To simulate Physical Layer projects within NS2 that needs to integrate elements such as signal transmission, modulation, interference, and other physical layer characteristics, which describe wireless communication. The network simulator NS2 concentrates primarily on the network layer, however it has limited support for physical layer characteristics within wireless simulations.
Below is a simple instruction on how we can simulate few features of the physical layer using NS2:
Steps to Simulate Physical Layer Aspects in NS2
- Install NS2
If NS2 is not already installed then we can download it from the NS2 Official Website and we follow the installation steps.
- Define Physical Layer Parameters
In NS2, physical layer characteristics are managed via metrics such as transmission power, propagation models, antenna types, and channel configurations. These parameters replicate signal transmission, path loss, and other factors, which impact the communication at the physical layer.
- Create a TCL Script for Physical Layer Simulation
Following is a simple script, which indicates how to simulate a few physical layer features, like signal propagation, wireless channel configuration, and antenna set up.
Example TCL Script for Physical Layer Simulation:
# Create a simulator object
set ns [new Simulator]
# Define trace and NAM files for analysis and visualization
set tracefile [open “physical_layer_trace.tr” w]
set namfile [open “physical_layer_simulation.nam” w]
$ns trace-all $tracefile
$ns namtrace-all $namfile
# Define a topography for wireless communication
set topo [new Topography]
$topo load_flatgrid 1000 1000 ;# 1000×1000 meters grid
# Set up the wireless channel and physical layer parameters
set chan [new Channel/WirelessChannel]
# Configure wireless network with physical layer parameters
$ns node-config -adhocRouting DSDV \
-llType LL \
-macType Mac/802_11 \
-ifqType Queue/DropTail/PriQueue \
-ifqLen 50 \
-antType Antenna/OmniAntenna \
-propType Propagation/TwoRayGround \
-phyType Phy/WirelessPhy \
-channelType Channel/WirelessChannel \
-topoInstance $topo \
-agentTrace ON \
-routerTrace ON \
-macTrace OFF \
-movementTrace OFF
# Create wireless nodes
set n0 [$ns node]
set n1 [$ns node]
# Set node positions manually
$n0 set X_ 100
$n0 set Y_ 100
$n1 set X_ 500
$n1 set Y_ 500
# Create wireless link using the propagation model
$ns duplex-link $n0 $n1 1Mb 10ms DropTail
# Define physical layer parameters for transmission power and energy models
$n0 set transmit-power 0.2818 ;# Transmission power in watts
$n1 set transmit-power 0.2818
$n0 set receive-power-threshold -95 ;# Threshold for receiving signal in dBm
$n1 set receive-power-threshold -95
# Attach UDP agents to simulate traffic
set udp0 [new Agent/UDP]
set udp1 [new Agent/UDP]
$ns attach-agent $n0 $udp0
$ns attach-agent $n1 $udp1
# Create a CBR (Constant Bit Rate) traffic generator
set cbr0 [new Application/Traffic/CBR]
$cbr0 set packetSize_ 512
$cbr0 set rate_ 1Mb
$cbr0 attach-agent $udp0
# Connect the UDP agents
$ns connect $udp0 $udp1
# Schedule the traffic flow
$ns at 1.0 “$cbr0 start”
$ns at 4.5 “$cbr0 stop”
# Define the finish procedure
proc finish {} {
global ns tracefile namfile
$ns flush-trace
close $tracefile
close $namfile
exit 0
}
# End the simulation after 5 seconds
$ns at 5.0 “finish”
# Run the simulation
$ns run
- Run the Simulation
We can save the script as physical_layer_simulation.tcl and then execute it in NS2:
ns physical_layer_simulation.tcl
- Visualize the Simulation Using NAM
We can open the .nam file made by the simulation to envision the physical layer interactions (node transmission and signal propagation):
nam physical_layer_simulation.nam
- Analyze the Trace File
The trace file (physical_layer_trace.tr) includes detailed data regarding the packet exchanges, signal transmissions, and network events, which can be investigated for:
- Signal strength and power consumption.
- Packet loss because of propagation characteristics.
- Transmission delays.
- Modify the Simulation
- Change Propagation Models: Switch to other propagation models (e.g., FreeSpace or Shadowing) to mimic diverse environments.
- Vary Antenna Types: Alter the antenna configuration (e.g., OmniAntenna, DirectionalAntenna) to monitor how signal coverage modifies.
- Adjust Transmission Power: Modify transmission power to replicate diverse communication ranges and signal strength.
- Mobility Models: Launch node mobility to mimic mobile scenarios and focus on how physical layer characteristics impact the communication.
Optional Enhancements:
- Interference Modeling: Launch several nodes and replicate the signal interference in the network.
- Energy Consumption: Insert an energy models to mimic power consumption at the physical layer for wireless sensor networks.
- Error Models: Execute an error models (such as bit error rates) to replicate how physical layer conditions impact the packet delivery.
From this manual, you learnt on how to simulate and analyse some features of Physical Layer Projects that were executed using NS2 simulation and TCL script via simulation guidelines. If you want more insights and in-depth information, we will be made available.
Provide us with your information, and we will help you enhance your project performance on Physical Layer Projects utilizing the NS2 tool. We offer straightforward guidance on simulating the Physical Layer with NS2 in your projects.
