How to Implement Network AP Selection in ns3

To implement network Access Point (AP) selection in ns3, we need to create a network topology with multiple APs and implement a mechanism for stations (STAs) to select the best AP on the basis of certain criteria, that includes signal strength or load.

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Here is the complete guide to implement AP selection in ns3.

Steps for implementation

Step 1: Set up the simulation

Make sure that ns3 is installed in the computer. If not, install it.

Step 2: Create the network topology

Define the network topology with multiple APs and STAs.

Step 3: Write the script

Here is an example script to create and configure a network topology with AP selection using ns3.

#include “ns3/core-module.h”

#include “ns3/network-module.h”

#include “ns3/internet-module.h”

#include “ns3/wifi-module.h”

#include “ns3/mobility-module.h”

#include “ns3/applications-module.h”

#include “ns3/flow-monitor-helper.h”

using namespace ns3;

NS_LOG_COMPONENT_DEFINE (“APSelectionExample”);

int main (int argc, char *argv[])

{

bool verbose = true;

uint32_t nWifi = 2;

uint32_t nAp = 2;

CommandLine cmd;

cmd.AddValue (“nWifi”, “Number of wifi STA devices”, nWifi);

cmd.AddValue (“nAp”, “Number of wifi AP devices”, nAp);

cmd.AddValue (“verbose”, “Tell echo applications to log if true”, verbose);

cmd.Parse (argc, argv);

if (verbose)

{

LogComponentEnable (“UdpEchoClientApplication”, LOG_LEVEL_INFO);

LogComponentEnable (“UdpEchoServerApplication”, LOG_LEVEL_INFO);

}

NodeContainer wifiStaNodes;

wifiStaNodes.Create (nWifi);

NodeContainer wifiApNodes;

wifiApNodes.Create (nAp);

YansWifiChannelHelper channel = YansWifiChannelHelper::Default ();

YansWifiPhyHelper phy = YansWifiPhyHelper::Default ();

phy.SetChannel (channel.Create ());

WifiHelper wifi;

wifi.SetRemoteStationManager (“ns3::AarfWifiManager”);

WifiMacHelper mac;

Ssid ssid1 = Ssid (“ns-3-ssid-1”);

Ssid ssid2 = Ssid (“ns-3-ssid-2”);

mac.SetType (“ns3::ApWifiMac”,

“Ssid”, SsidValue (ssid1));

NetDeviceContainer apDevices1 = wifi.Install (phy, mac, wifiApNodes.Get (0));

mac.SetType (“ns3::ApWifiMac”,

“Ssid”, SsidValue (ssid2));

NetDeviceContainer apDevices2 = wifi.Install (phy, mac, wifiApNodes.Get (1));

mac.SetType (“ns3::StaWifiMac”,

“Ssid”, SsidValue (ssid1),

“ActiveProbing”, BooleanValue (false));

NetDeviceContainer staDevices1 = wifi.Install (phy, mac, wifiStaNodes);

mac.SetType (“ns3::StaWifiMac”,

“Ssid”, SsidValue (ssid2),

“ActiveProbing”, BooleanValue (false));

NetDeviceContainer staDevices2 = wifi.Install (phy, mac, wifiStaNodes);

MobilityHelper mobility;

mobility.SetPositionAllocator (“ns3::GridPositionAllocator”,

“MinX”, DoubleValue (0.0),

“MinY”, DoubleValue (0.0),

“DeltaX”, DoubleValue (5.0),

“DeltaY”, DoubleValue (10.0),

“GridWidth”, UintegerValue (3),

“LayoutType”, StringValue (“RowFirst”));

 

mobility.SetMobilityModel (“ns3::ConstantPositionMobilityModel”);

mobility.Install (wifiApNodes);

mobility.Install (wifiStaNodes);

InternetStackHelper stack;

stack.Install (wifiApNodes);

stack.Install (wifiStaNodes);

Ipv4AddressHelper address;

