To simulate the LiFi (Light Fidelity) projects within NS3, which consists of modeling Visible Light Communication (VLC) that is the underlying technology for LiFi. LiFi uses visible light for wireless communication that delivering high-speed data transfer and security advantages compared to old RF-based communication systems. Even though NS3 does not natively contain a dedicated LiFi/VLC module, it can prolong using custom models or modifications to the current wireless models. Below we provide stepwise approach on how to simulate a LiFi project using NS3:
Steps to Simulate LiFi Projects in NS3
Step 1: Install NS3
Initially, make sure we have NS3 installed on the computer. We follow these steps to install it if we haven’t already.
- Clone the NS3 Repository:
git clone https://gitlab.com/nsnam/ns-3-dev.git
cd ns-3-dev
- Configure and Build NS3:
./waf configure
./waf
Step 2: Understanding the Components of a LiFi Network
In a LiFi simulation, the below components are essential:
- LiFi Access Points (LiFi-APs): These are the light-emitting diodes (LEDs) which work for as transmitters for visible light communication.
- LiFi Receivers: Devices such as smartphones, laptops, or sensors equipped with photodetectors, which acquire the light signals.
- VLC Channel Model: A channel model replicating the optical propagation characteristics of visible light.
- Communication Protocol: A protocol for data transmission, llike TCP/IP, built on top of the LiFi physical layer.
Step 3: Set Up a Basic LiFi Network Topology
- Create LiFi Access Points and User Nodes: In the NS3 simulation, signify the LiFi Access Points (APs) and user devices (receivers) as nodes.
NodeContainer lifiAPs, userNodes;
lifiAPs.Create(1); // 1 LiFi Access Point
userNodes.Create(2); // 2 user devices
Step 4: Implement a VLC (LiFi) Physical Layer
We want to execute or change an existing Wi-Fi model to represent VLC (LiFi) communication. A custom VLC model could normally contain:
- Optical Propagation Characteristics: Replicate the light propagation, containing line-of-sight (LOS), non-line-of-sight (NLOS), and reflection properties.
- Signal-to-Noise Ratio (SNR) Calculation: Adjust the physical layer to compute SNR rely on the distance among the transmitter (LED) and the receiver (photodetector).
The following is a simple outline of how to adjust the Wi-Fi PHY model to denote LiFi:
- Modify the Wi-Fi PHY Layer: We can begin by changing the Wi-Fi PHY layer to manage the VLC communication by making a custom LiFiPhy class derived from WifiPhy.
class LiFiPhy : public WifiPhy {
public:
void StartTransmission(Ptr<Packet> packet) override {
// Modify this function to simulate VLC transmission
// e.g., calculate the received signal power based on distance and line of sight (LOS)
}
double CalculateSNR(double receivedPower) override {
// Use VLC-specific SNR calculations (e.g., based on optical intensity)
return (receivedPower / NoiseFloor);
}
};
- VLC Channel Model: We will require a VLC channel model which signifies how light propagates from the LED (LiFi-AP) to the photodetector (user). This channel model should account for distance attenuation and the field of view (FOV) of the receiver.
class VLCChannel : public PropagationLossModel {
public:
double GetLoss(Ptr<MobilityModel> sender, Ptr<MobilityModel> receiver) const override {
// Implement optical path loss (based on distance and line-of-sight)
double distance = sender->GetDistanceFrom(receiver);
double pathLoss = CalculateOpticalPathLoss(distance);
return pathLoss;
}
double CalculateOpticalPathLoss(double distance) const {
// Optical path loss formula based on the distance and other factors
return 1 / (distance * distance); // Simplified example
}
};
- Configure the LiFi PHY Layer: Incorporate the custom LiFi PHY into the NS3 simulation.
Ptr<LiFiPhy> lifiPhy = CreateObject<LiFiPhy>();
Ptr<VLCChannel> vlcChannel = CreateObject<VLCChannel>();
lifiPhy->SetChannel(vlcChannel);
lifiPhy->SetDevice(lifiAPs.Get(0)->GetObject<NetDevice>());
Step 5: Configure Network Protocols and Devices
We can be used the Wi-Fi MAC or make a custom MAC layer for LiFi communication. For simplicity, let’s we reuse the Wi-Fi MAC layer.
