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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 
22 #include <ns3/mobility-model.h>
23 #include <ns3/friis-spectrum-propagation-loss.h>
24 #include <math.h>
25 
26 
27 
28 namespace ns3 {
29 
30 NS_OBJECT_ENSURE_REGISTERED (FriisSpectrumPropagationLossModel);
31 
32 
33 FriisSpectrumPropagationLossModel::FriisSpectrumPropagationLossModel ()
34 {
35 }
36 
37 FriisSpectrumPropagationLossModel::~FriisSpectrumPropagationLossModel ()
38 {
39 }
40 
41 
42 TypeId
43 FriisSpectrumPropagationLossModel::GetTypeId (void)
44 {
45  static TypeId tid = TypeId ("ns3::FriisSpectrumPropagationLossModel")
46  .SetParent<SpectrumPropagationLossModel> ()
47  .AddConstructor<FriisSpectrumPropagationLossModel> ()
48  ;
49  return tid;
50 }
51 
52 
53 Ptr<SpectrumValue>
54 FriisSpectrumPropagationLossModel::DoCalcRxPowerSpectralDensity (Ptr<const SpectrumValue> txPsd,
55  Ptr<const MobilityModel> a,
56  Ptr<const MobilityModel> b) const
57 {
58  Ptr<SpectrumValue> rxPsd = Copy<SpectrumValue> (txPsd);
59  Values::iterator vit = rxPsd->ValuesBegin ();
60  Bands::const_iterator fit = rxPsd->ConstBandsBegin ();
61 
62  NS_ASSERT (a);
63  NS_ASSERT (b);
64 
65  double d = a->GetDistanceFrom (b);
66 
67  while (vit != rxPsd->ValuesEnd ())
68  {
69  NS_ASSERT (fit != rxPsd->ConstBandsEnd ());
70  *vit /= CalculateLoss (fit->fc, d); // Prx = Ptx / loss
71  ++vit;
72  ++fit;
73  }
74  return rxPsd;
75 }
76 
77 
78 double
79 FriisSpectrumPropagationLossModel::CalculateLoss (double f, double d) const
80 {
81  NS_ASSERT (d >= 0);
82 
83  if (d == 0)
84  {
85  return 1;
86  }
87 
88  NS_ASSERT (f > 0);
89  double loss_sqrt = (4 * M_PI * f * d) / 3e8;
90  double loss = loss_sqrt * loss_sqrt;
91 
92  if (loss < 1)
93  {
94  loss = 1;
95  }
96  return loss;
97 }
98 
99 
100 
101 
102 
103 
104 
105 
106 
107 
108 
109 } // namespace ns3