How to Calculate Network Communication Links Quality in omnet++

To calculate the quality of network communication links in OMNeT++ has needs to measure the numerous performance metrics that determines how well the information is transferred among the nodes over network link. Basically the communication link quality is measured using numerous factors like packet loss, latency, jitter, throughput, and error rates. These parameters offer the valuable insights into the reliability, efficiency, and performance of the communication link.

Key Metrics to Evaluate Communication Link Quality

1. Packet Loss Rate:
   • The percentage of packets that is lost during transmission across the link.
   • Formula: Packet Loss Rate=Number of Lost PacketsTotal Number of Sent Packets×100\text{Packet Loss Rate} = \frac{\text{Number of Lost Packets}}{\text{Total Number of Sent Packets}} \times 100Packet Loss Rate=Total Number of Sent PacketsNumber of Lost Packets​×100
2. Latency (Delay):
   • The time it takes for a packet to travel from the source to the destination across the link.
   • Formula: Latency=Receive Time−Send Time\text{Latency} = \text{Receive Time} – \text{Send Time}Latency=Receive Time−Send Time
3. Jitter:
   • The variation in packet arrival times. High jitter can signifies instability in the link.
   • Formula: Jitter=∣Latency of Packetn−Latency of Packetn−1∣\text{Jitter} = | \text{Latency of Packet}_{n} – \text{Latency of Packet}_{n-1} |Jitter=∣Latency of Packetn​−Latency of Packetn−1​∣
4. Throughput:
   • The rate at which data is successfully transferred over the link.
   • Formula: Throughput=Total Data Received (in bits)Total Time (in seconds)\text{Throughput} = \frac{\text{Total Data Received (in bits)}}{\text{Total Time (in seconds)}}Throughput=Total Time (in seconds)Total Data Received (in bits)​
5. Bit Error Rate (BER):
   • The rate at which errors occur in the transmitted data.
   • Formula: BER=Number of Bit ErrorsTotal Number of Bits Transmitted\text{BER} = \frac{\text{Number of Bit Errors}}{\text{Total Number of Bits Transmitted}}BER=Total Number of Bits TransmittedNumber of Bit Errors​

Steps to Calculate Communication Link Quality in OMNeT++

1. Tracking and Calculating Metrics:
   • Execute functions to observe and estimate each of these parameters as packets are transmitted and received across the link.
2. Packet Loss Calculation:

int packetsSent = 0;

int packetsReceived = 0;

void onPacketSent() {

packetsSent++;

}

void onPacketReceived(cPacket *pkt) {

packetsReceived++;

}

double calculatePacketLossRate() {

return (packetsSent – packetsReceived) / (double)packetsSent * 100;

}

1. Latency and Jitter Calculation:

simtime_t lastLatency = 0;

simtime_t currentLatency;

simtime_t jitter = 0;

void onPacketReceived(cPacket *pkt) {

simtime_t sendTime = pkt->getCreationTime();

simtime_t receiveTime = simTime();

currentLatency = receiveTime – sendTime;

// Jitter calculation

if (lastLatency != 0) {

jitter = fabs(currentLatency – lastLatency);

}

lastLatency = currentLatency;

}

1. Throughput Calculation:

long totalBytesReceived = 0;

simtime_t startTime = simTime();

void onPacketReceived(cPacket *pkt) {

totalBytesReceived += pkt->getByteLength();  // Track the amount of data received

}

double calculateThroughput() {

simtime_t endTime = simTime();

simtime_t totalTime = endTime – startTime;

return (totalBytesReceived * 8) / totalTime.dbl();  // Throughput in bits per second (bps)

}

1. Bit Error Rate (BER) Calculation:

int totalBitsTransmitted = 0;

int bitErrors = 0;

void onPacketReceived(cPacket *pkt) {

// Assume we have a function to calculate the number of bit errors in the packet

bitErrors += calculateBitErrors(pkt);

totalBitsTransmitted += pkt->getBitLength();

}

double calculateBER() {

return (double)bitErrors / totalBitsTransmitted;

}

Example Implementation in OMNeT++

The below is the incorporated sample of how to execute the calculation of network communication link quality in an OMNeT++ module:

class LinkQualityMonitor : public cSimpleModule {

private:

int packetsSent;

int packetsReceived;

simtime_t lastLatency;

simtime_t currentLatency;

simtime_t jitter;

long totalBytesReceived;

int totalBitsTransmitted;

int bitErrors;

simtime_t startTime;

protected:

virtual void initialize() override {

packetsSent = 0;

packetsReceived = 0;

lastLatency = 0;

jitter = 0;

totalBytesReceived = 0;

totalBitsTransmitted = 0;

bitErrors = 0;

startTime = simTime();

}

virtual void handleMessage(cMessage *msg) override {

if (msg->isSelfMessage()) {

// Self-message handling logic (e.g., periodic reporting)

} else {

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

// Update metrics on packet receipt

onPacketReceived(pkt);

delete pkt;  // Clean up the packet

}

}

void onPacketSent() {

packetsSent++;

}

void onPacketReceived(cPacket *pkt) {

packetsReceived++;

totalBytesReceived += pkt->getByteLength();

simtime_t sendTime = pkt->getCreationTime();

simtime_t receiveTime = simTime();

currentLatency = receiveTime – sendTime;

// Calculate jitter

if (lastLatency != 0) {

jitter = fabs(currentLatency – lastLatency);

}

lastLatency = currentLatency;

// Assume bit errors are calculated by some external function

bitErrors += calculateBitErrors(pkt);

totalBitsTransmitted += pkt->getBitLength();

}

double calculatePacketLossRate() {

return (packetsSent – packetsReceived) / (double)packetsSent * 100;

}

double calculateThroughput() {

simtime_t endTime = simTime();

simtime_t totalTime = endTime – startTime;

return (totalBytesReceived * 8) / totalTime.dbl();  // Throughput in bits per second (bps)

}

double calculateBER() {

return (double)bitErrors / totalBitsTransmitted;

}

virtual void finish() override {

double packetLossRate = calculatePacketLossRate();

double throughput = calculateThroughput();

double ber = calculateBER();

recordScalar(“Packet Loss Rate (%)”, packetLossRate);

recordScalar(“Throughput (bps)”, throughput);

recordScalar(“Jitter (s)”, jitter.dbl());

recordScalar(“Bit Error Rate”, ber);

EV << “Packet Loss Rate: ” << packetLossRate << ” %” << endl;

EV << “Throughput: ” << throughput << ” bps” << endl;

EV << “Jitter: ” << jitter << ” s” << endl;

EV << “Bit Error Rate: ” << ber << endl;

}

};

Explanation:

1. Tracking and Updating Metrics:
   • The module tracks packets sent and received, estimates the latency and jitter, collects information for throughput, and tracks bit errors.
2. Calculating Quality Metrics:
   • At the end of the simulation, the module estimates the key quality parameters like packet loss rate, throughput, jitter, and BER.
3. Recording and Analysis:
   • These parameters are recorded using recordScalar, that permits for post-simulation analysis of the communication link quality.

In this page, we show the brief structure on how to calculate and analyse the quality of network communication links. Further exact details were provided about the quality of network communication links.

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