How to Start Wireless Topology Projects Using NS2

To start simulating Wireless Topology within NS2 (Network Simulator 2), we can configure a network in which nodes are wirelessly interact. NS2 environment offers the capability for replicating diverse kinds of wireless networks like Mobile Ad-hoc Networks (MANETs), Wireless Sensor Networks (WSNs), and other wireless interaction scenarios.

Below is a stepwise mechanism how to start the Wireless Topology project in NS2:

Steps to Start Wireless Topology in NS2

  1. Understand Wireless Topology
  • Structure:
    • Nodes are wirelessly associated within a network in which every single node can directly interact with others in range.
    • Interaction can be impacted by factors such as signal range, interference, and mobility.
  • Applications:
    • MANETs: Networks in which nodes are movable and self-organizing.
    • WSNs: Sensor nodes’ networks distribute around a geographic area.
    • Infrastructure networks: Networks including access points and devices such as Wi-Fi networks.
  1. Set Up NS2
  1. Install NS2: If NS2 isn’t installed on the system then we can set it up to utilise following command line:

sudo apt-get install ns2

  1. Verify Installation: Confirm NS2 installation by executing a sample script:

ns example.tcl

  1. Define Wireless Topology
  • Wireless Link: We will need to utilise the WirelessChannel and Phy/WirelessPhy objects to describe the wireless medium in NS2.
  • Mobile Nodes: Make use of the MobileNode class for nodes, which can transfer (for MANETs or mobile scenarios).
  • Routing: Describe a routing protocol which is appropriate for wireless networks like AODV, DSR, or OLSR for MANETs.
  1. TCL Script for Wireless Topology

Here’s a sample TCL simulation script for executing a simple Wireless Topology:

TCL Script Example

# Initialize NS2 Simulator

set ns [new Simulator]

set tracefile [open wireless_topology.tr w]

$ns trace-all $tracefile

# Define the number of nodes

set num_nodes 5

# Create mobile nodes

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

set node($i) [$ns node]

$node($i) random-motion 1  ;# Enable random motion (for mobility)

}

# Create wireless links and configure the wireless channel

set chan [new Channel/WirelessChannel]

set phy [new Phy/WirelessPhy]

set mac [new Mac/802_11]

set netif [new NetDevice/Wireless]

# Set up the channel for wireless communication

$chan duplex-link $node(0) $node(1) 5Mb 2ms DropTail

$chan duplex-link $node(1) $node(2) 5Mb 2ms DropTail

$chan duplex-link $node(2) $node(3) 5Mb 2ms DropTail

$chan duplex-link $node(3) $node(4) 5Mb 2ms DropTail

# Add mobility model for nodes (e.g., random movement)

$ns at 0.0 “$node(0) setdest 100.0 100.0 0.0”

$ns at 2.0 “$node(1) setdest 200.0 200.0 0.0”

$ns at 3.0 “$node(2) setdest 300.0 300.0 0.0”

$ns at 4.0 “$node(3) setdest 400.0 400.0 0.0”

# Attach agents for traffic simulation

# Example: Traffic from Node 0 to Node 4

set tcp0 [new Agent/TCP]

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

set sink0 [new Agent/TCPSink]

$ns attach-agent $node(4) $sink0

$ns connect $tcp0 $sink0

# Add a traffic generator (FTP)

set ftp [new Application/FTP]

$ftp attach-agent $tcp0

# Start traffic

$ns at 1.0 “$ftp start”

# End simulation

$ns at 5.0 “finish”

proc finish {} {

global ns tracefile

$ns flush-trace

close $tracefile

exit 0

}

$ns run

  1. Key Features to Simulate
  1. Wireless Communication:
    • In NS2, wireless communication is replicated by WirelessChannel, WirelessPhy, and Mac/802_11 modules.
  2. Mobility:
    • Mobility is allowed to utilise the MobileNode class and set up with the support of movement model for instance random motion or constant speed.
  3. Routing:
    • Handle the packet routing within the wireless network to utilise routing protocols such as AODV, DSR, or OLSR.
  1. Analyze the Trace File
  • The trace file as wireless_topology.tr saves simulation information like packet transmission, packet drops, and delays.
  • Obtain certain performance parameters such as throughput and packet loss:
    • Throughput:

grep “tcp” wireless_topology.tr > throughput.log

    • Dropped Packets:

grep “drop” wireless_topology.tr > dropped_packets.log

  1. Visualize Results

Make use of Gnuplot or another graphing tool for envisioning the data:

  1. Throughput Graph:

set title “Wireless Topology Throughput”

plot “throughput.log” using 1:2 with lines title “Throughput”

  1. Latency Graph:
    • Envision delays for interaction through the nodes.
  1. Extend the Simulation
  2. Implement Mobility Models
  • Replicate diverse movement models such as random, constant speed, or custom trajectories:

$ns at 2.0 “$node(0) setdest 300.0 300.0 10.0”  ;# Node 0 moves to (300, 300) at speed 10 m/s

  1. Simulate Node Failures or Link Breaks
  • Replicate the link breakdowns or node failures:

$ns at 3.0 “$ns reset-links $node(0) $node(1)”

  1. Simulate Multi-hop Communication
  • Launch additional nodes and then monitor the routing through numerous hops:

set tcp1 [new Agent/TCP]

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

set sink1 [new Agent/TCPSink]

$ns attach-agent $node(3) $sink1

$ns connect $tcp1 $sink1

  1. Routing Protocols
  • Allow and set up routing protocols such as AODV or DSR for mobile ad hoc networks:

set aodv [new Routing/AODV]

$aodv trace 1

  1. Modify NS2 Core for Advanced Features
  1. Custom Routing Algorithms:
    • We need to modify routing mechanisms to encounter the certain requirements of the wireless network within the core NS2 C++ code.
  2. Traffic Management:
    • Launch more traffic management schemes like congestion control or flow control within the simulation.

Tools and Resources

  • Wireshark: Examine the seized packet traces for observing the traffic models and network behaviors.
  • Gnuplot: Envision the performance parameters such as throughput, latency, and other network performance metrics to leverage Gnuplot.
  • NS2 Documentation: Suggest NS2 documentation to learn about in depth set up and module extensions.

Enhancements

  • Simulate Wireless Sensor Networks (WSNs): Utilise wireless communication to design the large-scale networks including numerous sensor nodes.
  • QoS Models: Execute the Quality of Service (QoS) to give precedence specific traffic types or make sure low latency for certain applications.
  • Real-world Applications: Design particular wireless technologies such as Wi-Fi, ZigBee, or Bluetooth for realistic applications of network simulations.

Here, Wireless Topology Projects has been set up and executed effectively through NS2 simulation environment utilising an innovative method, with an in-depth explanation to be shared in the forthcoming guide.