WifiMacHelper wifiMac;
wifiMac.SetType(“ns3::AdhocWifiMac”);
NetDeviceContainer lifiDevices;
lifiDevices = wifi.Install(lifiPhy, wifiMac, lifiAPs);
wifi.Install(lifiPhy, wifiMac, userNodes);
Step 6: Set Up Mobility Models
LiFi is highly sensitive to mobility due to its line-of-sight nature. We can model user mobility with a mobility model like the RandomWalk2dMobilityModel or ConstantPositionMobilityModel.
MobilityHelper mobility;
mobility.SetMobilityModel(“ns3::ConstantPositionMobilityModel”);
mobility.Install(lifiAPs); // LiFi APs are static (e.g., ceiling-mounted lights)
mobility.SetMobilityModel(“ns3::RandomWalk2dMobilityModel”,
“Bounds”, RectangleValue(Rectangle(0, 50, 0, 50)));
mobility.Install(userNodes); // User nodes move randomly in 2D space
Step 7: Set Up Applications for Data Transmission
- Install Data Transmission Applications: We can use the UDP Echo or TCP applications to replicate the data transmission among the user devices and the LiFi Access Point.
// Server on LiFi AP
UdpEchoServerHelper echoServer(9); // Port 9
ApplicationContainer serverApps = echoServer.Install(lifiAPs.Get(0));
serverApps.Start(Seconds(1.0));
serverApps.Stop(Seconds(10.0));
// Client on User Device
UdpEchoClientHelper echoClient(Ipv4Address(“10.1.1.1”), 9);
echoClient.SetAttribute(“MaxPackets”, UintegerValue(10));
echoClient.SetAttribute(“Interval”, TimeValue(Seconds(1.0)));
echoClient.SetAttribute(“PacketSize”, UintegerValue(1024));
ApplicationContainer clientApps = echoClient.Install(userNodes.Get(0));
clientApps.Start(Seconds(2.0));
clientApps.Stop(Seconds(10.0));
- Assign IP Addresses: Allocate an IP addresses to the LiFi devices for IP-based communication.
InternetStackHelper internet;
internet.Install(lifiAPs);
internet.Install(userNodes);
Ipv4AddressHelper ipv4;
ipv4.SetBase(“10.1.1.0”, “255.255.255.0”);
Ipv4InterfaceContainer interfaces = ipv4.Assign(lifiDevices);
Step 8: Enable Tracing and Run the Simulation
- Enable Tracing: Allow the packet-level tracing to capture and investigate the behaviour of the LiFi network.
lifiPhy.EnablePcap(“lifi-simulation”, lifiDevices.Get(0));
- Run the Simulation: Set the simulation duration and then we run it.
Simulator::Stop(Seconds(10.0));
Simulator::Run();
Simulator::Destroy();
Step 9: Analyze the Results
After running the simulation, then we investigate the following metrics:
- Signal-to-Noise Ratio (SNR): Estimate the signal strength at the receiver to compute the quality of the light signal.
- Throughput: The rate at which data is efficiently sent from the LiFi Access Point to the receiver.
- Latency: The delay experienced in delivering packets across the LiFi network.
- Packet Loss: Compute the percentage of lost packets because of mobility or line-of-sight obstructions.
Step 10: Extend the Simulation
- Multi-Cell LiFi Network: Configure numerous LiFi Access Points to replicate a multi-cell LiFi network in which users can move among the cells, like a handover in Wi-Fi or cellular networks.
- Hybrid LiFi and Wi-Fi Network: Replicate a hybrid network in which users are switch among the LiFi and Wi-Fi according to signal quality or location, preventing the seamless handover among the two technologies.
- Data Aggregation: Execute the data aggregation at the LiFi Access Points to enhance the transmission of high-bandwidth data like video streams.
- Security in LiFi: Mimic security aspects like encryption (e.g., AES) to make sure that secure communication across the LiFi channel.
These project ideas deliver a wide range of simulations process to replicate the LiFi through the simulation environment NS3. We plan to deliver the detailed instructions to these projects to in further scripts.
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