To implement the nearest antenna selection in ns3, we need to set-up a scenario based on the received signal strength or proximity in which the multiple antennas (or access points) are available, and mobile nodes (clients) select the nearest antenna.
The following steps will guide on implementing Nearest Antenna selection in ns3.
Step-by-step guide to implement Nearest Antenna Selection in ns3:
Step 1: Set Up the ns3 Environment
Make sure that ns3 is installed on the system.
Step 2: Create a Simulation Script
Create a new simulation script or modify an existing one to include the elements needed for nearest antenna selection.
Step 3: Define Network Topology
Define the network topology, including nodes, mobility models, and Wi-Fi configuration.
#include “ns3/core-module.h”
#include “ns3/network-module.h”
#include “ns3/mobility-module.h”
#include “ns3/wifi-module.h”
#include “ns3/internet-module.h”
#include “ns3/applications-module.h”
#include “ns3/config-store-module.h”
using namespace ns3;
NS_LOG_COMPONENT_DEFINE (“NearestAntennaSelection”);
int main (int argc, char *argv[])
{
// Set up default simulation parameters
uint32_t numApNodes = 3;
uint32_t numStaNodes = 2;
double simulationTime = 10.0; // seconds
CommandLine cmd;
cmd.Parse (argc, argv);
NodeContainer wifiApNodes;
wifiApNodes.Create (numApNodes);
NodeContainer wifiStaNodes;
wifiStaNodes.Create (numStaNodes);
YansWifiChannelHelper channel = YansWifiChannelHelper::Default ();
YansWifiPhyHelper phy = YansWifiPhyHelper::Default ();
phy.SetChannel (channel.Create ());
WifiHelper wifi;
wifi.SetStandard (WIFI_PHY_STANDARD_80211a);
WifiMacHelper mac;
Ssid ssid = Ssid (“ns3-ssid”);
mac.SetType (“ns3::ApWifiMac”,
“Ssid”, SsidValue (ssid));
NetDeviceContainer apDevices;
apDevices = wifi.Install (phy, mac, wifiApNodes);
mac.SetType (“ns3::StaWifiMac”,
“Ssid”, SsidValue (ssid),
“ActiveProbing”, BooleanValue (false));
NetDeviceContainer staDevices;
staDevices = wifi.Install (phy, mac, wifiStaNodes);
MobilityHelper mobility;
Ptr<ListPositionAllocator> positionAlloc = CreateObject<ListPositionAllocator> ();
positionAlloc->Add (Vector (0.0, 0.0, 0.0)); // Position of AP1
positionAlloc->Add (Vector (50.0, 0.0, 0.0)); // Position of AP2
positionAlloc->Add (Vector (100.0, 0.0, 0.0)); // Position of AP3
mobility.SetPositionAllocator (positionAlloc);
mobility.SetMobilityModel (“ns3::ConstantPositionMobilityModel”);
mobility.Install (wifiApNodes);
mobility.SetPositionAllocator (“ns3::RandomRectanglePositionAllocator”,
“X”, StringValue (“ns3::UniformRandomVariable[Min=0.0|Max=100.0]”),
“Y”, StringValue (“ns3::UniformRandomVariable[Min=0.0|Max=100.0]”));
mobility.SetMobilityModel (“ns3::RandomWalk2dMobilityModel”,
“Bounds”, RectangleValue (Rectangle (0, 100, 0, 100)));
mobility.Install (wifiStaNodes);
InternetStackHelper stack;
stack.Install (wifiApNodes);
stack.Install (wifiStaNodes);
Ipv4AddressHelper address;
address.SetBase (“10.1.1.0”, “255.255.255.0”);
Ipv4InterfaceContainer apInterfaces;
apInterfaces = address.Assign (apDevices);
Ipv4InterfaceContainer staInterfaces;
staInterfaces = address.Assign (staDevices);
// Install applications on the STA nodes
UdpEchoServerHelper echoServer (9);
ApplicationContainer serverApps = echoServer.Install (wifiApNodes.Get (0));
serverApps.Start (Seconds (1.0));
serverApps.Stop (Seconds (simulationTime));
UdpEchoClientHelper echoClient (apInterfaces.GetAddress (0), 9);
echoClient.SetAttribute (“MaxPackets”, UintegerValue (100));
echoClient.SetAttribute (“Interval”, TimeValue (Seconds (1.0)));
echoClient.SetAttribute (“PacketSize”, UintegerValue (1024));
ApplicationContainer clientApps = echoClient.Install (wifiStaNodes.Get (0));
clientApps.Start (Seconds (2.0));
clientApps.Stop (Seconds (simulationTime));
// Nearest antenna selection implementation
for (uint32_t i = 0; i < wifiStaNodes.GetN (); ++i)
{
Ptr<Node> staNode = wifiStaNodes.Get (i);
Ptr<NetDevice> staDevice = staNode->GetDevice (0);
Ptr<WifiNetDevice> wifiStaDevice = DynamicCast<WifiNetDevice> (staDevice);
Ptr<WifiPhy> phy = wifiStaDevice->GetPhy ();
Ptr<WifiRemoteStationManager> manager = wifiStaDevice->GetRemoteStationManager ();
double minDistance = std::numeric_limits<double>::max ();
Ptr<Node> nearestApNode;
for (uint32_t j = 0; j < wifiApNodes.GetN (); ++j)
{
Ptr<Node> apNode = wifiApNodes.Get (j);
double distance = staNode->GetObject<MobilityModel> ()->GetDistanceFrom (apNode);
if (distance < minDistance)
{
minDistance = distance;
nearestApNode = apNode;
}
}
if (nearestApNode != 0)
{
Ptr<NetDevice> apDevice = nearestApNode->GetDevice (0);
Ptr<WifiNetDevice> wifiApDevice = DynamicCast<WifiNetDevice> (apDevice);
manager->AddAp (wifiApDevice->GetBssid (), wifiApDevice->GetIfIndex ());
}
}
Simulator::Stop (Seconds (simulationTime));
Simulator::Run ();
Simulator::Destroy ();
return 0;
}
Step 4: Run the Simulation
Compile and run the simulation script to observe the nearest antenna selection.
./waf configure
./waf build
./waf –run scratch/your-script-name
Step 5: Analyze Results
After running the simulation, analyze the results to ensure that mobile nodes are connecting to the nearest antenna based on signal strength or proximity.
Additional Considerations
- Signal Strength: we can refine the selection criteria based on actual received signal strength instead of just distance.
- Mobility Model: Ensure that the mobility model accurately reflects the movement of nodes to test the selection mechanism.
- Dynamic Selection: Implement dynamic selection where nodes periodically reassess and switch to the nearest antenna as they move.
At last, we have implemented the Nearest Antenna Selection in ns3 by accessing multiple antennas which are available in the network for simulating and analyzing the result.
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