1、 Recommendation ITU-R P.1410-5(02/2012)Propagation data and prediction methods required for the design of terrestrial broadband radio access systems operating in a frequency range from 3 to 60 GHzP SeriesRadiowave propagationii Rec. ITU-R P.1410-5 Foreword The role of the Radiocommunication Sector i
2、s to ensure the rational, equitable, efficient and economical 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 func
3、tions of the Radiocommunication Sector are performed by 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 refe
4、renced in Annex 1 of Resolution ITU-R 1. Forms to be used 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
5、ITU-R patent information database can also be found. Series 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 s
6、ervice (television) F Fixed service M Mobile, radiodetermination, 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
7、and fixed service systems SM Spectrum management SNG Satellite 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,
8、 2012 ITU 2012 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without written permission of ITU. Rec. ITU-R P.1410-5 1 RECOMMENDATION ITU-R P.1410-5 Propagation data and prediction methods required for the design of terrestrial broadband radio access sys
9、tems operating in a frequency range from 3 to 60 GHz (Question ITU-R 203/3) (1999-2001-2003-2005-2007-2012) Scope Broadband wireless access is an important method of providing broadband to individual households as well as small business enterprises. This Recommendation addresses systems in a frequen
10、cy range from 3 to 60 GHz and gives guidance for line-of-sight (LoS) coverage and non-LoS propagation mechanisms of importance. For affected systems, rain methods are given to estimate diversity improvement by selecting the best base station from two and the coverage reduction under rainfall. Guidan
11、ce is given regarding wideband distortion. The ITU Radiocommunication Assembly, considering a) that for proper planning of terrestrial broadband radio access systems it is necessary to have appropriate propagation information and prediction methods; b) that Recommendations established for the design
12、 of individual links do not cover area aspects, recommends 1 that the propagation information and prediction methods set out in Annex 1 should be used when designing terrestrial broadband radio access systems, operating in a frequency range from 3 to 60 GHz. Annex 1 1 Introduction There is a growing
13、 interest in delivery of broadband services through local access networks to individual households as well as small business enterprises. Radio solutions are being increasingly considered as delivery systems, and these are now available on the market. Several systems are being considered and introdu
14、ced, such as local multipoint distribution system (LMDS), local multipoint communications system (LMCS), and point-to-multipoint (P-MP) system. Collectively, these systems may be termed broadband wireless access (BWA). International standards are being developed, for example WMAX based on IEEE 802.1
15、6 and HiperMAN. There is a need within the network planning, operator, and manufacturing communities and by regulators for good design guidance with respect to radiowave propagation issues. 2 Rec. ITU-R P.1410-5 2 Area coverage When a cellular system is planned the operator has to carefully select b
16、ase station location and height above the ground to be able to provide service to the target number of users within an area. The size of the cells may vary depending on the topography as well as on the number of users for which the radio service is being offered. This section presents a statistical
17、model for building blockage based on very simple characterization of buildings in an area and provides guidance based on detailed calculations. It also presents a vegetation attenuation model and some simple design rules. 2.1 Building blockage Building blockage probability is best estimated by ray-t
18、racing techniques using real data from detailed building and terrain databases. The requirements for ray-tracing techniques are briefly described in 2.1.1. However, in many areas, suitable databases are not available and the statistical model outlined in 2.1.2 is recommended. 2.1.1 Ray-tracing requi
19、rements An accurate coverage prediction can be achieved using ray-trace techniques in areas where a database of land coverage is available. Owing to the high frequency and short path lengths involved, straight line geometric optical approximations can be made. To a first order of approximation in es
