How to Implement Real Time Protocol in OMNeT++

To Implement the Real-Time Protocol (RTP) in OMNeT++ has needs to make a simulation model where the RTP is used to deliver real-time data, like audio or video, over a network. Basically RTP is usually used in the combination with SIP for VoIP (Voice over IP) and video conferencing applications.

The given below is the detailed procedure on how to implement the RTP in OMNeT++:

Step-by-Step Implementation:

Step 1: Set Up the OMNeT++ Environment

1. Install OMNeT++:
   • Make sure OMNeT++ is installed on system. We should download it from the official OMNeT++
2. Install the INET Framework:
   • Download and install the INET Framework, which offers the essential network protocol models such as TCP/UDP/IP, which RTP relies on.
   • The INET Framework can be downloaded from its GitHub repository.

Step 2: Create a New OMNeT++ Project

1. Create the Project:
   • Open OMNeT++ and generate a new OMNeT++ project through File > New > OMNeT++ Project.
   • Name project (e.g., RTP_Simulation) and set up the project directory.
2. Set Up Project Dependencies:
   • Make sure project references the INET Framework by right-clicking on project in the Project Explorer, navigating to Properties > Project References, and testing the INET project.

Step 3: Understand RTP Basics

Before implementing RTP, it’s significant to understand the core components of RTP:

• RTP Session: An RTP session is established for each multimedia stream that contains audio or video among participants.
• RTP Packets: RTP packets contain the actual media payload has audio samples or video frames along with a header that contains timing information and sequence numbers.
• RTCP (Real-Time Control Protocol): RTCP works alongside RTP to offers out-of-band statistics and control information for an RTP flow.
• RTP and RTCP Ports: Typically, RTP uses even-numbered ports, while the corresponding RTCP stream uses the next higher odd-numbered port.

Step 4: Define the Network Topology in OMNeT++

1. Create a NED File:
   • Describe the network topology using the NED language. The topology should take in RTP clients (sending and receiving RTP packets) and probably other network infrastructure alike routers.

Example:

network RTPNetwork

{

submodules:

sender: StandardHost;

receiver: StandardHost;

router: Router;

connections:

sender.ethg++ <–> Eth10Mbps <–> router.ethg++;

receiver.ethg++ <–> Eth10Mbps <–> router.ethg++;

}

1. Configure Network Parameters:
   • Set up link parameters like bandwidth, delay, and packet loss to mimic realistic network conditions for RTP traffic.

Step 5: Implement RTP Protocol

1. Define RTP Modules:
   • Generate NED modules for the RTP sender and receiver. These modules will manage the RTP-specific operations such as packetization, timestamping, and sequence numbering.

Example (in NED):

simple RTPSender

{

parameters:

@display(“i=block/cogwheel”);

gates:

inout udpIn;

inout udpOut;

}

simple RTPReceiver

{

parameters:

@display(“i=block/cogwheel”);

gates:

inout udpIn;

inout udpOut;

}

1. Implement RTP Logic in C++:
   • RTP Sender Implementation:
     • Write the C++ code for the RTP sender. The sender should produce RTP packets, encapsulate media data, set the appropriate RTP header fields (timestamp, sequence number, etc.), and send the packets over UDP.

Example (in C++):

void RTPSender::handleMessage(cMessage *msg) {

if (msg->isSelfMessage()) {

sendRTPPacket();

}

}

void RTPSender::sendRTPPacket() {

// Create RTP packet

RTPPacket *packet = new RTPPacket(“RTPPacket”);

packet->setSequenceNumber(sequenceNumber++);

packet->setTimestamp(simTime().inUnit(SIMTIME_MS));

packet->setPayloadType(0);  // Assume payload type 0 for PCM audio

 

// Generate media data (e.g., audio samples) and add to the packet

packet->setPayload(“SampleData”);

 

// Send packet over UDP

send(packet, “udpOut”);

}

1. • RTP Receiver Implementation:
     • To execute the RTP receiver module to listen for incoming RTP packets, extract the media data, and manage reordering and jitter if needed.

