1、 Report ITU-R P.2145(06/2009)Model parameters for an urban environment for the physical-statistical wideband LMSS model in Recommendation ITU-R P.681-6P SeriesRadiowave propagationRep. ITU-R P.2145 ii Foreword The role of the Radiocommunication Sector is to ensure the rational, equitable, efficient
2、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 functions of the Radiocommunication Sector are perf
3、ormed 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 referenced in Annex 1 of Resolution ITU-R 1. Forms
4、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 ITU-R patent information database can also be f
5、ound. Series of ITU-R Reports (Also available online at http:/www.itu.int/publications/R-REP/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, r
6、adiodetermination, amateur and related satellite services P Radiowave propagation RA Radio astronomy RS Remote sensing systems SA Space applications and meteorology SF Frequency sharing and coordination between fixed-satellite and fixed service systems SM Spectrum management Note: This ITU-R Report
7、was approved in English by the Study Group under the procedure detailed in Resolution ITU-R 1. Electronic Publication Geneva, 2010 ITU 2010 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without written permission of ITU. Rep. ITU-R P.2145 1 REPORT ITU-R
8、 P.2145 Model parameters for an urban environment for the physical-statistical wideband LMSS model in Recommendation ITU-R P.681-6 (2009) Summary This Report describes the physical-statistical wideband LMSS channel model proposed in draft Recommendation ITU-R P.681-7 7, providing all background and
9、relevant information. The relevant information was taken from input Document 3M/52, Annex 4, and input Document 3M/70. Annex 1 CONTENTS Page 1 Introduction 3 2 Software model download 4 3 Physical-statistical wideband model for mixed propagation conditions 4 3.1 Shadowing of the direct signal . 6 3.
10、1.1 House-front module . 6 3.1.2 Light pole module 9 3.1.3 Tree module . 10 3.2 Reflections 11 3.2.1 Synthesis of a single reflection 11 3.2.2 Number of coexisting reflections . 13 3.3 Model parameters for an urban environment 14 3.4 Model input . 14 3.5 Model output . 15 3.6 Model output usage . 16
11、 3.7 User Implementation Features: interpolation of series of time-continuous discrete impulses to FIR filter coefficients . 16 3.7.1 Low-pass interpolation of sampling points matching Dirac input impulses . 17 3.7.2 Low-pass interpolation of time-continuous Dirac input impulses . 20 3.7.3 Interpola
12、tion of time-continuous Dirac input impulses in frequency domain 21 2 Rep. ITU-R P.2145 Page 3.7.4 Comparison of the interpolation methods with a sampling frequency of 100 MHz . 24 4 Report on physical-statistical wideband LMSS model in urban and suburban scenarios in Munich 26 4.1 Environment descr
13、iption . 27 4.1.1 Urban measurements 27 4.1.2 Suburban city . 29 4.2 Model description of scenario specific features . 30 4.2.1 Urban vehicle . 32 4.2.2 Suburban vehicle 37 4.2.3 Urban pedestrian 43 4.2.4 Suburban pedestrian . 48 4.3 Geometric parameters . 54 4.3.1 User parameters 54 4.3.2 Building
14、parameters . 54 4.3.3 Tree parameters 57 4.3.4 Pole parameters 59 5 Data file interface descriptions . 61 5.1 Statistical data file description 62 5.1.1 Elevation vector . 62 5.1.2 Number of coexisting echoes . 62 5.2 Echo bandwidth 63 5.3 Life span of reflectors . 64 5.4 Rice factor of echoes 64 5.