20、timating coverage, an optical line-of-sight (LoS) determination of 60% of the 1st Fresnel zone clearance is sufficient to ensure negligible additional loss (see Fig. 1). Diffraction loss for non-LoS cases is severe. The accuracy of the buildings database will limit the accuracy of the ray prediction
21、 and the database must include an accurate representation of the terrain and buildings along the path. The Earth curvature must also be considered for paths 2 km. Buildings and vegetation should be considered as opaque for this procedure. FIGURE 1 Each building must lie below the LoS ray joining Tx
22、and Rx rrxrloshtxhloshrxMany buildingsRxTxMeasurements of signal characteristics when compared against ray-trace models have shown good statistical agreement, but the measurements demonstrated considerable signal variability with position and with time for paths without a clear LoS. Therefore, owing
23、 to the limited accuracy of real building databases, predictions of service quality for specific near LoS paths will not be possible. Rec. ITU-R P.1410-5 3 Vegetation, in particular tall trees and shrubs can cause severe service impairment and vegetation data should ideally be included in the databa
24、se. Measurements have indicated that, for service provision in a typical urban/suburban region, users impaired by multipath reflection effects are much rarer than those blocked by buildings or vegetation, owing to the narrow antenna beamwidth, and it is therefore not necessary to calculate reflectio
25、ns (see 4.2.1). The database used for ray-tracing evaluation may be a detailed object-oriented database, with terrain height, individual building outlines including roof height and shape data and with vegetation represented as individual trees or blocks of trees. As an alternative, in determining Lo
26、S, a raster database of spot height, such as generated from an airborne synthetic aperture radar (SAR) measurement may be used (see Table 1). TABLE 1 Minimum database requirements Object Format Horizontal resolution (m) Vertical resolution (m) Terrain Grid of spot heights 50 1 Buildings Object orien
27、ted or high resolution raster image 1 1 Vegetation 2.1.2 Dealing with reflections and scattering In an urban environment reflections off nearby buildings can be the dominant propagation mechanism in non-LoS conditions. Efficient methods to calculate reflections in large databases have been the subje
28、ct of much research and literature. When considering multiple reflections and diffractions the problem becomes intractable for all but the most trivial of scenarios. For this reason a single-bounce reflection model, with each path to and from the reflector being subject to its own vertical and horiz
29、ontal diffractions losses is recommended. The rough surface scatter model It is suggested that to minimize computational overhead the simple model given here be used. The model is a scalar model for the incoherent scatter from a rough surface. That is, it only considers scattered power and ignores p
30、hase and polarization effects. Geometry Consider a rough surface facet F of area A. Let T and R be a transmitter and receiver. iand mare unit vectors in the directions TF and FR and n is the normal to the facet, Fig. 2. 4 Rec. ITU-R P.1410-5 FIGURE 2 Reflection geometry TnmRlAFPtd2Prscatd1Ptand Prsc
31、atare the transmitted and received, scatter powers at T and R respectively and, without loss of generality, we assume omnidirectional antennas at T and R. Propagation from T to F Assuming free-space propagation, the power flux-density (pfd) S (W/m2) at distance d1from T is: tPdS21244= (1) where is t
32、he wavelength. The power Pfrimpinging on F is then: nl= SAPfr(2) This result assumes that any dimension of A 1 for a loss): 2221221)(21ddAddPPLnonspecLoSrscatrscat+=ni(7) All the terms in this expression are strictly 1 if A is too large compared to d1and d2. However as noted above, the model is only
33、 valid if any dimension of A 25 dB) attributed to this mechanism make it less significant in providing coverage, though it should be considered in evaluating interference. Inclusion of specular reflections in interference modelling has a significant impact on the interference level predicted, especi
34、ally when directional antennas are used. For a fixed network with directional antennas in an urban scenario reflections should be modelled for accurate interference prediction. 18 Rec. ITU-R P.1410-5 It is important to understand the limitations of the scenario. Firstly the results are applicable to
