How to Calculate Network Aggregate utility in omnet++

To calculate the network aggregate utility in OMNeT++, according to their utility function which naturally depends on parameters like throughput, delay, fairness, or energy consumption, we have to assess the overall performance or satisfaction level of the network. We use the accumulate utility also known as common metric in the network enhancement and resource allocation studies, their intent is to increase the collective benefit or efficiency of the network. There are some steps to be followed to calculate this:

Steps to Calculate Network Aggregate Utility in OMNeT++:

1. Define the Utility Function:
   • The utility function U(x)U(x)U(x) should be determined based on the network parameters you want to optimize. Usual utility functions contains:
     • Throughput Utility: U(x)=log⁡(x)U(x) = \log(x)U(x)=log(x), where xxx is the throughput.
     • Delay Utility: U(x)=−α×delayU(x) = -\alpha \times \text{delay}U(x)=−α×delay, where α\alphaα is a scaling factor.
     • Fairness Utility: Functions like the proportional fairness utility, U(x)=log⁡(x)U(x) = \log(x)U(x)=log(x), are often used.
   • Based on the performance criteria, we have to select the utility function which is most important for the network.
2. Set Up the Network Model:
   • In OMNeT++, with the help of NED files, we can state the network topology. Simulating the network conditions by setting up the nodes, links and traffic generators.
3. Measure Network Performance Metrics:
   • In the network, estimate the significant performance metrics (e.g., throughput, delay) for each flow or connection. These metrics will be the inputs to the utility function.
4. Calculate the Utility for Each Connection:
   • For each connection or flow in the network, Measure the performance metric to compute the utility of that flow by applying the utility function.
5. Sum the Utilities to Obtain the Aggregate Utility:
   • The aggregate utility of the network is the sum of the individual utilities of all flows or connections: Aggregate Utility=∑i=1NU(xi)\text{Aggregate Utility} = \sum_{i=1}^{N} U(x_i)Aggregate Utility=i=1∑N​U(xi​)
   • Here, NNN is the number of flows or connections in the network.

Example Implementation: Aggregate Utility Calculation

Below is an example of how to calculate the network aggregate utility in OMNeT++:

#include <omnetpp.h>

#include <cmath>

using namespace omnetpp;

class AggregateUtilityModule : public cSimpleModule {

private:

std::vector<double> throughputValues;  // Vector to store throughput for each flow

simsignal_t aggregateUtilitySignal;    // Signal to record the aggregate utility

protected:

virtual void initialize() override {

aggregateUtilitySignal = registerSignal(“aggregateUtilitySignal”);

// Example throughput values; in practice, these would be measured dynamically

throughputValues = {10e6, 20e6, 30e6};  // Example throughput values in bits per second

// Schedule the calculation of the aggregate utility

scheduleAt(simTime() + par(“calculationInterval”).doubleValue(), new cMessage(“calculateUtility”));

}

virtual void handleMessage(cMessage *msg) override {

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

double aggregateUtility = 0;

for (double throughput : throughputValues) {

// Apply the utility function (e.g., log utility)

double utility = log(throughput);

aggregateUtility += utility;

}

// Emit the aggregate utility signal

emit(aggregateUtilitySignal, aggregateUtility);

EV << “Aggregate Utility: ” << aggregateUtility << “\n”;

// Schedule the next calculation

scheduleAt(simTime() + par(“calculationInterval”).doubleValue(), msg);

} else {

delete msg;

}

}

};

Define_Module(AggregateUtilityModule);

Explanation:

• AggregateUtilityModule:
  • throughputValues: A vector to store the throughput values for each flow or connection in the network. It is usually calculated dynamically in the course of simulation.
  • aggregateUtilitySignal: Registers a signal to emit the computed aggregate utility.
• initialize() Function:
  • Initializes the module and schedules the first calculation of the aggregate utility.
• handleMessage() Function:
  • calculateUtility: Use utility function (e.g., logarithmic utility) to compute the utility for each flow based on the throughput and sums these to get the aggregate utility.
  • The result is emitted as a signal and logged for analysis.

5. Run the Simulation:

• Compile and run the OMNeT++ project. The simulation will sporadically calculate and log the network’s aggregate utility.

6. Analyze and Interpret Results:

• The aggregate utility offers a measure of the overall performance or satisfaction level of the network. Higher aggregate utility values point to better network performance based on chosen utility function.

Additional Considerations:

• Dynamic Metrics: During the simulation, the performance metrics (e.g., throughput, delay) can differ dynamically. Make sure that the utility computation imitates these changes.
• Utility Function Selection: The choice of utility function should align with the network’s objectives. For instance, a logarithmic utility function promotes fairness, while a linear utility function might prioritize maximizing throughput.
• Weighted Utility: If some flows or connections are more vital than others, consider using a weighted utility function where each utility is multiplied by a weight factor.

Finally, this procedure will walk you through the overall details of Network aggregate utility and how to calculate it in the OMNeT++ with the help of the example provided above. We will offer more simulation and implementation  regarding this network aggregation or when to use the utility functions as per the requirements.