institut eurécom † department of mobile communications sophia antipolis, france
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Neighborhood Changing Rate: A Unifying Parameter to Characterize and Evaluate Data Dissemination Scenarios. Institut Eurécom † Department of Mobile Communications Sophia Antipolis, France. J é r ô me H ä rri † , Biao Zhou ‡ , Mario Gerla ‡ , Fethi Filali † , Christian Bonnet † - PowerPoint PPT PresentationTRANSCRIPT
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Neighborhood Changing Rate:
A Unifying Parameter to Characterize and Evaluate
Data Dissemination Scenarios
Institut Eurécom†
Department of Mobile Communications
Sophia Antipolis, France
Jérôme Härri†, Biao Zhou‡, Mario Gerla‡, Fethi Filali†, Christian Bonnet†
{haerri,filali,bonnet}@eurecom.fr{zhb,gerla}@cs.ucla.edu
University of California‡ Department of Computer
Science Los Angeles, USA
4th IEEE/IFIP Wireless On demand Network Systems and Services (WONS) Obergurgl, AustriaJanuary 24th 2007
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2Härri et al. Neighborhood Changing Rate (NCR)
Agenda
• Data Dissemination in Mobile Ad Hoc Network
• NCR– Definition– Example– Justification
• The Mobeyes Protocol
• Performance Results
• Conclusion
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3Härri et al. Neighborhood Changing Rate (NCR)
Data Dissemination
t-3
t-2 t-1t
t-3
t-2t
t-1t
C2
C2C1
C3
C3
C1
• A single car has a packet to spread
• A car shares its packet with all vehicles reachable within its transmission range.
• Objective: Disseminating the packet throughout the network
• Example:
Spreading factor: 2
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4Härri et al. Neighborhood Changing Rate (NCR)
Data Dissemination
• At each encounter, the more vehicles the car meets, the more efficient is the spreading factor.
• Example:
Spreading factor: 5
t-3
C1
t-3
C3
t-3
C2
t-3
C4t-2
t
C4
t
C3
t-1
C1
C5
t-2
C6
C6
C6
t
t
C1
C5
t
C5
t-2
C1 C4
C3C2
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5Härri et al. Neighborhood Changing Rate (NCR)
Data Dissemination
• In order to reduce the broadcast storm effect, no relaying.
• Each car that receiving the set of data may in turn share it with any encountered vehicle.
• Best dissemination Strategy: At each encounter point, a single car with data shares it with a large set of vehicles.
• Group mobility does not help data dissemination, as in that case, a large set of cars containing data shares it with a potentially smaller set of vehicles.
Data Dissemination Efficiency : Time needed to spread a given set of data to the entire network.
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6Härri et al. Neighborhood Changing Rate (NCR)
Data Dissemination
• The data dissemination efficiency in therefore dependant to a large set of parameters:– The rate a car encounters other neighbors.– The number of vehicles met that do not follow a similar trajectory.– …
Objective: Define a single universal metric including all these parameters
In other terms, data dissemination efficiency may depend on a
Neighborhood Changing Rate
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7Härri et al. Neighborhood Changing Rate (NCR)
Agenda
• Data Dissemination in Mobile Ad Hoc Network
• NCR– Definition– Example– Justification
• The Mobeyes Protocol
• Performance Results
• Conclusion
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8Härri et al. Neighborhood Changing Rate (NCR)
Neighborhood Changing Rate (NCR)
• Let’s define– : Sampling interval equal to the time needed for
a node to move a distance equal to its transmission range
– : Expected Neighbor entering node i’s neighborhood during the time interval
– : Expected Neighbor leaving node i’s neighborhood during the time interval
– : Node i’s nodal degree at time t.
• Then,
[ ] [ ][ ] [ ])(#)(
)(#)(#)(
tNbEtDegE
tNbEtNbEttNCR
inew
i
inew
ileavei
Δ+
Δ+Δ=Δ+
[ ])(# tNbE inew Δ
[ ])(# tNbE ileave Δ
tΔ
tΔ
tΔ
)(tDeg i
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9Härri et al. Neighborhood Changing Rate (NCR)
Neighborhood ChangingRate (NCR)
• Example:
The NCR of Car 1 as a function of time, with Δt=1
t-3
t-2 t-1t
t-3t-2 t
t-1t
C2
C2
C1
C3
C3
C1
NCR=0
NCR=_
NCR=_
NCR=1
C4
C4
C1 C1
C4
C4
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10Härri et al. Neighborhood Changing Rate (NCR)
Neighborhood ChangingRate (NCR)
Definition (Uniform Mobility Model) :A Uniform Mobility Model (UMM) is a model preserving uniformly distributed velocities and densities
Theorem :Defining speedav- representing and densityav– representing the average node density both generated by an UMM, NCR has the following features
1. 0 ≤ NCR(t) ≤ 12. NCR speedav
3. NCR densityav
Proof: See paper
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11Härri et al. Neighborhood Changing Rate (NCR)
Neighborhood ChangingRate (NCR)
• The performance of protocols using data dissemination usually depends on multiple criteria– Speed– Velocity– Mobility pattern– …
• Evaluating a protocol depending on multi-criteria is hard and gives arguable results.
