给一个ns-3.27基于NS-3的WIFI性能仿真代码

以下是一个基于ns-3.27的NS-3 WIFI性能仿真代码，用于模拟802.11n网络的性能。

#include "ns3/core-module.h"
#include "ns3/mobility-module.h"
#include "ns3/wifi-module.h"
#include "ns3/internet-module.h"
#include "ns3/network-module.h"
#include "ns3/applications-module.h"
#include "ns3/flow-monitor-helper.h"
#include "ns3/flow-monitor-module.h"

using namespace ns3;

NS_LOG_COMPONENT_DEFINE ("WifiN");

int main (int argc, char *argv[])
{
  uint32_t nWifi = 3;
  bool verbose = false;
  CommandLine cmd;
  cmd.AddValue ("nWifi", "Number of wifi STA devices", nWifi);
  cmd.AddValue ("verbose", "Turn on all WifiNetDevice log components", verbose);
  cmd.Parse (argc,argv);

  if (verbose)
    {
      LogComponentEnableAll (LOG_LEVEL_INFO);
      LogComponentEnable ("WifiNetDevice", LOG_LEVEL_ALL);
    }

  NodeContainer wifiStaNodes;
  wifiStaNodes.Create (nWifi);

  NodeContainer wifiApNode;
  wifiApNode.Create (1);

  YansWifiChannelHelper channel = YansWifiChannelHelper::Default ();
  YansWifiPhyHelper phy = YansWifiPhyHelper::Default ();
  phy.SetChannel (channel.Create ());

  WifiHelper wifi = WifiHelper::Default ();
  wifi.SetRemoteStationManager ("ns3::AarfWifiManager");

  NqosWifiMacHelper mac = NqosWifiMacHelper::Default ();

  Ssid ssid = Ssid ("ns-3-ssid");
  mac.SetType ("ns3::StaWifiMac", "Ssid", SsidValue (ssid), "ActiveProbing", BooleanValue (false));

  NetDeviceContainer staDevices;
  staDevices = wifi.Install (phy, mac, wifiStaNodes);

  mac.SetType ("ns3::ApWifiMac", "Ssid", SsidValue (ssid));
  NetDeviceContainer apDevice;
  apDevice = wifi.Install (phy, mac, wifiApNode);

  MobilityHelper mobility;
  mobility.SetPositionAllocator ("ns3::GridPositionAllocator",
                                  "MinX", DoubleValue (0.0),
                                  "MinY", DoubleValue (0.0),
                                  "DeltaX", DoubleValue (5.0),
                                  "DeltaY", DoubleValue (10.0),
                                  "GridWidth", UintegerValue (3),
                                  "LayoutType", StringValue ("RowFirst"));
  mobility.SetMobilityModel ("ns3::RandomWalk2dMobilityModel",
                              "Bounds", RectangleValue (Rectangle (-50, 50, -50, 50)));
  mobility.Install (wifiStaNodes);
  mobility.SetMobilityModel ("ns3::ConstantPositionMobilityModel");
  mobility.Install (wifiApNode);

  InternetStackHelper stack;
  stack.Install (wifiApNode);
  stack.Install (wifiStaNodes);

  Ipv4AddressHelper address;
  address.SetBase ("10.1.1.0", "255.255.255.0");
  Ipv4InterfaceContainer staNodeInterface;
  staNodeInterface = address.Assign (staDevices);

  address.SetBase ("10.1.2.0", "255.255.255.0");
  Ipv4InterfaceContainer apNodeInterface;
  apNodeInterface = address.Assign (apDevice);

  UdpEchoServerHelper echoServer (9);

  ApplicationContainer serverApps = echoServer.Install (wifiApNode.Get (0));
  serverApps.Start (Seconds (1.0));
  serverApps.Stop (Seconds (10.0));

  UdpEchoClientHelper echoClient (apNodeInterface.GetAddress (0), 9);
  echoClient.SetAttribute ("MaxPackets", UintegerValue (1));
  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 (10.0));

  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 (std::map<FlowId, FlowMonitor::FlowStats>::const_iterator i = stats.begin (); i != stats.end (); ++i)
    {
      Ipv4FlowClassifier::FiveTuple t = classifier->FindFlow (i->first);
      std::cout << "Flow " << i->first << " (" << t.sourceAddress << " -> " << t.destinationAddress << ")\n";
      std::cout << "  Tx Bytes:   " << i->second.txBytes << "\n";
      std::cout << "  Rx Bytes:   " << i->second.rxBytes << "\n";
      std::cout << "  Throughput: " << i->second.rxBytes * 8.0 / 9.0 / 1000 / 1000 << " Mbps\n";
    }

  Simulator::Destroy ();

  return 0;
}

这个代码创建了一个包含一个AP和三个STA的802.11n网络，使用UDP Echo协议进行通信，并使用Flow Monitor模块监测网络流量。