1、 Recommendation ITU-R P.311-15 (07/2015) Acquisition, presentation and analysis of data in studies of radiowave propagation P Series Radiowave propagation ii Rec. ITU-R P.311-15 Foreword The role of the Radiocommunication Sector is to ensure the rational, equitable, efficient and economical use of t
2、he 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 by World and Regi
3、onal 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 used for the subm
4、ission 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. Series of ITU-R R
5、ecommendations (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, radiodetermination, amat
6、eur 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 Satellite news ga
7、thering 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 publication may be
8、 reproduced, by any means whatsoever, without written permission of ITU. Rec. ITU-R P.311-15 1 RECOMMENDATION ITU-R P.311-15 Acquisition, presentation and analysis of data in studies of radiowave propagation (1953-1956-1959-1970-1974-1978-1982-1990-1992-1994-1997-1999-2001-2003-2005-2009-2013-2015)
9、Keywords Experimental data, Radiowave propagation, Acquisition and presentation of data The ITU Radiocommunication Assembly, considering a) that for the design of communication systems, propagation prediction models with global validity are necessary; b) that propagation and radiometeorological data
10、 are of fundamental importance for the development and testing of such prediction models; c) that, to facilitate the comparison of data and results, it is desirable to acquire and present propagation and radiometeorological data in a uniform manner, recommends 1 that data on radiowave propagation, s
11、ubmitted to Radiocommunication Study Group 3, follow the principles and formats contained in Annex 1. Annex 1 Data banks to support evaluation of prediction methods 1 Introduction 2 Responsibilities and updates 3 Acceptance criteria 4 Testing criteria for comparing prediction methods 4.1 General con
12、siderations 4.2 Testing variable for comparing rain attenuation predictions 4.3 Testing method for comparing fade duration predictions 4.4 Testing method for comparing fade slope predictions 5 List of the data banks of Radiocommunication Study Group 3 concerning tropospheric propagation 5.1 Part I:
13、Terrestrial line-of-sight path data 5.2 Part II: Earth-space path data 5.3 Part III: Terrestrial trans-horizon path and rain scatter data 2 Rec. ITU-R P.311-15 5.4 Part IV: Radiometeorological data 5.5 Part V: Terrestrial land mobile data 5.6 Part VI: Terrestrial point-to-area data 5.7 Part VII: Dat
14、a for mobile-satellite services 5.8 Part VIII: Vegetation and building data 5.9 Part IX: Noise 5.10 Part X: Trans-ionospheric data 1 Introduction One of the essential requirements for the provision of reliable methods for prediction of radio propagation effects is the establishment of suitable compu
15、ter data banks. Such data banks must: contain all data available that are of an adequate standard, be widely accepted as the source material on which to conduct testing, be readily available. It is a principle of the data banks that they shall contain only such data as may be used for: testing predi
16、ction methods recommended by Radiocommunication Study Group 3 (and may of course be used to test other methods); and for the creation and updating of radiometeorological maps relevant to the prediction of radio propagation effects. In special cases in studies on tropospheric propagation, where no pr
17、ediction method has been adopted by Radiocommunication Study Group 3, tabular data remain in the annex of the relevant Recommendation to give guidance to the reader from the best measured data currently available. The current data banks relate to: evaluation of prediction methods for terrestrial lin
18、e-of-sight propagation; evaluation of prediction methods for Earth-space propagation; evaluation of prediction methods for interference or reliability over trans-horizon paths; radiometeorological data; evaluation of prediction methods for terrestrial land mobile services; evaluation of prediction m
19、ethods for terrestrial broadcasting services; evaluation of prediction methods for mobile-satellite services; vegetation and building data; radio noise; trans-ionospheric data. Administrations are urged to submit their data to Radiocommunication Study Group 3 and/or the relevant Working Party (WP) i
20、n accordance with the requirements given in this Annex. Section 2 outlines the more administrative aspects related to the data banks, and the procedure for input of the new data for inclusion in the data banks. Section 3 gives the criteria with which the data submitted must comply prior to being acc
21、epted. Section 4 lists the testing criteria used. Section 5 lists all the tables of the data banks. Blank pro forma for the data, showing in detail the nature and format of data required/available, are freely available from that part of the ITU-R website concerning Radiocommunication Study Group 3.
