Routing In Wireless Mesh Networks

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• Routing In Wireless Mesh Networks
• CST593 Final Project
• by
• Dilshad Haleem
• Division of Computing Studies, ASU Polytechnic

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CST593 Committee

• Chair Dr. Bruce R. Millard
• Member Dr. Alan Skousen
• Member Dr. Timothy E. Lindquist

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Introduction

• Wireless Mesh Networks are radio based self
  configuring networks, with minimal infrastructure
  requirements
• Nodes operate as host and also as a router
• Reliable, resilient and robust
• Different than Mobile Ad Hoc Networks

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Architecture
Reference http//www.primidi.com/2005/01/04.html
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Difference between WMNs and MANETs

• Mesh Routers are relatively static
• No power constraints
• Traffic concentration may be higher in certain
  paths (hot spots)
• Number of users

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Ad Hoc On Demand (AODV)

• A protocol developed for MANETs
• Reactive in operation
• Route discovery and maintenance using control
  packets (RREQ, RREP, RERR and HELLO)
• Uses minimum hop count as the performance metric

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Problem Statement

• Creating Wireless Mesh Network and Ad Hoc Network
  scenarios in OPNET Modeler
• Simulating AODV in Wireless Mesh and Wireless Ad
  Hoc Networks
• Performance comparison
• Implementation of Expected Transmission Count
  (ETX) as a Process Model in OPNET

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Wireless Ad Hoc Network VS WMN
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AODV and WLAN Parameters
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Simulation ResultsEnd to End Delay

• High Delay is observed in WMN
• Probable reason, nodes closer to the GW, are
  relaying theirs and other nodes traffic
• MAC layer Fairness

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Simulation ResultsRouting Traffic Received

• More RREQ and RREP in Ad Hoc Network
• Routes do not change frequently in WMN
• Mostly in case of node failure or new node
  joining

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Simulation ResultsRouting Traffic Sent
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Simulation ResultsThroughput

• Less throughput is observed in WMN
• Throughput decreases as the number of hops
  increases

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Simulation ResultsThroughput of node_7 node_9

• Node_7 enjoys a higher throughput, than node_9
• Node_9 is 3-hops away from the Gateway

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Expected Number of Transmission (ETX)

• Routing Protocol must be aware of the consequence
  of path selection
• Routing protocol must be aware of the link
  condition
• Link layer performance metric, ETX is the loss
  rate of broadcast packets between pair of nodes

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Implementation of ETX

• Nodes broadcast probe packets(134 bytes) once per
  second
• Nodes keep track of the number of probes received
  in 10 seconds
• Reverse delivery ratio pkt rcvd / pkt sent
• Forward delivery ratio is obtained from the
  neighbors probe

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Implementation of ETX in OPNETNode Model

• Pkt_src processor generates probe packets
• Calc_ETX module calculates ETX
• Rcv and xmt modules rcv and tx the packets

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Implementation of ETX in OPNETCalc_ETX Process
Model (FSM)

• INIT state performs initialization of State
  variables
• Time_out state reset the packet count every 10
  seconds and calculates ETX
• Idle state waits until a packet needs to be sent
  or received

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Implementation of ETX in OPNETCalc_ETX Network
Model

• 2 nodes Network Model
• Data rate is set to 11Mbps

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Simulation Results of ETX Model

• Reverse Delivery Ratio pkt rcvd / pkt sent
  10/10 1
• Forward Delivery ratio, piggybacked
• on neighbors probe 1

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Simulation Results of ETX ModelLink ETX

• Link ETX 1
• This implied a perfect link
• As link ETX increases link quality decrease
• ETX quantify the link

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Conclusion

• MANETs routing protocols are not suitable for
  WMNs
• Simulation confirmed that, throughput decreases ,
  when AODV is used in WMNs
• Routing protocol should be aware of the link
  condition
• Implementation of link quality metric (ETX) model
  in OPNET