1、 Recommendation ITU-R P.2001-2 (07/2015) A general purpose wide-range terrestrial propagation model in the frequency range 30 MHz to 50 GHz P Series Radiowave propagation ii Rec. ITU-R P.2001-2 Foreword The role of the Radiocommunication Sector is to ensure the rational, equitable, efficient and eco
2、nomical use of the radio-frequency spectrum by all radiocommunication services, including satellite services, and carry out studies without limit of frequency range on the basis of which Recommendations are adopted. The regulatory and policy functions of the Radiocommunication Sector are performed b
3、y World and Regional Radiocommunication Conferences and Radiocommunication Assemblies supported by Study Groups. Policy on Intellectual Property Right (IPR) ITU-R policy on IPR is described in the Common Patent Policy for ITU-T/ITU-R/ISO/IEC referenced in Annex 1 of Resolution ITU-R 1. Forms to be u
4、sed for the submission of patent statements and licensing declarations by patent holders are available from http:/www.itu.int/ITU-R/go/patents/en where the Guidelines for Implementation of the Common Patent Policy for ITU-T/ITU-R/ISO/IEC and the ITU-R patent information database can also be found. S
5、eries of ITU-R Recommendations (Also available online at http:/www.itu.int/publ/R-REC/en) Series Title BO Satellite delivery BR Recording for production, archival and play-out; film for television BS Broadcasting service (sound) BT Broadcasting service (television) F Fixed service M Mobile, radiodet
6、ermination, amateur and related satellite services P Radiowave propagation RA Radio astronomy RS Remote sensing systems S Fixed-satellite service SA Space applications and meteorology SF Frequency sharing and coordination between fixed-satellite and fixed service systems SM Spectrum management SNG S
7、atellite news gathering TF Time signals and frequency standards emissions V Vocabulary and related subjects Note: This ITU-R Recommendation was approved in English under the procedure detailed in Resolution ITU-R 1. Electronic Publication Geneva, 2015 ITU 2015 All rights reserved. No part of this pu
8、blication may be reproduced, by any means whatsoever, without written permission of ITU. Rec. ITU-R P.2001-2 1 RECOMMENDATION ITU-R P.2001-2 A general purpose wide-range terrestrial propagation model in the frequency range 30 MHz to 50 GHz (2012-2013-2015) Scope This Recommendation contains a genera
9、l purpose wide-range model for terrestrial propagation which predicts path loss due to both signal enhancements and fading over effectively the range from 0% to 100% of an average year. This makes the model particularly suitable for Monte-Carlo methods, and studies in which it is desirable to use th
10、e same propagation model, with no discontinuities in its output, for signals which may be either wanted or potentially interfering. The model covers the frequency range from 30 MHz to 50 GHz, and distances from 3 km to at least 1 000 km. The ITU Radiocommunication Assembly, considering a) that to su
11、pport efficient use of the radio spectrum there is a need for sharing studies in which the variability of both wanted and potentially interfering signal levels should be taken into account; b) that to plan high-performance radio systems the prediction of signal-level variability must include the sma
12、ll-probability tails of both fading and enhancement distributions; c) that Monte-Carlo simulations are useful for spectrum-planning purposes, noting a) that Recommendation ITU-R P.528 provides guidance on the prediction of point-to-area path loss for the aeronautical mobile service for the frequency
13、 range 125 MHz to 30 GHz and the distance range up to 1 800 km; b) that Recommendation ITU-R P.452 provides guidance on the detailed evaluation of microwave interference between stations on the surface of the Earth at frequencies above about 0.7 GHz; c) that Recommendation ITU-R P.617 provides guida
14、nce on the prediction of point-to-point path loss for trans-horizon radio-relay systems for the frequency range above 30 MHz and for the distance range 100 to 1 000 km; d) that Recommendation ITU-R P.1411 provides guidance on prediction for short-range (up to 1 km) outdoor services; e) that Recommen
15、dation ITU-R P.530 provides guidance on the prediction of point-to-point path loss for terrestrial line-of-sight systems; f) that Recommendation ITU-R P.1546 provides guidance on the prediction of point-to-area field strengths in the VHF and UHF bands based principally on statistical analyses of exp
16、erimental data; g) that Recommendation ITU-R P.1812 provides guidance on the prediction of point-to-area field strengths in the VHF and UHF bands based principally on deterministic method; h) that Recommendation ITU-R P.844 summarizes modes of long range propagation paths that may also occur at VHF
17、via the ionosphere, 2 Rec. ITU-R P.2001-2 recommends that the procedure given in the Annex be used for sharing studies over the full range of signal variability, including the small-probability tails for fading and enhancement, and for Monte-Carlo simulations. Annex Wide-range propagation model Desc
18、ription of the calculation method 1 Introduction This Recommendation describes a radio-wave propagation method for terrestrial paths. It has a wide range of applicability in frequency, distance, and percentage time. In particular, it predicts both fading and enhancements of signal level. It is thus
19、particularly suitable for Monte-Carlo simulations. Attachment J describes the structure of the model, and in particular how results representing different propagation mechanisms are combined. 1.1 Applicability The range of applicability is as follows: Frequency: 30 MHz to 50 GHz. Distance: The model
20、 is believed to be most accurate from about 3 km to 1 000 km. At shorter distances, the effect of clutter (buildings, trees, etc.) will tend to dominate unless the antenna heights are high enough to given an unobstructed path. There is no specific lower limit, although the path length must be greate
21、r than zero. A prediction of basic transmission loss less than 20 dB should be considered unreliable. Similarly, there is no specific maximum distance. Percentage time: The method predicts the basic transmission loss not exceeded for a given percentage of an average year. Any percentage time can be
22、used as an input to the model in the range 0% to 100%. This is limited in a progressive manner within the method such that the time used in the model varies from 0.00001% to 99.99999%. This internal limitation has no significant effect from 0.001% to 99.999% time. Antenna heights: Antennas heights a
