How to Implement Wireless Mesh Topology in NS2

 

To implement a Wireless Mesh Topology in NS2 has several steps that have to generate a network in which the multiple wireless nodes (or mesh points) are associated to form a mesh. In a wireless mesh network, each node can interact with other nodes, either directly or through intermediate nodes, that deliver the redundancy and consistent communication paths. The below is the brief structured procedure to implement the wireless mesh topology in ns2:

Steps to Implement Wireless Mesh Topology in NS2:

  1. Set Up the Wireless Environment:
    • Describe the wireless nodes and setup their communication range.
    • Position the nodes in a way that they can interact with multiple other nodes, forming a mesh.
  2. Configure Node Mobility and Communication:
    • Optionally, describe mobility patterns if we want to mimic movement in the network.
    • Configure communication patterns among the nodes to mimic traffic flow in the mesh topology.

Example of Wireless Mesh Topology Implementation in NS2:

Below is an example script that configures a simple wireless mesh topology with 6 nodes in NS2:

# Create a new simulator

set ns [new Simulator]

# Open trace file for output

set tracefile [open out.tr w]

$ns trace-all $tracefile

# Create a NAM (Network Animator) file for visualization

set namfile [open out.nam w]

$ns namtrace-all-wireless $namfile 300 300

# Define the wireless channel and radio-propagation model

set channel [new Channel/WirelessChannel]

set propagation [new Propagation/TwoRayGround]

set network_interface [new Phy/WirelessPhy]

set mac [new Mac/802_11]

set ifq [new Queue/DropTail/PriQueue]

set ll [new LL]

set antenna [new Antenna/OmniAntenna]

set topography [new Topography]

# Configure the topography

$topography load_flatgrid 300 300

# Set the initial position of the nodes in the topography

create-god 6

# Create wireless nodes (mesh points)

for {set i 0} {$i < 6} {incr i} {

set node($i) [$ns node]

$node($i) random-motion 0

$node($i) set X_ [expr $i * 50 + 50]

$node($i) set Y_ 150

$node($i) set Z_ 0.0

}

# Define a basic mesh topology by ensuring nodes are within communication range

# Node positions: Node(0) <-> Node(1) <-> Node(2) <-> Node(3) <-> Node(4) <-> Node(5)

# Set up connections between the mesh points

# No explicit links are required as this is a wireless mesh network;

# the nodes will communicate if they are within range.

# Define traffic sources and sinks

# Communication from node 0 to node 5

set tcp0 [new Agent/TCP]

set sink0 [new Agent/TCPSink]

$ns attach-agent $node(0) $tcp0

$ns attach-agent $node(5) $sink0

$ns connect $tcp0 $sink0

# Generate FTP traffic from node 0 to node 5

set ftp0 [new Application/FTP]

$ftp0 attach-agent $tcp0

$ns at 1.0 “$ftp0 start”   ;# Start traffic at 1 second

# Define a second communication pair (optional)

# Communication from node 1 to node 4

set tcp1 [new Agent/TCP]

set sink1 [new Agent/TCPSink]

$ns attach-agent $node(1) $tcp1

$ns attach-agent $node(4) $sink1

$ns connect $tcp1 $sink1

# Generate FTP traffic from node 1 to node 4

set ftp1 [new Application/FTP]

$ftp1 attach-agent $tcp1

$ns at 2.0 “$ftp1 start”   ;# Start traffic at 2 seconds

# End the simulation after 10 seconds

$ns at 10.0 “finish”

proc finish {} {

global ns tracefile namfile

$ns flush-trace

close $tracefile

close $namfile

exit 0

}

# Run the simulation

$ns run

Explanation of the Script:

  1. Wireless Channel Configuration:
    • The script describes a wireless channel and numerous components such as the radio propagation model (TwoRayGround), the MAC layer (802_11), and the omnidirectional antenna.
  2. Topography and Node Setup:
    • The network performs within a defined topographical grid of size 300×300 units.
    • Six wireless nodes are generated, and their positions are set along a line, spaced 50 units apart on the X-axis. This spacing is prioritizing to make sure that nodes are within communication range of their immediate neighbours, forming a mesh network.
  3. Traffic Simulation:
    • TCP agents mimic communication between nodes.
    • FTP (File Transfer Protocol) is used to create traffic among nodes. For instance, traffic is sent from node (0) to node (5) and optionally from node (1) to node (4).
  4. Simulation Duration:
    • The simulation executes for 10 seconds that permits traffic to flow across the mesh network.

Post-Simulation Analysis:

  1. Trace File Analysis:
    • Open the trace file (out.tr) to monitor on how packets are forwarded among nodes. Evaluate parameters such as packet delivery, delay, and throughput to get to know the performance of the mesh network.
  2. NAM Visualization:
    • Use NAM (Network Animator) to visualize the wireless mesh topology. We can see how the nodes are positioned and how traffic flows among them in the mesh.
  3. Performance Metrics:
    • Evaluate network parameters like delay, throughput, and packet loss to assess the effectiveness of the wireless mesh topology.

Enhancing the Simulation:

  1. Adding More Nodes:
    • Add more nodes to the mesh network and adapts their positions to form a more complex mesh topology. Test with numerous node placements to monitor on how the mesh network performs.
  2. Mobility:
    • Establish mobility to the nodes by setting up a random motion or predefined movement patterns. This mimic a dynamic mesh network in which the nodes move within the network.
  3. Varying Traffic Patterns:
    • Configure additional communication pairs among diverse nodes and mimic numerous traffic types like UDP, CBR to evaluate the effects on network performance.
  4. Changing Node Range:
    • Adapt the communication range of the nodes by varying the transmission power or the area size to monitor on how connectivity changes in the mesh topology.
  5. Simulating Network Failures:
    • To mimic the failure of one or more nodes or links in the mesh network to study the network’s flexibility and how it retransmits the traffic.

In this simulation, we can get knowledge about how the wireless mesh topology will perform and evaluate the outcomes using the ns2 simulation tool and we also provide more details about how the wireless mesh topology will perform in other simulation tool.

For best guidance on implementing Wireless Mesh Topology in NS2, feel free to reach out to us. Discover excellent topics and ideas at ns2project.com.