How to Implement Vertical Handover in OMNeT++

Implementing vertical handover in OMNeT++ involves several steps, including setting up the simulation environment, defining network and node models, implementing handover algorithms, and running the simulation. Vertical handover refers to the process of switching between different types of networks (e.g., from WiFi to LTE).

Step-by-Step Implementation:

Step 1: Install OMNeT++ and INET Framework

1. Download OMNeT++:
   • Download the OMNeT++ latest version.
2. Install OMNeT++:

• Based on the operating system install the OMNet++.

1. Download and Install INET Framework:
   • The INET framework delivers models for internet protocols and is frequently used with OMNeT++.

Step 2: Set Up Your Project

1. Create a New OMNeT++ Project:
   • Open the OMNeT++ IDE.
   • Go to File -> New -> OMNeT++ Project.
   • Enter a project name and select the appropriate options.
2. Set Up Directory Structure:
   • Make sure the projects have the essential folders like src for source files and simulations for NED files and configuration.

Step 3: Define Network Models Using NED

1. Create NED Files:
   • In the src directory, we need to generate a novel NED file (e.g., VerticalHandoverNetwork.ned).
   • Describe the network topology in the NED file. Here’s a simple example:

package handover;

import inet.node.inet.StandardHost;

import inet.node.wireless.AccessPoint;

import inet.node.cellular.cellular.NetworkNode;

import inet.networklayer.configurator.ipv4.Ipv4NetworkConfigurator;

import inet.mobility.static.StaticMobility;

import inet.mobility.single.RandomWaypointMobility;

import inet.linklayer.ethernet.EthernetInterface;

import inet.physicallayer.ieee80211.packetlevel.Ieee80211ScalarRadioMedium;

network VerticalHandoverNetwork

{

parameters:

int numHosts = default(5);

types:

channel radioChannel extends Ieee80211ScalarRadioMedium {}

submodules:

configurator: Ipv4NetworkConfigurator {

@display(“p=100,100”);

}

wifiAp: AccessPoint {

@display(“p=300,200”);

}

lteNode: NetworkNode {

@display(“p=500,200”);

}

host[numHosts]: StandardHost {

@display(“p=200+100*i,400”);

}

radioMedium: radioChannel {

@display(“p=400,100”);

}

connections:

for i=0..numHosts-1 {

host[i].ethg++ <–> radioMedium <–> wifiAp.wlan++;

host[i].ethg++ <–> radioMedium <–> lteNode.cellular++;

}

}

Step 4: Implement Handover Logic in C++

1. Create C++ Modules:
   • In the src directory, we need to generate C++ class (e.g., HandoverHost.cc).
   • Include necessary OMNeT++ headers and define your module:

#include <omnetpp.h>

#include “inet/common/ModuleAccess.h”

#include “inet/networklayer/contract/ipv4/Ipv4Address.h”

#include “inet/applications/udpapp/UdpBasicApp.h”

#include “inet/linklayer/common/MacAddress.h”

using namespace omnetpp;

using namespace inet;

class HandoverHost : public cSimpleModule

{

protected:

virtual void initialize() override;

virtual void handleMessage(cMessage *msg) override;

void performHandover();

void connectToWiFi();

void connectToLTE();

};

Define_Module(HandoverHost);

void HandoverHost::initialize()

{

// Initialization code

// Schedule handover check

scheduleAt(simTime() + par(“handoverCheckInterval”), new cMessage(“checkHandover”));

}

void HandoverHost::handleMessage(cMessage *msg)

{

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

performHandover();

scheduleAt(simTime() + par(“handoverCheckInterval”), msg);

}

}

void HandoverHost::performHandover()

{

// Perform handover decision based on criteria (e.g., signal strength, QoS)

// Example logic: If WiFi signal is weak, switch to LTE

double wifiSignalStrength = uniform(0, 1); // Placeholder for actual signal strength check

if (wifiSignalStrength < 0.5) {

connectToLTE();

} else {

connectToWiFi();

}

}

void HandoverHost::connectToWiFi()

{

// Code to connect to WiFi

EV << “Connecting to WiFi” << endl;

// Placeholder for actual WiFi connection logic

}

void HandoverHost::connectToLTE()

{

// Code to connect to LTE

EV << “Connecting to LTE” << endl;

// Placeholder for actual LTE connection logic

}

1. Modify NED to Use C++ Modules:
   • Update NED file to use custom handover host module:

network VerticalHandoverNetwork

{

parameters:

int numHosts = default(5);

types:

channel radioChannel extends Ieee80211ScalarRadioMedium {}

submodules:

configurator: Ipv4NetworkConfigurator {

@display(“p=100,100”);

}

wifiAp: AccessPoint {

@display(“p=300,200”);

}

lteNode: NetworkNode {

@display(“p=500,200”);

}

host[numHosts]: HandoverHost {

@display(“p=200+100*i,400”);

}

radioMedium: radioChannel {

@display(“p=400,100”);

}

connections:

for i=0..numHosts-1 {

host[i].ethg++ <–> radioMedium <–> wifiAp.wlan++;

host[i].ethg++ <–> radioMedium <–> lteNode.cellular++;

}

}

Step 5: Configure Simulation Parameters

1. Create omnetpp.ini:
   • In the simulations directory, create an omnetpp.ini file.
   • Define simulation parameters, such as the duration and network parameters:

network = VerticalHandoverNetwork

sim-time-limit = 10s

**.handoverCheckInterval = 1s

Step 6: Build and Run the Simulation

1. Build the Project:
   • In the OMNeT++ IDE, right-click on project and select Build Project.
2. Run the Simulation:
   • Go to Run -> Run Configurations.
   • Set up a new run configuration for your project and run the simulation.

Step 7: Analyse Results

1. View Simulation Results:
   • After the simulation completes, use OMNeT++’s tools to evaluate the results.
   • Open the ANF (Analysis Framework) to visualize and interpret the data.

This script demonstrate how to simulate the complete projects in OMNet++ for vertical handover that has generates the topology then apply the handover logic to deploy in the application to analyse the results. We also describe how the vertical handover is carried out with simulation  and performance analysis support.