03 WCDMA RNP CW Test and Propagation Model Tuning

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WCDMA RNP CW Test and Propagation Model

Tuning

Internal


Introduction

CW test (Continuous Wave test) is an importa

nt step of Propagation Model Tuning. Accor

ding to the CW test data (including latitude/l

ongitude and received level) and correspon

ding Digital maps, we can get the accurate

Propagation Model through tuning.


Chapter 1 Principle of Radio Propagation

and CW Test

Chapter 2 CW Test Flow

Chapter 3 Analysis of CW Test Data

Chapter 4 Propagation Model Tuning

CONTENT


Principle of Radio Propagation and CW Test

Section 1 Basic Principle of Radio Section 1 Basic Principle of Radio

PropagationPropagation

Section 2 Principle of Propagatio

n Model Tuning

Section 3 Purpose of CW Test

Section 4 Basic Principle of CW T

est


Radio Waveband ClassificationRadio Waveband Classification

Frequencies in different bands have different propagation characteristics.


Electric field Electric fieldElectric field

Oscillato

r

Transmission direction of electric wave

Magnetic fieldMagnetic field

Generation of Electromagnetic WaveBased on Maxwell equations set:

The variable magnetic field can excite eddy electric field and variable electric field can also excite eddy

magnetic field.

Continuous electromagnetic oscillation (electromagnetic wave) forms due to mutual excitation of

alternating electric and magnetic field.

The speed of electromagnetic wave only varies with electric and magnetic characteristics of medium.

The propagation speed of electric microwave in vacuum equals that of light in vacuum.

Light and electromagnetic wave are essentially the same. Light is electromagnetic wave of a certain

wavelength.


Perpendicular incidence wave and ground reflection wave

(most common propagation modes)

Troposphere reflection wave (the propagation is very random)

Mountain diffraction wave (shadow area signal source)

Ionosphere refraction wave (beyond-the-horizon communication path)

Propagation Path


Propagation of Electromagnetic Wave

Ripple in the pond: Energy is propagated around from the source point and gradually weakens.

Electromagnetic wave is similarly propagated except that (when the radiation source is isotropically eff

ective ideal point source):

It is propagated in the form of spherical wave in three-dimension space.

The propagation media are different, including air, obstacle and reflector.


①Reflected wave of building②Diffracted wave③Direct wave④Reflected wave on the ground

Characteristics of Radio Propagation

Electric wave propagation system

of Land Mobile Communications

Radio propagation in

actual environment

LOS and NLOS


Characteristics of Radio ChannelsCharacteristics of Radio Channels

d (m)

Pr (dBm)

10 20 30

-20

-40

-60

Slow fading

Fast fading Radio channels vary with user’s position and time.

Multipath scattering and obstruction result in acute changes to received power.

Slow fading• Attenuation: Pr is in direct

proportion to 1/dn.

• Shadow: obstructed by barriers

Fast fading• Multipath effect

Fast changes to signal strength at small distance and time interval

Doppler frequency shift Delay spread


Diversity TechnologyDiversity Technology

Measures against fast fading- diversity technologies

－ Explicit diversity• Space diversity• Polarization diversity• Frequency diversity ： GSM-frequency hopping; WCDMA-spread

spectrum

－ Implicit diversity• Implicit diversity uses signal processing technologies to hide diver

sity functions into signals under transmission, such as RAKE reception technology, interleaving and error code correction.

• Regarded as time diversity


Delay SpreadDelay Spread Multipath propagation: Signals on different paths reach the receiver at

different time.

When the receiver fails to distinguish multipath signals, co-channel interference (CCI) occurs. In the WCDMA system, only the multipath delay larger than one chip period (0.26µs) can be recognized.

Typical value (µs): Open < 0.2, Suburban = 0.5, Urban = 3

Solutions Equalization and RAKE technologyEqualization and RAKE technology


Doppler Frequency Shift Example of Doppler effect: A train is passing by you.

f1

f2

f3

V(km /h)

Doppler frequency shift in Mobile Communications


T

R

T

R

• Diffraction loss • Penetration loss

• Clutter loss

Loss


¦ È

¦ È¦ Å0¦ Ì 0 ¦ Å¦ Ì ¦ Å0¦ Ì 0

d

Dw1 w2

E1

E2

XdBmWdBm

Penetration loss=X-W=B dBPenetration loss=X-W=B dB Reflection and refraction of electromagnetic wave through the wall

Indoor signals depend on penetration loss of building.