23、bove ground level must be greater than zero. There is no specific maximum height above ground. The method is believed to be reliable for antenna altitudes up to 8 000 m above sea level. 1.2 Reciprocity, and the designation of terminals The terms “transmitting antenna” and “receiving antenna”, or mor
24、e briefly just “transmitter” and “receiver”, are used to distinguish the two terminals. This is convenient for the purposes of description. Rec. ITU-R P.2001-2 3 The method, however, is symmetrical. Which terminal is designated the “transmitter” makes no difference to the result. By convention the “
25、transmitter” is at the start of the terrain profile. 1.3 Iteration Some parts of the method require iterative calculations. Explicit iteration procedures are described which have been found to be efficient and stable. However, these are not necessarily optimal. Other iterative methods can be used if
26、 they are shown to give very similar results. 1.4 Organization of the Recommendation The inputs, and the symbols used to denote them, are described in 2. Preliminary calculations, including obtaining various radio-climatic parameters, are described in 3. Climatic parameters, and values derived from
27、the inputs, are listed in approximately alphabetical order of their symbols in Table 3.1. Many of these parameters are used in more than one place in the overall method, and all symbols in Table 3.1 are unique within this Recommendation. Section 4 describes the four main sub-models into which the me
28、thod is divided. The following subsections describe the calculation of these sub-models, most of which apply to a group of propagation mechanisms. These descriptions refer extensively to appendices which define various blocks of calculation. The sub-models in the wide-range propagation model (WRPM)
29、are independent of each other and each calculates results over the range 0% to 100%. Section 5 describes how the final prediction is obtained by combining results from the four main sub-models. The combination method takes account of the statistical correlation properties between the sub-models. Two
30、 alternative methods are given. One is appropriate when a direct calculation of the overall basic transmission loss is required for a given value of time percentage. This method involves an approximate treatment of uncorrelated statistics. The second method is appropriate when the WRPM is used withi
31、n a Monte-Carlo simulator. In this case, the uncorrelated statistics can be modelled more accurately by combining the sub-models within the Monte-Carlo method. 1.5 Style of description The method is described in a step-by-step manner, that is, expressions are given in the order in which they should
32、be evaluated. Equations are sometimes followed by a “where”, but this is limited to a few lines. Long lists of “where”s are avoided. Symbols appearing within the Appendices and which do not appear in Table 3.1 should be considered re-usable. They are defined close to where they are used, or cross-re
33、ferenced if appropriate. Logarithms are to the base 10 by default. That is, log(x) = log10(x). Natural logarithms where used are indicated as ln(x) = loge(x). 2 Inputs The inputs to the model consist of a terrain profile, described in 2.1, and other inputs described in 2.2. 2.1 Terrain profile A ter
34、rain profile giving heights above sea level of the Earths surface, whether land or water, at points along the great-circle radio path, must be available. Information is also required on the 4 Rec. ITU-R P.2001-2 distances over sea or a large body of water, and over low-lying coastal land or areas wi
35、th many lakes, according to the zones defined in Attachment D, D.1. In principle, the terrain profile consists of arrays each having the same number of values, n, as follows: di: distance from transmitter of i-th profile point (km) (2.1a) hi: height of i-th profile point above sea level (m) (2.1b) w
36、here: i: 1, 2, 3 . n = index of the profile point n: number of profile points. It is convenient to define an additional array holding zone codes as part of the profile: zi: zone code at distance di from transmitter (2.1c) where the z values are codes representing the zones in Table D.1. The profile
37、points must be spaced at equal intervals of distance. Thus d1 = 0 km, and dn = d km where d is the overall length of the path. Similarly, di = (i 1) d / (n 1) km. It is immaterial whether an array di is populated with distances, or whether di is calculated when needed. There must be at least one int
38、ermediate profile point between the transmitter and the receiver. Thus n must satisfy n 3. Such a small number of points is appropriate only for short paths, less than of the order of 1 km. Only general guidance can be given as to the appropriate profile spacing. Typical practice is a spacing in the
39、 range 50 to 250 m, depending on the source data and the nature of terrain. However, it is stressed that equally-spaced points should be included for the complete path, even where it passes over water. Expressions in this method assume that this is so. For instance, it is not acceptable to have zero
40、-height points only at the start and end of a section over sea when the length of the section exceeds the point spacing. Horizon points must be located taking Earth curvature into account, and omitting points in such a manner could result in the misinterpretation of a profile. 2.2 Other inputs Table
41、 2.2.1 lists the other inputs which must be provided by the user, in addition to the geographic information, including the terrain profile, described in 2.1 above. The symbols and units given here apply throughout this Recommendation. Rec. ITU-R P.2001-2 5 TABLE 2.2.1 Other inputs Symbol Description
42、 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
43、 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
44、-sight (LoS) path, otherwise of the antennas 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
45、 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
46、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. 6 Rec. ITU-R P.2001-2 TABLE 2.4.1 Digital products Filename Ref. Origin Latitude (rows) Longitude (columns First row (N) Spacing (degrees) Number of rows First col (
47、E) 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_v
48、5.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 2
49、41 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