Ipv4InterfaceContainer apInterfaces1, apInterfaces2, staInterfaces1, staInterfaces2;

address.SetBase (“10.1.1.0”, “255.255.255.0”);

apInterfaces1 = address.Assign (apDevices1);

staInterfaces1 = address.Assign (staDevices1);

address.SetBase (“10.1.2.0”, “255.255.255.0”);

apInterfaces2 = address.Assign (apDevices2);

staInterfaces2 = address.Assign (staDevices2);

UdpEchoServerHelper echoServer (9);

ApplicationContainer serverApps = echoServer.Install (wifiApNodes.Get (0));

serverApps.Start (Seconds (1.0));

serverApps.Stop (Seconds (10.0));

UdpEchoClientHelper echoClient (apInterfaces1.GetAddress (0), 9);

echoClient.SetAttribute (“MaxPackets”, UintegerValue (100));

echoClient.SetAttribute (“Interval”, TimeValue (Seconds (0.1)));

echoClient.SetAttribute (“PacketSize”, UintegerValue (1024));

ApplicationContainer clientApps = echoClient.Install (wifiStaNodes);

clientApps.Start (Seconds (2.0));

clientApps.Stop (Seconds (10.0));

// Enable Flow Monitor

FlowMonitorHelper flowmon;

Ptr<FlowMonitor> monitor = flowmon.InstallAll ();

// Run simulation

Simulator::Stop (Seconds (10.0));

Simulator::Run ();

// Print statistics

monitor->CheckForLostPackets ();

Ptr<Ipv4FlowClassifier> classifier = DynamicCast<Ipv4FlowClassifier> (flowmon.GetClassifier ());

std::map<FlowId, FlowMonitor::FlowStats> stats = monitor->GetFlowStats ();

for (std::map<FlowId, FlowMonitor::FlowStats>::const_iterator i = stats.begin (); i != stats.end (); ++i)

{

Ipv4FlowClassifier::FiveTuple t = classifier->FindFlow (i->first);

std::cout << “Flow ID: ” << i->first << ” Src Addr ” << t.sourceAddress << ” Dst Addr ” << t.destinationAddress << std::endl;

std::cout << “Tx Packets = ” << i->second.txPackets << std::endl;

std::cout << “Rx Packets = ” << i->second.rxPackets << std::endl;

std::cout << “Throughput: ” << i->second.rxBytes * 8.0 / 10.0 / 1024 / 1024 << ” Mbps” << std::endl;

}

Simulator::Destroy ();

return 0;

}

Explanation:

1. Create Nodes:
   • Create Wi-Fi nodes for APs and STAs.

1. Configure Wi-Fi:

• Configure the Wi-Fi PHY and MAC layers.
• Create Wi-Fi APs and STAs.

1. Install Mobility Model:

• For all nodes, set a constant position.

1. Install Internet Stack:

• On all nodes, install the Internet stack.

1. Assign IP Addresses:

• Assign IP addresses to the Wi-Fi interfaces.

1. Set Up Applications:

• On the first AP, create a UDP Echo server.
• On the STAs, create a UDP Echo client.

1. Enable Flow Monitor:

• Collect performance metrics by installing Flow Monitor.

1. Run Simulation:

• Run the simulation and print the statistics which was collected.

Step 4: Build and Run the Simulation

Save the script as ap-selection-example.cc and build the script using waf, then run the simulation.

./waf configure

./waf build

./waf –run ap-selection-example

Step 5: Analyze the results

The script will output performance metrics such as the number of transmitted and received packets, and throughput after running the simulation. We can analyze the data to understand the performance of the AP selection mechanism.

On the whole, we had a performance analysis on the implementation of network Access Point (AP) selection by creating a network topology with multiple APs and implementing a mechanism for stations (STAs) to select the best AP based on certain criteria, such as signal strength or load. Also, we provide a detailed explanation on Network Access Point (AP) Selection