, and they move in the opposite sense with a velocity of 30 Km/h.
The cars use the ad-hoc operation mode of the WiFi standard protocol for the file transfers.
Each car is equipped by a PROXIM ORINOCCO transceiver and a range extender antenna.
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8. Test Xi The CARLINK-UMA scenario
Introduction and Motivation
VANETs Simulation
The CARLINK-UMA Scenario
Results
Conclusions and Future Work
The CARLINK-UMA scenario
Each experiment is composed of different tests
The tests consist in repeatedly transferring a file in specific scenarios:
File type 1: traffic information documents (1 MB)
File type 2: multimedia files (10 MB)
The file transfers are carrying out by using the Vehicular Data Transfer Protocol (VDTP):
Chunk size: 25Kbytes
Retransmission time: 8 seconds
Max number of attempts per packet: 8
The test are named as follows:
Test A1
Test A2
Test B1
Test B2
It denotes the file type:
File type 1 = 1 MB
File type 2 = 10 MB
The experiments are composed by different test. The test consist in continuously transferring a file in the previously presented scenario.
We have used 2 types of file
The file type 1 with 1 MB size represents traffic information documents.
The file type 2 with 10 MB size represents multimedia files
The file transfers have been carried out by using the VDTP protocol, setting it up as follows:
- 25KB of Chunk size.
- 8 seconds of retransmission time
- and the maximum number of attempts of 8.
The test are named as Test A1, Test A2, Test B1, and Test B2.
Where the Uppercase letter describes the scenario and the number denotes the file type.
Test Xi
It describes the scenario:
Scenario A
Scenario B
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9. Results Test A1 (same sense, 1 MB files) Average values:
Introduction and Motivation
VANETs Simulation
The CARLINK-UMA Scenario
Results
Conclusions and Future Work
Results
Test A1 (same sense, 1 MB files)
Average values:
Now I will resent the results achieved.
In the Test A1 the average transmission time is around 1 dot 6 seconds for Real Experiments and VanetMobiSim/Ns-2, and 1 dot 8 for JANE
We can see that the Real test and VanetMobiSim/Ns-2 transmission time are close
Accurate results
Real Experiments
JANE
VanetMobiSim/Ns-2
Transmission Time
1.6 secs
1.8 secs
Data Rate
626.9 KB/s
563.8 KB/s
609.7 KB/s
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10. Results Test A2 (same sense, 10 MB files) Average values:
Introduction and Motivation
VANETs Simulation
The CARLINK-UMA Scenario
Results
Conclusions and Future Work
Results
Test A2 (same sense, 10 MB files)
Average values:
In the test A2, the transmission time is around 1.7 seconds, and in this case, the transmission time achieved during the real tests and the simulations have an absolute difference of 0.6 seconds.
Difference 0.6 secs
Real Experiments
JANE
VanetMobiSim/Ns-2
Transmission Time
17.3 secs
17.9 secs
16.7 secs
Data Rate
585.1 KB/s
564.4 KB/s
611.1 KB/s
Difference 0.6 secs
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11. Results Test B1 (opposite sense, 1 MB files) Average values:
Introduction and Motivation
VANETs Simulation
The CARLINK-UMA Scenario
Results
Conclusions and Future Work
Results
Test B1 (opposite sense, 1 MB files)
Average values:
JANE: Only 3 completed transfers
The results achieved during the Tests of Scenario B present the highest differences between the results of JANE simulator and the VMS/Ns-2 and the real tests results.
In the Test B1 JANE finished just 3 transfers and and VMS/Ns-2 and real tests finished al the transfers with an average transmission time of 2.7 seconds.
Accurate results
Real Experiments
JANE
VanetMobiSim/Ns-2
Transmission Time
2.7 secs
1.8 secs
2.6 secs
Data Rate
371.4 KB/s
563.7 KB/s
391.4 KB/s
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12. Results Test B2 (opposite sense, 10 MB files) Average values:
Introduction and Motivation
VANETs Simulation
The CARLINK-UMA Scenario
Results
Conclusions and Future Work
Results
JANE: No transfers completed
Test B2 (opposite sense, 10 MB files)
Average values:
In the Test B2, All file transfers were successfully finished taking an average time of 20 seconds. However ,in the JANE simulations no one file transfer were successful.
Accurate results
Real Experiments
JANE
VanetMobiSim/Ns-2
Transmission Time
20.1 secs
N/A
19.9 secs
Data Rate
502.1 KB/s
513.3 KB/s
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13. Results Global average results
Introduction and Motivation
VANETs Simulation
The CARLINK-UMA Scenario
Results
Conclusions and Future Work s
Results
Global average results
Mean data rate differences (absolute value in KB/s) between real and simulation results
Analyzing the global average transmission times, we can see that the results of the real tests and the VMS/Ns-2 simulations are closer than the results achieved with JANE.
Test A1
Test A2
Test B1
Test B2
JANE
63.1 KB/s
20.6 KB/s
192.3 KB/s
N/A
VanetMobiSim/Ns-2
17.2 KB/s
25.8 KB/s
20.0 KB/s
11.3 KB/s
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14. Introduction and Motivation
VANETs Simulation
The CARLINK-UMA Scenario
Results
Conclusions and Future Work
Conclusions
The real world is quite difficult to simulate in a trustworthy manner. Our simulations can be changed by including:
obstacles
signal reflections
etc.
At the CARLINK-UMA Scenario an important quantity of data can be transferred with a transmission data rate always higher than 300 KB/s
VanetMobiSim/Ns-2 is the most realistic simulator, if the goal is to model the VANET in a computer
JANE is useful for programming/testing high-level applications
As a future work:
perform simulations of other scenarios in order to predict the performance of the communications at urban and highway environments (almost finished)
combine the simulator (VMS/Ns-2) with optimization techniques in order to offer an optimal configuration of VDTP (in progress)
The analysis of the results achieved during this work are that:
The real world is quite difficult to simulate in a trustworthy manner. For this reason, our simulations can be changed by including obstacles, signals reflections, etc.
In the VANET defined in the Carlink-UMA scenario, the transfers of 1 MB files take around 2 seconds and the transfers of 10 MB files take around 18 seconds.
VMS/Ns-2 is the more realistic simulator, since its results are closer to the real world ones.
JANE is useful for programming and testing high level VANET applications
The defined future work after this study is:
Performing new simulations in order to predict the performance of the communication at urban and highway scenarios. This work is almost finished.
And Combining the VanetMobiSim/Ns-2 simulator with optimization techniques in order to offer an optimal configuration of the VDTP. Nowadays, this work is in progress..
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15. Thank you for your attention.
Introduction and Motivation
VANETs Simulation
The CARLINK-UMA Scenario
Results
Conclusions and Future Work
Thank you for your attention.
Any questions?
The analysis of the results achieved during this work are that:
The real world is quite difficult to simulate in a trustworthy manner. For this reason, our simulations can be changed by including obstacles, signals reflections, etc.
In the VANET defined in the Carlink-UMA scenario, the transfers of 1 MB files take around 2 seconds and the transfers of 10 MB files take around 18 seconds.
VMS/Ns-2 is the more realistic simulator, since its results are closer to the real world ones.
JANE is useful for programming and testing high level VANET applications
The defined future work after this study is:
Performing new simulations in order to predict the performance of the communication at urban and highway scenarios. This work is almost finished.
And Combining the VanetMobiSim/Ns-2 simulator with optimization techniques in order to offer an optimal configuration of the VDTP. Nowadays, this work is in progress..