Handbook of Propagation Effects for Vehicular and ... - Courses

More documents

Recommendations

Info

11-26 Propagation Effects for Vehicular and Personal Mobile Satellite Systems Figure 11-5: Measured L-Band signal level and phase fluctuations as a function of time relative to arbitrary reference as receiving vehicle passes by a wooden utility pole with a metal crossbar. The vehicle’s closest approach to the pole occurs at about 0.6 s. L-Band Relative Power (dB) L-Band Phase (deg) 5 0 -5 -10 -15 80 60 40 20 0 -20 -40 -60 -80 0 0.2 0.4 0.6 0.8 1 Time (s) 0 0.2 0.4 0.6 0.8 1 Time (s) Figure 11-6: Calculated L-Band signal level and phase fluctuations as a function of time for the geometry of Figure 11-5. Evaluating the model over a range of parameters, the following has been empirically determined:
Theoretical Modeling Considerations 11-27 • The peak-to-peak fluctuations of the received signal level (dB) due to multipath vary with the inverse of the square root of the satellite elevation angle. • The multipath power (dB) varies as the inverse distance to the scatterer taken to the 4/3 power. • Assuming two frequencies (at L-Band) are simultaneously received, the RMS deviation of the dB power difference between signal levels at the respective frequencies is proportional to the frequency difference. Employing this result, amplitude dispersion is found to be negligible for narrow band (bandwidth < 10 kHz) LMSS systems. 11.5.1.2 Fresnel Approaches to Tree Shadowing Several simplifying methods have been used to assess the effect of shadowing by a single tree. Modeling a tree trunk as a very long opaque strip of equal width, a diffraction pattern was obtained by LaGrone and Chapman [1961] and compared to measurements at UHF frequencies. Taking account of the tree crown, two different two-dimensional tree models have been studied, both capable of achieving rough quantitative agreement with observations of tree shadowing. One assumed a tree to be composed of a number of finite, canted opaque strips of varying width and length, representing the silhouette of a tree with branches of various sizes [Vogel and Hong, 1988]. Attenuations of up to about 12 dB were calculated at L-Band versus 8 dB at UHF. Spatial fluctuations in the shadow of the tree were found to be faster with higher signal frequency and closer proximity to the tree during a simulated drive-by scenario. The maximum fade was proportional to the logarithm of the number of limbs. In the second approach [Yoshikawa and Kagohara, 1989], the tree crown was modeled as a triangle which obscures a wedge of the first Fresnel zone. By comparisons with measurements, the results have been shown to correctly explain the average decrease of attenuation with increasing distance of the receiver from the tree. 11.5.2 Multiple Object Scattering Models 11.5.2.1 Two-Dimensional Model A two-dimensional geometric LMSS propagation model by Amoroso and Jones [1988] considered 1000 scatterers randomly distributed in an annular region with an outer radius of 2000 m and an inner radius of 400 m, corresponding to an average area per scatterer of 12,000 m 2 . The model has been used to correctly predict multipath Doppler spectra, both for omnidirectional and directive antennas. The simulated fading record of unmodulated carrier power for an omni-directional antenna shows unrealistic peak-to-peak variations of over 20 dB, however. This is the consequence of (1) using a two-dimensional approach, which eliminates realistic elevation angle and antenna effects, and (2) the avoidance of any scatterers in proximity to the vehicle, which in field measurements have been shown to dominate the signal variations in the absence of shadowing. The model therefore also overestimates delay spread.
Page 1:
A2A-98-U-0-021 (APL) EERL-98-12A (E
Page 5 and 6:
Table of Contents 1 Introduction __
Page 7:
10 Optical Methods for Assessing Fa
Page 11:
Table of Contents 1 Introduction __
Page 14 and 15:
1-2 Propagation Effects for Vehicul
Page 16 and 17:
Page 18 and 19:
Page 21 and 22:
Table of Contents 2 Attenuation Due
Page 23 and 24:
Chapter 2 Attenuation Due to Trees:
Page 25 and 26:
Attenuation Due to Trees: Static Ca
Page 27 and 28:
Page 29 and 30:
Page 31 and 32:
