How to Implement Satellite Optical Network in NS2

To implement a Satellite Optical Network in NS2 has several steps to mimic a scenario of a network in which the satellites use optical communication for high-speed data transmission among satellite nodes and probably in ground stations. In this scenario, optical links delivers the backbone for inter-satellite communication (ISL – Inter-Satellite Links) and satellite-to-ground communication (downlink/uplink). Although NS2 doesn’t natively support complex satellite or optical communication protocols, so we can design a simple satellite optical network using high-speed links and mimic the satellite movement.

Key Components of a Satellite Optical Network:

  1. Satellites (nodes): It denoted as mobile nodes with dynamic links among them.
  2. Inter-Satellite Links (ISL): High-speed optical links among satellites.
  3. Ground Stations: Static nodes that associate to the satellite network through uplink/downlink optical links.

Steps to Implement a Satellite Optical Network in NS2:

  1. Set up the Simulation Environment

Initially, configure the satellite network topology that contain satellites as mobile nodes and ground stations as static nodes. Optical links are used to mimic the high-speed communication among satellites and ground stations.

Example TCL Script for Basic Setup:

# Create a simulator instance

set ns [new Simulator]

# Set link parameters for optical links (high-speed)

set bw 10Gb          ;# Bandwidth for optical links (10 Gbps)

set delay 5ms        ;# Delay for optical links (adjust for satellite distances)

# Create satellite nodes

set sat1 [$ns node]

set sat2 [$ns node]

set sat3 [$ns node]

# Create ground station node

set ground1 [$ns node]

# Connect satellites with optical inter-satellite links (ISL)

$ns duplex-link $sat1 $sat2 $bw $delay DropTail

$ns duplex-link $sat2 $sat3 $bw $delay DropTail

# Create optical uplink/downlink between satellite and ground station

$ns duplex-link $sat1 $ground1 $bw $delay DropTail

In this configuration, there are three satellites (sat1, sat2, sat3) associated through inter-satellite optical links. The satellite sat1 is interconnected to a ground station through an optical uplink/downlink.

  1. Configure Mobility for Satellites

Satellites usually move in orbit, so we need to describe a mobility model to mimic the movement of the satellite nodes. NS2 delivers numerous mobility models, or we can describe custom mobility for the satellites.

Example of Defining Satellite Mobility:

# Set initial positions for satellites

$sat1 set X_ 0

$sat1 set Y_ 500

$sat2 set X_ 100

$sat2 set Y_ 600

$sat3 set X_ 200

$sat3 set Y_ 700

# Simulate satellite movement (example of circular orbit movement)

$ns at 1.0 “$sat1 setdest 200 500 10”  ;# Move sat1 to new coordinates at 10 m/s

$ns at 2.0 “$sat2 setdest 300 600 10”  ;# Move sat2 to new coordinates at 10 m/s

$ns at 3.0 “$sat3 setdest 400 700 10”  ;# Move sat3 to new coordinates at 10 m/s

This sample mimics satellites moving along a predefined path, stimulating their orbital movement.

  1. Configure Traffic between Satellites and Ground Station

To mimic data transmission among the satellites and the ground station (or between satellites), we can use UDP or TCP agents and setting up them with CBR (Constant Bit Rate) traffic to design high-speed optical communication.

Example of Configuring Traffic between Satellites and Ground Station:

# Create a UDP agent at satellite 1 for uplink traffic

set udp_sat1 [new Agent/UDP]

$ns attach-agent $sat1 $udp_sat1

# Create CBR traffic to simulate high-speed data transfer from satellite to ground station

set cbr_sat1 [new Application/Traffic/CBR]

$cbr_sat1 set packet_size_ 1000

$cbr_sat1 set rate_ 1Gb     ;# High data rate (1 Gbps)

$cbr_sat1 attach-agent $udp_sat1

# Create a UDP sink at ground station

set null_ground [new Agent/Null]

$ns attach-agent $ground1 $null_ground

# Connect satellite 1 to the ground station

$ns connect $udp_sat1 $null_ground

# Start and stop the traffic

$ns at 1.0 “$cbr_sat1 start”

$ns at 10.0 “$cbr_sat1 stop”

This mimics sat1 sending high-speed data to the ground station through the optical uplink. We can add more traffic flows among satellites and ground stations as needed.

