ITU Field-strength prediction methods for terrestrial point-to …€¦ · · 2010-08-25characteristics and operational procedures for ... Propagation of radio waves in ionized

63 Proceedings of WFMN07, Chemnitz, Germany

WFMN07_II_B3, pp. 63-67 http://archiv.tu-chemnitz.de/pub/2007/0210/

Abstract—The Radiocommunication Sector of the International

Telecommunication Union (ITU) develops Recommendations

providing information and propagation prediction methods for

various telecommunication services. This paper presents the

Recommendations concentrating on the work carried out in ITU

Study Group 3 “Radiowave Propagation”, in particular on

Recommendations for terrestrial point-to-area services, such as

terrestrial broadcasting and land mobile services. The respective

Recommendations cover propagation in the VHF and UHF range,

short range indoor and outdoor services in the frequency range

from 1 to 100 GHz and point-to-multipoint (e.g. WiMAX) services

in the frequency range of 3 to 60 GHz.

Index Terms—field strength prediction, point-to-area services,

propagation curves, radiowave propagation

I. INTRODUCTION

ITU is the leading United Nations agency for information

and communication technologies. As the global focal point for

governments and the private sector, ITU's role in helping the

world communicate spans 3 core sectors: radiocommunication,

standardization and development. ITU also organizes

TELECOM events and was the lead organizing agency of the

World Summit on the Information Society.

ITU is based in Geneva, Switzerland, and its membership

includes 191 Member States and more than 700 Sector

Members and Associates.

II. ITU-R RADIOCOMMUNICATION SECTOR

The mission of the ITU Radiocommunication Sector is,

inter alia, to ensure rational, equitable, efficient and

economical use of the radio-frequency spectrum by all

radiocommunication services and to carry out studies and

adopt recommendations on radiocommunication matters.

The ITU Radiocommunication Sector specializes in

facilitating international collaboration to ensure the rational,

equitable, efficient and economical use of the radio-frequency

spectrum and satellite orbits, by:

- holding World and Regional Radiocommunication

Conferences to expand and adopt Radio Regulations and

Regional Agreements covering the use of the radio-

frequency spectrum;

- establishing ITU-R Recommendations, developed by ITU-R

Study Groups (SG) in the framework set by

Radiocommunication Assemblies, on the technical

characteristics and operational procedures for

radiocommunication services and systems;

- coordinating endeavours to eliminate harmful interference

between radio stations of different countries;

- maintaining the Master International Frequency Register;

and

- offering tools, information and seminars to assist national

radiofrequency spectrum management.

III. ITU-R STUDY GROUPS

The work is organized in Study Groups. More than 1 500

specialists, from telecommunication organizations and

administrations throughout the world, participate in the work

of the Study Groups concerned with:

- drafting technical bases for Radiocommunication

Conferences

- developing Draft Recommendations

- compiling Handbooks

ITU-R Study Groups are established and assigned study

Questions by a Radiocommunication Assembly to prepare

draft Recommendations for approval by ITU Member States.

Compliance with ITU-R Recommendations is not

mandatory. However, since they are developed by well-

respected radiocommunication experts from all over the world,

they enjoy a high reputation and are implemented worldwide,

getting therefore the status of international standards in their

domain of application.

Studies focus on the following:

- efficient use of the spectrum/orbit resource by space and

terrestrial services;

- characteristics and performance of radio systems;

- operation of radio stations;

- radiocommunication aspects of distress and safety matters.

ITU-R Study Groups also carry out preparatory studies for

World and Regional Radiocommunication Conferences. On

the basis of the input material from the Study Groups the

Conference Preparatory Meeting prepares a Report on the

technical, operational and regulatory or procedural matters to

be considered by a given Conference.

ITU Field-strength prediction methods for

terrestrial point-to-area services Rainer Grosskopf

Institut für Rundfunktechnik, Floriansmühlstraße 60, D-80939 München, Germany



At present, there are seven Study Groups specializing in the

following areas:

- SG 1 Spectrum management

- SG 3 Radiowave propagation

- SG 4 Fixed-satellite service

- SG 6 Broadcasting services

- SG 7 Science services

- SG 8 Mobile, radiodetermination, amateur and related

satellite services

- SG 9 Fixed service

Subgroups, such as Working Parties (WP) and Task Groups

(TG) are established to study the Questions assigned to the

different Study Groups.

