How to Implement Cognitive adhoc network in ns2

To implement the Cognitive Ad-Hoc Network (CAHN) in ns2 requires us to replicate an ad-hoc network in which the nodes have the ability to find and dynamically modify their interaction parameter in terms of the situation, usually based on spectrum availability. Cognitive Radio Networks (CRNs) are a kind of CAHN where nodes can deviously use existed spectrum bands, evading meddling with primary users. In below, we provide the step-by-step procedure to help you complete it in ns2:

Step-by-Step Implementation:

Conceptual Overview

In a Cognitive Ad-Hoc Network:

  1. Cognitive Nodes: These are nodes armed with cognitive radio potential, referring they can find the spectrum, detecting existed channels, and change to those channels dynamically.
  2. Spectrum Sensing: The capability to identify unused spectrum or detect channels with the least intrusion.
  3. Dynamic Spectrum Access: Nodes dynamically picks channels for communication depends on availability and nosiness levels.

Step 1: Conceptualize the Cognitive Ad-Hoc Network Simulation

In this replication, we will set up a basic cognitive ad-hoc network in which nodes can shift channels according to the availability. We will simulate simple spectrum sensing and dynamic channel selection with the help of ns2.

Step 2: Create the Tcl Script

Follow the given example Tcl script that simulates a simple Cognitive Ad-Hoc Network scenario in ns2.

Example Tcl Script for Simulating Cognitive Ad-Hoc Network in ns2

# Create a simulator object

set ns [new Simulator]

# Define the topography object (for a moderate area)

set topo [new Topography]

$topo load_flatgrid 1000 1000  # 1km x 1km area

# Create the General Operations Director (GOD) for wireless simulations

create-god 5  # Number of nodes (5 cognitive nodes)

# Configure the nodes for Cognitive Ad-Hoc Network using AODV

$ns node-config -adhocRouting AODV \

-llType LL \

-macType Mac/802_11 \

-ifqType Queue/DropTail/PriQueue \

-ifqLen 50 \

-antType Antenna/OmniAntenna \

-propType Propagation/TwoRayGround \

-phyType Phy/WirelessPhy \

-channelType Channel/WirelessChannel \

-topoInstance $topo \

-agentTrace ON \

-routerTrace ON \

-macTrace ON \

-movementTrace OFF

# Open trace and NAM files for recording the simulation

set tracefile [open cahn_out.tr w]

$ns trace-all $tracefile

set namfile [open cahn_out.nam w]

$ns namtrace-all-wireless $namfile 1000 1000

# Define a finish procedure to close files and end the simulation

proc finish {} {

global ns tracefile namfile

$ns flush-trace

close $tracefile

close $namfile

exec nam cahn_out.nam &

exit 0

}

# Create cognitive nodes

set cognitive_node1 [$ns node]

set cognitive_node2 [$ns node]

set cognitive_node3 [$ns node]

set cognitive_node4 [$ns node]

set cognitive_node5 [$ns node]

# Set initial positions for cognitive nodes

$cognitive_node1 set X_ 100.0

$cognitive_node1 set Y_ 200.0

$cognitive_node1 set Z_ 0.0

$cognitive_node2 set X_ 200.0

$cognitive_node2 set Y_ 400.0

$cognitive_node2 set Z_ 0.0

$cognitive_node3 set X_ 400.0

$cognitive_node3 set Y_ 600.0

$cognitive_node3 set Z_ 0.0

$cognitive_node4 set X_ 600.0

$cognitive_node4 set Y_ 400.0

$cognitive_node4 set Z_ 0.0

$cognitive_node5 set X_ 800.0

$cognitive_node5 set Y_ 200.0

$cognitive_node5 set Z_ 0.0

# Define a custom procedure for dynamic spectrum access

proc cognitive_spectrum_access {src dst packetSize rate channel} {

global ns

# Simulate spectrum sensing by randomly selecting an available channel

set available_channels [list 1 6 11]

set selected_channel [lindex $available_channels [expr int(rand()*3)]]

# Set the channel

$src set channel_ $selected_channel

$dst set channel_ $selected_channel

# Set up communication between the nodes

set udp [new Agent/UDP]

$ns attach-agent $src $udp

set null [new Agent/Null]

$ns attach-agent $dst $null

$ns connect $udp $null

# Generate CBR traffic

set cbr [new Application/Traffic/CBR]

$cbr attach-agent $udp

$cbr set packetSize_ $packetSize

$cbr set rate_ $rate

$cbr start

}

# Simulate dynamic spectrum access between cognitive nodes

$ns at 2.0 “cognitive_spectrum_access $cognitive_node1 $cognitive_node3 512 100Kb 1”

$ns at 4.0 “cognitive_spectrum_access $cognitive_node2 $cognitive_node4 512 100Kb 6”

$ns at 6.0 “cognitive_spectrum_access $cognitive_node3 $cognitive_node5 512 100Kb 11”

# Schedule the end of the simulation

$ns at 20.0 “finish”

# Run the simulation

$ns run

Step 3: Run the Tcl Script

Save the script with a .tcl extension, for example, cahn_simulation.tcl. Then, use the given command into the terminal to execute the script:

ns cahn_simulation.tcl

Step 4: Visualize the Simulation

Open the created NAM file to visualize the simulation by using:

nam cahn_out.nam

Script Explanation

  • Cognitive Nodes: The nodes cognitive_node1, cognitive_node2, cognitive_node3, cognitive_node4, and cognitive_node5 indicate the cognitive radio-enabled nodes in the network.
  • Dynamic Spectrum Access: The cognitive_spectrum_access procedure replicates spectrum sensing by randomly picking an existed channel from a predefined list of channels.
  • Ad-hoc Routing: Use AODV routing protocol to handle the interaction amongst cognitive nodes.
  • Traffic Generation: CBR traffic is configured amongst set of cognitive nodes to recreate data communication across dynamically chose channels.

Customization

  • Complex Spectrum Sensing: Identify the channel availability by executing more difficult spectrum sensing algorithms depends on actual consumption or intrusion levels.
  • Multiple Channels: Replicate a larger amount of channels and more difficult channel selection techniques.
  • Mobility Models: Accomplish mobility models to recreate the movement of cognitive nodes in a dynamic environment.
  • Different Routing Protocols: Test with other ad-hoc routing protocols like DSR or OLSR to assess their performance in a cognitive ad-hoc network.
  • Varying Traffic Patterns: Research with various traffic patterns (such as FTP, VoIP) to mimic several communication situations in the network.

Limitations

  • Simplified Spectrum Sensing: The spectrum sensing in this sample is very simple and does not responsible for intrusion from primary users or other cognitive nodes.
  • Limited Cognitive Capabilities: ns2 does not natively backs advanced cognitive radio functionalities, so the simulation is restricted to basic dynamic spectrum access.
  • No Physical Layer Simulation: It does not simulates the physical layer characteristics certain to cognitive radios like signal identification, noise, or intrusion.

In this manual, we delivered the vital information on how to set up and implement the cognitive adhoc network using ns2 tool and their customization techniques. If you need any added details of cognitive adhoc network, we will provide you.

Discover cutting-edge Cognitive Adhoc network projects with implementation outcomes at ns2projects.com. We also provide performance analysis for your initiatives. Explore unique research topics and ideas, complete with thorough explanations. Our expertise spans all aspects of Cognitive Radio Networks.