How to Begin Implement Real Time Protocol in NS3

To begin implementing Real-Time Protocol (RTP) using NS3, we need to replicate the RTP’s behavior for real-time data transmission like audio and video streaming. RTP functions lying on the UDP and operates in combination with the Real-Time Control Protocol (RTCP) to observe the transmission statistics and handle the QoS.

Below is a step-by-step instruction on how to execute the RTP in NS3:

Steps to Begin Implement Real Time Protocol in NS3

Step 1: Understand RTP

1. Key Features of RTP:
   • It offers end-to-end delivery of real-time information.
   • It has advanced aspects for payload type identification, delivery monitoring sequence numbering, and time stamping.
   • Apply RTCP to log transmission statistics and manage the session.
2. RTP Packet Structure:
   • Header: It includes sequence numbers, timestamps, and other session-related data.
   • Payload: It has real-time information like audio or video frames.

Step 2: Set Up NS3 Environment

1. Create a Directory for RTP:
   • Make a new directory in src/applications/, for example src/rtp/.
2. Add Required Files:
   • rtp-header.h: Describe the RTP header structure.
   • rtp-header.cc: Execute the serialization and deserialization for the header.
   • rtp-application.h: For data delivery, delineate the RTP application.
   • rtp-application.cc: Execute the RTP application logic.
3. Update Build System:
   • Fine-tune the wscript with RTP module within the src/applications/ directory.

Step 3: Design RTP Components

1. RTP Header

Describe the RTP header structure and serialization logic components.

Header File (rtp-header.h)

#include “ns3/header.h”

class RtpHeader : public ns3::Header {

public:

static ns3::TypeId GetTypeId (void);

virtual ns3::TypeId GetInstanceTypeId () const;

void SetSequenceNumber (uint16_t seq);

uint16_t GetSequenceNumber () const;

void SetTimestamp (uint32_t timestamp);

uint32_t GetTimestamp () const;

void SetPayloadType (uint8_t payloadType);

uint8_t GetPayloadType () const;

virtual void Serialize (ns3::Buffer::Iterator start) const;

virtual uint32_t Deserialize (ns3::Buffer::Iterator start);

virtual void Print (std::ostream &os) const;

private:

uint16_t m_sequenceNumber;

uint32_t m_timestamp;

uint8_t m_payloadType;

};

Implementation File (rtp-header.cc)

For the RTP header, execute the serialization, deserialization, and accessor.

2. RTP Application

The RTP application handles the real-time data transmission, making RTP packets including proper headers and transmitting them on top of UDP.

Header File (rtp-application.h)

#include “ns3/application.h”

#include “ns3/socket.h”

#include “rtp-header.h”

class RtpApplication : public ns3::Application {

public:

static ns3::TypeId GetTypeId (void);

RtpApplication ();

virtual ~RtpApplication ();

void Setup (ns3::Ptr<ns3::Socket> socket, ns3::Address peerAddress, uint32_t packetSize, uint32_t packetInterval);

protected:

virtual void StartApplication (void);

virtual void StopApplication (void);

private:

void SendPacket ();

ns3::Ptr<ns3::Socket> m_socket;

ns3::Address m_peerAddress;

uint32_t m_packetSize;

uint32_t m_packetInterval; // Interval in milliseconds

uint16_t m_sequenceNumber;

uint32_t m_timestamp;

ns3::EventId m_sendEvent;

};

Implementation File (rtp-application.cc)

#include “rtp-application.h”

#include “ns3/log.h”

#include “ns3/simulator.h”

NS_LOG_COMPONENT_DEFINE (“RtpApplication”);

NS_OBJECT_ENSURE_REGISTERED (RtpApplication);

ns3::TypeId RtpApplication::GetTypeId (void) {

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

.SetParent<ns3::Application> ()

.SetGroupName (“Applications”)

.AddConstructor<RtpApplication> ();

return tid;

}

RtpApplication::RtpApplication ()

: m_socket (0),

m_packetSize (0),

m_packetInterval (0),

m_sequenceNumber (0),

m_timestamp (0) {}

RtpApplication::~RtpApplication () {

m_socket = nullptr;

