7.ns3 损失模型修改 - ns3

# 7.ns3 损失模型修改

在本节中，将介绍 ns3 中 wifi 损失模型模型修改 / 新增所需的一些内容，

# 代码

信道损失模型的源码位置如下

ns-3.xx/src/propagation/model

可以将自己的定义的信道损失模型添加到该路径，更改 wscript 文件，然后重新 build 一下 ns3

./waf build

主要更改 $DoCalcRxPower$ 函数即可
无线默认的损失模型是P_r=\frac{P_tG_tG_r\lambda^2}

Gt: tx gain (unit-less)
Gr: rx gain (unit-less)
Pt: tx power (W)
d: distance (m)
L: system loss
lambda: wavelength (m)
我改成了水下光学传播损耗模型中的 $P_r=P_te^{-c(\lambda)d}\eta_r\eta_t$
$\eta_r,\eta_t表示发射机的发射效率和接收机的接收效率$
$c(\lambda)$ 表示海水的衰减系数

以下是我定义的损失模型
MyPropagationLossModel.h

	/*************************************************************************
	> File Name: myLossModel.h
	> Author: yeyu
	> Mail: 554377661@qq.com
	> Created Time: Sun 17 Jan 2021 01:20:27 AM PST
	************************************************************************/
	#include "ns3/propagation-loss-model.h"
	#include "ns3/propagation-cache.h"
	namespace ns3 {
	class MyPropagationLossModel : public PropagationLossModel
	{
	private:
	//m_cLamada 海水的总衰减系数
	double m_cLamada;
	//m_nt 表示通信系统中发射机的发射效率，m_nr 表示通信系统中接收机的接收效率。
	double m_nt,m_nr;

	public:
	/**
	* \brief Get the type ID.
	* \return the object TypeId
	*/
	static TypeId GetTypeId (void);
	MyPropagationLossModel ();

	// 设置发送接收效率 (<=1)
	void SetSendReceiveEfficiency(double nt,double nr);

	//get 发送接收效率
	double GetReceiveEfficiency();
	double GetSendEfficiency();

	/**
	* set CLamada
	*/
	void SetCLamada (double cLamada);

	/**
	* get CLamada
	*/
	double GetCLamada ();
	/**
	* \param frequency (Hz)
	*
	* Set the carrier frequency used in the Friis model
	* calculation.
	*/
	void SetFrequency (double frequency);
	/**
	* \param systemLoss (dimension-less)
	*
	* Set the system loss used by the Friis propagation model.
	*/
	void SetSystemLoss (double systemLoss);

	/**
	* \param minLoss the minimum loss (dB)
	*
	* no matter how short the distance, the total propagation loss (in
	* dB) will always be greater or equal than this value
	*/
	void SetMinLoss (double minLoss);

	/**
	* \return the minimum loss.
	*/
	double GetMinLoss (void) const;

	/**
	* \returns the current frequency (Hz)
	*/
	double GetFrequency (void) const;
	/**
	* \returns the current system loss (dimension-less)
	*/
	double GetSystemLoss (void) const;

	private:
	/**
	* \brief Copy constructor
	*
	* Defined and unimplemented to avoid misuse
	*/
	MyPropagationLossModel (const MyPropagationLossModel &);
	/**
	* \brief Copy constructor
	*
	* Defined and unimplemented to avoid misuse
	* \returns
	*/
	MyPropagationLossModel & operator = (const MyPropagationLossModel &);

	virtual double DoCalcRxPower (double txPowerDbm,
	Ptr<MobilityModel> a,
	Ptr<MobilityModel> b) const;
	virtual int64_t DoAssignStreams (int64_t stream);

	/**
	* Transforms a Dbm value to Watt
	* \param dbm the Dbm value
	* \return the Watts
	*/
	double DbmToW (double dbm) const;

	/**
	* Transforms a Watt value to Dbm
	* \param w the Watt value
	* \return the Dbm
	*/
	double DbmFromW (double w) const;

	double m_lambda; //!< the carrier wavelength
	double m_frequency; //!< the carrier frequency
	double m_systemLoss; //!< the system loss
	double m_minLoss; //!< the minimum loss
	};
	} //end of namespace ns3

MyPropagationLossModel.cc 的具体实现

	#include "MyPropagationLossModel.h"
	#include "ns3/log.h"
	#include "ns3/mobility-model.h"
	#include "ns3/boolean.h"
	#include "ns3/double.h"
	#include "ns3/string.h"
	#include "ns3/pointer.h"
	#include <cmath>

	namespace ns3 {

	NS_LOG_COMPONENT_DEFINE ("MyLossModel");
	NS_OBJECT_ENSURE_REGISTERED (MyPropagationLossModel);

