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1 /* -*- Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil; -*- */ |
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2 /* |
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3 * Copyright (c) 2005,2006 INRIA |
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4 * |
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5 * This program is free software; you can redistribute it and/or modify |
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6 * it under the terms of the GNU General Public License version 2 as |
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7 * published by the Free Software Foundation; |
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8 * |
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9 * This program is distributed in the hope that it will be useful, |
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10 * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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12 * GNU General Public License for more details. |
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13 * |
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14 * You should have received a copy of the GNU General Public License |
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15 * along with this program; if not, write to the Free Software |
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16 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
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17 * |
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18 * Author: Mathieu Lacage <mathieu.lacage@sophia.inria.fr> |
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19 */ |
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20 #include "yans-error-rate-model.h" |
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21 #include "wifi-phy.h" |
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22 #include "ns3/log.h" |
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23 |
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24 NS_LOG_COMPONENT_DEFINE ("YansErrorRateModel"); |
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25 |
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26 namespace ns3 { |
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27 |
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28 NS_OBJECT_ENSURE_REGISTERED (YansErrorRateModel); |
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29 |
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30 TypeId |
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31 YansErrorRateModel::GetTypeId (void) |
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32 { |
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33 static TypeId tid = TypeId ("ns3::YansErrorRateModel") |
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34 .SetParent<ErrorRateModel> () |
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35 .AddConstructor<YansErrorRateModel> () |
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36 ; |
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37 return tid; |
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38 } |
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39 |
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40 YansErrorRateModel::YansErrorRateModel () |
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41 {} |
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42 |
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43 double |
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44 YansErrorRateModel::Log2 (double val) const |
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45 { |
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46 return log(val) / log(2.0); |
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47 } |
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48 double |
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49 YansErrorRateModel::GetBpskBer (double snr, uint32_t signalSpread, uint32_t phyRate) const |
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50 { |
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51 double EbNo = snr * signalSpread / phyRate; |
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52 double z = sqrt(EbNo); |
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53 double ber = 0.5 * erfc(z); |
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54 NS_LOG_INFO ("bpsk snr="<<snr<<" ber="<<ber); |
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55 return ber; |
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56 } |
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57 double |
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58 YansErrorRateModel::GetQamBer (double snr, unsigned int m, uint32_t signalSpread, uint32_t phyRate) const |
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59 { |
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60 double EbNo = snr * signalSpread / phyRate; |
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61 double z = sqrt ((1.5 * Log2 (m) * EbNo) / (m - 1.0)); |
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62 double z1 = ((1.0 - 1.0 / sqrt (m)) * erfc (z)) ; |
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63 double z2 = 1 - pow ((1-z1), 2.0); |
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64 double ber = z2 / Log2 (m); |
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65 NS_LOG_INFO ("Qam m="<<m<<" rate=" << phyRate << " snr="<<snr<<" ber="<<ber); |
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66 return ber; |
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67 } |
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68 uint32_t |
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69 YansErrorRateModel::Factorial (uint32_t k) const |
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70 { |
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71 uint32_t fact = 1; |
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72 while (k > 0) |
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73 { |
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74 fact *= k; |
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75 k--; |
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76 } |
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77 return fact; |
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78 } |
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79 double |
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80 YansErrorRateModel::Binomial (uint32_t k, double p, uint32_t n) const |
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81 { |
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82 double retval = Factorial (n) / (Factorial (k) * Factorial (n-k)) * pow (p, k) * pow (1-p, n-k); |
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83 return retval; |
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84 } |
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85 double |
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86 YansErrorRateModel::CalculatePdOdd (double ber, unsigned int d) const |
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87 { |
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88 NS_ASSERT ((d % 2) == 1); |
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89 unsigned int dstart = (d + 1) / 2; |
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90 unsigned int dend = d; |
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91 double pd = 0; |
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92 |
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93 for (unsigned int i = dstart; i < dend; i++) |
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94 { |
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95 pd += Binomial (i, ber, d); |
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96 } |
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97 return pd; |
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98 } |
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99 double |
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100 YansErrorRateModel::CalculatePdEven (double ber, unsigned int d) const |
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101 { |
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102 NS_ASSERT ((d % 2) == 0); |
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103 unsigned int dstart = d / 2 + 1; |
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104 unsigned int dend = d; |
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105 double pd = 0; |
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106 |
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107 for (unsigned int i = dstart; i < dend; i++) |
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108 { |
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109 pd += Binomial (i, ber, d); |
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110 } |
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111 pd += 0.5 * Binomial (d / 2, ber, d); |
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112 |
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113 return pd; |
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114 } |
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115 |
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116 double |
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117 YansErrorRateModel::CalculatePd (double ber, unsigned int d) const |
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118 { |
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119 double pd; |
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120 if ((d % 2) == 0) |
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121 { |
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122 pd = CalculatePdEven (ber, d); |
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123 } |
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124 else |
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125 { |
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126 pd = CalculatePdOdd (ber, d); |
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127 } |
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128 return pd; |
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129 } |
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130 |
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131 double |
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132 YansErrorRateModel::GetFecBpskBer (double snr, double nbits, |