• More specifically, Mobility Patterns are not easily quantifiable because they depend on a too large set of parameters.
• It would be preferable to evaluate it depending on a single
criterion.
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12Härri et al. Neighborhood Changing Rate (NCR)
Neighborhood ChangingRate (NCR)
• As NCR is independent to speedav and densityav, In all models where the real speed and density diverge
from the initial speedav and densityav,
NCR controls the set of parameters that generates the complex spatial and temporal dependencies we may observe in realistic mobility patterns
• Specific Topologies or Mobility Patterns may become less relevant to evaluate the performance of dissemination protocols
• With a given speedav , densityav, and NCR, we can perform cross-topology and cross-mobility patterns performance evaluation.
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13Härri et al. Neighborhood Changing Rate (NCR)
Neighborhood ChangingRate (NCR)
• A similar situation also exists in Transportation Planning:– How to represent traffic flows in transportation that depend
on multi-parameters such as:• Speed, density, volume/capacity ?
– Level of Service (LOS) : Works like an American report card grade, using the letters A through F, with A being best and F being worst.
– By using LOS classification and referring to a traffic situation as having a particular LOS , engineers can have a global knowledge of traffic condition in a particular area.
• NCR is designed to have the same usage:– By referring to data dissemination as having a particular
NCR, we can have an intuitive vision of its efficiency, and thus evaluate accurately VANET Protocols using this feature.
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14Härri et al. Neighborhood Changing Rate (NCR)
Agenda
• Data Dissemination in Mobile Ad Hoc Network
• NCR– Definition– Example– Justification
• The Mobeyes Protocol
• Performance Results
• Conclusion
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15Härri et al. Neighborhood Changing Rate (NCR)
The Mobeyes Protocol
• Mobeyes [1] is a protocol for sensed data mining in vehicular environments:– Periodic diffusion of a summary of sensed data– On demand harvesting of sensed data
• Mobeyes Architecture– Mobeyes Sensing Interface (MSI) : Interface responsible for the
access to the sensors or GPS– Mobeyes Data Processor (MDP): Reads raw data and generates the
summaries– Mobeyes Diffusion/Harvesting Processor (MDHP): Opportunistically
diffuses the summaries or on demand harvests the raw data.
• Mobeyes uses epidemic dissemination to diffuse the summaries. So, it is an appropriate choice to validate NCR.
[1] Uichin Lee et al. University of California, PerSeNS 2006
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16Härri et al. Neighborhood Changing Rate (NCR)
The Mobeyes Protocol
• Example:
Mobeyes Single Hop Passive Diffusion
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17Härri et al. Neighborhood Changing Rate (NCR)
Agenda
• Data Dissemination in Mobile Ad Hoc Network
• NCR– Definition– Example– Justification
• The Mobeyes Protocol
• Performance Results
• Conclusion
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18Härri et al. Neighborhood Changing Rate (NCR)
Simulation Results
Data Dissemination Protocol
Mobeyes
Simulator NS-2.27
Hello Intervals 3[s]
Data Generation intervals
10’000[s]
Simulation time 2000[s]
Simulation Area 2400[m] x 2400[m]
Number of Nodes 100
Tx Range 250[m]
Speed 5[m/s], 15[m/s], 25[m/s]
Simulation Parameters Simulation Environment
Urban Map Topology Triangle Topology
760m
2400m
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19Härri et al. Neighborhood Changing Rate (NCR)
Mobility Models
Track Model Random Waypoint Model
[1] Biao Zhou et al. University of California, MilCom 2004
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20Härri et al. Neighborhood Changing Rate (NCR)
Latency
Latency on a Triangle Topology as a function of speed
5 10 15 20 2520
30
40
50
60
70
80
90
100
Average velocity in [m/s]
Delay [s]
High NCRMedium NCRLow NCR
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21Härri et al. Neighborhood Changing Rate (NCR)
Latency
Latency on a Map Topology as a function of speed
5 10 15 20 25300
400
500
600
700
800
900
1000
1100
1200
1300