15、5 Movement of reflection points 65 5.6 Horizontal reflector position distribution . 65 5.7 The relative satellite-reflector azimuth angle . 67 5.8 Average power of echo signals . 67 6 Acronyms . 69 7 IPR protection . 70 References 70 Rep. ITU-R P.2145 3 1 Introduction The statistical data provided w
16、ith the physical-statistical wideband land mobile satellite services (LMSS) channel model also named in this Report as the land mobile multipath channel model (LMSCM), was derived from measurement data recorded in a comprehensive high resolution channel sounding campaign in and around Munich in 2002
17、. In this campaign different urban, suburban and rural environments were measured for car and pedestrian applications. In these measurements the satellite of a potential navigation system was simulated by a Zeppelin NT. The Zeppelin transmitted the measurement signal between 1 460 and 1 560 MHz towa
18、rds the ground using a hemispherical, circular polarized, antenna with 10W EIRP. The receiver was mounted in the measurement vehicle, which was driven through the measurement area. In the case of the pedestrian measurement the antenna was carried by the walking user followed by the measurement vehic
19、le. Based on this measurement data the LMSCM was developed. This model is a realistic high resolution deterministic-statistical model. A receiver can be moved through a synthetic environment with houses, trees and lamp posts. These obstacles influence the LoS path. In addition reflectors are produce
20、d causing echo signals. The statistical part of the model comprises: the house front, tree and lamp post generation in the synthetic environment; the position dependent LoS signal power variations in the shadow of tree tops; the position of reflectors dependent on the satellites azimuth and elevatio
21、n; the mean power of echoes depending on their distance to the receiver and on the; satellite elevation; Rice factor and bandwidth of echo signals depending on the satellite elevation; the life span of echoes depending on the satellite elevation; the number of coexisting echoes in the channel depend
22、ing on the satellite elevation; and the movement of reflection points, also depending on the satellite elevation. Deterministically modelled are: the diffraction of the LoS signal on houses, tree trunks and lamp posts; the delay of diffracted signals received in the shadow of houses; the mean attenu
23、ation through tree tops; and the delay and Doppler shift trends of echo signals due to the receiver and reflector movement. An important model feature is the high level of detail. Realistic correlation between echo signals is achieved due to the used reflector position statistics combined with the d
24、eterministically calculated delay and Doppler trends. Full satellite azimuth and elevation dependency is given for both LoS and the echo signals. As general model parameters the snapshot rate, the frequency band, the user type and the environment can be chosen. Parameters for the distribution of e.g
25、. house heights and widths, for tree and lamp post size and positions, but also for the street width and e.g. the receiver antenna height allow to model specific scenarios and to investigate their impact. High flexibility is also given by the way oriented deterministic and stochastic model approach.
26、 Receiver speed and heading input allows to simulate different movement situations, e.g. turns, a traffic jam, stop and go, or the relatively long stops at traffic lights. Also speeds which are even higher than during the measurement can be applied. 4 Rep. ITU-R P.2145 For a complete description of
27、the measurement, the data analysis and the modelling of the satellite to earth multipath channel see also Lehner 2007. The structure of this Annex is the following: Section 1 gives an introduction to the model, 2 describes in detail the characteristics of the channel model and implementation feature
28、s. Section 3 provide all features of the model which are dependent on the urban scenario where measurements were originally taken for the development of the model. Section 4 includes an Interface Control Document for users interested on understanding the software implementation or re-implement the m
29、odel. Acronyms are found in 6. Section 7 provides information on intellectual property rights associated to the models and References. 2 Software model download The MATLAB implementation of the model needs only 140 KB disk space including the statistic data for the urban city center environment for
30、car applications. It is a stand alone model generating its own scenery. The execution speed is reasonably fast with 250 complex channel impulse responses per second on a 1.5 GHz CPU. The model output is a complex time-variant channel impulse response with up to 80 discrete rays. Due to this time var
31、iant tapped delay line structure it can be easily incorporated in any simulator. The complete model implemented in MATLAB can be downloaded from: http:/www.kn-s.dlr.de/satnav/. 3 Physical-statistical wideband model for mixed propagation conditions For broadband LMSS with a multipath propagation chan
32、nel where different frequencies within the signal bandwidth are affected differently by the channel (frequency-selective channels), a model that implements a linear transversal filter whose output is a sum of delayed, attenuated and Doppler shifted versions of the input signal (wideband model) is mo