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133 uint32_t signalSpread, uint32_t phyRate, |
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134 uint32_t dFree, uint32_t adFree) const |
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135 { |
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136 double ber = GetBpskBer (snr, signalSpread, phyRate); |
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137 if (ber == 0.0) |
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138 { |
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139 return 1.0; |
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140 } |
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141 double pd = CalculatePd (ber, dFree); |
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142 double pmu = adFree * pd; |
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143 pmu = std::min (pmu, 1.0); |
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144 double pms = pow (1 - pmu, nbits); |
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145 return pms; |
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146 } |
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147 |
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148 double |
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149 YansErrorRateModel::GetFecQamBer (double snr, uint32_t nbits, |
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150 uint32_t signalSpread, |
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151 uint32_t phyRate, |
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152 uint32_t m, uint32_t dFree, |
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153 uint32_t adFree, uint32_t adFreePlusOne) const |
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154 { |
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155 double ber = GetQamBer (snr, m, signalSpread, phyRate); |
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156 if (ber == 0.0) |
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157 { |
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158 return 1.0; |
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159 } |
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160 /* first term */ |
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161 double pd = CalculatePd (ber, dFree); |
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162 double pmu = adFree * pd; |
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163 /* second term */ |
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164 pd = CalculatePd (ber, dFree + 1); |
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165 pmu += adFreePlusOne * pd; |
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166 pmu = std::min (pmu, 1.0); |
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167 double pms = pow (1 - pmu, nbits); |
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168 return pms; |
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169 } |
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170 |
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171 double |
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172 YansErrorRateModel::GetChunkSuccessRate (WifiMode mode, double snr, uint32_t nbits) const |
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173 { |
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174 if (mode == WifiPhy::g_6mba) |
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175 { |
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176 return GetFecBpskBer (snr, |
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177 nbits, |
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178 mode.GetBandwidth (), // signal spread |
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179 mode.GetPhyRate (), // phy rate |
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180 10, // dFree |
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181 11 // adFree |
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182 ); |
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183 } |
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184 else if (mode == WifiPhy::g_9mba) |
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185 { |
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186 return GetFecBpskBer (snr, |
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187 nbits, |
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188 mode.GetBandwidth (), // signal spread |
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189 mode.GetPhyRate (), // phy rate |
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190 5, // dFree |
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191 8 // adFree |
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192 ); |
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193 } |
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194 else if (mode == WifiPhy::g_12mba) |
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195 { |
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196 return GetFecQamBer (snr, |
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197 nbits, |
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198 mode.GetBandwidth (), // signal spread |
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199 mode.GetPhyRate (), // phy rate |
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200 4, // m |
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201 10, // dFree |
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202 11, // adFree |
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203 0 // adFreePlusOne |
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204 ); |
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205 } |
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206 else if (mode == WifiPhy::g_18mba) |
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207 { |
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208 return GetFecQamBer (snr, |
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209 nbits, |
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210 mode.GetBandwidth (), // signal spread |
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211 mode.GetPhyRate (), // phy rate |
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212 4, // m |
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213 5, // dFree |
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214 8, // adFree |
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215 31 // adFreePlusOne |
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216 ); |
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217 } |
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218 else if (mode == WifiPhy::g_24mba) |
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219 { |
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220 return GetFecQamBer (snr, |
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221 nbits, |
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222 mode.GetBandwidth (), // signal spread |
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223 mode.GetPhyRate (), // phy rate |
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224 16, // m |
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225 10, // dFree |
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226 11, // adFree |
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227 0 // adFreePlusOne |
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228 ); |
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229 } |
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230 else if (mode == WifiPhy::g_36mba) |
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231 { |
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232 return GetFecQamBer (snr, |
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233 nbits, |
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234 mode.GetBandwidth (), // signal spread |
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235 mode.GetPhyRate (), // phy rate |
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236 16, // m |
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237 5, // dFree |
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238 8, // adFree |
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239 31 // adFreePlusOne |
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240 ); |
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241 } |
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242 else if (mode == WifiPhy::g_48mba) |
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243 { |
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244 return GetFecQamBer (snr, |
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245 nbits, |
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246 mode.GetBandwidth (), // signal spread |
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247 mode.GetPhyRate (), // phy rate |
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248 64, // m |
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249 6, // dFree |
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250 1, // adFree |
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251 16 // adFreePlusOne |
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252 ); |
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253 } |
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254 else if (mode == WifiPhy::g_54mba) |
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255 { |
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256 return GetFecQamBer (snr, |
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257 nbits, |
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258 mode.GetBandwidth (), // signal spread |
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259 mode.GetPhyRate (), // phy rate |
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260 64, // m |
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261 5, // dFree |
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262 8, // adFree |
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263 31 // adFreePlusOne |
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264 ); |
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265 } |
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266 return 0; |
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267 } |
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268 |
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269 } // namespace ns3 |