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How to Implement Network AP Selection in OMNeT++

To implement the network Access Point (AP) selection in OMNeT++, we have to include generating a scenario where a mobile device can select among several available Access Points based on particular criteria like signal strength, load, or user preference. This process is vital in wireless networks where clients essential to join to the best available AP to optimize network performance and user experience. For additional simulation results, please reach out to omnet-manual.com experts.

The following is a procedure with examples to implement AP selection in OMNeT++ using the INET framework.

Step-by-Step Implementations:

  1. Set Up OMNeT++ and INET Framework:
  • Install OMNeT++: Make sure that OMNeT++ is installed and configured on the system.
  • Install INET Framework: Download and install the INET framework, which delivers models for wireless networking components like WiFi APs.
  1. Define the Network Topology:

Make a network topology with numerous Access Points (APs) and a mobile device that can connect to one of them.

Example NED File (APSelectionNetwork.ned):

package mynetwork;

import inet.node.inet.AccessPoint;

import inet.node.inet.StandardHost;

network APSelectionNetwork

{

submodules:

ap1: AccessPoint {

@display(“p=100,100”);

}

ap2: AccessPoint {

@display(“p=300,100”);

}

ap3: AccessPoint {

@display(“p=200,300”);

}

mobileDevice: StandardHost {

@display(“p=200,200”);

wlan[0].typename = “IdealWirelessNic”; // WiFi NIC

}

connections allowunconnected:

mobileDevice.wlan[0] <–> wlan[0] <–> ap1.wlan[0];

mobileDevice.wlan[0] <–> wlan[0] <–> ap2.wlan[0];

mobileDevice.wlan[0] <–> wlan[0] <–> ap3.wlan[0];

}

This instance states a network with three APs such as ap1, ap2, and ap3 and a mobile device that can connect to any of them.

  1. Implement AP Selection Logic:

The mobile device wants to calculate the available APs and choose the best one based on a particular criterion, like signal strength, load, or even a combination of factors.

Example: AP Selection Based on Signal Strength

void APSelection::handleMessage(cMessage *msg) {

double maxSignalStrength = -DBL_MAX;

int bestApIndex = -1;

for (int i = 0; i < numAps; i++) {

double signalStrength = getSignalStrength(aps[i]);

if (signalStrength > maxSignalStrength) {

maxSignalStrength = signalStrength;

bestApIndex = i;

}

}

if (bestApIndex != -1) {

connectToAp(aps[bestApIndex]);

}

scheduleAt(simTime() + 1, msg);  // Re-evaluate every second

}

double APSelection::getSignalStrength(cModule *ap) {

// Example function to calculate signal strength (simplified)

return ap->par(“txPower”).doubleValue() – distance(mobileDevice, ap);

}

void APSelection::connectToAp(cModule *ap) {

// Logic to connect to the selected AP

EV << “Connecting to AP: ” << ap->getName() << “\n”;

// Example connection process…

}

In this example:

  • The mobile device scans available APs and calculates the signal strength.
  • It then chooses the AP with the strongest signal and associates to it.
  1. Simulate AP Selection Process:

Use the omnetpp.ini configuration file to mimic the AP selection process and to set parameters like transmission power, AP load, and more.

Example Configuration (omnetpp.ini):

[General]

network = APSelectionNetwork

**.ap1.wlan[0].radio.transmitter.power = 20mW

**.ap2.wlan[0].radio.transmitter.power = 15mW

**.ap3.wlan[0].radio.transmitter.power = 25mW

**.ap1.load = 0.5

**.ap2.load = 0.7

**.ap3.load = 0.3

**.mobileDevice.wlan[0].scanInterval = 1s  # Re-scan APs every second

This configuration sets various transmission powers and loads for the APs, mimicking a real-world situation where the mobile device wants to choose the best AP.

  1. Record and Analyse the AP Selection Process:

Record metrics like signal strength, connection quality, and the number of transfers to estimate the efficiency of the AP selection strategy.

Example Configuration for Recording Metrics:

[General]

network = APSelectionNetwork

**.mobileDevice.wlan[0].mac.selectedAp.recordScalar = true

**.mobileDevice.wlan[0].mac.signalStrength.recordScalar = true

**.mobileDevice.wlan[0].mac.handoverCount.recordScalar = true

After running the simulation, we can examine which AP the mobile device chosen, how frequently it switched APs (handovers), and the signal strength it experienced.

  1. Advanced AP Selection Strategies:

Execute more advanced AP selection strategies that consider several factors like:

  • Load Balancing: Select APs with lower load even if their signal strength is slightly weaker.
  • QoS Requirements: Indicate APs based on the QoS requirements of the application like VoIP may prefer lower latency APs.
  • Energy Efficiency: Consider the energy consumption of the mobile device when connected to various APs.

Example: Load-Aware AP Selection

void APSelection::handleMessage(cMessage *msg) {

double bestScore = -DBL_MAX;

int bestApIndex = -1;

for (int i = 0; i < numAps; i++) {

double signalStrength = getSignalStrength(aps[i]);

double load = getApLoad(aps[i]);

double score = signalStrength / (1 + load);  // Example scoring formula

if (score > bestScore) {

bestScore = score;

bestApIndex = i;

}

}

if (bestApIndex != -1) {

connectToAp(aps[bestApIndex]);

}

scheduleAt(simTime() + 1, msg);  // Re-evaluate every second

}

double APSelection::getApLoad(cModule *ap) {

// Example function to get the current load on an AP

return ap->par(“load”).doubleValue();

}

This instance considers both signal strength and AP load to choose the best AP, which could develop the overall network performance by avoiding overloading a single AP.

  1. Run and Analyse the Simulation:
  • Run the simulation: Watch how the mobile device chooses and switches among APs.
  • Analyse results: Use recorded metrics to assess the performance of the AP selection strategy. Examine at connection quality, overall network load distribution, and the frequency of handovers.
  1. Document and Report Findings:

After completing the simulations, document the situations verified, the results gained, and any optimizations made. It will support in understanding the efficiency of various AP selection strategies in numerous network conditions.

We had collected the informations to help you by providing the step-by-step procedures on how to set up and execute the network AP Selection using the INET framework in OMNeT++. If needed, we will present any more details of this topic in other tools.

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