How to Begin Implement Physical Layer in NS3

To begin the Physical Layer in NS-3 has included the design on how the data is forwarded and received the physical medium. The physical layer has managed the challenges like as modulation, transmission power, noise, intrusion, and signal strength. NS-3 tool offers the specific foundational encourage for physical layer replication, nevertheless custom application can be required for detailed study or protocols.

Steps to Begin Implement Physical Layer in NS3

Step 1: Understand the Physical Layer

1. Core Responsibilities:
   • Modulation and Demodulation: Change the digital data for analog signals and vice versa.
   • Transmission Power: Handle the signal strength during communication.
   • Signal Propagation: It replicates the behavior for signals over distance for instance attenuation, path loss.
   • Interference and Noise: Design the impact for external factors on signal quality.
2. Use Cases:
   • Replicating a custom wireless communication protocols.
   • Validating the effect of environmental factors on signal quality.
3. NS-3 Framework:
   • Spectrum Framework: The frequency patterns are domain for transmission.
   • SpectrumPhy Class: Delivers the abstraction for physical layer.
   • Channel Models: It replicates the signal broadcast through changed the media.

Step 2: Set Up NS-3

1. Install NS-3:

git clone https://gitlab.com/nsnam/ns-3-dev.git

cd ns-3-dev

./ns3 configure –enable-examples –enable-tests

./ns3 build

1. Verify Installation: Run a sample example:

./ns3 run examples/tutorial/first

Step 3: Plan the Physical Layer Implementation

1. Core Components:
   • Phy Layer Abstraction: Encompass SpectrumPhy or SimpleWirelessChannel for design the physical layer.
   • Signal Propagation: Use path loss, fading, and intrusion patterns.
   • Transmission and Reception Logic: Apply the variation, demodulation, and error handling.
2. Workflow:
   • Make a custom for PHY layer class.
   • Execute the signal broadcast and handling logic.
   • Incorporate by higher-layer protocols for sample MAC.

Step 4: Implement the Physical Layer

Step 4.1: Define the Physical Layer Class

Encompass the SpectrumPhy class for describe the custom PHY layer.

#include “ns3/spectrum-phy.h”

#include “ns3/spectrum-value.h”

#include “ns3/spectrum-channel.h”

#include “ns3/net-device.h”

using namespace ns3;

class CustomPhy : public SpectrumPhy {

public:

static TypeId GetTypeId(void);

CustomPhy();

virtual ~CustomPhy();

virtual void Send(Ptr<Packet> packet, Ptr<SpectrumValue> txPower);

virtual void StartRx(Ptr<SpectrumValue> rxPower, Ptr<Packet> packet);

void SetChannel(Ptr<SpectrumChannel> channel);

void SetDevice(Ptr<NetDevice> device);

private:

Ptr<SpectrumChannel> m_channel;

Ptr<NetDevice> m_device;

double m_noiseFigure; // Noise figure in dB

};

Step 4.2: Implement Core Functions

• Set Channel and Device: Allocate the channel and device for transmission.

void CustomPhy::SetChannel(Ptr<SpectrumChannel> channel) {

m_channel = channel;

}

void CustomPhy::SetDevice(Ptr<NetDevice> device) {

m_device = device;

}

• Transmit Data: Replicate the transmission for packets completed the channel.

void CustomPhy::Send(Ptr<Packet> packet, Ptr<SpectrumValue> txPower) {

if (m_channel) {

m_channel->StartTx(packet, txPower, this);

}

}

• Receive Data: It replicate the reception for packets and process them.

void CustomPhy::StartRx(Ptr<SpectrumValue> rxPower, Ptr<Packet> packet) {

double snr = CalculateSnr(rxPower);

if (snr > ThresholdSnr()) {

// Process the packet

NS_LOG_INFO(“Packet received successfully.”);

} else {

NS_LOG_INFO(“Packet dropped due to low SNR.”);

}

}

double CustomPhy::CalculateSnr(Ptr<SpectrumValue> rxPower) {

double signalPower = rxPower->CalculateAveragePower();

double noisePower = CalculateNoise();

return signalPower / noisePower;

}

double CustomPhy::CalculateNoise() {

// Calculate noise power based on noise figure

return pow(10, m_noiseFigure / 10);

}

Step 4.3: Integrate Signal Propagation

Use NS-3’s SpectrumChannel for replicate the signal broadcast.

• Setup the Channel:

Ptr<SpectrumChannel> channel = CreateObject<SpectrumChannel>();

Ptr<CustomPhy> phy = CreateObject<CustomPhy>();

phy->SetChannel(channel);

• Configure Path Loss Model: Add a path loss model to the channel.

Ptr<LogDistancePropagationLossModel> pathLoss = CreateObject<LogDistancePropagationLossModel>();

channel->AddPropagationLossModel(pathLoss);

Step 5: Register the Physical Layer

Record the class by NS-3’s TypeId system:

TypeId CustomPhy::GetTypeId(void) {

static TypeId tid = TypeId(“ns3::CustomPhy”)

.SetParent<SpectrumPhy>()

.SetGroupName(“Spectrum”)

.AddConstructor<CustomPhy>();

return tid;

}

Step 6: Integrate into a Simulation

1. Simulation Script Example:

#include “ns3/internet-stack-helper.h”

#include “ns3/custom-phy.h”

int main(int argc, char *argv[]) {

NodeContainer nodes;

nodes.Create(2);

Ptr<SpectrumChannel> channel = CreateObject<SpectrumChannel>();

Ptr<CustomPhy> phy1 = CreateObject<CustomPhy>();

Ptr<CustomPhy> phy2 = CreateObject<CustomPhy>();

phy1->SetChannel(channel);

phy2->SetChannel(channel);

Ptr<Packet> packet = Create<Packet>(1024); // Create a 1024-byte packet

phy1->Send(packet, Create<SpectrumValue>()); // Transmit packet from phy1

Simulator::Run();

Simulator::Destroy();

return 0;

}

Step 7: Test and Debug

1. Enable Logging:

export NS_LOG=”CustomPhy=level_all|prefix_time”

./ns3 run my-simulation

1. Verify Behavior:
   • Validate the signal transmission and response.
   • Authorize the SNR and packet processing logic.

Step 8: Extend and Optimize

1. Enhancements:
   • It helps for enhance the changed modulation systems for instance QAM, PSK.
   • Apply further advanced broadcast patterns for sample Rayleigh fading.
2. Performance Testing:
   • Validate by numerous nodes.
   • Amount of packet has successfully delivery for below various environments.

We had understood about how to emulate the actual transmission and reception of signals over a network in the physical layer communication using ns3 framework. We will also elegant and deliver the additional details about physical layer communication.