How to Begin Implement Network Bit Error Rate in NS3

To begin implementing and analyzing Network Bit Error Rate (BER) using ns3, we follow numerous steps. BER determines the ratio of bits which are degraded in the course of transmission through the communication channel by reason of noise, interference, or other impairments. Here’s a common method to get started:

Steps to Begin Implement Network Bit Error Rate in NS3

1. Understand Bit Error Rate (BER)

• BER is determined as:

BER=Number of erroneous bitsTotal number of transmitted bits\text{BER} = \frac{\text{Number of erroneous bits}}{\text{Total number of transmitted bits}}BER=Total number of transmitted bitsNumber of erroneous bits​

• Below is components that are impacting the BER:
  • Signal-to-Noise Ratio (SNR).
  • Coding techniques like FEC.
  • Channel noise (e.g., AWGN).
  • Modulation scheme such as QPSK, BPSK.

2. Set Up Your Environment

We can install ns3 and set up correctly on the system.

3. Create the Network Topology

Example: Point-to-Point Network

NodeContainer nodes;

nodes.Create(2);

PointToPointHelper pointToPoint;

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

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

NetDeviceContainer devices;

devices = pointToPoint.Install(nodes);

Example: Wireless Network

YansWifiChannelHelper channel = YansWifiChannelHelper::Default();

YansWifiPhyHelper phy = YansWifiPhyHelper::Default();

phy.SetChannel(channel.Create());

WifiHelper wifi;

wifi.SetStandard(WIFI_PHY_STANDARD_80211n);

WifiMacHelper mac;

mac.SetType(“ns3::AdhocWifiMac”);

NodeContainer wifiNodes;

wifiNodes.Create(3);

NetDeviceContainer wifiDevices;

wifiDevices = wifi.Install(phy, mac, wifiNodes);

4. Set Up the Internet Stack

We should install the Internet stack for IP interaction:

InternetStackHelper stack;

stack.Install(nodes);

Ipv4AddressHelper address;

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

Ipv4InterfaceContainer interfaces = address.Assign(devices);

5. Generate Traffic

To replicate the network traffic, we need to install applications.

Example: UDP Traffic

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(0.01))); // 10ms interval

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

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

clientApps.Start(Seconds(2.0));

clientApps.Stop(Seconds(10.0));

6. Introduce BER in the Channel

We will want to design BER with Error Models in ns3.

Rate Error Model

Ptr<RateErrorModel> errorModel = CreateObject<RateErrorModel>();

errorModel->SetAttribute(“ErrorRate”, DoubleValue(0.01)); // 1% BER

devices.Get(1)->SetAttribute(“ReceiveErrorModel”, PointerValue(errorModel));

Custom Error Model

For custom BER logic:

class CustomErrorModel : public ErrorModel {

protected:

bool DoCorrupt(Ptr<Packet> p) override {

return (rand() % 100) < 1; // 1% BER

}

bool IsCorrupt(Ptr<Packet> p) override { return DoCorrupt(p); }

};

Ptr<CustomErrorModel> customErrorModel = CreateObject<CustomErrorModel>();

devices.Get(1)->SetAttribute(“ReceiveErrorModel”, PointerValue(customErrorModel));

7. Monitor BER

Log Sent and Received Bits

Compute the amount of bits that are effectively transmitting and inherited utilising callbacks:

uint64_t totalBitsSent = 0, totalBitsReceived = 0;

void TrackBitsSent(Ptr<const Packet> packet) {

totalBitsSent += packet->GetSize() * 8; // Convert bytes to bits

}

void TrackBitsReceived(Ptr<const Packet> packet) {

totalBitsReceived += packet->GetSize() * 8; // Convert bytes to bits

}

devices.Get(0)->TraceConnectWithoutContext(“MacTx”, MakeCallback(&TrackBitsSent));

devices.Get(1)->TraceConnectWithoutContext(“MacRx”, MakeCallback(&TrackBitsReceived));

Calculate BER

Towards the end of the simulation, we can determine the BER:

Simulator::Schedule(Seconds(10.0), [] {

uint64_t erroneousBits = totalBitsSent – totalBitsReceived;

double ber = static_cast<double>(erroneousBits) / totalBitsSent;

std::cout << “Total Bits Sent: ” << totalBitsSent << “\n”;

std::cout << “Total Bits Received: ” << totalBitsReceived << “\n”;

std::cout << “Bit Error Rate (BER): ” << ber << std::endl;

});

8. Enable Tracing

Packet-Level Tracing

Record all packet events for in-depth analysis of BER:

AsciiTraceHelper ascii;

pointToPoint.EnableAsciiAll(ascii.CreateFileStream(“ber_analysis.tr”));

PCAP Tracing

For detailed analysis, make PCAP files leveraging Wireshark:

pointToPoint.EnablePcapAll(“ber_analysis”);

9. Use FlowMonitor

FlowMonitor monitors the packet-level statistics with dropped packets that impact BER implicitly.

FlowMonitorHelper flowmon;

Ptr<FlowMonitor> monitor = flowmon.InstallAll();

Simulator::Stop(Seconds(10.0));

Simulator::Run();

monitor->CheckForLostPackets();

Ptr<Ipv4FlowClassifier> classifier = DynamicCast<Ipv4FlowClassifier>(flowmon.GetClassifier());

std::map<FlowId, FlowMonitor::FlowStats> stats = monitor->GetFlowStats();

for (auto& flow : stats) {

std::cout << “Flow ID: ” << flow.first

<< ” Throughput: ” << flow.second.rxBytes * 8.0 / (flow.second.timeLastRxPacket.GetSeconds() – flow.second.timeFirstTxPacket.GetSeconds()) / 1e6 << ” Mbps\n”;

}

10. Visualize Results

• Transfer the outcomes of BER into a file using MATLAB or Excel tools for graphing analysis.
• Envision real-time packet to apply NetAnim tools:

AnimationInterface anim(“ber_simulation.xml”);

11. Experiment and Optimize

• Experiment the performance of BER in various scenarios like:
  • Modify ErrorRate within the error model.
  • Alter channel conditions such as delay, bandwidth.
  • Replicate the mobility in dynamic scenarios for examining the BER.

12. Run the Simulation

Now, we can execute the simulation and examine BER:

Simulator::Run();

Simulator::Destroy();

We’ve provided a comprehensive guide to implement and examine the Network Bit Error Rate, including NS3 code snippets and we are ready to explore more advanced topics as required.