How to Implement Physical Layer in OMNeT++

To implementing a custom Physical Layer (PHY) in OMNeT++ has contains to modelling how the information is exchange over a physical medium that considers the features like signal processing, modulation, and error correction. In the OMNeT++ tool will delivers the robust model to execute and mimic the PHY layer, but the particular execution will depend on the type of network such as wireless, wired and the level of detail required.

The given below is the detailed procedures on how to execute the basic custom Physical Layer in OMNeT++ using the INET framework.

Step-by-Step Implementation:

Step 1: Set Up OMNeT++ and INET Framework

1. Install OMNeT++:
   • Make sure OMNeT++ is installed on system. Download it from the OMNeT++
2. Install the INET Framework:
   • Download and install the INET Framework, which delivers different networking protocols and models that contains existing physical layer models. INET can be downloaded from the INET GitHub repository.

Step 2: Create a New OMNeT++ Project

1. Create the Project:
   • Open OMNeT++ and generate a new OMNeT++ project through File > New > OMNeT++ Project.
   • Name project such as CustomPhysicalLayerSimulation and set up the project directory.
2. Set Up Project Dependencies:
   • Make sure project references the INET Framework by right-clicking on project in the Project Explorer, navigating to Properties > Project References, and scrutiny the INET project.

Step 3: Define the Network Topology

1. Create a NED File:
   • Describe network topology using the NED language. This topology will contain the nodes that interact through the custom physical layer.

Example:

network CustomPHYNetwork

{

parameters:

int numNodes = default(2); // Number of nodes in the network

submodules:

node[numNodes]: CustomNode {

@display(“i=device/laptop”);

}

connections allowunconnected:

node[0].radio++ <–> node[1].radio++;

}

1. Configure Network Parameters:
   • Set up necessary link of performance metrics like bandwidth, delay, and packet loss to mimic a realistic network environment.

Step 4: Implement the Custom Physical Layer

1. Create the Physical Layer Module in NED

Example (in NED):

module CustomPHYLayer

{

parameters:

@display(“i=block/phy”);

gates:

input upperLayerIn;

output upperLayerOut;

input lowerLayerIn;

output lowerLayerOut;

}

2. Implement the Physical Layer in C++

Below are the simple snippet to implement the custom PHY layer in C++:

#include “inet/common/INETDefs.h”

#include “inet/common/packet/Packet.h”

#include “inet/physicallayer/common/PhysicalLayerDefs.h”

#include “inet/physicallayer/contract/packetlevel/IPhysicalLayer.h”

#include “inet/physicallayer/contract/packetlevel/SignalTag_m.h”

class CustomPHYLayer : public cSimpleModule, public inet::physicallayer::IPhysicalLayer

{

protected:

virtual void initialize(int stage) override;

virtual void handleMessage(cMessage *msg) override;

 

// PHY Layer functionalities

void processUpperLayerPacket(Packet *packet);

void processLowerLayerPacket(Packet *packet);

void modulateSignal(Packet *packet);

void demodulateSignal(Packet *packet);

void addNoise(Packet *packet);

void handleReception(Packet *packet);

};

Define_Module(CustomPHYLayer);

void CustomPHYLayer::initialize(int stage) {

if (stage == inet::INITSTAGE_LOCAL) {

// Initialization of PHY-specific variables

}

}

void CustomPHYLayer::handleMessage(cMessage *msg) {

Packet *packet = check_and_cast<Packet *>(msg);

if (msg->arrivedOn(“upperLayerIn”)) {

processUpperLayerPacket(packet);

} else {

processLowerLayerPacket(packet);

}

}

void CustomPHYLayer::processUpperLayerPacket(Packet *packet) {

// Handle packet coming from the upper layer (e.g., MAC layer)

modulateSignal(packet);

send(packet, “lowerLayerOut”);

}

void CustomPHYLayer::processLowerLayerPacket(Packet *packet) {

// Handle packet received from the lower layer (e.g., from another PHY)

handleReception(packet);

demodulateSignal(packet);

send(packet, “upperLayerOut”);

}

void CustomPHYLayer::modulateSignal(Packet *packet) {

// Simulate modulation (e.g., BPSK, QPSK)

auto modulatedSignal = packet->addTag<inet::physicallayer::SignalTag>();

modulatedSignal->setModulationType(inet::physicallayer::ModulationType::BPSK);

modulatedSignal->setPower(1.0);  // Set signal power

}

void CustomPHYLayer::demodulateSignal(Packet *packet) {

// Simulate demodulation

auto modulatedSignal = packet->findTag<inet::physicallayer::SignalTag>();

if (modulatedSignal) {

// Process demodulation based on the modulation type

}

}

void CustomPHYLayer::addNoise(Packet *packet) {

// Simulate adding noise to the signal

auto signalNoise = packet->addTag<inet::physicallayer::SignalNoiseTag>();

signalNoise->setNoiseLevel(0.1);  // Example noise level

}

void CustomPHYLayer::handleReception(Packet *packet) {

// Handle the reception logic, e.g., checking for errors

addNoise(packet);

}

Step 5: Integrate the Custom PHY Layer into a Node

We need to incorporate custom PHY layer into a node. For example, we need to generate a CustomNode module that contains the PHY layer along with MAC and other essential layers.

Example (in NED):

module CustomNode

{

submodules:

radio: CustomPHYLayer {

@display(“p=100,100;i=block/phy”);

}

mac: Ieee80211Mac {

@display(“p=200,100;i=block/mac”);

}

connections allowunconnected:

radio.upperLayerOut –> mac.lowerLayerIn;

mac.lowerLayerOut –> radio.upperLayerIn;

}

Step 6: Configure the Simulation

1. Set Up the Simulation in omnetpp.ini:
   • Describe the emulated metrics like the network to use, simulation time, and custom PHY layer behavior.

Example:

network = CustomPHYNetwork

sim-time-limit = 100s

**.scalar-recording = true

**.vector-recording = true

1. Compile and Run the Simulation:
   • Make sure everything is properly applied and compiled. Run the simulation using OMNeT++’s IDE or command line.

Step 7: Analyze the Results

1. Monitor PHY Layer Behavior:
   • Monitor how packets are modulated, transmitted, received, and demodulated at the PHY layer. We need to measure the effects of noise, modulation, and other PHY characteristics.
2. Evaluate Performance:
   • Measure key performance metrics like error rate, signal-to-noise ratio (SNR), and throughput.
   • Scalars and Vectors: Use OMNeT++ tools to record and evaluate scalar and vector data, like packet loss, bit error rates, and signal quality.

Step 8: Optimize and Extend the PHY Layer

1. Address Any Issues:
   • If the simulation reveals any challenges like incorrect modulation/demodulation, unexpected packet loss then it modify the PHY layer logic or network configuration as needed.
2. Extend the PHY Layer:
   • To execute the further PHY layer features like more advanced modulation schemes, error correction coding, channel models, or power control mechanisms.

In the final, we provide the basic knowledge about how to implement the Physical Layer (PHY) in OMNeT++ simulator that transmit the information lover the physical medium and additionally we provide more information of Physical Layer (PHY). Implementation of Physical Layer in OMNeT++tool are worked by us, so stay in touch with us to get bets developers support on simulation process.