- •Foreword
- •Policy on Intellectual Property Right (ipr)
- •A general purpose wide-range terrestrial propagation model in the frequency range 30 mHz to 50 gHz
- •Annex Wide-range propagation model Description of the calculation method
- •1 Introduction
- •1.1 Applicability
- •1.2 Reciprocity, and the designation of terminals
- •1.3 Iteration
- •1.4 Organization of the Recommendation
- •1.5 Style of description
- •2 Inputs
- •2.1 Terrain profile
- •2.2 Other inputs
- •Other inputs
- •2.3 Constants
- •Constants
- •2.4 Integral digital products
- •Digital products
- •3 Preliminary calculations
- •Principal parameters
- •3.1 Limited percentage times
- •3.2 Path length, intermediate points, and fraction over sea
- •3.3 Antenna altitudes and path inclination
- •3.4 Climatic parameters
- •3.4.1 Refractivity in the lowest 1 km
- •3.4.2 Refractivity in the lowest 65 m
- •3.4.3 Precipitation parameters
- •3.5 Effective Earth-radius geometry
- •3.6 Wavelength
- •3.7 Path classification and terminal horizon parameters
- •Case 1. Path is LoS
- •Case 2. Path is nLoS
- •Continue for both cases
- •3.8 Effective heights and path roughness parameter
- •3.9 Tropospheric-scatter path segments
- •3.10 Gaseous absorption on surface paths
- •3.11 Free-space basic transmission loss
- •3.12 Knife-edge diffraction loss
- •4 Obtaining predictions for the principal sub-models
- •5 Combining sub-model results
- •5.1 Combining sub-models 1 and 2
- •5.3 Combining sub-models within a Monte-Carlo simulator
- •Appendix a Diffraction loss a.1 Introduction
- •A.2 Spherical-Earth diffraction loss
- •A.3 First-term spherical-Earth diffraction loss
- •Start of calculation to be performed twice
- •A.4 Bullington diffraction loss for actual profile
- •Case 1. Path is LoS for effective Earth curvature not exceeded for p% time
- •Case 2. Path is nLoS for effective Earth curvature not exceeded for p% time
- •A.5 Bullington diffraction loss for a notional smooth profile
- •Case 1. Path is LoS for effective Earth radius exceeded for p% time
- •Case 2. Path is nLoS for effective Earth radius exceeded for p% time
- •Appendix b Clear-air enhancements and fading b.1 Introduction
- •B.2 Characterize multi-path activity
- •For LoS path:
- •For nLoS path:
- •B.3 Calculation of the notional zero-fade annual percentage time
- •B.4 Percentage time a given clear-air fade level is exceeded on a surface path
- •B.5 Percentage time a given clear-air fade level is exceeded on a troposcatter path
- •Appendix c Precipitation fading c.1 Introduction
- •C.2 Preliminary calculations
- •Probability distribution of rain height
- •C.3 Percentage time a given precipitation fade level is exceeded
- •C.4 Melting-layer model
- •Factor (abscissa) plotted against relative height h (ordinate)
- •C.5 Path-averaged multiplier
- •Example of path geometry in relation to melting layer slices
- •Appendix d Anomalous/layer-reflection model
- •D.1 Characterize the radio-climatic zones dominating the path
- •Radio-climatic zones
- •Large bodies of inland water
- •Large inland lake or wet-land areas
- •D.2 Point incidence of ducting
- •D.3 Site-shielding losses with respect to the anomalous propagation mechanism
- •D.4 Over-sea surface duct coupling corrections
- •D.5 Total coupling loss to the anomalous propagation mechanism
- •D.6 Angular-distance dependent loss
- •D.7 Distance and time-dependent loss
- •D.8 Basic transmission loss associated with ducting
- •Appendix e Troposcatter e.1 Introduction
- •E.2 Climatic classification
- •Climatic zones
- •Meteorological and atmospheric structure parameters
- •E.3 Calculation of troposcatter basic transmission loss
- •Appendix f Attenuation due to gaseous absorption f.1 Introduction
- •F.2 Gaseous absorption for surface path
- •F.3 Gaseous absorption for a troposcatter path
- •F.4 Gaseous absorption for terminal/common-volume troposcatter path
- •F.5 Water-vapour density in rain
- •F.6 Specific sea-level attenuations
- •Appendix g Sporadic-e propagation
- •G.1 Derivation of foEs
- •Conditions for setting p1 and p2
- •G.4 Basic transmission loss
- •Appendix h Great-circle path calculations h.1 Introduction
- •H.2 Path length and bearing
- •H.3 Calculation of intermediate path point
- •Appendix I Iterative procedure to invert a cumulative distribution function
- •I.1 Introduction
- •I.2 Iteration method
- •Stage 1: setting the search range
- •Stage 2: binary search
- •Appendix j Structure of the wide-range propagation model j.1 Introduction
- •J.2 Combining the sub-models
Other inputs
Symbol |
Description |
f (GHz) |
Frequency |
Tpol |
Code indicating either horizontal or vertical linear polarization |
re, rn (degrees) |
Longitude, latitude, of receiver |
te, tn (degrees) |
Longitude, latitude, of transmitter |
htg, rg (m) |
Height of electrical centre of transmitting, receiving antenna above ground. |
Tpc (%) |
Percentage of average year for which the predicted basic transmission loss is not exceeded |
Gt, Gr (dBi) |
Gain of transmitting, receiving, antenna in the azimuthal direction of the path towards the other antenna, and at the elevation angle above the local horizontal of the other antenna in the case of a line-of-sight (LoS) path, otherwise of the antenna’s radio horizon, for median effective Earth radius. |
Longitudes and latitudes in this method are positive east and north.