33、re suitable. Definitions on multipath propagation are found in Recommendation ITU-R P.1407-2. The model is given for a situation where a satellite is transmitting from a known position to a receiver on ground, where an elevation and an azimuth can be computed relative to the receiver heading and pos
34、ition. The model can be applied for frequencies between 1 and 2 GHz. It is suitable to serve the requirements of wideband transmission systems with a bandwidth up to 100 MHz. The model is based on deterministic and stochastic parameters and it is able to generate vectors that include complex envelop
35、e time-series of direct signal and reflections, with corresponding path delay vectors. The parameters determining the stochastic behaviour of the model are derived from measurements obtained on a given scenario. The geometry of the model is based on a synthetic environment representation. In the sce
36、nery there is a local Cartesian coordinate system. To keep the model simple, the receiver is moving in the x-direction only. Turns (changes of the receiver heading) are modelled by changing the satellite azimuth. Therefore, the model azimuth is calculated by: satRx= (1) where: Rx: absolute heading o
37、f the receiver sat: absolute satellite azimuth. Rep. ITU-R P.2145 5 For the movement model, in the local coordinate system the receiver position is calculated by: () ()=tRxttvtx0d (2) where ()tvRxis the velocity of the receiver. The y and z coordinates stay constant during the simulation run. The ch
38、annel model is realized in a modular way consisting of a combination of the following parts: Shadowing of the direct signal: house front module; tree module; light pole module; Reflections module. The structure of the model is illustrated in Fig. 1 including the following input, intermediate and out
39、put time-variant signals: vu(t): user speed hdu(t): user heading els(t): satellite elevation azs(t): satellite azimuth xu(t): user position in x-axis (y and z axis are considered constant) azu(t): user azimuth yu(t): output signals, where each i is related to direct signal and reflectors. FIGURE 1 S
40、tructure of the model ReflectormodelReflectormodelReflectormodelReport P. 2145-01House frontTreeLight poleSynthetic environmentx(t)Uel (t)Saz (t)Uv(t)Uhd (t)Uel (t)Saz (t)SMotionmodely(t)1Reflectormodel6 Rep. ITU-R P.2145 3.1 Shadowing of the direct signal The shadowing and diffraction of the direct
41、 signal path at house fronts, trees and light poles within the scenery is calculated from a single knife-edge model (see Recommendation ITU-R P.526). A sketch of the general geometry is given in Fig. 2. FIGURE 2 Communicating antennas over an obstacle Report P. 2145-02r2r1b1l2y1l1hh1h2d2d1hh1h2d2d1r
42、2r1l1y1b1l221With the normalized Fresnel variable: 21211212112)cos(2ddddyddddb+=+= (3) the diffraction coefficient D() can be computed from the Fresnel integral F() by: +=+=21de1121)(11)(022jujjFjDuj(4) The distance y1is defined positive if there is a direct sight between the antennas, whereas it is
43、 negative if the considered obstacle is shadowing the signal, i.e. =otherwise|shadowedLoSif|111yyy 3.1.1 House-front module Let P denote the point where the direct signal between satellite and receiver intersects with the considered house front. Then diffraction occurs at the roof of the house above
44、 or below that point, and at the closest walls to the left and to the right of it (see Fig. 3): If the intersection point P falls inside a house (the direct ray is shadowed), the LoS signal is shadowed. In this case the model returns three paths, with relative delays, roof, wall,left, wall,rightand
45、complex amplitude factor . D(roof), D(wall,left), D(wall,right) respectively corresponding to the roof, the left wall and the right wall around P. If the intersection point P does not fall inside a house (the direct ray is not shadowed), the model returns a single path with amplitude factor D() corr
46、esponding to the smallest y1and with equal to zero. Rep. ITU-R P.2145 7 FIGURE 3 Diffraction at roofs and walls of house front Report P. 2145-03P y1The diffraction coefficients can be computed from the following variables: Diffraction at house roof The diffraction coefficient and relative delay due
47、to diffraction at house roof are computed by the model according to the following steps: Step 1: The distance between the intersection point P and the receiver on ground plane is calculated as follows: 221)()(RxPRxPyyxxd += (5) Step 2: The distance between P and the satellite is calculated as follow
48、s: 222)()(PSatPSatyyxxd += (6) Step 3: The distance between the vertical distance between P and house roof is calculated as follows: roofProofXXy =,1(7) Step 4: Calculate the normalized Fresnel variable roofaccording to equation (3), being the elevation angle of the satellite from the receiver. Step
49、 5: The diffraction coefficient due to diffraction at house roof D(roof) is calculated according to equation (4). Step 6: The path delay roofis calculated as follows: 011212)sin()cos()( cyddzzRxroofroof+= (8) 8 Rep. ITU-R P.2145 Diffraction at house walls The diffraction coefficients and relative delays due to diffraction at house walls are computed by the model according to the following steps: Step 1: The distance between the int
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