Example (in C++):

void RTPReceiver::handleMessage(cMessage *msg) {

if (msg->arrivedOn(“udpIn”)) {

handleRTPPacket(check_and_cast<RTPPacket *>(msg));

}

}

void RTPReceiver::handleRTPPacket(RTPPacket *packet) {

// Process RTP packet: check sequence number, timestamp, etc.

int sequenceNumber = packet->getSequenceNumber();

simtime_t timestamp = packet->getTimestamp();

const char* payload = packet->getPayload();

// Simulate playing or processing the media data

EV << “Received RTP packet with sequence number ” << sequenceNumber << ” and timestamp ” << timestamp << endl;

// Further processing like jitter buffer, out-of-order handling, etc.

delete packet;

}

1. Implement RTCP (Optional):
   • RTCP Sender Implementation:
     • RTCP packets are sent periodically to deliver the feedback on the quality of the RTP stream like packet loss, jitter, and round-trip time (RTT).

Example (in C++):

void RTCPHandler::sendRTCPReport() {

RTCPPacket *rtcpPacket = new RTCPPacket(“RTCPReport”);

rtcpPacket->setReportType(RTCPPacket::RECEIVER_REPORT);

rtcpPacket->setFractionLost(0);

rtcpPacket->setCumulativeLost(0);

rtcpPacket->setJitter(0);

rtcpPacket->setLastSR(0);

rtcpPacket->setDlsr(0);

// Send RTCP report

send(rtcpPacket, “udpOut”);

}

1. Create RTP Message Types:
   • Define custom message types for RTP and RTCP packets.

Example (in C++):

class RTPPacket : public cMessage {

public:

int sequenceNumber;

simtime_t timestamp;

std::string payload;

…

};

class RTCPPacket : public cMessage {

public:

enum ReportType { RECEIVER_REPORT, SENDER_REPORT };

ReportType reportType;

int fractionLost;

int cumulativeLost;

simtime_t jitter;

simtime_t lastSR;

simtime_t dlsr;

…

};

Step 6: Configure the Simulation

1. Set Up the UDP Stack:
   • In the omnetpp.ini file, configure the RTP sender and receiver to use the UDP stack as long as by the INET Framework.

Example:

network = RTPNetwork

*.sender.numUdpApps = 1

*.sender.udpApp[0].typename = “UDPBasicApp”

*.sender.udpApp[0].destPort = 5004  // Port 5004 for RTP

*.sender.udpApp[0].destAddress = “receiver”

*.receiver.numUdpApps = 1

*.receiver.udpApp[0].typename = “UDPBasicApp”

*.receiver.udpApp[0].localPort = 5004

1. Define RTP Scenarios:
   • Specify the RTP scenarios to simulate, like numerous media types (audio, video) and varying network conditions (e.g., jitter, packet loss).

Step 7: Simulate and Test RTP

1. Compile the Project:
   • Build OMNeT++ project to make sure everything is applied appropriately.
2. Run the Simulation:
   • Run the simulation and monitor how RTP packets are sent from the sender to the receiver. Validate that the receiver correctly processes the RTP packets.
3. Analyse Results:
   • Use OMNeT++ tools to monitor RTP packet flows, analyze sequence numbers and timestamps, and evaluate the performance of the RTP stream under different network conditions.

Step 8: Refine and Extend

1. Enhance RTP Functionality:
   • To add the additional features to RTP implementation, like handling various payload types and execute the jitter buffers, and supporting multiple RTP sessions.
2. Test with Different Network Configurations:
   • To emulate the various network conditions like high latency, packet loss, jitter to validate the robustness of RTP implementation.
3. Implement RTCP Reporting:
   • Toexecute RTCP in detail to gather statistics and feedback on the quality of the RTP stream.
4. Optimize Performance:
   • Improve the implementation for scalability; make sure it can manage the multiple concurrent RTP streams effectively.

In this setup we had successfully executed the real time protocol in OMNeT++ tool that has generate the network then describes the RTP modules after that need to implement the RTP logic in C++ language using the OMNeT++ tool. We work on the implementation of Real Time Protocol in the OMNeT++ tool, so keep in touch with us for the best developer support during the simulation process. Our focus is on delivering real-time data, such as audio and video, related to this project.