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dsss-error-rate-model.cc
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1 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
2 /*
3  * Copyright (c) 2010 The Boeing Company
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: Gary Pei <guangyu.pei@boeing.com>
19  */
20 
21 #include "ns3/log.h"
22 #include "dsss-error-rate-model.h"
23 #include <cmath>
24 
25 NS_LOG_COMPONENT_DEFINE ("DsssErrorRateModel");
26 
27 namespace ns3 {
28 
29 #ifndef ENABLE_GSL
30 const double DsssErrorRateModel::WLAN_SIR_PERFECT = 10.0;
32 #endif
33 
34 double
36 {
38  return ((std::sqrt (2.0) + 1.0) / std::sqrt (8.0 * 3.1415926 * std::sqrt (2.0)))
39  * (1.0 / std::sqrt (x)) * std::exp ( -(2.0 - std::sqrt (2.0)) * x);
40 }
41 
42 double
43 DsssErrorRateModel::GetDsssDbpskSuccessRate (double sinr, uint32_t nbits)
44 {
46  double EbN0 = sinr * 22000000.0 / 1000000.0; // 1 bit per symbol with 1 MSPS
47  double ber = 0.5 * std::exp (-EbN0);
48  return std::pow ((1.0 - ber), static_cast<double> (nbits));
49 }
50 
51 double
52 DsssErrorRateModel::GetDsssDqpskSuccessRate (double sinr,uint32_t nbits)
53 {
55  double EbN0 = sinr * 22000000.0 / 1000000.0 / 2.0; // 2 bits per symbol, 1 MSPS
56  double ber = DqpskFunction (EbN0);
57  return std::pow ((1.0 - ber), static_cast<double> (nbits));
58 }
59 
60 double
62 {
64 #ifdef ENABLE_GSL
65  // symbol error probability
66  double EbN0 = sinr * 22000000.0 / 1375000.0 / 4.0;
67  double sep = SymbolErrorProb16Cck (4.0 * EbN0 / 2.0);
68  return std::pow (1.0 - sep,nbits / 4.0);
69 #else
70  NS_LOG_WARN ("Running a 802.11b CCK Matlab model less accurate than GSL model");
71  // The matlab model
72  double ber;
73  if (sinr > WLAN_SIR_PERFECT)
74  {
75  ber = 0.0;
76  }
77  else if (sinr < WLAN_SIR_IMPOSSIBLE)
78  {
79  ber = 0.5;
80  }
81  else
82  {
83  // fitprops.coeff from matlab berfit
84  double a1 = 5.3681634344056195e-001;
85  double a2 = 3.3092430025608586e-003;
86  double a3 = 4.1654372361004000e-001;
87  double a4 = 1.0288981434358866e+000;
88  ber = a1 * std::exp (-std::pow ((sinr - a2) / a3, a4));
89  }
90  return std::pow ((1.0 - ber), static_cast<double> (nbits));
91 #endif
92 }
93 
94 double
96 {
98 #ifdef ENABLE_GSL
99  // symbol error probability
100  double EbN0 = sinr * 22000000.0 / 1375000.0 / 8.0;
101  double sep = SymbolErrorProb256Cck (8.0 * EbN0 / 2.0);
102  return std::pow (1.0 - sep, nbits / 8.0);
103 #else
104  NS_LOG_WARN ("Running a 802.11b CCK Matlab model less accurate than GSL model");
105  // The matlab model
106  double ber;
107  if (sinr > WLAN_SIR_PERFECT)
108  {
109  ber = 0.0;
110  }
111  else if (sinr < WLAN_SIR_IMPOSSIBLE)
112  {
113  ber = 0.5;
114  }
115  else
116  {
117  // fitprops.coeff from matlab berfit
118  double a1 = 7.9056742265333456e-003;
119  double a2 = -1.8397449399176360e-001;
120  double a3 = 1.0740689468707241e+000;
121  double a4 = 1.0523316904502553e+000;
122  double a5 = 3.0552298746496687e-001;
123  double a6 = 2.2032715128698435e+000;
124  ber = (a1 * sinr * sinr + a2 * sinr + a3) / (sinr * sinr * sinr + a4 * sinr * sinr + a5 * sinr + a6);
125  }
126  return std::pow ((1.0 - ber), static_cast<double> (nbits));
127 #endif
128 }
129 
130 #ifdef ENABLE_GSL
131 double
132 IntegralFunction (double x, void *params)
133 {
134  double beta = ((FunctionParameters *) params)->beta;
135  double n = ((FunctionParameters *) params)->n;
136  double IntegralFunction = std::pow (2 * gsl_cdf_ugaussian_P (x + beta) - 1, n - 1)
137  * std::exp (-x * x / 2.0) / std::sqrt (2.0 * M_PI);
138  return IntegralFunction;
139 }
140 
141 double
142 DsssErrorRateModel::SymbolErrorProb16Cck (double e2)
143 {
144  double sep;
145  double error;
146 
147  FunctionParameters params;
148  params.beta = std::sqrt (2.0 * e2);
149  params.n = 8.0;
150 
151  gsl_integration_workspace * w = gsl_integration_workspace_alloc (1000);
152 
153  gsl_function F;
154  F.function = &IntegralFunction;
155  F.params = &params;
156 
157  gsl_integration_qagiu (&F,-params.beta, 0, 1e-7, 1000, w, &sep, &error);
158  gsl_integration_workspace_free (w);
159  if (error == 0.0)
160  {
161  sep = 1.0;
162  }
163 
164  return 1.0 - sep;
165 }
166 
167 double DsssErrorRateModel::SymbolErrorProb256Cck (double e1)
168 {
169  return 1.0 - std::pow (1.0 - SymbolErrorProb16Cck (e1 / 2.0), 2.0);
170 }
171 
172 #endif
173 
174 } // namespace ns3
static double GetDsssDqpskCck11SuccessRate(double sinr, uint32_t nbits)
Return the chunk success rate of the differential encoded QPSK for 11Mbps data rate.
static const double WLAN_SIR_PERFECT
NS_LOG_COMPONENT_DEFINE("DsssErrorRateModel")
static double GetDsssDqpskSuccessRate(double sinr, uint32_t nbits)
Return the chunk success rate of the differential encoded QPSK.
#define NS_LOG_FUNCTION_NOARGS()
Output the name of the function.
Definition: log.h:309
static double GetDsssDqpskCck5_5SuccessRate(double sinr, uint32_t nbits)
Return the chunk success rate of the differential encoded QPSK for 5.5Mbps data rate.
#define NS_LOG_WARN(msg)
Definition: log.h:280
static const double WLAN_SIR_IMPOSSIBLE
static double DqpskFunction(double x)
A function DQPSK.
static double GetDsssDbpskSuccessRate(double sinr, uint32_t nbits)
Return the chunk success rate of the differential BPSK.