Signals are different at the indoor window and in the middle of room.

Building materials have great effect on penetration loss.

The reference angle of electromagnetic wave have great effect

on penetration loss.

Penetration Loss


• Obstacle/penetration loss is: Partition obstruction: 5～ 20dB

Floor obstruction: ＞ 20dB

Obstruction of furniture and other barriers: 2～ 15dB

Thick glass: 6～ 10dB

Penetration loss of the carriage of the train: 15～ 30dB

Penetration loss of lift: 30dB or so

Loss of thick leaves: 10dB

Penetration Loss


Ground type WaterPaddy

fieldField

City,

mountain and

forest

Equivalent ground

reflection coefficient0.9～ 1 0.6～ 0.8 0.3～ 0.5 0.1～ 0.2

Reflection loss (dB) 0～ 1 2～ 4 6～ 10 14～ 20

Reflection Loss


Radio Propagation EnvironmentRadio Propagation Environment

Radio propagation environment determines the propagation models directly. And propagation environment is impacted by the following factors:• Landform: mountain, hill, plain, waters, and vegetation • Clutter: building, road and bridge• Noise: natural noise and artificial noise• Climate: rain, snow and ice (tiny effect on UHF band)


Radio Propagation EnvironmentRadio Propagation EnvironmentType of radio environment

Radio environment is classified as follows, according to ITU-R P.1411-1

and specific conditions in China.

Propagation

environmentDescription

Dense urbanMany tall buildings, signals fail to diffract from the roof of

building .

UrbanSignals can diffract from the roof due to low buildings and wide

streets.

Suburban Low and sparse buildings

Rural Low and sparse buildings, but with lots of vegetation

Mountainous areas

Road

Indoor


Radio Propagation EnvironmentRadio Propagation Environment

Type of propagation environment

The corresponding cell type is as follows:

Cell type Cell type Typical antenna installation

Macro-cell >500 mInstalled outdoors, higher than average height of

surrounding roofs

Micro-cell 100~500mInstalled outdoors, lower than average height of

surrounding roofs

Pico-cell <100mInstalled outdoors or indoors, lower than height of all

roofs

Type of other new cells, such as Mini-cell…



Section 1 Basic Principle of

Radio Propagation

Section 2 Theory of Propagation Section 2 Theory of Propagation

Model TuningModel Tuning


Section 4 Basic Principle of CW

Test


Radio Propagation Model

Propagation model is used to predict the effect of terrain, obstacle and artificial environment on the path loss.

WCDMA common propagation modelsWCDMA common propagation models


Okumura/Hata model

For: 900M－ 2000MHz

COST231-Hata model

For: 1500-2000MHz

COST231 Walfish-Ikegami model

For: 800M-2000MHz

Keenan-Motley model

For indoor propagation

Propagation model in UNET

For macro cell on 300M－ 2000M

Common propagation models




L=K1 + K2log(d) + K3log(HTxeff) + K4×Diffraction + K5log(d)×log(HTxeff) + K6(HRxeff) + Kclutterf(clutter)

K1: constant (dB)K2: multiplier factor of log(d)d: distance between Tx antenna and Rx antenna (m)K3: multiplier factor of log(HTxeff)HTxeff: effective height of Tx antenna (m)K4: multiplier factor of diffraction loss, which must be a positive valueDiffraction loss: diffraction loss through the path with barriers (dB)K5: multiplier factor of log(HTxeff)log(d)K6: multiplier factor of HRxeffHRxeff : effective height of Rx antenna (m)Kclutter: multiplier factor of for f(clutter)f(clutter): average weighted loss caused by clutter

Model in UNET:



Section 1 Basic Principle of Rad

io Propagation

Section 2 Theory of Propagatio

n Model Tuning

Section 3 Purpose of CW TestSection 3 Purpose of CW Test

Section 4 Basic Principle of CW

Test


Purpose of CW Test

Compare CW test data w

ith prediction results, and

then tune the propagatio

n parameters to improve

the accuracy of coverage

prediction.

