To calculate the network channel capacity in ns3, that includes Shannon-Hartley theorem that delivers a theoretical maximum data rate (channel capacity) for a given bandwidth and signal-to-noise ratio (SNR).
The give below formula is a channel capacity CCC:
C=Blog2(1+SNR)C = B \log_2(1 + \text{SNR})C=Blog2(1+SNR)
Here,
BBB is bandwidth in Hz
SNR\text {SNR} SNR is a signal-to-noise ratio.
Step-by-Step Guide to Calculate Network Channel Capacity in ns3
- Set Up the Simulation Environment:
- Download and setup an ns3 in the computer.
- Take account of essential modules in the simulation (e.g., LTE, WiFi, Internet, Mobility).
- Create Network Topology:
- Define nodes for the base stations (eNodeBs) and user equipment (UEs).
- Set up the wireless network with appropriate configurations.
- Configure Applications:
- Install traffic generating applications (e.g., UDP, TCP) on the UEs.
- Enable Tracing and Metrics Collection:
- Enable tracing to capture relevant metrics such as received signal power and noise power.
- Run the Simulation:
- Execute the simulation and collect the trace data.
- Calculate Channel Capacity:
- Post-process the trace data to calculate the channel capacity using the Shannon-Hartley theorem.
Example Code Snippet for LTE Network
In this direction, we provide the sample snippet on how to a set up an LTE network, generate traffic, and capture SNR values to calculate the channel capacity 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”
#include “ns3/lte-module.h”
#include “ns3/epc-helper.h”
#include “ns3/mobility-module.h”
#include “ns3/config-store.h”
#include “ns3/log.h”
using namespace ns3;
NS_LOG_COMPONENT_DEFINE (“LteChannelCapacityExample”);
// Function to calculate and log Channel Capacity
void CalculateChannelCapacity (Ptr<LtePhy> phy, Ptr<OutputStreamWrapper> stream)
{
double bandwidth = phy->GetBandwidth () * 180000.0; // Bandwidth in Hz (assuming 180 kHz per RB)
double signalPower = phy->GetDlSpectrumPhy ()->GetTxPower (); // Current transmission power
double noisePower = phy->GetDlSpectrumPhy ()->GetNoisePower (); // Get the noise power
double snr = signalPower / noisePower;
double capacity = bandwidth * std::log2 (1 + snr);
*stream->GetStream () << Simulator::Now ().GetSeconds () << “\t” << bandwidth << “\t” << snr << “\t” << capacity / 1e6 << ” Mbps” << std::endl;
// Schedule the function to run again
Simulator::Schedule (Seconds (1.0), &CalculateChannelCapacity, phy, stream);
}
int main (int argc, char *argv[])
{
// Set up logging
LogComponentEnable (“UdpClient”, LOG_LEVEL_INFO);
LogComponentEnable (“UdpServer”, LOG_LEVEL_INFO);
// Create LTE network nodes
NodeContainer ueNodes;
NodeContainer enbNodes;
ueNodes.Create (10);
enbNodes.Create (3);
// Install Mobility model
MobilityHelper mobility;
mobility.SetMobilityModel (“ns3::ConstantPositionMobilityModel”);
mobility.Install (enbNodes);
mobility.SetPositionAllocator (“ns3::GridPositionAllocator”,
“MinX”, DoubleValue (0.0),
“MinY”, DoubleValue (0.0),
“DeltaX”, DoubleValue (50.0),
“DeltaY”, DoubleValue (50.0),
“GridWidth”, UintegerValue (3),
“LayoutType”, StringValue (“RowFirst”));
mobility.Install (ueNodes);
// Create LTE helper and EPC helper
Ptr<LteHelper> lteHelper = CreateObject<LteHelper> ();
Ptr<PointToPointEpcHelper> epcHelper = CreateObject<PointToPointEpcHelper> ();
lteHelper->SetEpcHelper (epcHelper);
// Install LTE devices to the nodes
NetDeviceContainer enbLteDevs = lteHelper->InstallEnbDevice (enbNodes);
NetDeviceContainer ueLteDevs = lteHelper->InstallUeDevice (ueNodes);
