How to Begin Implement Network Jitter in NS3

To begin implementing and estimating the network jitter using NS3, we can determine the difference within packet delay (latency) over time. Jitter is crucial performance parameters like VoIP, video conferencing, and streaming in real-time communication systems.

Steps to Begin Implement Network Jitter in NS3

1. Understand Network Jitter

• Definition: Network jitter signifies the difference within latency (packet delay) among the successive packets.
• Mathematical Expression:
  • Jitter for consecutive packets iii and i+1i+1i+1 is: Jitter=∣Delayi+1−Delayi∣Jitter = |Delay_{i+1} – Delay_i|Jitter=∣Delayi+1​−Delayi​∣
• Components:
  • It needs to monitor each packet’s delay and equate it including the delay of the preceding packet.

2. Set Up NS3 Simulation

1. Install NS3:
   • We can install and download NS3 on the system.
2. Choose a Base Network Topology:
   • For initial testing, we can utilize a basic point-to-point or wireless network.

3. Add Packet Timestamps

• Make use of packet tagging or metadata for logging the send time on the source.
• Determine the delay for each packet and save it for jitter calculation at the receiver.

4. Calculate Jitter

1. Track Packet Delays:
   • Log the delay for every single packet on the receiver.
2. Compute Jitter:
   • Equate the present packet’s delay including the delay of the preceding packet for estimating jitter.

5. Implement Network Jitter Measurement

Here’s an instance script, which illustrates the jitter measurement within a point-to-point network.

Example Script: Network Jitter in NS3

#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”

using namespace ns3;

class JitterCalculator {

public:

JitterCalculator() : m_lastDelay(Seconds(0)), m_firstPacket(true) {}

void CalculateJitter(Time delay) {

if (!m_firstPacket) {

Time jitter = Abs(delay – m_lastDelay);

NS_LOG_UNCOND(Simulator::Now().GetSeconds() << “s: Jitter = ” << jitter.GetMilliSeconds() << ” ms”);

} else {

m_firstPacket = false;

}

m_lastDelay = delay;

}

private:

Time m_lastDelay;

bool m_firstPacket;

};

JitterCalculator jitterCalc;

void ReceivePacket(Ptr<Socket> socket) {

Ptr<Packet> packet = socket->Recv();

Time sendTime = packet->GetCreationTime();

Time receiveTime = Simulator::Now();

Time delay = receiveTime – sendTime;

// Calculate jitter

jitterCalc.CalculateJitter(delay);

}

void SendPacket(Ptr<Socket> socket) {

Ptr<Packet> packet = Create<Packet>(1024); // 1024 bytes

packet->SetCreationTime(Simulator::Now());

socket->Send(packet);

Simulator::Schedule(Seconds(0.1), &SendPacket, socket); // Send every 100ms

}

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

CommandLine cmd;

cmd.Parse(argc, argv);

NodeContainer nodes;

nodes.Create(2);

PointToPointHelper pointToPoint;

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

pointToPoint.SetChannelAttribute(“Delay”, StringValue(“5ms”));

NetDeviceContainer devices = pointToPoint.Install(nodes);

InternetStackHelper stack;

stack.Install(nodes);

Ipv4AddressHelper address;

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

Ipv4InterfaceContainer interfaces = address.Assign(devices);

// Create sockets

Ptr<Socket> sender = Socket::CreateSocket(nodes.Get(0), TypeId::LookupByName(“ns3::UdpSocketFactory”));

Ptr<Socket> receiver = Socket::CreateSocket(nodes.Get(1), TypeId::LookupByName(“ns3::UdpSocketFactory”));

InetSocketAddress remote = InetSocketAddress(interfaces.GetAddress(1), 8080);

receiver->Bind(InetSocketAddress(Ipv4Address::GetAny(), 8080));

receiver->SetRecvCallback(MakeCallback(&ReceivePacket));

sender->Connect(remote);

// Schedule packet sending

Simulator::Schedule(Seconds(1.0), &SendPacket, sender);

Simulator::Run();

Simulator::Destroy();

return 0;

}

Explanation of the Script

1. Jitter Calculation:
   • The JitterCalculator class monitors the previous packet’s delay and determines jitter for each new packet.
2. Packet Timestamps:
   • Set the creation time of every single packet with SetCreationTime at the sender.
   • Delay is computed at the receiver by leveraging:

Time delay = Simulator::Now() – packet->GetCreationTime();

1. Logging Jitter:
   • The calculated jitter is recorded to the console for each packet.
2. Packet Sending Interval:
   • Packets are transmitting each 0.1 seconds (100ms) for jitter measurement to make a steady stream.

6. Run the Simulation

1. Build the simulation script:

./waf –run “your-script-name”

1. Monitor the console outcome for observing the values of jitter for each received packet.

Advanced Extensions

1. Vary Network Conditions:
   • Modify the link delay or launch random packet loss to replicate the real-world network conditions.
2. Complex Topologies:
   • Mimic larger topologies or wireless networks for estimating the jitter in dynamic environments.
3. Application-Level Jitter:
   • Replicate the real-world traffic models to utilize OnOffApplication or similar.
4. Visualization:
   • Transfer jitter data into a file to envision and examine the outcomes using external tools such as MATLAB or Excel.

By following these steps, you can begin the implementation and computation of Network Jitter in NS3 environment. We will also be provided more advanced topics and relevant insights on this subject as required.