How to Calculate QOS in omnet++

To Calculate the Quality of Service (QoS) in OMNeT++ has needs to assess the Key network performance metrics that includes latency (delay), jitter, packet loss, and throughput and these metrics help to measure the network’s capability to meet the service requirements of applications especially in scenarios where reliable and consistent performance is vital like in real-time communications, video streaming, or sensor networks.

We provide the complete procedure on how to calculate QoS metrics in OMNeT++:

Step-by-step Implementation:

1. Set Up the Network Model:

• Describe network topology in OMNeT++ using NED files and contains to generate nodes, links, and the essential modules like applications, routing protocols.
• For example, a simple network might concludes two nodes connected by a point-to-point link, or a more complex topology with multiple nodes and routing.

2. Implement Traffic Generation:

• Use or generate modules to create traffic. Applications such as UdpApp, TcpApp, or custom traffic generators can emulate the data flow.
• Configure the traffic to signifies the kinds of service that we want to measure (e.g., constant bit rate for video streaming or bursty traffic for file transfers).

3. Measure QoS Metrics:

• Latency (Delay): The time it takes for a packet to travel from the source to the destination.
  • We need to evaluate latency by recording the timestamp when a packet is sent and comparing it with the timestamp when the packet is received.
• Jitter: The variation in packet delay.
  • Jitter can be estimated as the difference in delay among consecutive packets.
• Packet Loss: The percentage of packets that are sent but not successfully received.
  • Track the number of packets sent and received, and calculate packet loss as (packets_sent – packets_received) / packets_sent * 100.
• Throughput: The rate at which data is successfully delivered over the network.
  • Throughput is estimated as the total amount of data received divided by the time it took to receive that data.

4. Implement QoS Calculation in OMNeT++:

• Adjust or generate a C++ class in OMNeT++ that extends cSimpleModule to manage the traffic generation and QoS metric calculations.
• Use OMNeT++’s event-driven simulation environment to track packet transmissions and calculate the essential metrics.

Example: Basic QoS Calculation in OMNeT++

The given below is the sample on how to setup a basic QoS measurement for a point-to-point network in OMNeT++:

#include <omnetpp.h>

using namespace omnetpp;

class QoSModule : public cSimpleModule {

private:

int packetsSent;

int packetsReceived;

simtime_t totalDelay;

simtime_t lastArrivalTime;

double totalJitter;

protected:

virtual void initialize() override {

packetsSent = 0;

packetsReceived = 0;

totalDelay = SIMTIME_ZERO;

lastArrivalTime = SIMTIME_ZERO;

totalJitter = 0.0;

// Schedule first packet send

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

}

virtual void handleMessage(cMessage *msg) override {

if (msg->isSelfMessage()) {

// Simulate sending a packet

packetsSent++;

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

send(packet, “out”);

delete msg;

// Schedule next packet send

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

} else {

// Packet received

packetsReceived++;

// Calculate delay

simtime_t delay = simTime() – msg->getCreationTime();

totalDelay += delay;

// Calculate jitter

if (lastArrivalTime != SIMTIME_ZERO) {

simtime_t interArrivalTime = simTime() – lastArrivalTime;

totalJitter += fabs(interArrivalTime.dbl() – delay.dbl());

}

lastArrivalTime = simTime();

delete msg;

}

}

virtual void finish() override {

// Calculate and print QoS metrics

double averageDelay = totalDelay.dbl() / packetsReceived;

double averageJitter = totalJitter / (packetsReceived – 1);

double packetLoss = ((double)(packetsSent – packetsReceived) / packetsSent) * 100;

double throughput = (packetsReceived * par(“packetSize”).doubleValue() * 8) / simTime().dbl() / 1e6; // Mbps

EV << “Average Delay: ” << averageDelay << ” s\n”;

EV << “Average Jitter: ” << averageJitter << ” s\n”;

EV << “Packet Loss: ” << packetLoss << ” %\n”;

EV << “Throughput: ” << throughput << ” Mbps\n”;

}

};

Define_Module(QoSModule);

Explanation:

• initialize() Function:
  • Initializes the variables to monitor the number of packets sent, received, total delay, and jitter.
  • Schedules the first packet transmission.
• handleMessage() Function:
  • Manages both self-messages (indicating a new packet should be sent) and incoming packets.
  • When a packet is received, it estimates the delay and jitter.
• finish() Function:
  • At the end of the simulation, this function calculates and logs the average delay, average jitter, packet loss, and throughput.

5. Run the Simulation:

• After implementing the QoS measurement, compile OMNeT++ project and execute the simulation.
• Measure the outcomes by examining the logged QoS metrics.

6. Analyse and Interpret Results:

• Use the calculated QoS metrics to measure the performance of network.
• If needed, modify the network configuration or parameters to enhance the QoS.

From the module, we understood how to calculate and mimic the scenario for quality of service in OMNeT++ tool that were calculate in real time interaction. If you have any doubts regarding the quality of service we will provide that in further works.

At omnet-manual.com, our developers are here to help you understand the network performance of your project. Share your parameter details with us, and we’ll assist you in calculating Quality of Service (QoS) in OMNeT++. Our team specializes in real-time communications, video streaming, and sensor networks tailored to your project needs.