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How to Implement MAC protocol design in ns3

To implement a custom MAC (Medium Access Control) protocol in ns3, we needs to follow several steps. This implementation process can be complex, for this we should have a good understanding of the ns3 architecture and its extension mechanisms. This process also includes creating a new MAC layer class, configuring it, and integrating it into a network topology.

We can help you with a comparative  analysis of MAC protocol design in ns3tool. Our resources are available to assist you in your work.

The following steps will guide on how to implement this in ns3.

Step-by-step guide to implement a basic custom MAC protocol in ns3:

Step 1: Set Up the Simulation Environment

Make sure ns3 is installed on the system.

Step 2: Create the Network Topology

Create a basic network topology using ns3 with multiple nodes.

Step 3: Define the Custom MAC Protocol

Create a new class for the custom MAC protocol. For simplicity, we will base it on a simple modification of the existing ns3 MAC protocols.

Step 4: Implement the Custom MAC Protocol

An example given on how to implement a basic custom MAC protocol in ns3:

  1. Create a New MAC Layer Class:
    • Create a new header file (my-mac.h) and source file (my-mac.cc) for the custom MAC protocol.
  2. my-mac.h:

#ifndef MY_MAC_H

#define MY_MAC_H

#include “ns3/mac48-address.h”

#include “ns3/net-device.h”

#include “ns3/packet.h”

#include “ns3/queue.h”

#include “ns3/wifi-mac.h”

namespace ns3 {

class MyMac : public WifiMac

{

public:

static TypeId GetTypeId (void);

MyMac ();

virtual ~MyMac ();

void Enqueue (Ptr<const Packet> packet, Mac48Address to);

protected:

virtual void DoInitialize (void);

private:

void SendPacket ();

Ptr<Queue<Packet>> m_queue;

};

} // namespace ns3

#endif /* MY_MAC_H */

  1. my-mac.cc:

#include “my-mac.h”

#include “ns3/log.h”

#include “ns3/simulator.h”

#include “ns3/queue.h”

namespace ns3 {

NS_LOG_COMPONENT_DEFINE (“MyMac”);

NS_OBJECT_ENSURE_REGISTERED (MyMac);

TypeId

MyMac::GetTypeId (void)

{

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

.SetParent<WifiMac> ()

.SetGroupName (“Network”)

.AddConstructor<MyMac> ();

return tid;

}

MyMac::MyMac ()

{

NS_LOG_FUNCTION (this);

m_queue = CreateObject<Queue<Packet>> ();

}

MyMac::~MyMac ()

{

NS_LOG_FUNCTION (this);

}

void

MyMac::DoInitialize (void)

{

NS_LOG_FUNCTION (this);

WifiMac::DoInitialize ();

}

void

MyMac::Enqueue (Ptr<const Packet> packet, Mac48Address to)

{

NS_LOG_FUNCTION (this << packet << to);

Ptr<Packet> p = packet->Copy ();

m_queue->Enqueue (p);

Simulator::ScheduleNow (&MyMac::SendPacket, this);

}

void

MyMac::SendPacket ()

{

NS_LOG_FUNCTION (this);

if (!m_queue->IsEmpty ())

{

Ptr<Packet> packet = m_queue->Dequeue ();

Mac48Address to = Mac48Address::Allocate ();

NotifyTx (packet);

// Here you can add custom transmission logic

}

}

} // namespace ns3

Step 5: Integrate the Custom MAC Protocol into a Simulation

We need to create a simulation script that use custom MAC protocol.

#include “ns3/core-module.h”

#include “ns3/network-module.h”

#include “ns3/internet-module.h”

#include “ns3/point-to-point-module.h”

#include “ns3/applications-module.h”

#include “my-mac.h”

using namespace ns3;

NS_LOG_COMPONENT_DEFINE (“CustomMacExample”);

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

{

CommandLine cmd;

cmd.Parse (argc, argv);

// Create nodes

NodeContainer nodes;

nodes.Create (2);

// Create point-to-point links between nodes

PointToPointHelper pointToPoint;

pointToPoint.SetDeviceAttribute (“DataRate”, StringValue (“5Mbps”));

pointToPoint.SetChannelAttribute (“Delay”, StringValue (“2ms”));

NetDeviceContainer devices;

devices = pointToPoint.Install (nodes);

// Install the Internet stack on the nodes

InternetStackHelper stack;

stack.Install (nodes);

// Assign IP addresses to the devices

Ipv4AddressHelper address;

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

Ipv4InterfaceContainer interfaces = address.Assign (devices);

// Use the custom MAC protocol

Ptr<MyMac> myMac = CreateObject<MyMac> ();

// Set up applications

UdpEchoServerHelper echoServer (9);

ApplicationContainer serverApps = echoServer.Install (nodes.Get (1));

serverApps.Start (Seconds (1.0));

serverApps.Stop (Seconds (10.0));

UdpEchoClientHelper echoClient (interfaces.GetAddress (1), 9);

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

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

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

ApplicationContainer clientApps = echoClient.Install (nodes.Get (0));

clientApps.Start (Seconds (2.0));

clientApps.Stop (Seconds (10.0));

// Enable packet capturing

pointToPoint.EnablePcapAll (“custom-mac”);

// Run the simulation

Simulator::Run ();

Simulator::Destroy ();

return 0;

}

Explanation:

  1. Create a New MAC Layer Class:
    • Define a new MAC layer class MyMac that inherits from WifiMac.
    • For enqueuing and sending packets implement basic methods.
  2. Integrate the Custom MAC Protocol:
    • Create a simulation script that uses the custom MAC protocol.
    • Set up nodes, point-to-point links, and IP addresses.
    • Use the custom MAC protocol for the network devices.
    • To generate traffic set up UDP echo applications.
  3. Compile and Run the Script:
    • Save the custom MAC protocol files (my-mac.h and my-mac.cc) in the src/network/model/ directory of your ns-3 installation.
    • Save the simulation script (custom-mac-example.cc) in the scratch directory.
    • Compile and run the script using the following commands:

./waf configure

./waf build

./waf –run custom-mac-example

Step 6: Analyze the Results

We can analyze the results using packet captures and logs to verify the behavior of the custom MAC protocol, after running the simulation.

Finally, we all get to know how to implement MAC protocol in ns3 by understanding ns3s architecture and its extension mechanisms, setting up UDP echo applications to generate traffic.