#include <math.h>
#include <stdlib.h>
#include <iostream.h>
Include dependency graph for threshold.cc:
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Defines | |
| #define | M_PI 3.14159265359 |
Functions | |
| double | Friis (double Pt, double Gt, double Gr, double lambda, double L, double d) |
| double | inv_erfc (double y) |
| double | inv_Q (double y) |
| int | main (int argc, char **argv) |
| double | TwoRay (double Pt, double Gt, double Gr, double ht, double hr, double L, double d, double lambda) |
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Definition at line 59 of file threshold.cc. |
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Definition at line 62 of file threshold.cc. Referenced by TwoRay(). 00063 { 00064 /* 00065 * Friis free space propagation equation: 00066 * 00067 * Pt * Gt * Gr * (lambda^2) 00068 * P = -------------------------- 00069 * (4 *pi * d)^2 * L 00070 */ 00071 double M = lambda / (4 * M_PI * d); 00072 return (Pt * Gt * Gr * (M * M)) / L; 00073 }
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Definition at line 105 of file threshold.cc. Referenced by inv_Q(). 00106 { 00107 double s, t, u, w, x, z; 00108 00109 z = y; 00110 if (y > 1) { 00111 z = 2 - y; 00112 } 00113 w = 0.916461398268964 - log(z); 00114 u = sqrt(w); 00115 s = (log(u) + 0.488826640273108) / w; 00116 t = 1 / (u + 0.231729200323405); 00117 x = u * (1 - s * (s * 0.124610454613712 + 0.5)) - 00118 ((((-0.0728846765585675 * t + 0.269999308670029) * t + 00119 0.150689047360223) * t + 0.116065025341614) * t + 00120 0.499999303439796) * t; 00121 t = 3.97886080735226 / (x + 3.97886080735226); 00122 u = t - 0.5; 00123 s = (((((((((0.00112648096188977922 * u + 00124 1.05739299623423047e-4) * u - 0.00351287146129100025) * u - 00125 7.71708358954120939e-4) * u + 0.00685649426074558612) * u + 00126 0.00339721910367775861) * u - 0.011274916933250487) * u - 00127 0.0118598117047771104) * u + 0.0142961988697898018) * u + 00128 0.0346494207789099922) * u + 0.00220995927012179067; 00129 s = ((((((((((((s * u - 0.0743424357241784861) * u - 00130 0.105872177941595488) * u + 0.0147297938331485121) * u + 00131 0.316847638520135944) * u + 0.713657635868730364) * u + 00132 1.05375024970847138) * u + 1.21448730779995237) * u + 00133 1.16374581931560831) * u + 0.956464974744799006) * u + 00134 0.686265948274097816) * u + 0.434397492331430115) * u + 00135 0.244044510593190935) * t - 00136 z * exp(x * x - 0.120782237635245222); 00137 x += s * (x * s + 1); 00138 if (y > 1) { 00139 x = -x; 00140 } 00141 return x; 00142 }
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Definition at line 148 of file threshold.cc. References inv_erfc(). 00149 { 00150 double x; 00151 x = sqrt(2.0) * inv_erfc(2.0 * y); 00152 return x; 00153 }
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Definition at line 156 of file threshold.cc. 00157 { 00158 00159 // specify default values 00160 char** propModel = NULL; // propagation model 00161 double Pt = 0.28183815; // transmit power 00162 double Gt = 1.0; // transmit antenna gain 00163 double Gr = 1.0; // receive antenna 00164 double freq = 914.0e6; // frequency 00165 double sysLoss = 1.0; // system loss 00166 00167 // for two-ray model 00168 double ht = 1.5; // transmit antenna height 00169 double hr = 1.5; // receive antenna height 