How to Implement Channel Interference Avoidance in NS2

To implement the channel interference avoidance using the simulation environment NS2, we require to simulate how nodes are prevent the interference from other transmissions on the similar or nearby channels. It happens while several nodes are transfer concurrently on the similar or overlapping frequencies, causing packet loss, delay, or lower network throughput. Channel interference avoidance can be executed by choosing the non-overlapping channels or scheduling transmissions in a way which decreases the interference.

In the simulation environment NS2, channel interference can be addressed by:

  1. Allocating various channels to distinct nodes or groups of nodes.
  2. Carrier Sense Multiple Access (CSMA) techniques that nodes are sense the channel before transmitting to prevent the collisions.
  3. Scheduling transmissions to prevent the concurrent transmissions by close nodes.
  4. Power control to decrease the interference by limiting the transmission range.

Key Strategies for Channel Interference Avoidance

  • Multiple Channels: We can use the various channels (frequencies) for distinct nodes or clusters.
  • CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance): Avoid concurrent transmissions on the similar channel by using backoff timers or detecting the medium before transmission.
  • Power Control: Modify the transmission power to prevent meddling from distant nodes
  • Time Scheduling: Schedule transmissions in various time slots to avoid the overlapping transmissions.
  1. Set up NS2 Environment

Make sure NS2 is installed and setup properly. We will make a simulation, which allocates various channels to distinct nodes and avoids the interference using CSMA/CA methods and power control.

  1. Create a TCL Script for Channel Interference Avoidance

Given below is a specimen TCL script, which establishes how to execute the channel interference avoidance in the simulation environment NS2 by allocating various channels to the nodes and using CSMA/CA for collision avoidance.

Example TCL Script for Channel Interference Avoidance:

# Create a new NS2 simulator

set ns [new Simulator]

# Open trace and NAM output files

set tracefile [open channel_interference_avoidance.tr w]

$ns trace-all $tracefile

set namfile [open channel_interference_avoidance.nam w]

$ns namtrace-all $namfile

# Define scalable network parameters

set num_nodes 10                     ;# Number of nodes (can be scaled up)

set area_size_x 1000                  ;# X-dimension of the simulation area

set area_size_y 1000                  ;# Y-dimension of the simulation area

set num_traffic_sources 5             ;# Number of traffic sources

set simulation_time 100.0             ;# Duration of the simulation

# Define wireless network parameters

set val(chan0)   Channel/WirelessChannel ;# Channel 0 (one set of nodes)

set val(chan1)   Channel/WirelessChannel ;# Channel 1 (another set of nodes)

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

# Create topography for the network

set topo [new Topography]

$topo load_flatgrid $area_size_x $area_size_y

# Configure node parameters for the two channels

proc configure_node_channel {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 nodes dynamically and assign channels

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

if {$i % 2 == 0} {

# Assign to channel 0

configure_node_channel $i $val(chan0)

} else {

# Assign to channel 1

configure_node_channel $i $val(chan1)

}

# Randomly assign positions to nodes within the area size

set x_pos [expr rand() * $area_size_x]

set y_pos [expr rand() * $area_size_y]

$node($i) set X_ $x_pos

$node($i) set Y_ $y_pos

$node($i) set Z_ 0

}

# Enable carrier sense multiple access (CSMA) mechanism

# Nodes will sense the medium before transmission to avoid collisions

proc setup_csma_ca {} {

global ns

foreach node [array names node] {

set mac [$node($node) set mac_]

$mac set CSMA_CA_ true

$mac set CWMin_ 15   ;# Minimum contention window

$mac set CWMax_ 1023 ;# Maximum contention window

}

}

setup_csma_ca

# Create traffic sources for nodes, avoiding interference by using different channels

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

set src_node [expr $i % $num_nodes]        ;# Traffic source

set dst_node [expr ($i + 1) % $num_nodes]  ;# Destination node

# Create a UDP agent for the source node

set udp($i) [new Agent/UDP]

$ns attach-agent $node($src_node) $udp($i)

# Create a Null agent for the destination node (to sink traffic)

set null($i) [new Agent/Null]

$ns attach-agent $node($dst_node) $null($i)

# Connect the UDP agent to the Null agent

$ns connect $udp($i) $null($i)

# Create CBR traffic over the UDP agent

set cbr($i) [new Application/Traffic/CBR]

$cbr($i) set packetSize_ 512

$cbr($i) set rate_ 1Mb

$cbr($i) attach-agent $udp($i)

# Schedule traffic start and stop times

set start_time [expr rand() * 5]  ;# Random start time between 0 and 5 seconds

set stop_time [expr $simulation_time – 10] ;# Stop 10 seconds before simulation ends

$ns at $start_time “$cbr($i) start”

$ns at $stop_time “$cbr($i) stop”

}

# 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 channel_interference_avoidance.nam &

exit 0

}

# Run the simulation

$ns run

  1. Explanation of Key Components
  • Multiple Channels: We describe the two various wireless channels like chan0 and chan1 that using Channel/WirelessChannel. These nodes are split into two groups, including every group using a various channel.
  • Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA):
    • The setup_csma_ca technique configures the CSMA/CA mechanism on every node by setting up the MAC layer, before transmitting to detect the medium.
    • It is completed by setting CSMA_CA_ to true and setting up the decrease and increase the contention windows (CWMin_ and CWMax_).
  • Node Configuration and Dynamic Assignment: These nodes are actively made and randomly located in the simulation area. The nodes are alternately allocated to various channels (chan0 or chan1) that supports to decrease the interference among nodes using various channels.
  • Traffic Generation: Traffic sources are made among randomly chosen nodes, and traffic is carried across the UDP protocol with CBR (Constant Bit Rate) traffic.
  1. Run the Simulation

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

ns channel_interference_avoidance.tcl

When the simulation finishes, we can visualize the network using NAM:

nam channel_interference_avoidance.nam

  1. Explanation of Interference Avoidance

In this simulation, interference is prevented via:

  1. Multiple Channels: These nodes are operating on various channels do not interfere with each other that permitting for simultaneous transmissions on the non-overlapping frequencies.
  2. CSMA/CA: The CSMA/CA mechanism make sure that nodes are detect the channel before transmitting, decreasing the likelihood of collisions on the similar channel.
  3. Node Separation: By allocating various channels and carefully scheduling traffic, we decrease the possibility of interference in this simulated environment.
  1. Advanced Features for Channel Interference Avoidance

We can expand this replication by appending more advanced features:

  • Dynamic Channel Selection: Execute the dynamic channel selection, in which nodes are switch channels depending on the level of interference they experience.
  • Interference Detection: Launch the interference detection mechanisms that nodes are observe the packet loss or delays and switch channels while interference is sensed.
  • Power Control: Execute the power control methods in which nodes are modify their transmission power to decrease interference with distant nodes.
  • Channel Scheduling: Append the time-based scheduling that nodes are use various channels or timeslots to prevent the simultaneous transmissions.

Hence, we successfully learned and gain knowledge about the implement and simulate process to execute the Channel Interference Avoidance in NS2 with the help of above procedure and examples. Complete instances and additional details will be offered according to your needs. To successfully implement Channel Interference Avoidance in NS2, make sure to stick with ns2project.com, where we provide top-notch support from our leading developers.