noiseFloor -> noiseFigure (bug 543)

src/devices/wifi/interference-helper.cc

@@ -137,15 +137,15 @@ InterferenceHelper::GetMaxPacketDuration (void) const
 }
 
 void 
-InterferenceHelper::SetNoiseFloorW (double noiseFloor)
+InterferenceHelper::SetNoiseFigure (double value)
 {
-  m_noiseFloorW = noiseFloor;
+  m_noiseFigure = value;
 }
 
 double 
-InterferenceHelper::GetNoiseFloorW (void) const
+InterferenceHelper::GetNoiseFigure (void) const
 {
-  return m_noiseFloorW;
+  return m_noiseFigure;
 }
 
 void 
@@ -260,9 +260,10 @@ InterferenceHelper::CalculateSnr (double signal, double noiseInterference, WifiM
 {
   // thermal noise at 290K in J/s = W
   static const double BOLTZMANN = 1.3803e-23;
+  // Nt is the power of thermal noise in W
   double Nt = BOLTZMANN * 290.0 * mode.GetBandwidth ();
-  // receiver noise Floor (W)
-  double noiseFloor = m_noiseFloorW * Nt;
+  // receiver noise Floor (W) which accounts for thermal noise and non-idealities of the receiver
+  double noiseFloor = m_noiseFigure * Nt;
   double noise = noiseFloor + noiseInterference;
   double snr = signal / noise;
   return snr;

src/devices/wifi/interference-helper.h

@@ -50,10 +50,10 @@ public:
   ~InterferenceHelper ();
 
   void Configure80211aParameters (void);
-  void SetNoiseFloorW (double noiseFloor);
+  void SetNoiseFigure (double value);
   void SetErrorRateModel (Ptr<ErrorRateModel> rate);
 
-  double GetNoiseFloorW (void) const;
+  double GetNoiseFigure (void) const;
   Ptr<ErrorRateModel> GetErrorRateModel (void) const;
 
 
@@ -99,7 +99,7 @@ private:
   WifiMode m_shortPlcpHeaderMode;
   uint32_t m_plcpHeaderLength;
   Time m_maxPacketDuration;
-  double m_noiseFloorW;
+  double m_noiseFigure; /**< noise figure (linear) */
   Events m_events;
   bool m_80211a;
   Ptr<ErrorRateModel> m_errorRateModel;

src/devices/wifi/yans-wifi-phy.cc

@@ -93,11 +93,17 @@ YansWifiPhy::GetTypeId (void)
                    MakeDoubleAccessor (&YansWifiPhy::SetTxPowerStart, 
                                        &YansWifiPhy::GetTxPowerStart),
                    MakeDoubleChecker<double> ())
-    .AddAttribute ("RxNoise",
-                   "Ratio of energy lost by receiver (dB).",
+    .AddAttribute ("RxNoiseFigure",
+                   "Loss (dB) in the Signal-to-Noise-Ratio due to non-idealities in the receiver."
+                   " According to Wikipedia (http://en.wikipedia.org/wiki/Noise_figure), this is "
+                   "\"the difference in decibels (dB) between"
+                   " the noise output of the actual receiver to the noise output of an "
+                   " ideal receiver with the same overall gain and bandwidth when the receivers "
+                   " are connected to sources at the standard noise temperature T0 (usually 290 K)\"."
+                   " For",
                    DoubleValue (7),
-                   MakeDoubleAccessor (&YansWifiPhy::SetRxNoise,
-                                       &YansWifiPhy::GetRxNoise),
+                   MakeDoubleAccessor (&YansWifiPhy::SetRxNoiseFigure,
+                                       &YansWifiPhy::GetRxNoiseFigure),
                    MakeDoubleChecker<double> ())
     .AddAttribute ("Standard", "The standard chosen configures a set of transmission modes"
                    " and some PHY-specific constants.",
@@ -155,10 +161,10 @@ YansWifiPhy::SetStandard (enum WifiPhyStandard standard)
 
 
 void 
-YansWifiPhy::SetRxNoise (double db)
+YansWifiPhy::SetRxNoiseFigure (double noiseFigureDb)
 {
-  NS_LOG_FUNCTION (this << db);
-  m_interference.SetNoiseFloorW (DbToRatio (db));
+  NS_LOG_FUNCTION (this << noiseFigureDb);
+  m_interference.SetNoiseFigure (DbToRatio (noiseFigureDb));
 }
 void 
 YansWifiPhy::SetTxPowerStart (double start)
@@ -219,9 +225,9 @@ YansWifiPhy::SetMobility (Ptr<Object> mobility)
 }
 
 double 
-YansWifiPhy::GetRxNoise (void) const
+YansWifiPhy::GetRxNoiseFigure (void) const
 {
-  return RatioToDb (m_interference.GetNoiseFloorW ());
+  return RatioToDb (m_interference.GetNoiseFigure ());
 }
 double 
 YansWifiPhy::GetTxPowerStart (void) const

src/devices/wifi/yans-wifi-phy.h

@@ -75,7 +75,7 @@ public:
                            WifiPreamble preamble);
 
   void SetStandard (enum WifiPhyStandard standard);
-  void SetRxNoise (double ratio);
+  void SetRxNoiseFigure (double noiseFigureDb);
   void SetTxPowerStart (double start);
   void SetTxPowerEnd (double end);
   void SetNTxPower (uint32_t n);
@@ -86,7 +86,7 @@ public:
   void SetErrorRateModel (Ptr<ErrorRateModel> rate);
   void SetDevice (Ptr<Object> device);
   void SetMobility (Ptr<Object> mobility);
-  double GetRxNoise (void) const;
+  double GetRxNoiseFigure (void) const;
   double GetTxGain (void) const;
   double GetRxGain (void) const;
   double GetEdThreshold (void) const;