IV. STUDY GROUP 3 – RADIOWAVE PROPAGATION

Chairman: Mr. B. Arbesser-Rastburg (European Space

Agency)

Scope: Propagation of radio waves in ionized and non-

ionized media and the characteristics of radio noise, for the

purpose of improving radiocommunication systems.

The following four Working Parties carry out studies on the

Questions assigned to Study Group 3:

WP 3J - Propagation

fundamentals

Chairman: M. Pontes

(Brazil)

WP 3K - Terrestrial point-

to-area propagation

Chairman: R. Grosskopf

(Germany)

WP 3L - Ionospheric

propagation

Chairman: J. Wang (USA)

WP 3M - Terrestrial point-

to-point and Earth-space

propagation

Chairman: C. Wilson

(Australia)

The principal aim of the Working Parties is to draft

Recommendations in the ITU-R P Series for subsequent

adoption by Study Group 3, and approval by the Member

States. The Working Parties also develop Handbooks, which

provide descriptive and tutorial material, especially useful for

developing countries. A further task of the Working Parties is

to provide, through Study Group 3, propagation information

and advice to other ITU-R Study Groups in their preparation

of the technical bases for Radiocommunication Conferences.

Such information typically concerns identifying relevant

propagation effects and mechanisms, and providing

propagation prediction methods. The predictions are needed

for the design and operation of radiocommunication systems

and services, and also for the assessment of frequency sharing

between them.

V. ITU-R WORKING PARTY 3K – POINT-TO-AREA

PROPAGATION

Chairman: Mr. R. Grosskopf, Germany

WP 3K is responsible for developing prediction methods for

terrestrial point-to-area propagation paths. In the main, these

are associated with

- terrestrial broadcasting and mobile services

- short-range indoor and outdoor communication systems

(e.g. Wireless Local Area Networks)

- point-to-multipoint wireless access systems

In the following an overview is given on the ITU-R

Recommendations in the responsibility of Working Party 3K.

To find the respective Recommendation providing information

for a particular application it is best to look into

Recommendation ITU-R P.1144 “Guide to the application of

the propagation methods of Radiocommunication Study

Group 3”.

WG 3K developed and maintains the Handbook on

Terrestrial Land Mobile Radiowave Propagation. This

Handbook gives the technical basis for predicting radiowave

propagation in terrestrial point-to-point, point-to-area, and

point-to-multipoint mobile networks.

P.528 Propagation curves for aeronautical mobile and

radionavigation services using the VHF, UHF and SHF bands

This Recommendation provides propagation curves for the

above mentioned services. The Recommendation has not been

changed since 1986.

P.1406 Propagation effects relating to terrestrial land mobile

service in the VHF and UHF bands

Basic information is given on:

- Attenuation due to land cover

- Signal strength variability (shadowing, local reflections)

- Delay spread (local and large distance scatterers)

- Antenna effects (height gain, polarisation diversity)

- Portable effects (body loss)

- Temporal variations

VI. VHF AND UHF BANDS

In the VHF and UHF bands, field strength prediction takes

account of the effects of terrain in the vicinity of the

transmitter and receiver, and of the refractive nature of the

atmosphere. Allowance is also made for location variability for

land area coverage prediction with account taken of local

clutter surrounding the receiver. Consideration is also given to

mixed paths crossing both land and sea.

P.1546 Method for point-to-area predictions for terrestrial

services in the frequency range 30 MHz to 3 000 MHz

A consolidated prediction procedure has been developed,

suitable for broadcasting, land mobile, maritime mobile and

certain fixed services (e.g. those using point-to-multipoint

systems), allowing the appropriate values of antenna height

and path distance to be applied. Such a prediction procedure

represents a major tool for the frequency planning of

broadcasting and mobile services, particularly in the range 1-3

GHz, and for coordination when frequency sharing is involved.

