How to Implement Spectrum & Power Allocation in NS2

To implement Spectrum and Power Allocation in NS2 has needs to mimic on how the network enthusiastically allocates diverse frequency channels (spectrum) and power levels to users, particularly in scenarios such as Cognitive Radio Networks (CRNs) or Wireless Networks in which effective spectrum and power management is vital to improve throughput, diminish interference, and enhance network performance.

Below is the step-by-step procedure to implement the Spectrum and Power Allocation in NS2:

Key Steps:

Set up the network with multiple nodes (users) and channels (spectrum bands).
Assign different channels dynamically based on spectrum availability.
Allocate transmission power to each node enthusiastically based on distance or interference levels.
Simulate traffic and evaluate the impact of spectrum and power allocation on the network performance.

Step-by-Step Implementation:

NS2 Setup for Spectrum and Power Allocation

We initiate by generating a simple network setup in NS2, in which we have multiple nodes denotes users that enthusiastically access the spectrum. We can then execute the spectrum allocation based on the availability of diverse channels.

Example: Setting Up Nodes and Channels

# Create an NS2 simulator instance

set ns [new Simulator]

# Open trace and NAM files for logging the simulation

set tracefile [open “spectrum_power_allocation.tr” w]

set namfile [open “spectrum_power_allocation.nam” w]

$ns trace-all $tracefile

$ns namtrace-all-wireless $namfile 1000 1000

# Define wireless channel for communication

set chan_1_ [new Channel/WirelessChannel]

set chan_2_ [new Channel/WirelessChannel]

# Define topography for wireless communication

set topo [new Topography]

$topo load_flatgrid 1000 1000

# Define network parameters (MAC, propagation, PHY)

set prop [new Propagation/TwoRayGround]

set netif [new Phy/WirelessPhy]

set mac [new Mac/802_11] ;# Wi-Fi MAC protocol for wireless access

set ll [new LL]

set ifq [new Queue/DropTail/PriQueue] ;# Priority queue for packet handling

set ant [new Antenna/OmniAntenna]

# Configure node settings (basic configuration for all users)

$ns node-config -llType $ll \

-macType $mac \

-ifqType $ifq \

-ifqLen 50 \

-antType $ant \

-propType $prop \

-phyType $netif \

-channel $chan_1_ \

-topoInstance $topo

Dynamic Spectrum Allocation

Spectrum allocation means enthusiastically allocating diverse channels to different users. In a Cognitive Radio Network (CRN), secondary users need to sense the spectrum and use an available channel. In this case, we will disstribute different channels to users based on their availability.

Example: Dynamic Spectrum Allocation Based on Availability

We will describe multiple channels and distribute them to diverse nodes according on availability. We can execute a channel sensing mechanism in which each node validate the availability of channels and then choose an appropriate one.

# Define nodes (users)

set node1 [$ns node]

set node2 [$ns node]

set node3 [$ns node]

# Position the nodes

$node1 set X_ 200

$node1 set Y_ 200

$node2 set X_ 400

$node2 set Y_ 400

$node3 set X_ 600

$node3 set Y_ 600

# Procedure for dynamic channel allocation

proc allocate_spectrum {node channels} {

global ns

# Randomly choose an available channel from the list of channels

set channel_index [expr int(rand() * [llength $channels])]

set allocated_channel [lindex $channels $channel_index]

puts “Node $node allocated to Channel $allocated_channel”

$ns at 0.1 “$node set channel_ $allocated_channel”

}

# Define available channels

set available_channels [list $chan_1_ $chan_2_]

# Allocate channels to the nodes

allocate_spectrum $node1 $available_channels

allocate_spectrum $node2 $available_channels

allocate_spectrum $node3 $available_channels

In this sample, each node enthusiastically choose a channel from the list of available channels.

Dynamic Power Allocation

Power allocation is vital to reduce interference and enhance the network’s energy efficiency. In this step, we enthusiastically adapt the transmission power of each node based on its distance from other nodes or interference levels.

Example: Power Allocation Based on Distance

We can execute a simple power control mechanism in which the transmission power is inversely proportional to the distance among nodes.

# Function to calculate distance between two nodes

proc calculate_distance {node1 node2} {

set x1 [$node1 set X_]

set y1 [$node1 set Y_]

set x2 [$node2 set X_]

set y2 [$node2 set Y_]

return [expr sqrt(($x1 – $x2) * ($x1 – $x2) + ($y1 – $y2) * ($y1 – $y2))]

}

# Procedure for power allocation based on distance

proc allocate_power {node1 node2} {

global ns

# Calculate the distance between node1 and node2

set distance [calculate_distance $node1 $node2]

# Inverse relationship between power and distance

set tx_power [expr 100.0 / $distance]

puts “Node $node1 allocated power $tx_power for transmission to $node2”

$ns at 0.1 “$node1 set transmit_power_ $tx_power”

}

# Allocate power for communication between nodes

allocate_power $node1 $node2

allocate_power $node2 $node3

This sample will show on how to modify the transmission power of nodes according to their distance. We can improve this method by considering interference levels, congestion, or QoS requirements.

Simulating Traffic

Replicate the real traffic among the nodes after allocating spectrum and power. We can use UDP or TCP traffic to mimic data transmission.

Example: UDP Traffic Simulation

# Create UDP agents and CBR traffic for communication

set udp1 [new Agent/UDP]

set udp2 [new Agent/UDP]

set null1 [new Agent/Null]

set null2 [new Agent/Null]

# Attach agents to nodes

$ns attach-agent $node1 $udp1

$ns attach-agent $node2 $null1

$ns attach-agent $node2 $udp2

$ns attach-agent $node3 $null2

# Connect the agents for communication

$ns connect $udp1 $null1

$ns connect $udp2 $null2

# Create CBR traffic to simulate continuous data transfer

set cbr1 [new Application/Traffic/CBR]

$cbr1 attach-agent $udp1

$cbr1 set packetSize_ 512

$cbr1 set rate_ 1Mb

set cbr2 [new Application/Traffic/CBR]

$cbr2 attach-agent $udp2

$cbr2 set packetSize_ 512

$cbr2 set rate_ 512Kb

# Start and stop traffic at specific times

$ns at 1.0 “$cbr1 start”

$ns at 10.0 “$cbr1 stop”

$ns at 2.0 “$cbr2 start”

$ns at 12.0 “$cbr2 stop”

Running the Simulation

Set the simulation duration and run it.

# Set the simulation end time

$ns at 15.0 “finish”

# Finish procedure to close trace files and end the simulation

proc finish {} {

global ns tracefile namfile

$ns flush-trace

close $tracefile

close $namfile

exit 0

}

# Run the simulation

$ns run

Analyzing the Results

After execution the simulation, evaluating the trace files and network animation (NAM) to measure how spectrum and power allocation impacts the network’s performance:

Throughput: Evaluate on how much data is successfully transmitted.
Packet Loss: Validate for any packet drops because of interference or insufficient power allocation.
Power Efficiency: Measure the power consumption of nodes according to the dynamic power allocation.
Spectrum Efficiency: Evaluate how efficiently the available spectrum is utilized.

At the end of the presented manual, we have seen and focussed on brief demonstration related to the implementation of spectrum and power allocation with the help of ns2 simulator. We also provide some snippets and evaluation process to help you to execute. We plan to deliver additional information regarding how the spectrum and power allocation will simulate in diverse environment. We work on Cognitive Radio Networks (CRNs) or Wireless Networks related for your projects; Stay in touch with ns2project.com we implement your projects and carry on network performance analysis.