00170 00171 // for shadowing model 00172 double pathlossExp_ = 2.0; // path loss exponent 00173 double std_db_ = 4.0; // shadowing deviation 00174 double dist0_ = 1.0; // reference distance 00175 double prob = 0.95; // correct reception rate 00176 00177 double rxThresh_; // receiving threshold 00178 00179 // check arguments 00180 if (argc < 4) { 00181 cout << "USAGE: find receiving threshold for certain communication range (distance)" << endl; 00182 cout << endl; 00183 cout << "SYNOPSIS: threshold -m <propagation-model> [other-options] distance" << endl; 00184 cout << endl; 00185 cout << "<propagation-model>: FreeSpace, TwoRayGround or Shadowing" << endl; 00186 cout << "[other-options]: set parameters other than default values:" << endl; 00187 cout << endl << "Common parameters:" << endl; 00188 cout << "-Pt <transmit-power>" << endl; 00189 cout << "-fr <frequency>" << endl; 00190 cout << "-Gt <transmit-antenna-gain>" << endl; 00191 cout << "-Gr <receive-antenna-gain>" << endl; 00192 cout << "-L <system-loss>" << endl; 00193 cout << endl << "For two-ray ground model:" << endl; 00194 cout << "-ht <transmit-antenna-height>" << endl; 00195 cout << "-hr <receive-antenna-height>" << endl; 00196 cout << endl << "For shadowing model:" << endl; 00197 cout << "-pl <path-loss-exponent>" << endl; 00198 cout << "-std <shadowing-deviation>" << endl; 00199 cout << "-d0 <reference-distance>" << endl; 00200 cout << "-r <receiving-rate>" << endl; 00201 return 0; 00202 } 00203 00204 // parse arguments 00205 double dist = atof(argv[argc-1]); 00206 cout << "distance = " << dist << endl; 00207 00208 int argCount = (argc - 2) / 2; // number of parameters 00209 argv++; 00210 for (int i = 0; i < argCount; i++) { 00211 if(!strcmp(*argv,"-m")) { // propagation model 00212 propModel = argv + 1; 00213 cout << "propagation model: " << *propModel << endl; 00214 } 00215 if(!strcmp(*argv,"-Pt")) { // transmit power 00216 Pt = atof(*(argv + 1)); 00217 } 00218 if(!strcmp(*argv,"-fr")) { // frequency 00219 freq = atof(*(argv + 1)); 00220 } 00221 if(!strcmp(*argv,"-Gt")) { // transmit antenna gain 00222 Gt = atof(*(argv + 1)); 00223 } 00224 if(!strcmp(*argv,"-Gr")) { // receive antenna gain 00225 Gr = atof(*(argv + 1)); 00226 } 00227 if(!strcmp(*argv,"-L")) { // system loss 00228 sysLoss = atof(*(argv + 1)); 00229 } 00230 if(!strcmp(*argv,"-ht")) { // transmit antenna height (Two ray model) 00231 ht = atof(*(argv + 1)); 00232 } 00233 if(!strcmp(*argv,"-hr")) { // receive antenna height (Two ray model) 00234 hr = atof(*(argv + 1)); 00235 } 00236 if(!strcmp(*argv,"-pl")) { // path loss exponent (Shadowing model) 00237 pathlossExp_ = atof(*(argv + 1)); 00238 } 00239 if(!strcmp(*argv,"-std")) { // shadowing deviation (Shadowing model) 00240 std_db_ = atof(*(argv + 1)); 00241 } 00242 if(!strcmp(*argv,"-d0")) { // close-in reference distance (Shadowing model) 00243 dist0_ = atof(*(argv + 1)); 00244 } 00245 if(!strcmp(*argv,"-r")) { // rate of correct reception (Shadowing model) 00246 prob = atof(*(argv + 1)); 00247 } 00248 argv += 2; 00249 } 00250 00251 if (propModel == NULL) { 00252 cout << "Must specify propagation model: -m <propagation model>" << endl; 00253 return 0; 00254 } 00255 00256 double lambda = 3.0e8/freq; 00257 00258 // compute threshold 00259 if (!strcmp(*propModel, "FreeSpace")) { 