Page 33 and 34:
Page 35 and 36:
Page 37 and 38:
Page 39:
Page 43 and 44:
Table of Contents 3 Attenuation Due
Page 45:
Figure 3-23: Fade distributions at
Page 48 and 49:
Page 50 and 51:
3-4 Relative Signal Level (dB) 5 0
Page 52 and 53:
Page 54 and 55:
Page 56 and 57:
3-10 Percent of Distance the Fade >
Page 58 and 59:
3-12 Propagation Effects for Vehicu
Page 60 and 61:
3-14 3.4.3 Austin, Texas at K-Band
Page 62 and 63:
Page 64 and 65:
Page 66 and 67:
3-20 Relative Signal Level (dB) 5 0
Page 68 and 69:
Page 70 and 71:
3-24 Percentage of Distance Fade >
Page 72 and 73:
3-26 and where 1 2 Propagation Effe
Page 74 and 75:
3-28 Percentage of the Time Fade >
Page 76 and 77:
Page 78 and 79:
3-32 3.7.5 Comparative Summary of M
Page 80 and 81:
Page 83:
Chapter 4 Signal Degradation for Li
Page 86 and 87:
Table of Tables Table 4-1: Summary
Page 88 and 89:
Page 90 and 91:
4-4 Percentage of Distance Fade > A
Page 92 and 93:
Page 94 and 95:
Page 96 and 97:
Page 98 and 99:
Page 100 and 101:
4-14 Percentage of Distance or Time
Page 102 and 103:
Page 105 and 106:
Table of Contents 5 Fade and Non-Fa
Page 107 and 108:
Chapter 5 Fade and Non-Fade Duratio
Page 109 and 110:
Fade and Non-Fade Durations and Pha
Page 111 and 112:
Page 113 and 114:
Page 115 and 116:
Page 117 and 118:
Page 119 and 120:
Page 121:
Page 125 and 126:
Table of Contents 6 Polarization, A
Page 127 and 128:
Chapter 6 Polarization, Antenna Gai
Page 129 and 130:
Polarization, Antenna Gain and Dive
Page 131 and 132:
Page 133 and 134:
Page 135 and 136:
Page 137 and 138:
Page 139 and 140:
Page 141 and 142:
Page 143:
Page 147 and 148:
Table of Contents 7 Investigations
Page 149:
was derived from measurements over
Page 152 and 153:
Page 154 and 155:
Page 156 and 157:
7-6 7.3 Belgium (PROSAT Experiment)
Page 158 and 159:
Page 160 and 161:
7-10 Probability Fade > Abscissa (%
Page 162 and 163:
Page 164 and 165:
7-14 Percentage of Time Fade > Absc
Page 166 and 167:
Page 168 and 169:
Page 170 and 171:
Page 172 and 173:
Page 174 and 175:
7-24 Probability (%) > Abscissa 100
Page 176 and 177:
Page 178 and 179:
Page 181:
Chapter 8 Earth-Satellite Propagati
Page 184 and 185:
Table of Figures Figure 8-1: Maximu
Page 187 and 188:
Chapter 8 Earth-Satellite Propagati
Page 189 and 190:
Earth-Satellite Propagation Effects
Page 191 and 192:
Page 193 and 194:
Page 195 and 196:
Page 197 and 198:
Page 199 and 200:
Page 201 and 202:
Page 203 and 204:
Page 205 and 206:
Page 207 and 208:
Page 209 and 210:
Page 211 and 212:
Page 213 and 214:
Page 215 and 216:
Page 217 and 218:
Page 219 and 220:
Page 221 and 222:
Page 223:
Chapter 9 Maritime-Mobile Satellite
Page 226 and 227:
Figure 9-7: Fading depth versus pat
Page 228 and 229:
Page 230 and 231:
Page 232 and 233:
9-6 Roughness Parameter, u (Rad) 28
Page 234 and 235:
9-8 Cθ = ( θo − 7) / 2 dB for
Page 236 and 237:
9-10 Fading Depth (dB) 6 5 4 3 2 1
Page 238 and 239:
9-12 Fading Depth (dB) 6 5 4 3 2 1
Page 240 and 241:
Page 242 and 243:
Page 244 and 245:
9-18 Mean Fade Occurrence Interval,
Page 246 and 247:
9-20 Mean Fade Duration, T D (sec)
Page 248 and 249:
9-22 Fade Depth (dB) 7.0 6.5 6.0 5.
Page 250 and 251:
Page 252 and 253:
Page 255 and 256: Table of Contents 10 Optical Method
Page 257 and 258: Chapter 10 Optical Methods for Asse
Page 259 and 260: Optical Methods for Assessing Fade
Page 275: Optical Methods for Assessing Fade
Page 279 and 280: Table of Contents 11 Theoretical Mo
Page 281 and 282: Chapter 11 Theoretical Modeling Con
Page 283 and 284: Theoretical Modeling Considerations
Page 305: Theoretical Modeling Considerations
Page 313: Theoretical Modeling Considerations
Page 317 and 318: Table of Contents 12 Summary of Rec
Page 319: Table 12-7: Tabulation of azimuth a
Page 322 and 323: 12-2 Propagation Effects for Vehicu
Page 330 and 331: 12-10 12.6.5 Satellite Diversity Pr
Page 332 and 333: 12-12 Propagation Effects for Vehic
Page 334 and 335: 12-14 Standard Deviation (dB) 4 3 2
Page 338 and 339: 12-18 Fade Depth (dB) 7.0 6.5 6.0 5
Page 345 and 346: Index 13-1 Index 2 2-state Markov m
Page 347 and 348: Index 13-3 Jongejans, A. et al., 3-
show all

Handbook of Propagation Effects for Vehicular and ... - Courses

Create successful ePaper yourself

Delete template?

Save as template?