}

void RtpApplication::Setup (ns3::Ptr<ns3::Socket> socket, ns3::Address peerAddress, uint32_t packetSize, uint32_t packetInterval) {

m_socket = socket;

m_peerAddress = peerAddress;

m_packetSize = packetSize;

m_packetInterval = packetInterval;

}

void RtpApplication::StartApplication () {

NS_LOG_INFO (“Starting RTP Application”);

m_socket->Connect (m_peerAddress);

SendPacket ();

}

void RtpApplication::StopApplication () {

NS_LOG_INFO (“Stopping RTP Application”);

if (m_socket) {

m_socket->Close ();

}

Simulator::Cancel (m_sendEvent);

}

void RtpApplication::SendPacket () {

ns3::Ptr<ns3::Packet> packet = ns3::Create<ns3::Packet> (m_packetSize);

RtpHeader rtpHeader;

rtpHeader.SetSequenceNumber (m_sequenceNumber++);

rtpHeader.SetTimestamp (m_timestamp);

rtpHeader.SetPayloadType (96); // Example payload type for video

packet->AddHeader (rtpHeader);

m_socket->Send (packet);

NS_LOG_INFO (“Sent RTP packet with Sequence Number: ” << rtpHeader.GetSequenceNumber () << ” Timestamp: ” << rtpHeader.GetTimestamp ());

m_timestamp += m_packetInterval;

// Schedule the next packet

m_sendEvent = Simulator::Schedule (ns3::MilliSeconds (m_packetInterval), &RtpApplication::SendPacket, this);

}

Step 4: Write a Simulation Script

Make a simulation script for replicating real-time data delivery with RTP application.

#include “ns3/core-module.h”

#include “ns3/network-module.h”

#include “ns3/internet-module.h”

#include “rtp-application.h”

using namespace ns3;

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

NodeContainer nodes;

nodes.Create (2);

InternetStackHelper stack;

stack.Install (nodes);

PointToPointHelper p2p;

p2p.SetDeviceAttribute (“DataRate”, StringValue (“10Mbps”));

p2p.SetChannelAttribute (“Delay”, StringValue (“2ms”));

NetDeviceContainer devices = p2p.Install (nodes);

Ipv4AddressHelper address;

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

Ipv4InterfaceContainer interfaces = address.Assign (devices);

// RTP sender

Ptr<Socket> senderSocket = Socket::CreateSocket (nodes.Get (0), UdpSocketFactory::GetTypeId ());

Ptr<RtpApplication> senderApp = CreateObject<RtpApplication> ();

senderApp->Setup (senderSocket, InetSocketAddress (interfaces.GetAddress (1), 5000), 1024, 20); // 1024 bytes, 20ms interval

nodes.Get (0)->AddApplication (senderApp);

senderApp->SetStartTime (Seconds (1.0));

senderApp->SetStopTime (Seconds (10.0));

// RTP receiver (PacketSink)

PacketSinkHelper sinkHelper (“ns3::UdpSocketFactory”, InetSocketAddress (Ipv4Address::GetAny (), 5000));

ApplicationContainer sinkApp = sinkHelper.Install (nodes.Get (1));

sinkApp.Start (Seconds (0.0));

sinkApp.Stop (Seconds (10.0));

Simulator::Run ();

Simulator::Destroy ();

return 0;

}

Step 5: Compile and Run

1. Build the Code:

./waf configure

./waf build

1. Run the Simulation:

./waf –run your-script

Step 6: Validate and Extend

1. Validation:
   • Confirm RTP packet flow to utilising NS3 tracing tools such as AsciiTraceHelper, PcapHelper.
   • Verify sequence numbers, timestamps, and delivery correctness.
2. Extensions:
   • For session statistics and control, we need to execute the RTCP.
   • Integrate support for various payload types such as audio, video.
   • We will replicate the jitter, packet loss, and retrieval approaches.

In this approach, we successfully walk you through the comprehensive implementation procedure for executing Real Time Protocol using NS3 simulator. We are furnished to deliver more insights according to your needs.