How to Implement Channel Modeling in ns3

To implement channel modeling in ns3, we need to set-up the wireless channel characteristics such as path loss, fading, and interference. The following steps will guide on how to implement Channel Modeling in ns3.

Step-by-step guide to implement channel modeling

Step 1: Set Up the ns3 Environment

1. Install ns3: Make sure that ns3 is installed on the system.

sudo apt-get update

sudo apt-get install ns3

Create a New ns-3 Project: Create a directory for the new project within the ns3 workspace.

cd ns3

mkdir scratch/channel-modeling

Step 2: Understand Existing Channel Models

Here ns3 provides several predefined channel models, such as:

• YansWifiChannel: Models path loss, propagation delay, and interference for WiFi networks.
• SpectrumChannel: A more generic channel model that can be used for various wireless technologies.
• SingleModelSpectrumChannel: A simplified spectrum channel model.

Step 3: Create a Custom Channel Model (Optional)

For extending the existing classes, we can use existing models or create a custom channel model. Here’s how can implement a custom channel model:

1. Create the Custom Channel Model: Create a new header file for the custom channel model.

// CustomChannel.h

#ifndef CUSTOM_CHANNEL_H

#define CUSTOM_CHANNEL_H

#include “ns3/spectrum-channel.h”

namespace ns3 {

class CustomChannel : public SpectrumChannel {

public:

static TypeId GetTypeId (void);

CustomChannel ();

virtual ~CustomChannel ();

// Add custom methods and attributes here

};

} // namespace ns3

#endif // CUSTOM_CHANNEL_H

Create the implementation file for the custom channel model.

// CustomChannel.cc

#include “CustomChannel.h”

#include “ns3/log.h”

namespace ns3 {

NS_LOG_COMPONENT_DEFINE (“CustomChannel”);

TypeId CustomChannel::GetTypeId (void) {

static TypeId tid = TypeId (“ns3::CustomChannel”)

.SetParent<SpectrumChannel> ()

.SetGroupName (“Custom”)

.AddConstructor<CustomChannel> ();

return tid;

}

CustomChannel::CustomChannel () {

NS_LOG_FUNCTION (this);

}

CustomChannel::~CustomChannel () {

NS_LOG_FUNCTION (this);

}

} // namespace ns3

Step 4: Use or Integrate the Channel Model in a Simulation

We can either use an existing channel model or the custom one you created. Here’s an example using the YansWifiChannel model:

1. Create a New Simulation Script:

// channel-modeling.cc

#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/propagation-module.h”

 

using namespace ns3;

NS_LOG_COMPONENT_DEFINE (“ChannelModeling”);

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

CommandLine cmd;

cmd.Parse (argc, argv);

NodeContainer wifiStaNodes;

wifiStaNodes.Create (3);

NodeContainer wifiApNode = wifiStaNodes.Get (0);

YansWifiChannelHelper channel = YansWifiChannelHelper::Default ();

channel.AddPropagationLoss (“ns3::LogDistancePropagationLossModel”);

YansWifiPhyHelper phy = YansWifiPhyHelper::Default ();

phy.SetChannel (channel.Create ());

WifiHelper wifi;

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

WifiMacHelper mac;

Ssid ssid = Ssid (“ns-3-ssid”);

mac.SetType (“ns3::StaWifiMac”,

“Ssid”, SsidValue (ssid),

“ActiveProbing”, BooleanValue (false));

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

mac.SetType (“ns3::ApWifiMac”,

“Ssid”, SsidValue (ssid));

NetDeviceContainer apDevices = wifi.Install (phy, mac, wifiApNode);

 

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 (wifiStaNodes);

InternetStackHelper stack;

stack.Install (wifiStaNodes);

Ipv4AddressHelper address;

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

Ipv4InterfaceContainer staInterfaces = address.Assign (staDevices);

Ipv4InterfaceContainer apInterface = address.Assign (apDevices);

UdpEchoServerHelper echoServer (9);

ApplicationContainer serverApp = echoServer.Install (wifiApNode);

serverApp.Start (Seconds (1.0));

serverApp.Stop (Seconds (10.0));

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

echoClient.SetAttribute (“MaxPackets”, UintegerValue (1));

echoClient.SetAttribute (“Interval”, TimeValue (Seconds (1.0)));

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

ApplicationContainer clientApp = echoClient.Install (wifiStaNodes.Get (1));

clientApp.Start (Seconds (2.0));

clientApp.Stop (Seconds (10.0));

Ipv4GlobalRoutingHelper::PopulateRoutingTables ();

Simulator::Stop (Seconds (10.0));

Simulator::Run ();

Simulator::Destroy ();

return 0;

}

Compile the Script: Compile the script using the waf build system.

./waf build

Run the Simulation: Run the simulation script and observe the results.

./waf –run scratch/channel-modeling

Step 5: Enable Tracing and Analyze Results

1. Enable Tracing: Add tracing to collect data for analysis.

AsciiTraceHelper ascii;

phy.EnableAsciiAll (ascii.CreateFileStream (“channel-modeling.tr”));

Run the Simulation: Set the simulation stop time and run it.

Simulator::Stop (Seconds (10.0));

Simulator::Run ();

Simulator::Destroy ();

Finally, we had learnt to implement the Channel Modeling in ns3 by using the various characteristics of wireless channel and creating a custom routing model to extend the existing model, integrating the channel model in a simulation and enabling the tracing for simulating and analyzing the result.

Various project ideas on Channel Modeling in ns3tool are executed for scholars.