How to Implement M2M Satellite Communication in NS2

To implement the Machine-to-Machine (M2M) satellite communication within NS2 (Network Simulator 2), we will be modeling communication among the devices (machines), which communicate via satellites instead of the terrestrial networks. M2M satellite communication is refers to the devices interchanging data autonomously without the human intervention. In the framework of the satellite networks, M2M devices (nodes) will relate through the satellite links, possibly using a satellite as a relay among the ground stations.

In this model, we will configure the M2M devices (ground nodes), which communicate through a satellite performing as a communication relay. This satellite will route data among various M2M nodes or from M2M nodes to a centralized ground station.

Steps to Implement M2M Satellite Communication in NS2:

  1. Set up the Simulation Environment

Initially, make a nodes that denote M2M devices and the satellite node and we will setup links among the M2M devices and the satellite for communication.

Example TCL Script for Basic Setup:

# Create a simulator instance

set ns [new Simulator]

# Set link parameters (optical or RF communication links)

set bw 1Gb          ;# Bandwidth for satellite links

set delay 50ms      ;# Delay for satellite communication (based on distance to/from satellites)

# Create M2M devices (ground nodes)

set m2m1 [$ns node]

set m2m2 [$ns node]

# Create a satellite node

set satellite [$ns node]

# Create ground station node (optional, for centralized control)

set ground_station [$ns node]

# Connect M2M devices to the satellite with duplex links

$ns duplex-link $m2m1 $satellite $bw $delay DropTail

$ns duplex-link $m2m2 $satellite $bw $delay DropTail

# Optionally, connect the satellite to the ground station

$ns duplex-link $satellite $ground_station $bw $delay DropTail

This configure two M2M devices (m2m1, m2m2), which communicate through a satellite. An optional ground station can contain if we require a centralized communication hub.

  1. Define Traffic between M2M Devices

In M2M communication, the devices are transfer and receive the data autonomously. We can replicate this data exchange using UDP or TCP agents along with CBR (Constant Bit Rate) traffic to mimic continuous data transfer among the devices.

Example of Creating Traffic between M2M Devices:

# Create UDP agent for M2M device 1 (uplink to satellite)

set udp_m2m1 [new Agent/UDP]

$ns attach-agent $m2m1 $udp_m2m1

# Create CBR traffic generator for M2M device 1

set cbr_m2m1 [new Application/Traffic/CBR]

$cbr_m2m1 set packet_size_ 500

$cbr_m2m1 set rate_ 500Kb

$cbr_m2m1 attach-agent $udp_m2m1

# Create UDP sink for M2M device 2 (downlink from satellite)

set null_m2m2 [new Agent/Null]

$ns attach-agent $m2m2 $null_m2m2

# Connect M2M device 1 to M2M device 2 via satellite

$ns connect $udp_m2m1 $null_m2m2

# Start and stop the traffic

$ns at 1.0 “$cbr_m2m1 start”

$ns at 10.0 “$cbr_m2m1 stop”

In the above instance, M2M device 1 transfer data to M2M device 2 via the satellite, mimicking M2M communication via the satellite link.

  1. Handle Communication via Satellite (Routing or Forwarding)

This satellite performs as a relay among the M2M devices. In real-world situations, and the satellite may perform basic packet forwarding or use a routing protocol such as AODV (Ad hoc On-Demand Distance Vector) for dynamic route discovery.

Example of Enabling AODV for Routing:

# Enable AODV as the routing protocol for satellite communication

set val(rp) AODV

# Attach the routing protocol to all nodes (satellite and M2M devices)

for {set i 1} {$i <= 3} {incr i} {

$ns at 0.0 “$m2m$i set ragent [new Agent/AODV]”

}

With AODV, the satellite will actively discover the routes among the M2M devices as they communicate.

  1. Simulate Mobility for M2M Devices (Optional)

If the M2M devices are mobile, we can append the mobility models to replicate its movement. The simulation platform NS2 permits to describe the mobility of nodes to replicate real-world scenarios in which devices or satellites are not stationary.

Example of Defining Mobility for M2M Devices:

# Set initial positions for M2M devices

$m2m1 set X_ 0

$m2m1 set Y_ 0

$m2m2 set X_ 100

$m2m2 set Y_ 100

# Simulate movement of M2M devices

$ns at 2.0 “$m2m1 setdest 200 200 10”  ;# Move m2m1 to new coordinates at 10 m/s

$ns at 3.0 “$m2m2 setdest 300 300 10”  ;# Move m2m2 to new coordinates at 10 m/s

This mimics M2M devices moving while the simulation, then permitting to observe how the network performs with mobile nodes.

  1. Monitor and Trace the Simulation

Allow tracing to take the performance of the satellite M2M network, like packet transmissions, routing updates, and delays. We can be examined these trace files to assess network performance.

Enable Trace Files:

# Enable tracing for the simulation

set tracefile [open “m2m_satellite_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 be recorded the events such as packet transmissions and routing updates, permitting to investigate the performance of the satellite M2M network.

  1. Run the Simulation

Lastly, we run the simulation to monitor how M2M devices communicate via the satellite.

# Run the simulation

$ns run

Example Complete TCL Script for M2M Satellite Communication Simulation

# Create a simulator instance

set ns [new Simulator]

# Set link parameters (for satellite links)

set bw 1Gb

set delay 50ms

# Create M2M devices (ground nodes)

set m2m1 [$ns node]

set m2m2 [$ns node]

# Create a satellite node

set satellite [$ns node]

# Create ground station node (optional)

set ground_station [$ns node]

# Connect M2M devices to the satellite with duplex links

$ns duplex-link $m2m1 $satellite $bw $delay DropTail

$ns duplex-link $m2m2 $satellite $bw $delay DropTail

# Connect the satellite to the ground station (optional)

$ns duplex-link $satellite $ground_station $bw $delay DropTail

# Create UDP agent for M2M device 1 (uplink to satellite)

set udp_m2m1 [new Agent/UDP]

$ns attach-agent $m2m1 $udp_m2m1

# Create CBR traffic generator for M2M device 1

set cbr_m2m1 [new Application/Traffic/CBR]

$cbr_m2m1 set packet_size_ 500

$cbr_m2m1 set rate_ 500Kb

$cbr_m2m1 attach-agent $udp_m2m1

# Create UDP sink for M2M device 2 (downlink from satellite)

set null_m2m2 [new Agent/Null]

$ns attach-agent $m2m2 $null_m2m2

# Connect M2M device 1 to M2M device 2 via satellite

$ns connect $udp_m2m1 $null_m2m2

# Start and stop the traffic

$ns at 1.0 “$cbr_m2m1 start”

$ns at 10.0 “$cbr_m2m1 stop”

# Enable tracing

set tracefile [open “m2m_satellite_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

To conclude, we learned and gain more knowledge about the M2M satellite communication that were configured and implemented in the NS2 using basic methods. Additional insights will be presented in another manual depends on your needs.

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