以wifi-example-sim.cc为例说明NS3统计数据模型

http://blog.csdn.net/yanerhao/article/details/53979539

利用NS3已有的Trace系统或者Log机制收集记录和统计数据，例如MAC层收发帧数目，网络层以上收发包数目的跟踪与统计，这里选取example/stats/wifi-example-sim.cc为例来很好说明问题：

这个仿真程序是一个简单的实验，包括两个节点，基于AdhocMAC信道模型，包含NS3仿真所需常见模型如节点/网络设备/协议栈和应用进程，这里的应用进程Sender   和Receiver，基于UDP的不可靠连接。

#include <ctime>
#include <sstream>
#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/stats-module.h"
#include "wifi-example-apps.h"
using namespace ns3;
using namespace std;
NS_LOG_COMPONENT_DEFINE ("WiFiDistanceExperiment");
void TxCallback (Ptr<CounterCalculator<uint32_t> > datac,
                 std::string path, Ptr<const Packet> packet) {
  NS_LOG_INFO ("Sent frame counted in " <<
               datac->GetKey ());
  datac->Update ();
  // end TxCallback
}
//----------------------------------------------------------------------
//-- main
//----------------------------------------------
int main (int argc, char *argv[]) {

  double distance = 50.0;
  string format ("omnet");

  string experiment ("wifi-distance-test");
  string strategy ("wifi-default");
  string input;
  string runID;

  {
    stringstream sstr;
    sstr << "run-" << time (NULL);
    runID = sstr.str ();
  }

  // Set up command line parameters used to control the experiment.
  CommandLine cmd;
  cmd.AddValue ("distance", "Distance apart to place nodes (in meters).",
                distance);
  cmd.AddValue ("format", "Format to use for data output.",
                format);
  cmd.AddValue ("experiment", "Identifier for experiment.",
                experiment);
  cmd.AddValue ("strategy", "Identifier for strategy.",
                strategy);
  cmd.AddValue ("run", "Identifier for run.",
                runID);
  cmd.Parse (argc, argv);

  if (format != "omnet" && format != "db") {
      NS_LOG_ERROR ("Unknown output format '" << format << "'");
      return -1;
    }

  #ifndef STATS_HAS_SQLITE3
  if (format == "db") {
      NS_LOG_ERROR ("sqlite support not compiled in.");
      return -1;
    }
  #endif

  {
    stringstream sstr ("");
    sstr << distance;
    input = sstr.str ();
  }
  //------------------------------------------------------------
  //-- Create nodes and network stacks
  //--------------------------------------------
  NS_LOG_INFO ("Creating nodes.");
  NodeContainer nodes;
  nodes.Create (2);

  NS_LOG_INFO ("Installing WiFi and Internet stack.");
  WifiHelper wifi;
  WifiMacHelper wifiMac;
  wifiMac.SetType ("ns3::AdhocWifiMac");
  YansWifiPhyHelper wifiPhy = YansWifiPhyHelper::Default ();
  YansWifiChannelHelper wifiChannel = YansWifiChannelHelper::Default ();
  wifiPhy.SetChannel (wifiChannel.Create ());
  NetDeviceContainer nodeDevices = wifi.Install (wifiPhy, wifiMac, nodes);

  InternetStackHelper internet;
  internet.Install (nodes);
  Ipv4AddressHelper ipAddrs;
  ipAddrs.SetBase ("192.168.0.0", "255.255.255.0");
  ipAddrs.Assign (nodeDevices);
  //------------------------------------------------------------
  //-- Setup physical layout
  //--------------------------------------------
  NS_LOG_INFO ("Installing static mobility; distance " << distance << " .");
  MobilityHelper mobility;
  Ptr<ListPositionAllocator> positionAlloc =
    CreateObject<ListPositionAllocator>();
  positionAlloc->Add (Vector (0.0, 0.0, 0.0));
  positionAlloc->Add (Vector (0.0, distance, 0.0));
  mobility.SetPositionAllocator (positionAlloc);
  mobility.Install (nodes);
  //------------------------------------------------------------
  //-- Create a custom traffic source and sink
  //--------------------------------------------
  NS_LOG_INFO ("Create traffic source & sink.");
  Ptr<Node> appSource = NodeList::GetNode (0);
  Ptr<Sender> sender = CreateObject<Sender>();
  appSource->AddApplication (sender);
  sender->SetStartTime (Seconds (1));

  Ptr<Node> appSink = NodeList::GetNode (1);
  Ptr<Receiver> receiver = CreateObject<Receiver>();
  appSink->AddApplication (receiver);
  receiver->SetStartTime (Seconds (0));

