How to Calculate Network Error Rate in omnet++

To calculate the network error rate in OMNeT++ requires to include determining the rate at which errors happen during packet transmission. The error rate can state to the bit error rate (BER) or the packet error rate (PER), depending on what we need to compute. The error rate is normally communicated as the ratio of erroneous bits or packets to the total number of bits or packets transmitted.

Steps to Calculate Network Error Rate in OMNeT++:

1. Set Up the Network Model:
   • Use NED files in OMNeT++ define the network topology. It contains setting up nodes, links, and configuring any related parameters, like the data rate and the physical layer model, which can introduce errors during transmission.
2. Introduce Error Models:
   • To mimic the conditions under which errors might happen by using error models. OMNeT++ and its frameworks like INET provide modules to mimic several error conditions, like bit errors in the physical layer.
3. Track Sent and Erroneous Packets or Bits:
   • To estimate the error rate, we want to track the number of bits or packets transmitted and the number of erroneous bits or packets received.
4. Calculate Error Rate:
   • Bit Error Rate (BER): BER=Number of Erroneous BitsTotal Number of Bits Transmitted\text{BER} = \frac{\text{Number of Erroneous Bits}}{\text{Total Number of Bits Transmitted}}BER=Total Number of Bits TransmittedNumber of Erroneous Bits​
   • Packet Error Rate (PER): PER=Number of Erroneous PacketsTotal Number of Packets Transmitted\text{PER} = \frac{\text{Number of Erroneous Packets}}{\text{Total Number of Packets Transmitted}}PER=Total Number of Packets TransmittedNumber of Erroneous Packets​

Example Implementation: Packet Error Rate (PER)

Given below is an example to calculate the packet error rate (PER) in OMNeT++:

#include <omnetpp.h>

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

#include “inet/common/INETDefs.h”

using namespace omnetpp;

using namespace inet;

class ErrorRateModule : public cSimpleModule {

private:

int totalPacketsSent;       // Total number of packets sent

int erroneousPackets;       // Number of packets received with errors

simsignal_t perSignal;      // Signal to record packet error rate (PER)

protected:

virtual void initialize() override {

totalPacketsSent = 0;

erroneousPackets = 0;

perSignal = registerSignal(“perSignal”);

// Schedule the first packet transmission

scheduleAt(simTime() + par(“sendInterval”).doubleValue(), new cMessage(“sendPacket”));

}

virtual void handleMessage(cMessage *msg) override {

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

// Create and send a packet

Packet *packet = new Packet(“dataPacket”);

totalPacketsSent++;

send(packet, “out”);

// Schedule the next packet transmission

scheduleAt(simTime() + par(“sendInterval”).doubleValue(), new cMessage(“sendPacket”));

delete msg;

} else {

// Simulate receiving a packet

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

// Check for errors (this could be done using a specific error model)

bool hasError = par(“simulateError”).boolValue();  // Example: randomly decide if the packet has an error

if (hasError) {

erroneousPackets++;

EV << “Packet received with errors.\n”;

}

// Process the received packet

delete packet;

}

}

virtual void finish() override {

// Calculate and emit the Packet Error Rate (PER)

double per = (totalPacketsSent > 0) ? (double)erroneousPackets / totalPacketsSent : 0.0;

emit(perSignal, per);

EV << “Total Packets Sent: ” << totalPacketsSent << “\n”;

EV << “Erroneous Packets: ” << erroneousPackets << “\n”;

EV << “Packet Error Rate (PER): ” << per << “\n”;

}

};

Define_Module(ErrorRateModule);

Explanation:

• ErrorRateModule:
  • totalPacketsSent: Calculates the total number of packets sent by the module.
  • erroneousPackets: Counts the number of packets that were received with errors.
  • perSignal: A signal to emit the determined packet error rate (PER) at the end of the simulation.
• initialize() Function:
  • Initializes the counters and lists the first packet transmission.
• handleMessage() Function:
  • Manages both sending and receiving of packets. When sending, it increments the totalPacketsSent counter. When receiving, it checks for errors (simulated by a simple random decision in this example) and increments the erroneousPackets counter if an error is noticed.
• finish() Function:
  • Calculates the PER by dividing the number of erroneous packets by the total number of packets sent, and logs the result at the end of the simulation.

5. Run the Simulation:

• Compile and run the OMNeT++ project. The simulation will send and receive packets, compute the number of erroneous packets, and then verify the packet error rate (PER).

6. Analyse and Interpret Results:

• The calculated PER offers to calculate of how repeatedly packets are received with errors in the network. A higher PER shows a higher frequency of errors, which could be due to poor link quality, interference, or further factors affecting the transmission.

Additional Considerations:

• Bit Error Rate (BER): If we need to measure BER instead of PER, we can follow the number of bits transmitted and the number of erroneous bits detected.
• Error Models: Consider using more sophisticated error models available in OMNeT++ frameworks like INET, which can mimic realistic error conditions based on the physical layer characteristics of the network.
• Simulation Parameters: Modify parameters like signal-to-noise ratio (SNR), interference levels, or transmission power to watch their impact on the error rate.

Hence, we had demonstrate how to create the network model in NED file, calculate error rate, the way to calculate packet error rate in OMNeT++ tool. We will give more appropriate information about Network Error Rate using other tool.

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