00260 rxThresh_ = Friis(Pt, Gt, Gr, lambda, sysLoss, dist); 00261 cout << endl << "Selected parameters:" << endl; 00262 cout << "transmit power: " << Pt << endl; 00263 cout << "frequency: " << freq << endl; 00264 cout << "transmit antenna gain: " << Gt << endl; 00265 cout << "receive antenna gain: " << Gr << endl; 00266 cout << "system loss: " << sysLoss << endl; 00267 } else if (!strcmp(*propModel, "TwoRayGround")) { 00268 rxThresh_ = TwoRay(Pt, Gt, Gr, ht, hr, sysLoss, dist, lambda); 00269 cout << endl << "Selected parameters:" << endl; 00270 cout << "transmit power: " << Pt << endl; 00271 cout << "frequency: " << freq << endl; 00272 cout << "transmit antenna gain: " << Gt << endl; 00273 cout << "receive antenna gain: " << Gr << endl; 00274 cout << "system loss: " << sysLoss << endl; 00275 cout << "transmit antenna height: " << ht << endl; 00276 cout << "receive antenna height: " << hr << endl; 00277 } else if (!strcmp(*propModel, "Shadowing")) { 00278 // calculate receiving power at reference distance 00279 double Pr0 = Friis(Pt, Gt, Gr, lambda, sysLoss, dist0_); 00280 00281 // calculate average power loss predicted by path loss model 00282 double avg_db = -10.0 * pathlossExp_ * log10(dist/dist0_); 00283 00284 // calculate the the threshold 00285 double invq = inv_Q(prob); 00286 double threshdb = invq * std_db_ + avg_db; 00287 rxThresh_ = Pr0 * pow(10.0, threshdb/10.0); 00288 00289 #ifdef DEBUG 00290 cout << "Pr0 = " << Pr0 << endl; 00291 cout << "avg_db = " << avg_db << endl; 00292 cout << "invq = " << invq << endl; 00293 cout << "threshdb = " << threshdb << endl; 00294 #endif 00295 00296 cout << endl << "Selected parameters:" << endl; 00297 cout << "transmit power: " << Pt << endl; 00298 cout << "frequency: " << freq << endl; 00299 cout << "transmit antenna gain: " << Gt << endl; 00300 cout << "receive antenna gain: " << Gr << endl; 00301 cout << "system loss: " << sysLoss << endl; 00302 cout << "path loss exp.: " << pathlossExp_ << endl; 00303 cout << "shadowing deviation: " << std_db_ << endl; 00304 cout << "close-in reference distance: " << dist0_ << endl; 00305 cout << "receiving rate: " << prob << endl; 00306 } else { 00307 cout << "Error: unknown propagation model." << endl; 00308 cout << "Available model: FreeSpace, TwoRayGround, Shadowing" << endl; 00309 return 0; 00310 } 00311 00312 cout << endl << "Receiving threshold RXThresh_ is: " << rxThresh_ << endl; 00313 00314 }
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Definition at line 75 of file threshold.cc. 00076 { 00077 /* 00078 * if d < crossover_dist, use Friis free space model 00079 * if d >= crossover_dist, use two ray model 00080 * 00081 * Two-ray ground reflection model. 00082 * 00083 * Pt * Gt * Gr * (ht^2 * hr^2) 00084 * Pr = ---------------------------- 00085 * d^4 * L 00086 * 00087 * The original equation in Rappaport's book assumes L = 1. 00088 * To be consistant with the free space equation, L is added here. 00089 */ 00090 00091 double Pr; // received power 00092 double crossover_dist = (4 * M_PI * ht * hr) / lambda; 00093 00094 if (d < crossover_dist) 00095 Pr = Friis(Pt, Gt, Gr, lambda, L, d); 00096 else 00097 Pr = Pt * Gt * Gr * (hr * hr * ht * ht) / (d * d * d * d * L); 00098 00099 return Pr; 00100 }
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1.4.6