Radio Disjoint MultiPath Routing in MANET

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Radio Disjoint Multi-Path Routing in MANET

• Carmelita Görg
• Mobile Technology Research Center
• TZI-ikom University of Bremen

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Abstract

• MANET research with focus on maintaining multiple
  routing paths mostly concentrate on the
  utilization of multiple paths as backup paths due
  to failures in the main routing path.
• Simultaneous use of multiple paths could be used
  to split packets of a flow or independent flows.
• This paper discusses an approach to choose
  multiple paths to be used simultaneously,
  reducing the effect of interference between nodes
  as far as possible, which is termed as radio
  disjoint paths.
• This paper discusses
• Simulation results of the use of multi-path
  routing considering the interference between them
  and different load conditions
• Implementation details of the algorithm to select
  the radio disjoint paths in DYMO protocol

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Biography

• Prof. Dr. Carmelita Görg MTRC Mobile Technology
  Research CenterSFB 637 Collaborative Research
  Center tzi-ikom University of Bremen, Germany
• Diploma degree, Department of Computer Science,
  University of Karlsruhe, Germany
• Dr. rer. nat. degree and Habilitation,
  Department of Electrical Engineering, Aachen
  University of Technology, Germany
• Research Interests Performance Analysis of
  Mobile and Wireless Communication Networks,
  Stochastic Simulation, Mobility Support
• Joint work MTRC (K. Kuladinithi, M. Becker) and
  CEWIT (Samir Das)

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Agenda

• Previous research in multi-path routing
  motivation
• Detailed analysis of the Flow in the Middle
  Problem with simultaneous use of multi-path
  routing
• How to select multiple routing paths to have
  better performance
• Implementation details (in DYMO in OPNET)
• Summary

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Research in Multi-path (Reactive MANET)

• Reactive MANET Protocols (Route Discovery Route
  Maintenance) Standards only keep a single path
• Multi-Path Routing for Reactive Protocols
• Use of an Alternate/Backup Path (to reduce the
  frequency of route discoveries)
• AODV-BR, AOMDV, SMR, etc.
• Load Balancing per packet basis (SMR)

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Motivation

• Use of Multi-Path Routing simultaneously
• Balance the load in the network (Reduce the
  congestion/packet loss in the network)
• but
• Probability of interference is higher when using
  multiple routes simultaneously (MANET nodes
  share the same channel)
• Higher interference -gt Lower performance
• How to select Multiple Routing Paths with less
  interference (i.e. Radio Disjoint Multi-Path
  Routing)?

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Radio Disjoint Multi-Path Routing

• Multiple Routes with less interference,
• Try to avoid Flow in the Middle Problem
• Simulation of the Flow in the Middle Problem
• WLAN nodes set to ad hoc mode
• In a statically configured environment
• All nodes use the same frequency channel at 11Mbps

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Flow in the Middle Problem Simulation Setup

• LP, MP RP
• FD (Fully Radio Disjoint) All 3 paths are not
  in the interference of each other
• PD (Partially Radio Disjoint) Only the MP is in
  the interference of LP and RP
• ND (Non Radio Disjoint) All 3 paths are in the
  interference of each other

Right Path (RP)
Left Path (LP)
Middle Path (MP)
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Flow in the Middle Problem (cont.)

• Results were taken for different loads
• LL (Low Load)
• ML (Medium Load)
• HL (Heavy Load) causes losses at the WLAN layer
  due to congestion (buffer overflows)
• 2 types of applications
• Unreliable Transmission, UDP (Video Transmission)
  
• Reliable Transmission, TCP (FTP Downloads)

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Flow in the Middle Problem - FTP
FTP Download Response Time in Seconds
No Flow in the Middle Problem
35
-11.6
1.8
0.4
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Flow in the Middle Problem - FTP
When using a download of 100,000 bytes PD case
Use of 2 Paths Simultaneously (No flow in the
middle problem)
Use of 3 Paths Simultaneously
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FTP Results Analysis

• FD case
• No interference between 3 paths
• Performance degrades for the Heavy Load due to
  congestion
• PD case
• LL Flow in the middle Problem is not visible
  for low loads
• ML Avoiding MP (No flow in the middle problem)
  causes the performance to improve by
  35
• HL Avoiding MP will not help due to the
  congestion
• ND case
• All 3 paths are suffering heavily due to mutual
  interference
• Avoiding MP helps to gain 2 performance
  improvement

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Flow in the Middle Problem Video Transmission
Mean Packets end-to-end delay in ms
20.5
?
6
?
Packets are lost due to congestion
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Flow in the Middle Problem Video Transmission
Increase of Load and use of 3 paths
simultaneously (except for FD case) causes -
Higher Packets delay variation (at the
application) - Higher Delay in WLAN - More
Data dropped at WLAN
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Result Analysis Video Transmission