35、 an urban area with high transmitter locations with large elevation angles over the short ranges that were examined. Lower transmitter locations might change the conclusions drawn. It is expected that rural and suburban scenarios would give significantly different results with regard to the breakdow
36、n of dominant propagation mechanisms. The absence of large reflective objects would reduce the influence of specular reflection though scattering may still be important. For suburban and rural scenarios inclusion and correct modelling of vegetation data is also very important. 2.4 Path loss dependen
37、ce on subscriber station (SS) antenna height Figure 10 shows the mechanism of the propagation over the rooftops based on a geometrical propagation model. We can divide the height variation of the path loss due to the base station (BS) subscriber station (SS) horizontal distance into three regions de
38、pending on the arriving wave that is dominant over the entire level. Figure 11 shows the geometry for the calculation of the height variation of the path loss in the following three regions. a) The direct wave dominant region where the BS-SS horizontal distance is very short (Fig. 11(a) In this regi
39、on, the direct wave can arrive at any height of the SS antenna. The path loss and the height variation of the path loss at the SS are dominated by the propagation loss of the direct wave (LoS region at any height of the SS antenna). b) The reflected wave dominant region where the BS-SS distance is r
40、elatively short (Fig. 11(b) In this region, a strong reflected wave as a one- or two-time reflected wave and diffracted wave can arrive at any height of the SS antenna in the non-line-of-sight (NLoS) region. The propagation loss of the minimum-time reflected wave arriving at any height of the SS ant
41、enna is lower than that of the diffracted waves in the NLoS region. The path loss and height variation of the path loss at the SS in this region are dominated by the reflected waves. The path loss in the relatively near region corresponds to the direct, one-, and two-time reflected wave components a
42、t the minimum height where the direct, one-, and two-time reflected waves arrive at the SS. c) The diffracted wave dominant region where the BS-SS distance is relatively long (Fig. 11(c) In this region, a strong reflected wave as a one- or two-time reflected wave can only just barely arrive at the S
43、S antenna in the NLoS region where the SS antenna height is lower than that of the surrounding buildings, and only weak many-time reflected waves and diffracted waves can arrive at the SS antenna. The propagation loss of the minimum-time reflected wave arriving at the SS becomes higher than that for
44、 the diffracted wave. The path loss and height variation of the path loss at the SS in the far region are dominated by the diffracted waves from the edge of the building roof. The path loss and height variation of the path loss at the SS nearly correspond to those for the diffracted wave. Rec. ITU-R
45、 P.1410-5 19 FIGURE 10 Mechanism of propagation over rooftops based on geometrical propagation model hBSDominantwavePropagationlossDirectwaveDirectwaveDiffracted waveReflected wave1 - time 2 - time k - timeMinimum time-reflected wavediffracted waveHeight variationof SS antenna, hssdDominant waveNon-
46、dominant waveBSSSBuildingww1w220 Rec. ITU-R P.1410-5 FIGURE 11 Propagation model based on dominant waves that influence height variation of path loss (a) Direct wave dominant region where BS-SS horizontal distance is very short (LoS) CrosssectionhBShSSdsinPlanBSdSS(b) Reflected wave dominant region
47、where BS-SS distance is relatively short CrosssectionhBShSSdsinPlanBSdkSSAhbhSSwAw1w2(c) Diffracted wave dominant region where BS-SS distance is relatively long BuildingCrosssectionBSSShSSdsinAhSShbPlandw1w2hBSRec. ITU-R P.1410-5 21 The relevant parameters for each situation are given hereafter: f:
48、frequency (GHz) : angle between building row and line of visibility/LoS (degrees) hBS: base station antenna height (m) hSS: subscriber station antenna height (m) hSS: depth to the shadow region (m) hb: average building height (m) w: distance between buildings (m) d: horizontal distance between anten
49、nas (m). Here, this model is valid for the following: f: 2 to 30 GHz : 10 to 90 degrees hBS: up to 70 m (higher than hb) hSS: 2 to (hb+3) m w: 10 to 25 m d: 10 to 5 000 m. (NOTE The range of the antenna height of the SS covers continuously from LoS to NLoS regions.) Based on these propagation mechanisms, the loss due to the SS antenna height between isotropic antennas can be divided into three regions in terms of the dominant arriving waves at the SS. These are the direct wave dominant region (LoS region), reflected wave dom