2.3 Constants
Table 2.3.1 gives values of constants used in the method.
TABLE 2.3.1
Constants
Symbol |
Value |
Description |
c (m/s) |
2.998 108 |
Speed of propagation |
Re (km) |
6 371 |
Average Earth radius |
rland |
22.0 |
Relative permittivity for land |
rsea |
80.0 |
Relative permittivity for sea |
land (S/m) |
0.003 |
Conductivity for land |
sea (S/m) |
5.0 |
Conductivity for sea |
2.4 Integral digital products
Only the file versions provided with this Recommendation should be used. They are an integral part of the Recommendation. Table 2.4.1 gives details of the digital products used in the method.
TABLE 2.4.1
Digital products
Filename |
Ref. |
Origin |
Latitude (rows) |
Longitude (columns |
||||
First row (ºN) |
Spacing (degrees) |
Number of rows |
First col (ºE) |
Spacing (degrees) |
Number of cols |
|||
DN_Median.txt |
§ 3.4.1 |
P.2001 |
90 |
1.5 |
121 |
0 |
1.5 |
241 |
DN_SupSlope.txt |
§ 3.4.1 |
P.2001 |
90 |
1.5 |
121 |
0 |
1.5 |
241 |
DN_SubSlope.txt |
§ 3.4.1 |
P.2001 |
90 |
1.5 |
121 |
0 |
1.5 |
241 |
dndz_01.txt |
§ 3.4.2 |
P.453-10 |
90 |
1.5 |
121 |
0 |
1.5 |
241 |
Esarain_Pr6_v5.txt |
§ C.2 |
P.837-5 |
90 |
1.125 |
161 |
0 |
1.125 |
321 |
Esarain_Mt_v5.txt |
§ C.2 |
P.837-5 |
90 |
1.125 |
161 |
0 |
1.125 |
321 |
Esarain_Beta_v5.txt |
§ C.2 |
P.837-5 |
90 |
1.125 |
161 |
0 |
1.125 |
321 |
h0.txt |
§ C.2 |
P.839-4 |
90 |
1.5 |
121 |
0 |
1.5 |
241 |
Surfwv_50_fixed.txt(1) |
Appx F |
P.836-4 (corrected) |
90 |
1.5 |
121 |
0 |
1.5 |
241 |
FoEs50.txt |
Appx G |
P.2001 |
90 |
1.5 |
121 |
0 |
1.5 |
241 |
FoEs10.txt |
Appx G |
P.2001 |
90 |
1.5 |
121 |
0 |
1.5 |
241 |
FoEs01.txt |
Appx G |
P.2001 |
90 |
1.5 |
121 |
0 |
1.5 |
241 |
FoEs0.1.txt |
Appx G |
P.2001 |
90 |
1.5 |
121 |
0 |
1.5 |
241 |
TropoClim.txt |
§ E.2 |
P.2001 |
89.75 |
0.5 |
360 |
–179.75 |
0.5 |
720 |
(1) The file “surfwv_50_fixed.txt” is a corrected version of the file “surfwv_50.txt” associated with Recommendation ITU-R P.836-4. “surfwv_50.txt” has one column less than expected according to the “surfwv_lat.txt” and “surfwv_lon.txt” files provided with the data. It has been assumed that the column corresponding to a longitude of 360° was omitted from the file, and this has been corrected in “surfwv_50_fixed.txt. |
||||||||
The “First row” value is the latitude of the first row.
The “First col” value is the longitude of the first column. The last column is the same as the first column (360° = 0°) and is provided to simplify interpolation.
“Spacing” gives the latitude/longitude increment between rows/columns.
Except for file “TropoClim.txt”, a parameter value at a particular latitude/longitude should be obtained by bilinear interpolation using the four nearest grid points, as described in Rec. ITU‑R P.1144.
TropoClim.txt contains integer zone identifiers rather than continuous meteorological variables. Consequently, the values should not be interpolated to obtain a value at a particular latitude/longitude. Instead the value at the closest grid point should be taken. For this file, note that a) the grid is offset by half a pixel compared to the other files, b) the values in the last column are not a duplicate of the first column. Consequently, the latitudes of the rows range from 89.75°N to 89.75°S, and the longitudes of the columns range from 179.75°W to 179.75°E.
The files are contained in the zip file R-REC-P.2001-1-201309-I!!ZIP-E.