How to Calculate Network Goodput in omnet++

To calculate the network goodput in OMNeT++ has needs to evaluate the amount of useful data successfully provided over the network that usually excluding the protocol overhead, retransmissions, and any corrupted or duplicated packets and the Goodput is an significant parameter for measuring the effectiveness of a network that reflects the actual application-level data rate that a user can achieve. The below are the implementation procedures for goodput in OMNeT++:

Step-by-Step Implementation:

1. Define Goodput:

• Goodput is the amount of useful data received by the destination per unit of time. It’s usually measured in bits per second (bps) or bytes per second (Bps).

Goodput=Total Useful Data ReceivedTotal Time\text{Goodput} = \frac{\text{Total Useful Data Received}}{\text{Total Time}}Goodput=Total TimeTotal Useful Data Received​

2. Identify Useful Data:

• Useful Data contains only the payload of successfully delivered packets that reach the application layer at the receiver.
• Exclude protocol headers, retransmissions, and any erroneous or duplicate information from the total data transferred.

3. Modify or Implement a Simple Network Model in OMNeT++:

• Use OMNeT++ to generate or adjust an existing network model that contains the sources and destinations of data packets.

4. Track the Useful Data Received:

• In receiver application, track the total amount of useful data received. This is usually contains to summing up the payload sizes of successfully received packets.

long totalUsefulDataReceived = 0; // Variable to store total useful data

// Inside your packet receive handling function

void receivePacket(cPacket *pkt) {

// Check if the packet is not corrupted and is useful

if (pkt->hasBitError() == false) {

// Accumulate the payload size to totalUsefulDataReceived

totalUsefulDataReceived += pkt->getByteLength(); // or getBitLength() if using bits

}

}

5. Measure the Total Simulation Time:

• The total time over which the goodput is measured can be either the whole simulation duration or a particular time window of interest.

simtime_t startTime = simTime(); // Start time of measurement

simtime_t endTime = simTime();   // End time (update this at the end of the simulation)

simtime_t totalTime = endTime – startTime;

6. Calculate Goodput:

• At the end of the simulation, estimate the goodput using the total useful data received and the total time.

double goodput = (totalUsefulDataReceived * 8) / totalTime.dbl(); // Goodput in bits per second (bps)

• If we want the goodput in bytes per second, skip the multiplication by 8.

double goodput = totalUsefulDataReceived / totalTime.dbl(); // Goodput in bytes per second (Bps)

7. Recording and Displaying Goodput:

• Record the cimputed goodput for analysis. We need to use the recordScalar function in OMNeT++ to record this value in the results file.

recordScalar(“Network Goodput (bps)”, goodput);

• we also display the goodput in the simulation output.

EV << “Network Goodput: ” << goodput << ” bps” << endl;

8. Analyse the Results:

• After the simulation, we need to evaulate the recorded goodput in OMNeT++’s outcome analysis tools or using external tools such as Python or MATLAB.

Example Implementation in OMNeT++:

// Example pseudo-code for a receiver application in OMNeT++

class ReceiverApp : public cSimpleModule {

private:

long totalUsefulDataReceived;

simtime_t startTime;

protected:

virtual void initialize() override {

totalUsefulDataReceived = 0;

startTime = simTime();

}

virtual void handleMessage(cMessage *msg) override {

cPacket *pkt = check_and_cast<cPacket*>(msg);

// Accumulate useful data if the packet is not corrupted

if (!pkt->hasBitError()) {

totalUsefulDataReceived += pkt->getByteLength(); // or getBitLength()

}

delete pkt;

}

virtual void finish() override {

simtime_t totalTime = simTime() – startTime;

double goodput = (totalUsefulDataReceived * 8) / totalTime.dbl(); // Goodput in bps

recordScalar(“Network Goodput (bps)”, goodput);

EV << “Network Goodput: ” << goodput << ” bps” << endl;

}

};

In this demonstration we learned to calculate the goodput in the network using the OMNeT++ tool that needs to apply the basic network model then track the data after that simulate and calculate the goodput. If you need more details about how the goodput will perform in other simulation tool, we will provide it.

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