How to Calculate Network Channel Capacity in omnet++

To calculate the network channel capacity in OMNeT++ has requires to include defining the maximum data rate can be constantly transmitted through the communication channel, giving the channel conditions like interference and noise. The channel capacity is a major concept in information theory and is usually calculated using the Shannon-Hartley theorem.

Steps to Calculate Network Channel Capacity in OMNeT++:

Set Up the Wireless Network Model:
- Define the network topology using NED files in OMNeT++. Contain wireless nodes like access points, base stations, and mobile devices. Configure the wireless channel model.
Configure the Channel Model:
- In OMNeT++ with the INET framework, modules like Ieee80211Radio, RadioMedium, and others can be used to mimic wireless communication with proper channel conditions. Use a channel model that accounts for the effects of noise and interference
Measure or Set Signal-to-Noise Ratio (SNR):
- SNR is normally given by the ratio of the received signal power to the noise power at the receiver.
- The SNR is a key parameter in measuring the channel capacity. It can be calculated based on the simulation scenario during the simulation or set.
Apply the Shannon-Hartley Theorem:
- The channel capacity CCC in bits per second in bps can be measured using the Shannon-Hartley theorem like C=B⋅log⁡2(1+SNR)C = B \cdot \log_2\left(1 + \text{SNR}\right)C=B⋅log2(1+SNR)
  - BBB is the bandwidth of the channel in Hertz (Hz).
  - SNR\text{SNR}SNR is the Signal-to-Noise Ratio (linear scale, not dB).
  - CCC is the channel capacity in bps.
Log or Analyze Channel Capacity:
- Estimate the channel capacity for each link or node and log the results for analysis during the simulation,.

Example Implementation: Channel Capacity Calculation

The following is an example of how to calculate the channel capacity in OMNeT++ using the INET framework:

#include <omnetpp.h>

#include <cmath>

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

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

using namespace omnetpp;

using namespace inet;

using namespace inet::physicallayer;

class ChannelCapacityModule : public cSimpleModule {

private:

IRadio *radio; // Pointer to the radio module

IRadioMedium *radioMedium; // Pointer to the radio medium module

simsignal_t capacitySignal; // Signal to record channel capacity

protected:

virtual void initialize() override {

// Find the radio and radio medium modules

radio = check_and_cast<IRadio *>(getParentModule()->getSubmodule(“radio”));

radioMedium = check_and_cast<IRadioMedium *>(getModuleByPath(“radioMedium”));

// Register the channel capacity signal

capacitySignal = registerSignal(“capacitySignal”);

// Schedule the first channel capacity calculation

scheduleAt(simTime() + par(“calculationInterval”).doubleValue(), new cMessage(“calculateCapacity”));

}

virtual void handleMessage(cMessage *msg) override {

if (strcmp(msg->getName(), “calculateCapacity”) == 0) {

// Access the received signal power (in Watts)

W receivedPower = radio->getReceptionPower(radio->getLastTransmittedSignal());

// Get the noise power from the radio medium

W noisePower = radioMedium->getBackgroundNoise();

// Calculate the SNR (linear scale)

double snr = receivedPower.get() / noisePower.get();

// Get the channel bandwidth (in Hz)

double bandwidth = par(“bandwidth”).doubleValue();

// Calculate the channel capacity using the Shannon-Hartley theorem

double capacity = bandwidth * log2(1 + snr);

// Emit the channel capacity signal

emit(capacitySignal, capacity);

EV << “Channel Capacity: ” << capacity / 1e6 << ” Mbps\n”;

// Schedule the next capacity calculation

scheduleAt(simTime() + par(“calculationInterval”).doubleValue(), msg);

} else {

delete msg;

}

};

Define_Module(ChannelCapacityModule);

Explanation:

ChannelCapacityModule:
- radio: A pointer to the radio module that manages signal transmission and reception.
- radioMedium: A pointer to the radio medium module that handles the wireless channel and evaluates noise power.
- capacitySignal: Registers a signal to emit the measured channel capacity for logging or analysis.
initialize() Function:
- Sets the radio and radio medium modules and lists the first calculation of channel capacity.
handleMessage() Function:
- calculateCapacity: Recovers the received signal power and noise power, measures the SNR, and then calculates the channel capacity using the Shannon-Hartley theorem. The capacity is emitted as a signal and logged for analysis.
- The next calculation is listed to happen periodically.

Run the Simulation:

Compile and run the OMNeT++ project. The simulation will periodically determine and log the channel capacity for the wireless links.

Analyse and Interpret Results:

Higher capacities suggest better channel conditions and potential for higher data rates.
The channel capacity offers insights into the maximum achievable data rate for the wireless link under current conditions.

Additional Considerations:

Dynamic Conditions: Channel capacity can modify over time due to varying SNR caused by mobility, interference, and changing network load. Make sure that the simulation captures these dynamics.
Environmental Effects: Consider environmental effects like shadowing, fading and obstacles which can influence both the signal and noise levels, so affecting channel capacity.
Bandwidth Configuration: Make certain that the channel bandwidth is suitably set for the simulation scenario, as it directly impacts the determined capacity.

Over this paper, we had concluded that how to calculate Network Channel Capacity using Shannon-Hartley theorem in OMNeT++. We are providing added informations about Network channel capacity in other tools.

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