Diverse Mobility Patterns in Mobile Ad Hoc Network

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Diverse Mobility Patterns in Mobile Ad Hoc Network

• Huazhi, Gong
• hankgong_at_kjist.ac.kr

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Introduction

• Mobile Ad Hoc Networks (MANETs)
• Formed by wireless mobile nodes
• Do not rely on any existing infrastructure
• Routes between mobile nodes are typically
  multi-hop
• Network topology can be highly dynamic
• Ad hoc routing protocols
• Reactive protocols AODV, DSR
• Proactive protocols DSDV
• Hybrid protocols ZRP

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Mobility Models
mobility model
random model
deterministic model
hybrid model
movement bounded by environmental constraints
arbitrary movement without constraints
predefined movement path or real mobility trace
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Motivation

• most of MANET simulations based on random
  mobility models, e.g. random waypoint model

• random models insufficient to reflect the
  environmental constraints
• deterministic mobility models too complex and
  real user traces hard to obtain

? In some real situation, we need hybrid model
such as RPGM
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RPGM

• Reference Point Group Mobility Model
• Logical relationship between nodes
• Group motion represented by virtual center
• Motion of reference point
• Relative random motion around reference point

? GM1
Parameters Angle Deviation Ratio(ADR) and Speed
Deviation Ratio(SDR), number of groups, max
velocity Vmax.
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Parameterized Mobility Model

• Freeway Model (FW)
• Each mobile node is restricted to its lane on the
  freeway
• The velocity of mobile node is temporally
  dependent on its previous velocity
• If two mobile nodes on the same freeway lane are
  within the Safety Distance (SD), the velocity of
  the following node cannot exceed the velocity of
  preceding node
• Parameter Map layout, Vmax
• Manhattan Model (MH)
• Similar to Freeway model, but it allows node to
  make turns at each corner of street
• Parameter Map layout, Vmax

Map for FW
Map for MH
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Performance Metrics

• Relative Speed (mobility metric I)
• The magnitude of relative speed of two nodes,
  average over all neighborhood pairs and all time
• Spatial Dependence (mobility metric II)
• The value of extent of similarity of the
  velocities of two nodes that are not too far
  apart, average over all neighborhood pairs and
  all time

• Average link duration (connectivity metric I)
• The value of link duration, average over all
  nodes pairs

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Mobility Metrics

• Objective
• validate whether proposed mobility models span
  the mobility space we explore
• Relative speed
• For same Vmax, MH/FW is higher than RWP, which is
  higher than SG/MG
• Spatial dependence
• For SG/MG, strong degree of spatial dependence
• For RWP/FW/MH, no obvious spatial dependence is
  observed

Relative Speed
Spatial Dependence
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Connectivity Graph Metrics

• Link duration
• For same Vmax, SG/MG is higher than RWP, which is
  higher than FW, which is higher than MH
• Summary
• Freeway and Manhattan model exhibits a high
  relative speed
• Spatial Dependence for group mobility is high,
  while it is low for random waypoint and other
  models
• Link Duration for group mobility is higher than
  Freeway, Manhattan and random waypoint

Link duration
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Performance Comparison

• Performance of routing protocols may vary
  drastically across mobility patterns
• Eg DSR
• There is a difference of 40 for throughput and
  an order of magnitude difference for routing
  overhead by mobility models!

Throughput
Routing Overhead
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Throughput vs. Protocols

• We observe that using different mobility models
  may alter the ranking of protocols in terms of
  the throughput!

Manhattan AODV or DSR?
Random Waypoint DSR?
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Overhead vs. Protocols

• We observe that using different mobility models
  may alter the ranking of protocols in terms of
  the routing overhead!
• Conclusion Mobility DOES matter, significantly,
  in evaluation of protocol performance and in
  comparison of various protocols!

RPGM(single group) DSR?
Manhattan DSDV?
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Analysis of the results

• Recall If mobility affects protocol performance,
  why?
• We observe a very clear trend between mobility
  metric, connectivity and performance
• With similar average spatial dependency
• Relative Speed increases? Link Duration
  decreases? Routing Overhead increases and
  throughput decreases
• With similar average relative speed
• Spatial Dependence increase ?Link Duration
  increases?Throughput increases and routing
  overhead decreases
• Conclusion Mobility Metrics influence
  Connectivity Metrics which in turn influence
  protocol performance metrics !

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Put all the pieces together
Throughput
Relative Velocity
Link Duration
Spatial Dependence
Overhead
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Conclusion

• Researched protocol independent metrics to
  capture a few mobility characteristics of
  interest and compared a rich set of mobility
  models
• Evaluated protocols over mobility models that
  span the above mobility characteristics
• Performance trends and comparison results vary
  widely with the choice of mobility
• Understood the logical relationship between
  mobility and protocol performance
• Mobility patterns are IMPORTANT

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Future Work

• To extend mobility pattern to multicast
  protocols.
• MAODV
• Geocast Protocols
• To analyze the reason of effect of diverse
  mobility pattern

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Reference

• 1 N.Sadagopan, F.Bai, B.Krishnamachari,
  A.Helmy, PATHS analysis of PATH duration
  Statistics and their impact on reactive MANET
  routing protocols MobiHoc 2003.
• 2 F.Bai, N.Sadagopan, A.Helmy, BRICS A
  Building-block approach for analyzing RoutIng
  protoCols in ad hoc networkS- a case study of
  reactive routing protocols, USC-CS-TR-02-775, in
  submission.
• 3 http//www-scf.usc.edu/fbai/mobility.html