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# How to Calculate Download rate in Ns3

To calculate the download rate in ns3, we need to follow several steps. Because download rate is used for evaluating the performance of file downloads or similar applications that measures the amount of data received on the particular period of time.

The following steps will guide to calculate the download rate by setting up the network in ns3:

Steps to Calculate Download Rate in ns3

1. Set Up ns3 Environment:
• Make sure ns3 is installed on the system.
2. Create a New ns-3 Script:
• Create a new script file in the scratch directory of ns3, e.g., download_rate_calculation.cc.
3. Include Necessary Headers:
• Include the necessary ns3 headers in the script.
4. Define Network Topology:
• Set up a network topology with multiple nodes.
5. Implement Download Simulation:
• Use the PacketSink application to simulate the receiver and generate traffic from the source.
6. Measure Download Rate:
• Track the amount of data received over time to calculate the download rate.

Example Code:

#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;

NS_LOG_COMPONENT_DEFINE (“DownloadRateCalculationExample”);

void CalculateDownloadRate(Ptr<PacketSink> sink, Time interval)

{

static uint64_t lastTotalRx = 0;

uint64_t totalRx = sink->GetTotalRx();

uint64_t rxBytes = totalRx – lastTotalRx;

lastTotalRx = totalRx;

double downloadRate = (rxBytes * 8) / interval.GetSeconds(); // bits per second

std::cout << Simulator::Now().GetSeconds() << “s: Download Rate = ” << downloadRate / 1e6 << ” Mbps” << std::endl;

Simulator::Schedule(interval, &CalculateDownloadRate, sink, interval); // Schedule next calculation

}

void GenerateTraffic(Ptr<Socket> socket, uint32_t pktSize, uint32_t pktCount, Time interPacketInterval)

{

if (pktCount > 0)

{

socket->Send(Create<Packet>(pktSize));

Simulator::Schedule(interPacketInterval, &GenerateTraffic, socket, pktSize, pktCount – 1, interPacketInterval);

}

}

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

{

uint32_t nNodes = 2; // Number of nodes

double simulationTime = 10.0; // Total simulation time in seconds

Time calculationInterval = Seconds(1.0); // Interval to calculate download rate

uint32_t packetSize = 1024; // Packet size in bytes

uint32_t numPackets = 1000; // Number of packets to send

Time interPacketInterval = MilliSeconds(10); // Interval between packets

CommandLine cmd;

cmd.AddValue(“nNodes”, “Number of nodes”, nNodes);

cmd.AddValue(“simulationTime”, “Total simulation time”, simulationTime);

cmd.AddValue(“calculationInterval”, “Interval to calculate download rate”, calculationInterval);

cmd.AddValue(“packetSize”, “Size of each packet”, packetSize);

cmd.AddValue(“numPackets”, “Number of packets to send”, numPackets);

cmd.AddValue(“interPacketInterval”, “Interval between packets”, interPacketInterval);

cmd.Parse(argc, argv);

NodeContainer nodes;

nodes.Create(nNodes);

PointToPointHelper pointToPoint;

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

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

NetDeviceContainer devices;

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);

uint16_t port = 9;

Address sinkAddress(InetSocketAddress(interfaces.GetAddress(1), port));

PacketSinkHelper packetSinkHelper(“ns3::UdpSocketFactory”, sinkAddress);

ApplicationContainer sinkApps = packetSinkHelper.Install(nodes.Get(1));

sinkApps.Start(Seconds(0.0));

sinkApps.Stop(Seconds(simulationTime));

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

sourceSocket->Connect(sinkAddress);

Simulator::ScheduleWithContext(sourceSocket->GetNode()->GetId(), Seconds(1.0), &GenerateTraffic, sourceSocket, packetSize, numPackets, interPacketInteral);

Simulator::Schedule(calculationInterval, &CalculateDownloadRate, DynamicCast<PacketSink>(sinkApps.Get(0)), calculationInterval);

Simulator::Stop(Seconds(simulationTime));

Simulator::Run();

Simulator::Destroy();

return 0;

}

Explanation:

1. Nodes and Links:
• Created two nodes and configured a point-to-point network between them.
• Set up the network with nodes connected using point-to-point links.
2. Applications:
• Installed a PacketSink application on one node to simulate the receiver (download).
• Created a UDP socket on another node to send packets (simulate download source).
3. Traffic Generation:
• Implemented the GenerateTraffic function to send packets from the source node to the sink node at regular intervals.
4. Download Rate Calculation:
• Implemented the CalculateDownloadRate function to calculate the download rate by measuring the amount of data received over time.
• Scheduled the download rate calculation at regular intervals using the Simulator::Schedule function.
5. Running the Simulation:
• The simulation runs, sending and receiving packets.
• The download rate is calculated and printed at regular intervals.

Finally, the download rate is calculated in ns3 by using calculate download rate function to measure the amount of data received in a particular time for calculation.

We calculate the download rate in ns3 for your project where the parameters will be distinguished so get best results from ns3simulation.com.