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friis-spectrum-propagation-loss.cc
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1 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
2 /*
3  * Copyright (c) 2009 CTTC
4  *
5  * This program is free software; you can redistribute it and/or modify
6  * it under the terms of the GNU General Public License version 2 as
7  * published by the Free Software Foundation;
8  *
9  * This program is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12  * GNU General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program; if not, write to the Free Software
16  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
17  *
18  * Author: Nicola Baldo <nbaldo@cttc.es>
19  */
20 
21 #include <ns3/mobility-model.h>
22 #include <ns3/friis-spectrum-propagation-loss.h>
23 #include <cmath> // for M_PI
24 
25 
26 namespace ns3 {
27 
28 NS_OBJECT_ENSURE_REGISTERED (FriisSpectrumPropagationLossModel);
29 
30 
31 FriisSpectrumPropagationLossModel::FriisSpectrumPropagationLossModel ()
32 {
33 }
34 
35 FriisSpectrumPropagationLossModel::~FriisSpectrumPropagationLossModel ()
36 {
37 }
38 
39 
40 TypeId
41 FriisSpectrumPropagationLossModel::GetTypeId (void)
42 {
43  static TypeId tid = TypeId ("ns3::FriisSpectrumPropagationLossModel")
44  .SetParent<SpectrumPropagationLossModel> ()
45  .AddConstructor<FriisSpectrumPropagationLossModel> ()
46  ;
47  return tid;
48 }
49 
50 
51 Ptr<SpectrumValue>
52 FriisSpectrumPropagationLossModel::DoCalcRxPowerSpectralDensity (Ptr<const SpectrumValue> txPsd,
53  Ptr<const MobilityModel> a,
54  Ptr<const MobilityModel> b) const
55 {
56  Ptr<SpectrumValue> rxPsd = Copy<SpectrumValue> (txPsd);
57  Values::iterator vit = rxPsd->ValuesBegin ();
58  Bands::const_iterator fit = rxPsd->ConstBandsBegin ();
59 
60  NS_ASSERT (a);
61  NS_ASSERT (b);
62 
63  double d = a->GetDistanceFrom (b);
64 
65  while (vit != rxPsd->ValuesEnd ())
66  {
67  NS_ASSERT (fit != rxPsd->ConstBandsEnd ());
68  *vit /= CalculateLoss (fit->fc, d); // Prx = Ptx / loss
69  ++vit;
70  ++fit;
71  }
72  return rxPsd;
73 }
74 
75 
76 double
77 FriisSpectrumPropagationLossModel::CalculateLoss (double f, double d) const
78 {
79  NS_ASSERT (d >= 0);
80 
81  if (d == 0)
82  {
83  return 1;
84  }
85 
86  NS_ASSERT (f > 0);
87  double loss_sqrt = (4 * M_PI * f * d) / 3e8;
88  double loss = loss_sqrt * loss_sqrt;
89 
90  if (loss < 1)
91  {
92  loss = 1;
93  }
94  return loss;
95 }
96 
97 
98 
99 
100 
101 
102 
103 
104 
105 
106 
107 } // namespace ns3