routing in wireless mesh networks cst593 final project by dilshad haleem

Dilshad Haleem CST593 summer 2007

Routing In Wireless Mesh NetworksCST593 Final Project

by

Dilshad HaleemDivision of Computing Studies, ASU Polytechnic


CST593 Committee

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


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


Architecture

Reference: http://www.primidi.com/2005/01/04.html


Difference between WMNs and MANETs

Mesh Routers are relatively staticNo power constraintsTraffic concentration may be

higher in certain paths (hot spots)Number of users


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


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


Wireless Ad Hoc Network VS WMN


AODV and WLAN Parameters


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


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


Simulation ResultsRouting Traffic Sent


Simulation ResultsThroughput

Less throughput is observed in WMN

Throughput decreases as the number of hops increases


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


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


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


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


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


Implementation of ETX in OPNETCalc_ETX Network Model

2 nodes Network Model

Data rate is set to 11Mbps


Simulation Results of ETX Model

Reverse Delivery Ratio = pkt rcvd / pkt sent = 10/10 =1

Forward Delivery ratio, piggybacked

on neighbor’s probe = 1


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


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

routing in wireless mesh networks cst593 final project by dilshad haleem

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