// Install Internet stack on UEs
InternetStackHelper internet;
internet.Install (ueNodes);
// Assign IP addresses to UEs
Ipv4InterfaceContainer ueIpIface;
ueIpIface = epcHelper->AssignUeIpv4Address (NetDeviceContainer (ueLteDevs));
// Attach UEs to eNodeBs
for (uint32_t i = 0; i < ueNodes.GetN (); ++i)
{
lteHelper->Attach (ueLteDevs.Get (i), enbLteDevs.Get (i % enbNodes.GetN ()));
}
// Install and start applications on UEs and remote host
uint16_t dlPort = 1234;
ApplicationContainer clientApps;
ApplicationContainer serverApps;
for (uint32_t i = 0; i < ueNodes.GetN (); ++i)
{
UdpServerHelper myServer (dlPort);
serverApps.Add (myServer.Install (ueNodes.Get (i)));
UdpClientHelper myClient (ueIpIface.GetAddress (i), dlPort);
myClient.SetAttribute (“MaxPackets”, UintegerValue (1000));
myClient.SetAttribute (“Interval”, TimeValue (MilliSeconds (100)));
myClient.SetAttribute (“PacketSize”, UintegerValue (1024));
clientApps.Add (myClient.Install (ueNodes.Get (i)));
}
serverApps.Start (Seconds (1.0));
serverApps.Stop (Seconds (10.0));
clientApps.Start (Seconds (2.0));
clientApps.Stop (Seconds (10.0));
// Create output stream for logging Channel Capacity
AsciiTraceHelper ascii;
Ptr<OutputStreamWrapper> stream = ascii.CreateFileStream (“channel-capacity-trace.txt”);
*stream->GetStream () << “Time(s)\tBandwidth(Hz)\tSNR\tCapacity(Mbps)\n”;
// Connect to trace sources
Ptr<LteEnbPhy> enbPhy = enbLteDevs.Get (0)->GetObject<LteEnbNetDevice> ()->GetPhy ()->GetObject<LteEnbPhy> ();
Simulator::Schedule (Seconds (1.0), &CalculateChannelCapacity, enbPhy, stream);
// Run the simulation
Simulator::Stop (Seconds (11.0));
Simulator::Run ();
// Clean up
Simulator::Destroy ();
return 0;
}
Explanation:
- Setup Logging:
- Enable logging for the UDP applications to track their activities.
- Create Nodes and Network:
- Create nodes representing UEs and eNodeBs.
- Configure mobility models for UEs and eNodeBs.
- Install LTE and EPC Helper:
- Create and configure LTE and EPC helpers.
- Install LTE devices on the UEs and eNodeBs.
- Install Internet Stack:
- Install the Internet stack on UEs.
- Assign IP addresses to the UEs.
- Attach UEs to eNodeBs:
- Attach each UE to an eNodeB. Here, a round-robin attachment is used for simplicity.
- Install Applications:
- Install UDP server applications on the UEs.
- Install UDP client applications on the UEs, sending traffic to the server.
- Connect to Trace Sources:
- Create an output stream for logging channel capacity values.
- Connect to the trace source for calculating channel capacity.
- Run Simulation:
- Run the simulation for the specified duration.
- Calculate and Log Channel Capacity:
- The CalculateChannelCapacity function calculates the channel capacity periodically during the simulation.
- The channel capacity is calculated using the Shannon-Hartley theorem: C=Blog2(1+SNR)C = B \log_2(1 + \text{SNR})C=Blog2(1+SNR)
Where BBB is the bandwidth in Hz, and SNR\text{SNR}SNR is the signal-to-noise ratio.
Analysing the Results:
- Channel Capacity:
- The channel capacity values for each eNodeB are logged along with the simulation time, bandwidth, and SNR.
- These metrics provide an indication of the theoretical maximum data rate for the network.
Network Channel Capacity had been Calculated and Executed in the simulation by use of Shannon-Hartley theorem in ns3 tools. Also, we provide related information regarding Network Channel Capacity.
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