How to Calculate Network Download rate in omnet++

To calculate the download rate in OMNeT++ has includes evaluating the amount of information successfully received over a network connection during a particular time period. The download rate is characteristically uttered in bits per second (bps) or bytes per second (Bps). To calculate this metric, we need to monitor the amount of data received by a node and the time interval over which this data is received. The below are the step-by-procedures to implement the network download rate in OMNeT++:

Steps to Calculate Download Rate in OMNeT++

1. Define Download Rate:
   • Download Rate is the rate at which data is received by a node. It can be calculated as: Download Rate=Total Data ReceivedTotal Time\text{Download Rate} = \frac{\text{Total Data Received}}{\text{Total Time}}Download Rate=Total TimeTotal Data Received​
   • The rate is often expressed in bits per second (bps) or bytes per second (Bps).
2. Track Data Reception:
   • During the simulation, we need to track the total amount of data received by the node over the simulation period or a particular time interval.

long totalBytesReceived = 0;  // To track total data received

simtime_t startTime;

1. Record the Start Time:
   • Capture the start time of the download that could be when the first packet is received or when the download process starts.

startTime = simTime();

1. Update the Total Data Received:
   • Each time a packet is received, update the totalBytesReceived counter by adding the size of the packet.

void onPacketReceived(cPacket *pkt) {

totalBytesReceived += pkt->getByteLength();  // Add the size of the received packet to the total

}

1. Calculate and Record the Download Rate:
   • At the end of the simulation or after a particular event, estimate the download rate by dividing the total data received by the elapsed time.

simtime_t endTime = simTime();

simtime_t totalTime = endTime – startTime;

double downloadRate = (totalBytesReceived * 8) / totalTime.dbl();  // Download rate in bps

1. • we can also compute the download rate in bytes per second (Bps) if preferred:

double downloadRateBps = totalBytesReceived / totalTime.dbl();  // Download rate in Bps

1. Record and Analyse the Download Rate:
   • Use the recordScalar function to record the download rate for analysis.

recordScalar(“Download Rate (bps)”, downloadRate);

EV << “Download Rate: ” << downloadRate << ” bps” << endl;

Example Implementation in OMNeT++

The below is the instance of how to implement the download rate calculation in an OMNeT++ module:

class DownloadNode : public cSimpleModule {

private:

long totalBytesReceived;

simtime_t startTime;

simtime_t endTime;

double downloadRate;

protected:

virtual void initialize() override {

totalBytesReceived = 0;

startTime = simTime();  // Start tracking from the beginning of the simulation

}

virtual void handleMessage(cMessage *msg) override {

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

// Update the total data received

onPacketReceived(pkt);

// Handle the packet (process, store, etc.)

// …

delete pkt;  // Clean up the packet

}

void onPacketReceived(cPacket *pkt) {

totalBytesReceived += pkt->getByteLength();

}

virtual void finish() override {

endTime = simTime();

simtime_t totalTime = endTime – startTime;

downloadRate = (totalBytesReceived * 8) / totalTime.dbl();  // Download rate in bps

recordScalar(“Download Rate (bps)”, downloadRate);

EV << “Download Rate: ” << downloadRate << ” bps” << endl;

}

};

Explanation:

1. Tracking Total Data Received:
   • The totalBytesReceived variable keeps track of the cumulative size of all packets received by the node.
2. Calculating Download Rate:
   • At the end of the simulation (in the finish() method), the download rate is estimated by dividing the total data received by the total time elapsed since the start of the simulation.
3. Recording the Download Rate:
   • The recordScalar function is used to log the download rate that can be evaluated after the simulation ends.

In the above simulation, we had gained the knowledge on how to calculate and analyse the network download rate in the particular time period uisng OMNeT++ tool. We will intend to offer how the network download rate will simulate in other scenarios.

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