  1. Simulate Handover between Satellites (Optional)

In satellite networks, handover happens when a satellite moves out of range, and the communication is passed to another satellite. We can replicate handover by adapting the connectivity of the satellites to ground stations during the simulation.

Example of Simulating Handover Between Satellites:

# Initially, the ground station is connected to satellite 1

$ns duplex-link $sat1 $ground1 $bw $delay DropTail

# At time 5.0, switch the ground station to satellite 2 (handover)

$ns at 5.0 “$ns rtmodel-at 5.0 down $sat1 $ground1”

$ns at 5.0 “$ns rtmodel-at 5.0 up $sat2 $ground1”

This example mimics a handover in which the ground station connection is transferred from sat1 to sat2.

  1. Monitor and Trace the Simulation

Allow tracing in NS2 to observe the characteristics of the network, like packet transmissions, delays, and handover events. The trace file will support you to evaluate the performance of the satellite optical network.

Enable Trace Files:

# Enable tracing for the simulation

set tracefile [open “satellite_optical_trace.tr” w]

$ns trace-all $tracefile

# Define a finish procedure to end the simulation and close the trace file

proc finish {} {

global ns tracefile

$ns flush-trace

close $tracefile

exit 0

}

# Set the simulation end time

$ns at 20.0 “finish”

The trace file will log all network events, like packet transmissions and handover events, that permits to measure on how the network act as in different conditions.

  1. Run the Simulation

Finally, execute the simulation to monitor on how the satellites interact with each other and with the ground station through optical links.

# Run the simulation

$ns run

Example Complete TCL Script for Satellite Optical Network Simulation

# Create a simulator instance

set ns [new Simulator]

# Set optical link parameters

set bw 10Gb

set delay 5ms

# Create satellite nodes

set sat1 [$ns node]

set sat2 [$ns node]

set sat3 [$ns node]

# Create ground station node

set ground1 [$ns node]

# Connect satellites with optical inter-satellite links (ISL)

$ns duplex-link $sat1 $sat2 $bw $delay DropTail

$ns duplex-link $sat2 $sat3 $bw $delay DropTail

# Create uplink/downlink between satellite and ground station

$ns duplex-link $sat1 $ground1 $bw $delay DropTail

# Set initial positions for satellites (example coordinates)

$sat1 set X_ 0

$sat1 set Y_ 500

$sat2 set X_ 100

$sat2 set Y_ 600

$sat3 set X_ 200

$sat3 set Y_ 700

# Simulate satellite movement (example of circular orbit movement)

$ns at 1.0 “$sat1 setdest 200 500 10”

$ns at 2.0 “$sat2 setdest 300 600 10”

$ns at 3.0 “$sat3 setdest 400 700 10”

# Create UDP agent for satellite-to-ground communication

set udp_sat1 [new Agent/UDP]

$ns attach-agent $sat1 $udp_sat1

# Create CBR traffic for satellite 1

set cbr_sat1 [new Application/Traffic/CBR]

$cbr_sat1 set packet_size_ 1000

$cbr_sat1 set rate_ 1Gb

$cbr_sat1 attach-agent $udp_sat1

# Create UDP sink at ground station

set null_ground [new Agent/Null]

$ns attach-agent $ground1 $null_ground

# Connect satellite 1 to the ground station

$ns connect $udp_sat1 $null_ground

# Start and stop the traffic

$ns at 1.0 “$cbr_sat1 start”

$ns at 10.0 “$cbr_sat1 stop”

# Simulate handover of ground station from sat1 to sat2

$ns at 5.0 “$ns rtmodel-at 5.0 down $sat1 $ground1”

$ns at 5.0 “$ns rtmodel-at 5.0 up $sat2 $ground1”

# Enable tracing

set tracefile [open “satellite_optical_trace.tr” w]

$ns trace-all $tracefile

# End simulation

$ns at 20.0 “finish”

proc finish {} {

global ns tracefile

$ns flush-trace

close $tracefile

exit 0

}

# Run the simulation

$ns run

In the end of the simulation, we utterly demonstrated the basic techniques including implementation procedures with sample code snippets will help you to implement and setup the Satellite Optical Network in the ns2 environment. We plan to offer more details regarding this process in numerous tools. Rely on us for a detailed implementation guidance , share with us all your research details we aid you with good support.