How to Implement Network Frequency Hopping in NS2

To implement the Network Frequency Hopping is a method used in the wireless communication that helps to decrease interference and improve security by often modifying the transmission frequency. In the simulation environment NS2, we can simulate the frequency hopping by actively switching the communication channel among various frequency bands while the simulation. It supports to enhance the robustness in the environments including high interference, jamming, or signal fading. Here is a simple guide on how to approach the frequency hopping within NS2:

Steps to Implement Frequency Hopping in NS2

To simulate frequency hopping in NS2, we can:

  1. Describe several wireless channels, which denote various frequency bands.
  2. Dynamically switch between these channels at predefined intervals or based on specific events such as interference or congestion.
  3. Make certain that both the sender and receiver hop to the similar frequency at the same time.
  1. Set up NS2 Environment

Make sure that NS2 is installed and setup appropriately on the system. We will make a simulation in which nodes are actively hop among several channels while communication to prevent interference or replicate a more secure transmission.

  1. Create a TCL Script for Frequency Hopping

The following is an instance TCL script, which determines how to execute the frequency hopping in the simulation NS2. We describe numerous channels and switch among them actively when the simulation.

Example TCL Script for Frequency Hopping:

# Create a new NS2 simulator

set ns [new Simulator]

# Open trace and NAM output files

set tracefile [open frequency_hopping.tr w]

$ns trace-all $tracefile

set namfile [open frequency_hopping.nam w]

$ns namtrace-all $namfile

# Define wireless network parameters

set val(chan0)   Channel/WirelessChannel  ;# Channel 0 (frequency band 1)

set val(chan1)   Channel/WirelessChannel  ;# Channel 1 (frequency band 2)

set val(chan2)   Channel/WirelessChannel  ;# Channel 2 (frequency band 3)

set val(prop)    Propagation/TwoRayGround

set val(ant)     Antenna/OmniAntenna

set val(netif)   Phy/WirelessPhy

set val(mac)     Mac/802_11

set val(ifq)     Queue/DropTail/PriQueue

set val(ifqlen)  50

set val(ll)      LL

set val(rp)      AODV                      ;# Use AODV routing protocol

set simulation_time 100.0                   ;# Duration of the simulation

# Create topography for the network

set topo [new Topography]

$topo load_flatgrid 1000 1000

# Configure node parameters with flexible channel assignment

proc configure_node {node_id channel_id} {

global ns val topo

$ns node-config -adhocRouting $val(rp) \

-llType $val(ll) \

-macType $val(mac) \

-ifqType $val(ifq) \

-ifqLen $val(ifqlen) \

-antType $val(ant) \

-propType $val(prop) \

-phyType $val(netif) \

-channelType $channel_id \

-topoInstance $topo \

-agentTrace ON \

-routerTrace ON \

-macTrace ON

set node($node_id) [$ns node]

}

# Create two nodes

set node0 [configure_node 0 $val(chan0)]

set node1 [configure_node 1 $val(chan0)]

# Position the nodes in the simulation area

$node(0) set X_ 100

$node(0) set Y_ 100

$node(0) set Z_ 0

$node(1) set X_ 400

$node(1) set Y_ 400

$node(1) set Z_ 0

# Function to switch channels dynamically (Frequency Hopping)

proc switch_channel {node_id new_channel time} {

global ns

$ns at $time “$node($node_id) set channelType_ $new_channel”

puts “Node $node_id switched to new channel at time $time”

}

# Create UDP agent for communication

set udp0 [new Agent/UDP]

$ns attach-agent $node(0) $udp0

# Create Null agent to receive packets at node1

set null0 [new Agent/Null]

$ns attach-agent $node(1) $null0

# Connect the UDP agent to the Null agent

$ns connect $udp0 $null0

# Create CBR traffic over the UDP agent

set cbr0 [new Application/Traffic/CBR]

$cbr0 set packetSize_ 512

$cbr0 set rate_ 1Mb

$cbr0 attach-agent $udp0

# Schedule traffic start and stop times

$ns at 1.0 “$cbr0 start”

$ns at [expr $simulation_time – 5] “$cbr0 stop”

# Define a channel hopping schedule (hopping between different frequencies)

set hop_interval 5.0

# Hop both nodes to a new channel at regular intervals

for {set t 5.0} {$t < $simulation_time} {set t [expr $t + $hop_interval]} {

set new_channel [expr $t % 3]   ;# Cycle through 3 channels (0, 1, 2)

switch_channel 0 $val(chan$new_channel) $t

switch_channel 1 $val(chan$new_channel) $t

}

# Schedule simulation end

$ns at $simulation_time “finish”

# Finish procedure to close trace and NAM files

proc finish {} {

global ns tracefile namfile

$ns flush-trace

close $tracefile

close $namfile

exec nam frequency_hopping.nam &

exit 0

}

# Run the simulation

$ns run

  1. Explanation of Key Components
  • Multiple Channels: We describe the three channels such as chan0, chan1, and chan2 that denote various frequency bands. The nodes will hop among these channels while the simulation.
  • Node Configuration: The configure_node function allocates every node to the particular channel primarily. Both nodes are begin on Channel 0.
  • Frequency Hopping (Channel Switching): The switch_channel function that alters the channel actively for every node at particular times (hop_interval is set to 5 seconds). These nodes are hop to a new channel (cycled between 0, 1, and 2) in every 5 seconds.
  • Traffic Generation: UDP traffic is produced from node0 to node1 using the traffic CBR (Constant Bit Rate). The traffic continues even during the nodes are switch channels.
  1. Run the Simulation

We can save the script as frequency_hopping.tcl then we run it in NS2:

ns frequency_hopping.tcl

When the simulation done, we can envision the network using NAM:

nam frequency_hopping.nam

  1. Explanation of Frequency Hopping
  • Channel Switching: These nodes are actively switch among the three various channels such as chan0, chan1, chan2 at regular intervals. This mimics frequency hopping to prevent the interference or enhance the security.
  • Synchronized Hopping: Both the sender (node0) and the receiver (node1) must hop to the similar channel at the same time to maintain the communication. In this replication, the hopping schedule make sure that both nodes are on the same channel when the communication.
  1. Advanced Features for Frequency Hopping

We can expand this simulation by appending more advanced features:

  • Adaptive Frequency Hopping: Execute an adaptive frequency hopping in which nodes are switch channels depends on the detected interference or network conditions like signal strength, packet loss.
  • Hopping Patterns: We can use the predefined or pseudo-random hopping patterns to enhance the security that the hopping sequence is known only to the communicating nodes.
  • Dynamic Network: Execute the frequency hopping in a more dynamic environment in which several nodes are communicating, and also each pair of nodes may be followed various hopping series.

Clearly, we shown the details about how to implement and simulate the Network Frequency Hopping with the help of simplified procedure in NS2. We will also provide various informations regarding this topic, if needed. Get your performance analysis done at the best by our researchers so share with us all your  project details for best implementation