This Recommendation provides a path general propagation

prediction method based on propagation curves (Fig.1) for

- Frequencies 100, 600, 2000 MHz

- Effective transmitting/base antenna heights

- Time percentage 50%, 10%, 1%



- Land, sea (cold, warm)

Field strength for a certain distance can be achieved by

inter- and/or extrapolation between the respective propagation

curves. Corrections can be calculated for

- receiving/mobile antenna heights

- ground cover types at receiving location

- location percentages (location variability)

- indoor reception (building entry loss)

- site shielding, e.g. terrain clearance angle

Fig.1 Field strength versus distance curve

P.[Path specific] A path specific propagation prediction

method for point-to-area terrestrial services in the VHF and

UHF band

A Draft New Recommendation was drafted in April 2007

providing a path specific propagation prediction method where

a terrain profile is needed. This propagation prediction method

takes account of the following model elements:

- line-of-sight;

- diffraction (embracing smooth-Earth, irregular terrain and

sub-path cases);

- tropospheric scatter;

- anomalous propagation (ducting and layer

reflection/refraction);

- height-gain variation in clutter;

- location variability;

- building entry losses.

The prediction procedure requires two radio-meteorological

parameters to describe the variability of atmospheric

refractivity.

- ∆N (N-units/km), the average radio-refractive index lapse-

rate through the lowest 1 km of the atmosphere, provides

the data upon which the appropriate effective Earth radius

can be calculated for path profile and diffraction obstacle

analysis (Fig. 2).

- N0 (N-units), the sea-level surface refractivity, is used only

by the troposcatter model as a measure of variability of the

troposcatter mechanism (´Fig. 3).

Global maps of ∆N and N0, and data files containing the

digitized maps are available.

Fig. 2 Average annual values ∆N

Fig. 3 Sea-level surface refractivity N0

VII. FREQUENCY RANGE ~1 TO 100 GHZ

At higher frequencies (typically from around 1 to 100 GHz),

the emphasis is on short-range systems, either indoor or

outdoor, as might be used by WLAN and personal mobile

communications.

P.1411 Propagation data and prediction methods for the

planning of short-range outdoor radiocommunication systems

and radio local area networks in the frequency range 300

MHz to 100 GHz

The Recommendation describes the relevant propagation

mechanisms such as reflection, scattering and diffraction

associated with buildings which give rise to effects such as

attenuation and multipath. The latter plays a vital part in the

channel modelling of a radio link, with which an assessment of

performance quality may be obtained. Models are developed

describing different types of environment (urban to rural) and

1 5 4 6 - 0 9

1 2 0 0 m

6 0 0 m

3 0 0 m

1 5 0 m

7 5 m

2 0 m

1 0 m

1 2 0

1 1 0

1 0 0

9 0

8 0

7 0

6 0

5 0

4 0

3 0

2 0

1 0

0

– 1 0

– 2 0

– 3 0

– 4 0

– 5 0

– 6 0

– 7 0

– 8 0

1 0 1 0 0 1 0 0 0

h 1 = 1 2 0 0 m

h 1 = 1 0 m

1

D i s t a n c e ( k m )

Fie

ld s

tren

gth

(d

B(µ

V/m

)) f

or

1 k

W e

.r.p

.

5 0 % o f l o c a t i o n s

h 2 : r e p r e s e n t a t i v e c l u t t e r h e i g h t

F I G U R E 9

6 0 0 M H z , l a n d p a t h , 5 0 % t i m e

M a x i m u m ( f r e e s p a c e )

T r a n s m i t t i n g / b a s e

a n t e n n a h e i g h t s , h 1

3 7 . 5 m



expressions are developed for quantifying the resulting path

loss.

Environments described in this Recommendation are

categorized solely from the radio propagation perspective.

Radiowave propagation is influenced by the environment, i.e.

building structures and heights, the usage of the mobile

terminal (pedestrian/vehicular) and the positions of the

antennas. Four different environments are identified,

considered to be the most typical, these are urban high-rise,

urban/suburban low-rise, residential and rural.

Different cell types depending on cell radius and typical

position of the base station antenna are defined. Physical

operating environments and the respective propagation

impairments by building heights, trees, traffic and street width

are described, as well as path categories for propagation over

rooftops, along street canyons or for line-of-sight paths. For

these scenarios models are given to evaluate path loss and the

characteristics of multipath, polarization, direction of arrival

and fading.