• FD case
• No interference between 3 paths
• Performance degrades for Heavy Load due to
  congestion
• PD case
• LL Flow in the middle Problem is not visible
  for low loads
• ML Avoiding MP causes performance to improve by
  20
• HL Avoiding MP will not help due to congestion
  (due to unreliable transmission)
• ND case
• All 3 paths are suffering heavily due to mutual
  interference
• Avoiding MP helps to increase the performance by
  6

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Comparison of Single Path vs. Simultaneous use of
Multi-Paths

• Scenario 1
• FTP 1 Download Response time for multiple
  downloads of the size of 100,000 bytes at each 5
  sec.
• Video1 Mean of packets end to end delay for
  uni-directional video transmission at the rate of
  350bytes X 2 (5.6 kbps)
• Video2 Mean of packets end to end delay for
  uni-directional video transmission at the rate of
  350bytes X 2 (5.6 kbps)
• Scenario 2
• FTP 1 Download Response time for multiple
  downloads of the size of 100,000 bytes at 5 sec
  each.
• FTP 2 Download Response time for multiple
  downloads of the size of 100,000 bytes at 5 sec
  each.
• Video 1 Mean of packets end to end delay for
  uni-directional video transmission at the rate of
  350bytes X 2 (5.6 kbps)

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Comparison of Single Path vs Simultaneous use of
Multi-Paths
Scenario 1
w.r.t. delays in single path
Scenario 2
WLAN Delay
Single Path
Radio Disjoint Multi-Path
Non-Radio Disjoint Multi-Path
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Simultaneous Use of Multi-Path Routing to Improve
Performance

• Selection of Multi-Path Routing
• Less Interference
• Best Use of Fully Radio Disjoint Paths
• Ok Use of Partially Radio Disjoint
• Less Load on a path (to avoid congestion)
• Distribution of Flows (Applications) to Multiple
  Paths
• Distribute the load so that paths will not be
  overloaded (to avoid congestion)
• To know the remaining capacity of the path and
  the capacity of application

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How to Compute Interference Level and Load of a
Path?

• NL Node Load, PL Path Load, HC Hop Count
• NL (packets transmitted and received by the
  node X) (packets heard from other nodes in
  the vicinity Y)
• X Current Load of the Node
• Y Interference Level of the Node
• NL is computed by a weighted average over a
  periodical interval to consider the latest value

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How to Compute the Node Load?
X packets transmitted and received by the
node Y packets heard from other nodes in the
vicinity
IP addr
MAC addr
X1 Y1
X2 Y2
X3 Y3
X4 Y4
X2 Y2
X3 Y3
X4 Y4
X5 Y5

• Example NL is measured at each 1 sec and up to
  4 measurements are held to compute weighted
  average of the NL (i.e. Avg. Of the past 4 sec)
• Current Node Load,
• NL 0.1 (X2Y2) 0.2 (X3Y3) 0.3(X4Y4)
  0.4(X5Y5)

Weighted average to consider the latest values
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How to Compute Interference Level between Paths?

• Pathload PL max NL1, NL2 , NL3 , NL4 .. NLm
  , where m Number of nodes in a path
• Best Path min(PL) considering also the Hop
  Count
• A path with less interference and less load
• Implementation Requirements
• 1. How to compute the path load during the route
  discovery?
• RREQ should be extended to include NL of each
  node
• Implementation with interface set to
  promiscuous mode, X Y could be computed and
  packets should be identified based on the MAC
  address
• 2. Max, number of paths to be selected
• Threshold value should be defined for max. number
  of routing paths to be used
• 3. Computation of path load periodically
• Sending a periodic packet to compute the path
  load even after the first route discovery

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Details of Simulation

• Based on DYMO Protocol (OPNET Simulator)

• DYMO Reactive Protocol like AODV, but with path
  accumulation feature

I1
I2
I3
D
S
RREQ
RREQ
RREQ
RREQ
RREQ
RE-S
RE-S
RE-S
RE-S
RE-I1
RE-I1
RE-I1
RE-I2
RE-I2
RE-I3
RREP
RE-S Route Element with NL of S RE-I1 Route
Element with NL of I1
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Details of Simulation
Weighted Avg of NL
IP addr
X Y
IP addr
MAC addr
X1 Y1
X2 Y2
X3 Y3
X4 Y4

• Open Issues
• Period for the computation of weighted average
• Any weight between X Y?

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Summary

• Investigated the behavior of flow in the middle
  problem in a statically configured environment
• Simultaneous Use of Multiple Paths in MANET
• To achieve best performance while selecting less
  interfered and less loaded paths
• Discussed the implementation of radio disjoint
  multi-path routing in one of the reactive MANET
  protocols (DYMO)

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Thank YouQuestions Answers
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Scenario 2
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