	TypeId
	MyPropagationLossModel::GetTypeId (void)
	{
	static TypeId tid = TypeId ("ns3::MyPropagationLossModel")
	.SetParent<PropagationLossModel> ()
	.SetGroupName ("Propagation")
	.AddConstructor<MyPropagationLossModel> ()
	.AddAttribute ("Frequency",
	"The carrier frequency (in Hz) at which propagation occurs (default is 5.15 GHz).",
	DoubleValue (5.150e9),
	MakeDoubleAccessor (&MyPropagationLossModel::SetFrequency,
	&MyPropagationLossModel::GetFrequency),
	MakeDoubleChecker<double> ())
	.AddAttribute ("SystemLoss", "The system loss",
	DoubleValue (1.0),
	MakeDoubleAccessor (&MyPropagationLossModel::m_systemLoss),
	MakeDoubleChecker<double> ())
	.AddAttribute ("MinLoss",
	"The minimum value (dB) of the total loss, used at short ranges. Note: ",
	DoubleValue (0.0),
	MakeDoubleAccessor (&MyPropagationLossModel::SetMinLoss,
	&MyPropagationLossModel::GetMinLoss),
	MakeDoubleChecker<double> ())
	/*
	.AddAttribute("CLamada",
	"CLamada is a double value",
	DoubleValue(0.056),
	MakeDoubleAccessor (&MyPropagationLossModel::m_cLamada,
	&MyPropagationLossModel::GetCLamada),
	MakeDoubleChecker<double> ()
	)
	*/
	;
	return tid;
	}

	MyPropagationLossModel::MyPropagationLossModel ()
	{
	m_cLamada=0.056;
	m_nr=1;
	m_nt=1;
	}
	// 设置发送接收效率 (<=1)
	void MyPropagationLossModel::SetSendReceiveEfficiency(double nt,double nr){
	m_nt=nt;
	m_nr=nr;
	}
	double MyPropagationLossModel::GetSendEfficiency(){
	return m_nt;
	}
	double MyPropagationLossModel::GetReceiveEfficiency(){
	return m_nr;
	}

	/**
	* set CLamada
	*/
	void MyPropagationLossModel::SetCLamada (double cLamada){
	m_cLamada=cLamada;
	}

	/**
	* get CLamada
	*/
	double MyPropagationLossModel::GetCLamada (){
	return m_cLamada;
	}

	void
	MyPropagationLossModel::SetSystemLoss (double systemLoss)
	{
	m_systemLoss = systemLoss;
	}
	double
	MyPropagationLossModel::GetSystemLoss (void) const
	{
	return m_systemLoss;
	}
	void
	MyPropagationLossModel::SetMinLoss (double minLoss)
	{
	m_minLoss = minLoss;
	}
	double
	MyPropagationLossModel::GetMinLoss (void) const
	{
	return m_minLoss;
	}

	void
	MyPropagationLossModel::SetFrequency (double frequency)
	{
	m_frequency = frequency;
	static const double C = 299792458.0; // speed of light in vacuum
	m_lambda = C / frequency;
	}

	double
	MyPropagationLossModel::GetFrequency (void) const
	{
	return m_frequency;
	}

	double
	MyPropagationLossModel::DbmToW (double dbm) const
	{
	double mw = std::pow (10.0,dbm/10.0);
	return mw / 1000.0;
	}

	double
	MyPropagationLossModel::DbmFromW (double w) const
	{
	double dbm = std::log10 (w * 1000.0) * 10.0;
	return dbm;
	}

	double
	MyPropagationLossModel::DoCalcRxPower (double txPowerDbm,
	Ptr<MobilityModel> a,
	Ptr<MobilityModel> b) const
	{
	NS_LOG_WARN("this a test model");


	double distance = a->GetDistanceFrom (b);
	if (distance <= 0)
	{
	return txPowerDbm - m_minLoss;
	}
	double myLossDb=-10 * log10 (pow(M_E,-m_cLamada*distance));

	//NS_LOG_WARN ("distance=" << distance<< "m, loss=" << myLossDb <<"dB");
	//return txPowerDbm - std::max (myLossDb, m_minLoss);
	double tmp=txPowerDbm - std::max (myLossDb, m_minLoss);
	NS_LOG_WARN ("发射dbm="<<txPowerDbm <<", distance=" <<distance<< "m, loss=" << myLossDb <<"dB"<<" 实际损失为:"<< tmp<<"dB");
	return tmp;


	}

	int64_t
	MyPropagationLossModel::DoAssignStreams (int64_t stream)
	{
	return 0;
	}

	}

使用方法
修改 wscript 文件，将 MyPropagationLossModel.h 和 MyPropagationLossModel.cc 添加到对应的位置
然后重新编译

	// 先导入已经编译好的头文件
	#include "ns3/MyPropagationLossModel.h"
	#include "ns3/applications-module.h"

	WifiMacHelper wifiMac;
	wifiMac.SetType ("ns3::AdhocWifiMac");
	YansWifiPhyHelper wifiPhy = YansWifiPhyHelper::Default ();
	YansWifiChannelHelper wifiChannel=YansWifiChannelHelper::Default();
	Ptr<MyPropagationLossModel> lossModel=CreateObject<MyPropagationLossModel>();
	lossModel->SetCLamada(0.398);
	printf("clamada:%f\n",lossModel->GetCLamada());
	Ptr<YansWifiChannel> myChannel=wifiChannel.Create();
	myChannel->SetPropagationLossModel(lossModel);
	wifiPhy.SetChannel (myChannel);

结果展示
最后的结果都是 dbm，之前写错了，一直没改 ==
图片标题

ns3

# 7.ns3 损失模型修改

# 代码

6.wifi模型扩展

8.ns3 wifi设备定向发送的实现