P.1238 Propagation data and prediction methods for the

planning of indoor radiocommunication systems and radio

local area networks in the frequency range 900 MHz to 100

GHz

Indoor wireless communication services can be

characterized by the following features:

- high/medium/low data rate

- coverage area (e.g. room, floor, building)

- mobile/portable/fixed

- real time/non-real time/quasi-real time

- network topology (e.g. point-to-point, point-to-multipoint,

each-point-to-each-point)

Propagation impairments in an indoor radio channel are

caused mainly by reflection from, and diffraction around,

objects (including walls and floors) within the rooms,

transmission loss through walls, floors and other obstacles,

channelling of energy, especially in corridors at high

frequencies and motion of persons and objects in the room.

These effects give rise to impairments such as path loss,

temporal and spatial variation of path loss, multipath effects

from reflected and diffracted components of the wave and

polarization mismatch due to random alignment of mobile

terminal.

ITU-R P.1238 gives information on path loss calculation

(site general), delay spread models (impulse response,

statistical models, site specific models), effect of polarization

and antenna radiation pattern, effect of building materials,

furnishings and furniture, effect of movement of objects in the

room and angular spread models.

P.[time and spatial profile] The prediction of the time and the

spatial profile for broadband land mobile services using UHF

and SHF bands

This Draft New Recommendation describes empirical

models for time and spatial profiles that are valid for a

frequency range from 0.7 GHz to 9 GHz. It is based on

measurements in both urban and suburban environments.

Broadband mobile systems have a focus to use techniques such

as multi-input-multi-output and adaptive array antenna.

Temporal and spatial profiles of multipath are fundamental

parameters for the study of those new techniques. Those

profiles are also influenced by propagation conditions such as

length and properties of the propagation path.

The delay profile and the arrival angular profile are

fundamental parameters for evaluating the multipath

characteristics. Once the profiles are modelled, multipath

parameters such as delay spread and correlation bandwidth, or

arrival angular spread and spatial correlation distance can be

derived from the profiles.

P.1791 Propagation prediction methods for assessment of the

impact of ultra-wideband devices

This Recommendation provides methods valid for a

frequency range from 1-10 GHz to calculate an ultra-wideband

(UWB) path loss in indoor and outdoor operating

environments for line-of-sight (LoS) and obstructed path

categories and to assess the power received by a conventional

narrow-band receiver from a UWB transmitter.

VIII. POINT-TO-MULTIPOINT

With the growing interest in delivery of broadband services

through local access networks, WP 3K studies the propagation

effects associated with millimetric radio systems (e.g.

operating around 3-60 GHz) used for point-to-multipoint

distribution. The frequency range was recently extended down

to approximately 3 GHz to cover WiMAX.

P.1410 Propagation data and prediction methods required for

the design of terrestrial broadband radio access systems

operating in a frequency range from 3 to 60 GHz

Prediction of area coverage has to address the effects of

buildings, their spatial distribution, attenuation and scattering

from vegetation, and attenuation by rain. Methods to quantify

the relevant propagation effects such as attenuation, and

distortion due to multipath, are a key area of study in WP 3K.

The Recommendation provides methods to calculate area

coverage (building blockage) by ray tracing or statistical

methods, vegetation attenuation, effects of precipitation on

availability (route diversity improvement with 2 base stations)

and propagation channel distortion by frequency selective

vegetation attenuation and multipath from reflections.

IX. FUTURE TASKS

An ongoing important task for Working Party 3K is to

improve existing Recommendations, either based on inputs

from member organisations or through liaisons with other

ITU-R Study Groups requesting for guidance on propagation

problems for new or existing services.

Working Party 3K is progressing toward Recommendations

that allow smooth transitions of propagation predictions:

- from short-path to long-path situations;

- from terrestrial broadcasting and terrestrial mobile to

combined situations;



- and from first-order propagation predictions (site general)

to more detailed and accurate predictions (site specific)

based upon terrain and surface features.

It is believed this progression will produce better

Recommendations that will be easier for the service Study

Groups to utilize and provide better results. There is also a

need to extend the frequency range of point-to-area prediction

methods up to approximately 6 GHz for future terrestrial

services.

Another important issue is the development of a new

Recommendation on the effect of objects such as buildings or

vegetation, generally termed “clutter”.

REFERENCES

ITU homepage at http://www.itu.int/ITU-R/ in particular

brochure on ITU-R Study Groups http://www.itu.int/ITU-

R/study-groups/docs/brochure-sg-en.pdf

Documents

ITU Field-strength prediction methods for terrestrial point-to …€¦ · · 2010-08-25characteristics and operational procedures for ... Propagation of radio waves in ionized