  Config::Set ("/NodeList/*/ApplicationList/*/$Sender/Destination",
               Ipv4AddressValue ("192.168.0.2"));
  //------------------------------------------------------------
  //-- Setup stats and data collection
  //--------------------------------------------

  // Create a DataCollector object to hold information about this run.
  DataCollector data;
  data.DescribeRun (experiment,//experiment 是对象
                    strategy,//strategy 是被检查的代码或者参数
                    input,//2个节点距离
                    runID);

  // Add any information we wish to record about this run.
  data.AddMetadata ("author", "tjkopena");

  // Create a counter to track how many frames are generated.  Updates
  // are triggered by the trace signal generated by the WiFi MAC model
  // object.  Here we connect the counter to the signal via the simple
  // TxCallback() glue function defined above.
  Ptr<CounterCalculator<uint32_t> > totalTx =
    CreateObject<CounterCalculator<uint32_t> >();
  totalTx->SetKey ("wifi-tx-frames");
  totalTx->SetContext ("node[0]");
  Config::Connect ("/NodeList/0/DeviceList/*/$ns3::WifiNetDevice/Mac/MacTx",
                   MakeBoundCallback (&TxCallback, totalTx));
  data.AddDataCalculator (totalTx);

  // This is similar, but creates a counter to track how many frames
  // are received.  Instead of our own glue function, this uses a
  // method of an adapter class to connect a counter directly to the
  // trace signal generated by the WiFi MAC.
  Ptr<PacketCounterCalculator> totalRx =
    CreateObject<PacketCounterCalculator>();
  totalRx->SetKey ("wifi-rx-frames");
  totalRx->SetContext ("node[1]");
  Config::Connect ("/NodeList/1/DeviceList/*/$ns3::WifiNetDevice/Mac/MacRx",
                   MakeCallback (&PacketCounterCalculator::PacketUpdate,
                                 totalRx));
  data.AddDataCalculator (totalRx);
  // This counter tracks how many packets---as opposed to frames---are
  // generated.  This is connected directly to a trace signal provided
  // by our Sender class.
  Ptr<PacketCounterCalculator> appTx =
    CreateObject<PacketCounterCalculator>();
  appTx->SetKey ("sender-tx-packets");
  appTx->SetContext ("node[0]");
  Config::Connect ("/NodeList/0/ApplicationList/*/$Sender/Tx",
                   MakeCallback (&PacketCounterCalculator::PacketUpdate,
                                 appTx));
  data.AddDataCalculator (appTx);

  // Here a counter for received packets is directly manipulated by
  // one of the custom objects in our simulation, the Receiver
  // Application.  The Receiver object is given a pointer to the
  // counter and calls its Update() method whenever a packet arrives.
  Ptr<CounterCalculator<> > appRx =
    CreateObject<CounterCalculator<> >();
  appRx->SetKey ("receiver-rx-packets");
  appRx->SetContext ("node[1]");
  receiver->SetCounter (appRx);
  data.AddDataCalculator (appRx);
  /**
   * Just to show this is here...
   Ptr<MinMaxAvgTotalCalculator<uint32_t> > test =
   CreateObject<MinMaxAvgTotalCalculator<uint32_t> >();
   test->SetKey("test-dc");
   data.AddDataCalculator(test);

   test->Update(4);
   test->Update(8);
   test->Update(24);
   test->Update(12);
  **/

  // This DataCalculator connects directly to the transmit trace
  // provided by our Sender Application.  It records some basic
  // statistics about the sizes of the packets received (min, max,
  // avg, total # bytes), although in this scenaro they're fixed.
  Ptr<PacketSizeMinMaxAvgTotalCalculator> appTxPkts =
    CreateObject<PacketSizeMinMaxAvgTotalCalculator>();
  appTxPkts->SetKey ("tx-pkt-size");
  appTxPkts->SetContext ("node[0]");
  Config::Connect ("/NodeList/0/ApplicationList/*/$Sender/Tx",
                   MakeCallback
                     (&PacketSizeMinMaxAvgTotalCalculator::PacketUpdate,
                     appTxPkts));
  data.AddDataCalculator (appTxPkts);
  // Here we directly manipulate another DataCollector tracking min,
  // max, total, and average propagation delays.  Check out the Sender
  // and Receiver classes to see how packets are tagged with
  // timestamps to do this.
  Ptr<TimeMinMaxAvgTotalCalculator> delayStat =
    CreateObject<TimeMinMaxAvgTotalCalculator>();
  delayStat->SetKey ("delay");
  delayStat->SetContext (".");
  receiver->SetDelayTracker (delayStat);
  data.AddDataCalculator (delayStat);


  //------------------------------------------------------------
  //-- Run the simulation
  //--------------------------------------------
  NS_LOG_INFO ("Run Simulation.");
  Simulator::Run ();
  //------------------------------------------------------------
  //-- Generate statistics output.
  //--------------------------------------------