GPS



Section 1 Basic Principle of Rad

io Propagation

Section 2 Theory of Propagatio

n Model Tuning


Section 4 Basic Principle of CW Section 4 Basic Principle of CW

TestTest


Basic Principle of CW Test

Typification

The CW test data must represent the characteristic of elec

tromagnetic wave in this area.

Balance

The CW test data must represent the characteristic of elec

tromagnetic wave by the proportion of different clutters in t

his area.



and CW Test




CONTENT


CW Test Flow

Section 1 Site SelectionSection 1 Site Selection

Section 2 Building Test

Platform in Networking

Section 3 Drive Test


Site Selection

Principles of site selection

Number of sites: It is usually agreed that a minimum of 5 sites should be

tested in large and dense city, but one site is enough in the city, which

mainly depends on antenna height and EIRP.

Representation: Site selection should aim to cover all types of clutter

(from the digital map) in the coverage zone.

Multiple models: Define the corresponding zone of each model if the test

environment requires multiple models to describe its propagation

characteristics.

Overlap: Increase measurement overlap area between each site as

much as possible. But reasonable inter-site distance should be ensured.

Obstacle: The data should be filtered in the subsequent processing if

obvious obstacle exists.


Site SelectionStandards of site selection

a. Antenna height should be greater than 20m.

b. The antenna should be 5m higher than the nearest

obstacle.

c. The obstacle mainly refers to the highest building on the roof where the antenna is installed. The building where the site is located should be higher than average height of surrounding buildings.

5m


CW Test Flow

Section 1 Site Selection

Section 2 Building Test Section 2 Building Test

Platform in NetworkingPlatform in Networking

Section 3 Drive Test


Building Test Platform in Networking

Tx subsystem: Tx antenna, feeder, high-frequency signal source and

antenna holder

Rx subsystem: test receiver, GPS receiver, test software and laptop

High frequency signal

source

Signal source TMA

Power supply

Tx antenna

Rx antenna Drive test instrument

Build-in GPS

Laptop

RF cable 1 RF cable 2


Building Test Platform in Networking

Record the gain of the following parts on signals durin

g networking:

Tx power of signal source

Loss of RF cable

Gain of Tx antenna

Gain of Rx antenna


CW Test Flow

Section 1 Site Selection

Section 2 Building Test

Platform in Networking

Section 3 Drive TestSection 3 Drive Test


Drive Test

Keep to the following standards to select a test path

Landform: The test route must cover all main landforms in the area.

Height: The test route must cover landforms with different height in this area if t

he landforms are up-and-down.

Distance: The test route must cover different positions from the site in the area.

Direction: The test points must be consistent on the horizontal and vertical rout

e.

Length： The total distance of one CW test should be longer than 60km.

Number of test points: The more, the better.

Overlap: Overlap the test route in different sites as much as possible to improv

e the reliability of models.

Obstacle: Shadow areas behind this wall should be avoided when antenna sig

nals are obstructed by the wall at a side.


Drive Test

Lee criteria for sampling: 50 samples by 40λ

The maximum vehicle speed: Vmax=0.8λ/Tsample

Delete test results from the sampled data under abnormal conditi

ons:

Fading over 15~30db without reasonable causes

In tunnels

Under the viaducts

Select test routes from the main lobe coverage area if directional

antennas are adopted for a CW test.



and CW Test




CONTENT


Analysis of Test Data

Section 1 Data FilteringSection 1 Data Filtering

Section 2 Data Dispersion

Section 3 Data Binning

Section 4 Format Conversion


Data Filtering

Data to be filtered is as follows:

1. Data tested in the places where

GPS is unable to locate accurately

(such as under the overhead rack,

in the tunnel).

2. Data obtained when the distance

to antenna is too near or far.

3. Data obtained with too weak

signals.

4. Error data caused by inexact AP

(antenna pattern).

5. Other data inconsistent with the

requirements during the route

design of CW test.



Section 1 Data Filtering

Section 2 Data DispersionSection 2 Data Dispersion




Data Dispersion

Propagation in mobile communications can be indicated as

follows:

r(x) = m(x)r0(x)

X: distance

r(x): received signals

r0(x): Raileigh Fading

m(x): local mean value, the combination of long-term fading

and space propagation loss

2L: average length between sampling areas, also called

intrinsic length

Lx

Lx

dyyrL

xm )(2

1)(


Data Dispersion

The CW test is to obtain the local mean value of each geography

location in some areas as far as possible, i.e. the difference of r(x) and

m(x) should be the minimum value. In this sense, effect of Raileigh

Fading should be excluded.

