Dilshad Haleem CST593 summer 2007
Routing In Wireless Mesh NetworksCST593 Final Project
by
Dilshad HaleemDivision of Computing Studies, ASU Polytechnic
Dilshad Haleem CST593 summer 2007
CST593 Committee
Chair : Dr. Bruce R. Millard Member : Dr. Alan Skousen Member: Dr. Timothy E. Lindquist
Dilshad Haleem CST593 summer 2007
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
Dilshad Haleem CST593 summer 2007
Architecture
Reference: http://www.primidi.com/2005/01/04.html
Dilshad Haleem CST593 summer 2007
Difference between WMNs and MANETs
Mesh Routers are relatively staticNo power constraintsTraffic concentration may be
higher in certain paths (hot spots)Number of users
Dilshad Haleem CST593 summer 2007
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
Dilshad Haleem CST593 summer 2007
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
Dilshad Haleem CST593 summer 2007
Wireless Ad Hoc Network VS WMN
Dilshad Haleem CST593 summer 2007
AODV and WLAN Parameters
Dilshad Haleem CST593 summer 2007
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
Dilshad Haleem CST593 summer 2007
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
Dilshad Haleem CST593 summer 2007
Simulation ResultsRouting Traffic Sent
Dilshad Haleem CST593 summer 2007
Simulation ResultsThroughput
Less throughput is observed in WMN
Throughput decreases as the number of hops increases
Dilshad Haleem CST593 summer 2007
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
Dilshad Haleem CST593 summer 2007
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
Dilshad Haleem CST593 summer 2007
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
Dilshad Haleem CST593 summer 2007
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
Dilshad Haleem CST593 summer 2007
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
Dilshad Haleem CST593 summer 2007
Implementation of ETX in OPNETCalc_ETX Network Model
2 nodes Network Model
Data rate is set to 11Mbps
Dilshad Haleem CST593 summer 2007
Simulation Results of ETX Model
Reverse Delivery Ratio = pkt rcvd / pkt sent = 10/10 =1
Forward Delivery ratio, piggybacked
on neighbor’s probe = 1
Dilshad Haleem CST593 summer 2007
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
Dilshad Haleem CST593 summer 2007
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