  // Pick an output writer based in the requested format.
  Ptr<DataOutputInterface> output = 0;
  if (format == "omnet") {
      NS_LOG_INFO ("Creating omnet formatted data output.");
      output = CreateObject<OmnetDataOutput>();
    } else if (format == "db") {
    #ifdef STATS_HAS_SQLITE3
      NS_LOG_INFO ("Creating sqlite formatted data output.");
      output = CreateObject<SqliteDataOutput>();
    #endif
    } else {
      NS_LOG_ERROR ("Unknown output format " << format);
    }

  // Finally, have that writer interrogate the DataCollector and save
  // the results.
  if (output != 0)
    output->Output (data);

  // Free any memory here at the end of this example.
  Simulator::Destroy ();

  // end main
}

一 给定本次仿真参数distance，format，experiment，strategy，runID在初始化的同时也可以通过命令行改变，这些参数用于从多次实验中快速区分和组合数据。

二 创建节点和网络模型

三 安装协议栈，并分配IP

四 设置移动模型，这里为静止，并给定初始位置

五 安装应用，这里安装Sender / Receiver，自定义的见examples/stats/wifi-example-apps.h|cc

六 数据统计与收集，这是本文重点，下面具体分析。

这里创建DataCollector对象来存储运行信息，并通过Trace机制记录收发端帧和分组传输情况。

1 记录发端帧传输（基WIFI MAC对界）

通过CounterCalculator(src/stats/model/basic-data-calculators.h )类实现计数，利用Trace机制，当节点0上wifiNetDevice/Mac/MacTx变化（source），通过Config::Connect关联，定义的TxCallback作为sink函数调用，导致CounterCalculator::update调用即m_count++从而起到计数功能;

2 记录收端帧传输（基WIFI MAC对界）

类似情况1，虽然这里的sink函数是PacketConterCalculator::PacketUpdate（src/network/utils/packet-data-calculators.cc），但是该函数仍然是通过CounterCalculator::update实现计数，即利用Trace机制，当节点1上wifiNetDevice/Mac/MacRx变化（source），通过Config::Connect关联;

3 记录发端分组传输

 也是通过PacketConterCalculator::PacketUpdate实现计数，利用Trace机制，当节点0上/Application/*/$Sender/Tx变化（source），通过通过Config::Connect关联，定义的PacketConterCalculator::PacketUpdate作为sink函数调用;

4 记录收端分组接收

由于收端应用Receiver没有定义traced source，故这里没有采用Trace机制，而是直接利用Receiver:;SetCounter直接操作，通过SetCounter显示类型转换，j将appRx赋值给Receiver内部计数器，从而实现计数

以上均是通过PacketConterCalculator(src/network/utils/packet-data-calculators.cc)或者CounterCalculator(src/stats/model/basic-data-calculators.h )实现传输单元的计数，下一个将通过引入PacketSizeMinMaxAvgTotalCalculator (src/network/utils/packet-data-calculators.h|cc)和MinMaxAvgTotalCalculator(src/stats/model/basic-data-calculators.h)实现单元内大小的记录。

5 记录发端分组大小

这里采用Trace机制，节点0上/Application/*/$Sender/Tx变化（source），通过通过Config::Connect关联，定义的PacketSizeMinMaxAvgTotalCalculator::PacketUpdate作为sink函数调用，从而MinMaxAvgTotalCalculator::Update实现大小的记录。

6 记录端到端产生分组时的延迟

类似情况4，不采用Trace机制，直接利用Receiver:;SetDelayTracker记录传世时延最值/平均值等

七 运行程序命令

八 统计结果输出

对于输出要么OMNet++(纯文本输出格式)要么SQLite(数据库格式输出)，这取决于程序头部定义的参数format，并最终DataCollector对象进行存储。

九 控制脚本实现最后运行

通过 一个简单的控制脚本实现该仿真程序在不同距离下大量重复（作为输入）实验后运行画图。可参考example/stats/wifi-example-db.sh（以后自己写多个不同输入下重复仿真项目时可参考这个）。该运行脚本每次都是基于一个不同的距离作为输入，收集每次仿真结果到SQLite数据库，其中对于每个距离输入，进行5次重复实验以减小波动。全部仿真完成只需几十秒，在完成存储到数据库后，可通过SQLite命令行进行SQL查询。并调用 wifi-example.gnuplot画图

进入该目录

cd /NS3/ns-allinone-3.25/ns-3.25/examples/stats
./wifi-example-db.sh

产生data.db数据库，wifi-default.data和wifi-default.eps图

图是对应距离下的丢包率以表征WiFi模型性能。