When the intrinsic length equals 40 wavelength and the number of

sampling points is 50, the difference of test data and actual local mean

value can be less than 1dB according to Lee criteria.

Intrinsic length is average length for binning (2G band is 6 m long,

namely, 40 wavelength)

Since the locating speed of GPS is far lower than the receiving

speed of the receiver, the dispersion processing is required before the

binning.


Data Dispersion

The principle of dispersion processing is as follows:

Conditions:

− There are many test records arranged under each locating

point in time sequence because the receiving speed of the

receiver is far higher than the locating speed of GPS.

− The vehicle speed between two locating points is uniform.

− The time interval between every two measurement records is

the same.

Processing:

− Equally distribute these records to the route section between

two points in time sequence so that there will be sufficient

points in every 6m range on test route.



Section 1 Data filtering


Section 3 Data BinningSection 3 Data Binning



Data BinningObjectives:

Reserve the impact of slow fading but eliminate the fast

fading

Methods:

Method 1: make grids for the whole area with 6m side,

perform the arithmetic average for the data located in each

grid, and then take the grid center as the new location.

Method 2: divide the path into sections in equal interval

with 6m for each, and perform the arithmetic binning for the

data in each section to select some point for the location of

mean value.

Tool: CW Data Editor



Section 1 Data Filtering



Section 4 Format ConversionSection 4 Format Conversion


Format Conversion

The data format exported by Agilent E74xx Series is

Data format imported to UNET is

Format conversion can be implemented manually (saved a

s .dat file)

X Y CW_Power_List_

_Freq__Hz

CW_Power_List__A

mpl__dBm

Time Date

X Y CW_Power_List__Ampl__dBm



and CW Test




CONTENT


Propagation Model Tuning

Section 1 PreparationSection 1 Preparation

Section 2 Propagation Model

Tuning


Preparations

Installing network planning software:

UNET is powerful planning and optimization

software and model tuning is only one of its

functional modules.

Creating a project

In UNET, perform planning and optimization

model tuning based on each project.

Importing antenna pattern file

Correctly import the antenna pattern varying with

different manufacturers



Section 1 Preparations

Section 2 Propagation ModSection 2 Propagation Mod

el Tuningel Tuning


Propagation Model Tuning Flow



Establishing a model

Establish a standard macrocell model to be tu

ned.

Select the effective antenna height.

Select a calculation method of diffraction loss.

Importing data

Import CW test data file into the project.


Propagation Model TuningMap correction

GPS locating in CW test usually adopts WGS84 and UTM

projection. However, digital maps in China do not use such

projections and reference plane. Correct digital maps if CW

test data does not correspond to them.

Correction method:

− Correct four parameters on rectangular coordinates

in a digital map to realize the optimal match with the

test data.



Setting Filtering

Distance filtering:

− Filter the data of which r is less than

150m or r is greater than 3000m.

Signal strength filtering:

− Filter the data of which Signal is greater

than -40dBm or Signal is less than -

121dB.

Clutter filtering

− Filter the Clutter in which sampling

points are less than 300.



Parameter tuning

L=K1 + K2log(d) + K3log(Heff) + 4×Diffraction

+ K5log(d)×log(HTxeff) + K6(HRxeff)

+ Kclutterf(clutter)

Tune such parameters as log(d), log(Heff),

Diff, log(d)log(Heff), Hmeff and Klutter to

finally tune SPM propagation model.



calculated values for the variable

ERROR (measurement – prediction)

Regression line



Correction of propagation model parameters in a city

Parameter K Reference value

K1 23.2

K2 44.90

K3 5.83

K4 0.5

K5 -6.55

K6 0


Propagation Model TuningAnalysis of correction results

Analyze correctness of the acquired model after correction.

Evaluate the correctness of the model with Std Dev, which

refer to the binding degree of the acquired model and actual

test environment.

Make Std Dev less than 8 as much as possible in actual mo

del tuning, which indicates that the tuned model and actual t

est environment are well bound.


Summary

After completing this course, you should be able

to master:

Principle and purpose of CW test

Process of CW test

Process of propagation model tuning

Thank youwww.huawei.com

03 WCDMA RNP CW Test and Propagation Model Tuning

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