Average velocity in [m/s]
Delay [s]
High NCRMedium NCRLow NCR
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22Härri et al. Neighborhood Changing Rate (NCR)
Harvesting Efficiency
NCR on a Triangle Topology with a speed of 5 m/s
0 50 100 150 2000
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Time [s]
Harversting efficiency [%]
High NCR, speed=5m/sMedium NCR speed=5m/sLow NCR speed=5m/s
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23Härri et al. Neighborhood Changing Rate (NCR)
Harvesting Efficiency
0 10 20 30 40 50 60 70 800
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Time [s]
Harversting efficiency [%]
High NCR, speed=15m/sMedium NCR speed=15m/sLow NCR speed=15m/s
NCR on a Triangle Topology with a speed of 15 m/s
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24Härri et al. Neighborhood Changing Rate (NCR)
Harvesting Efficiency
0 10 20 30 40 500
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Time [s]
Harversting efficiency [%]
High NCR, speed=25m/sMedium NCR speed=25m/sLow NCR speed=25m/s
NCR on a Triangle Topology with a speed of 25 m/s
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25Härri et al. Neighborhood Changing Rate (NCR)
Harvesting Efficiency
• Mobeyes on a triangle topology:
Time before which 100% of the data is harvested
High Medium Low
5 m/s 75.08 s102.58
s181.89
s
15 m/s 50.27 s 55.97 s 77.41 s
25 m/s 38.1 s 47.23 s 49.08 s
velocityav
NCR
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26Härri et al. Neighborhood Changing Rate (NCR)
0 500 1000 1500 20000
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Time [s]
Harversting efficiency [%]
High NCR, speed=5m/sMedium NCR speed=5m/sLow NCR speed=5m/s
Harvesting Efficiency
NCR on a Map Topology with a speed of 5 m/s
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27Härri et al. Neighborhood Changing Rate (NCR)
0 500 1000 1500 20000
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Time [s]
Harversting efficiency [%]
High NCR, speed=15m/sMedium NCR speed=15m/sLow NCR speed=15m/s
Harvesting Efficiency
NCR on a Map Topology with a speed of 15 m/s
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28Härri et al. Neighborhood Changing Rate (NCR)
0 500 1000 1500 20000
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Time [s]
Harversting efficiency [%]
High NCR, speed=25m/sMedium NCR speed=25m/sLow NCR speed=25m/s
Harvesting Efficiency
NCR on a Map Topology with a speed of 5 m/s
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29Härri et al. Neighborhood Changing Rate (NCR)
Harvesting Efficiency
• Mobeyes on a map topology:
Time before which 100% of the data is harvested
High Medium Low
5 m/s 1986.3 s>>
2000s>>
2000s
15 m/s 1344 s1548.5
s>>
2000s
25 m/s 1093.1 s1246.1
s 1610.7
s
velocityav
NCR
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31Härri et al. Neighborhood Changing Rate (NCR)
10 15 20 250
5
10
15
20
25
30
35
40
Speed [m/s]
Harvesting delay [s]
MAPTriangleRWM
Cross-Topology Comparison
Latency for scenarios with same speed, density and NCR, and for different mobility models and topologies
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32Härri et al. Neighborhood Changing Rate (NCR)
Cross-Topology Comparison
0 10 20 30 40 50 60 700
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Time [s]
Harversting efficiency [%]
MAP NCR, speed=15m/sTriangle NCR speed=15m/sRWM NCR speed=15m/s
Harvesting rate for scenarios with same density, speed and NCR, and different mobility models and topologies
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33Härri et al. Neighborhood Changing Rate (NCR)
Cross-Topology Comparison
• All Models having the same NCR
Time before which 100% of the data is harvested
Mobeyes + Map
Mobeyes + Triangle
RWM + Triangle
15 m/s 58.43s 50.26s 61.58 s
velocityav
topology
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34Härri et al. Neighborhood Changing Rate (NCR)
Conclusion
• NCR is a novel parameter describing data dissemination
• NCR is able to describe spatial and temporal dependencies, not covered by speed or density.
• NCR is an unifying parameter, as it regroup mobility patterns and topology parameters.
• Data dissemination in any kind of topology and for any type of mobility pattern, can be the fully control by three parameters:– Average Speed– Average Density– NCR