22、Rec. ITU-R P.311-15 3 Moreover, the total data banks are available in spreadsheet form from the same website. Paper and diskette copies of the format sheets, and diskette copies of the total data bank, can be made available, on request, from the Radiocommunication Bureau (BR). Table III-1a is curren
23、tly available as a separate database. The Table currently includes approximately 100 000 measurements recorded over 1 326 paths. They were obtained from measurements lasting from 10 min to 1 h. The database is also available from the Radiocommunication Study Group 3 website. 2 Responsibilities and u
24、pdates The responsibility for the data banks lies with Radiocommunication Study Group 3, taking full advantage of the WPs for technical input and management, and the services of the BR for publication and distribution. Responsibility as to the accuracy and significance of the data remains with the a
25、uthors given in the references and/or with the administrations that have submitted the data. However, in order to facilitate the transformation of the given data to computer-data, and to ensure the quality of the data banks, the data shall first be reviewed by the relevant WP according to the set of
26、 criteria explained in 3. Non-compliant data may still be accepted after additional information and/or adequate explanations are sought and received from the relevant administration. Ensuring adequate procedures for technical maintenance and production of the data banks will be a continuing requirem
27、ent to keep under review. It is proposed that each table of the data bank be allocated to a WP to consider, and that the relevant WPs nominate, for each table for which they are responsible, an individual to coordinate updates. 3 Acceptance criteria Data given for inclusion in the data banks will be
28、 reviewed as to their suitability according to the following criteria: The information on the data for the evaluation shall be provided using the template described in the blank proforma documents (defined as SG 3 Databanks Formatted Tables). All the data shall be provided in computer files using th
29、e file format indicated by Study Group 3. Compliance of the given information with the formats described in the blank proforma. In particular, the units of measure should consistently adhere to the ones listed in the table description sheets. With few exceptions they are based on the international s
30、ystem of units (SI system). For the definitions of terms, see Recommendation ITU-R P.310. It is recommended to use copies of the tables in the pro forma for submission of the data and to enter additional important information under “Remarks”. For Tables I-1 and II-1, cumulative statistics of rainfal
31、l rate, rain attenuation and total attenuation, strictly concurrent data are requested. Strictly concurrent data means that the statistical analysis of rainfall rate and attenuation data shall only include measurements collected during identical time periods. In addition, if periods of rain attenuat
32、ion or of total attenuation data are missing or are marked as invalid due to system failure or malfunction, then these periods of rainfall rate data shall be excluded from the statistical analysis for Tables I-1 and II-1. The same process shall be applied to rain attenuation or total attenuation dat
33、a in the case of invalid periods of rainfall rate measurements. In any case the full statistics of valid rainfall rate data shall be provided in Table IV-1. For long-term, and yearly cumulative statistics the observation period shall be an integer multiple of 12 months and the equipment up-time shou
34、ld be at least 90% of the total time reported. 4 Rec. ITU-R P.311-15 The worst-month and monthly cumulative statistics (see Recommendation ITU-R P.581) must have been derived from all the 12 monthly statistics of the relevant year. The equipment up-time must be at least 75% of each month. Accuracy o
35、f interpolation: when converting the measured cumulative statistics into the format requested (for several fixed percentages), interpolation may be required. For this, a sufficiently large number of reference levels must be chosen such that for successive reference levels the ratio of the probabilit
36、ies is greater than 0.8 and less than 1.25. Extrapolated values should not be submitted. For terrestrial wideband data the receiver dynamic range should be at least 18 dB to provide for a minimum peak-to-noise ratio of 15 dB. For rainfall rate statistics, it is preferable that an integration time of
37、 1 min be used for consistency with the prediction methods of Radiocommunication Study Group 3. The reviewers of the given data shall apply the above criteria. In special cases, however, some of the criteria may be relaxed (e.g. in multipath phenomena the fade statistics show a definite linear trend
38、 in the tail of the distribution when plotted on a logarithmic-linear graph, so that interpolation becomes less of a problem). It is also appropriate to apply less stringent acceptance criteria in cases where the statistical data come from a region that is hardly represented in the respective data t
39、able. Data which are accepted in spite of not meeting the acceptance criteria (due to reasons given above) will be marked with a particular flag by the responsible table coordinator and are subject to removal from the data bank once a sufficient number of fully compliant data have been entered. 4 Te
40、sting criteria for comparing prediction methods 4.1 General considerations In order to judge the relative merits of a prediction method, an objective set of criteria needs to be defined. In general, the data used for the comparison have to be suitable for the purpose of the application (see data acc
41、eptance criteria, 3). While the database generally lists all data that are suitable for at least one type of test, some data entries may not be suitable for certain types of predictions and need therefore to be excluded from such tests. (Example: some of the data in Table III-1 are not suitable for
42、testing trans-horizon reliability they are therefore marked in the flag-field.) It is also important to exclude any dependent data (where one entry is a sub-set of another entry). However, data from measurements made at the same station during the same period with different elevation angle or polari
43、zation can be treated as independent data. In addition, in most cases, the duration of the measurement (in multiples of years) is to be used as a weighting function. (Note that the duration is defined as the actual number of days made up by the complete set of valid data which is normally less than
44、the time from start date to end date; the difference is the “down-time” of the experiment.) The general requirements for models are (in decreasing order of importance). 4.1.1 Best performance in terms of testing variable This testing variable (i.e. minimum mean of difference between predicted and me
45、asured value or minimum standard deviation of the difference) has to be agreed upon within the responsible WP. It should be noted that the test needs to be carried out on the full data set currently applicable and on agreed-upon sub-sets of the data. Rec. ITU-R P.311-15 5 4.1.2 “Physical basis” of t
46、he method chosen Most propagation prediction methods used are semi-empirical in nature because the details of the physical process are either not precisely known or because the number of input parameters would simply be impractical to provide. The better the underlying physical principles are repres
47、ented in a model, the better the chances that the model can also be applied in hitherto unexplored domains (new frequencies, new climatic zones, etc.). A purely empirical method that is simply derived from curve-fitting to measured data is normally not suitable for being applied outside the domain o
48、f the measurements made and should therefore be avoided. 4.1.3 “Simplicity” This criterion, which to some degree may be interpreted as contradictory to the “physical basis” requirement should only be applied to keep the number of required input parameters to a minimum and to assure that the descript
49、ion of the algorithm lends itself to a clear and unambiguous implementation in a computer program. Nomographs can be highly useful simplified representations of a prediction method but they cannot be accepted as the method per se. 4.2 Testing variable for comparing rain attenuation predictions Attenuation predictions are generally made for a number of transmission paths at a fixed set of probability levels. Data for comparison of prediction methods are to be tabulated at fixed probability levels, e.g. 0.001%, 0.01% and 0.1% of the year.
