Atoll 2.8.2 Model Calibration Guide E0

Atoll RF Planning & Optimisation Software

Measurements and ModelCalibration Guide

v e r s i o n 2.8.2

AT282_MCG_E0

Contact Information

Atoll 2.8.2 Measurements and Model Calibration Guide Release AT282_MCG_E0

© Copyright 1997 - 2010 by Forsk

The software described in this document is provided under a licence agreement. The software may only be used/copiedunder the terms and conditions of the licence agreement. No part of this document may be copied, reproduced ordistributed in any form without prior authorisation from Forsk.

The product or brand names mentioned in this document are trademarks or registered trademarks of their respectiveregistering parties.

IntroductionTo find an accurate propagation model for determining path losses is a leading issue when planning a mobile radionetwork. Two strategies for predicting propagation losses are in use these days. One of these strategies is to derive anempirical propagation model from measurement data, and the other is to use a deterministic propagation model. Atoll’sStandard Propagation Model is a macrocell propagation model based on empirical formulas and a set of parameters.

When Atoll is installed, the SPM and Hata model parameters are set to their default values. However, they can be adjustedto tune the propagation model according to actual propagation conditions. This calibration process of the StandardPropagation and Hata Models facilitates improving the reliability of path loss and, hence, coverage predictions.

This guide describes the way to import and manage the necessary measurement data. It also indicates the calibrationmethod and the steps to calibrating the SPM and Hata models, from planning the CW measurement surveys to obtainingthe final propagation model. The resulting tuned propagation model is directly usable in Atoll as an additional model.

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Table of Contents

Table of Contents

1 Introduction ..................................................................................... 11

2 Standard Propagation Model .......................................................... 152.1 SPM Formula.................................................................................................................................. 15

2.2 The Correspondence Between the SPM and Hata ..................................................... 152.2.1 Hata Formula.................................................................................................................................... 152.2.2 Correspondence Between Hata and SPM Parameters .................................................................... 16

2.2.2.1 Reducing the Hata and SPM Equations ..................................................................................... 162.2.2.2 Equating the Coefficients ............................................................................................................ 16

2.2.3 Typical SPM Parameter Values ....................................................................................................... 162.3 Making Calculations in Atoll .................................................................................................... 17

2.3.1 Visibility and Distance Between Transmitter and Receiver .............................................................. 172.3.2 Effective Transmitter Antenna Height............................................................................................... 17

2.3.2.1 Height Above Ground ................................................................................................................. 172.3.2.2 Height Above Average Profile..................................................................................................... 172.3.2.3 Slope at Receiver Between 0 and Minimum Distance ................................................................ 182.3.2.4 Spot Ht........................................................................................................................................ 182.3.2.5 Absolute Spot Ht......................................................................................................................... 182.3.2.6 Enhanced Slope at Receiver ...................................................................................................... 18

2.3.3 Effective Receiver Antenna Height................................................................................................... 202.3.4 Correction for Hilly Regions in Case of LOS .................................................................................... 212.3.5 Diffraction ......................................................................................................................................... 212.3.6 Losses Due to Clutter ....................................................................................................................... 212.3.7 Recommendations for Using Clutter with the SPM .......................................................................... 22

3 Collecting CW Measurement Data.................................................. 293.1 Before You Start............................................................................................................................ 29

3.1.1 Geographic Data .............................................................................................................................. 293.1.2 Measurement Data ........................................................................................................................... 29

3.2 Guidelines for CW Measurement Surveys ....................................................................... 303.2.1 Selecting Base Stations ................................................................................................................... 303.2.2 Planning the Survey Routes ............................................................................................................. 303.2.3 Radio Criteria ................................................................................................................................... 313.2.4 Additional Deliverable Data .............................................................................................................. 31

4 The Model Calibration Process....................................................... 354.1 Setting Up Your Calibration Project..................................................................................... 35

4.1.1 Creating an Atoll Calibration Document ........................................................................................... 354.1.1.1 Setting Coordinates .................................................................................................................... 364.1.1.2 Importing Geo Data .................................................................................................................... 36

4.1.2 Importing CW Measurements........................................................................................................... 364.1.2.1 Importing a CW Measurement Path ........................................................................................... 374.1.2.2 Importing Several CW Measurement Paths ............................................................................... 384.1.2.3 Creating a CW Measurement Import Configuration.................................................................... 404.1.2.4 Defining the Display of CW Measurements ................................................................................ 41

4.1.3 Verifying the Correspondence Between Geo and Measurement Data ............................................ 434.1.4 Filtering Measurement Data ............................................................................................................. 44

4.1.4.1 Filtering on Clutter Classes......................................................................................................... 454.1.4.2 Signal and Distance Filtering ...................................................................................................... 46

4.1.4.2.1 Typical Values....................................................................................................................... 464.1.4.2.2 Using Manual Filtering on CW Points ................................................................................... 464.1.4.2.3 Creating an Advanced Filter.................................................................................................. 474.1.4.2.4 Using the Filtering Assistant on CW Measurement Points.................................................... 48

4.1.4.3 Filtering by Geo Data Conditions................................................................................................ 504.1.4.3.1 About Diffraction ................................................................................................................... 504.1.4.3.2 About Specific Sections ........................................................................................................ 504.1.4.3.3 About Potentially Invalid Measurement Levels ..................................................................... 51

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Atoll User Manual

4.1.4.3.4 Deleting a Selection of Measurement Points .........................................................................534.1.4.3.5 Using Filtering Zones on CW Measurement Points ...............................................................544.1.4.3.6 Filtering by Angle ...................................................................................................................54

4.1.5 Selecting Base Stations for Calibration and for Verification..............................................................554.2 Calibrating the SPM .....................................................................................................................55

4.2.1 Quality Targets..................................................................................................................................554.2.2 Setting Initial Parameters in the SPM ...............................................................................................56

4.2.2.1 Parameters Tab...........................................................................................................................564.2.2.2 Clutter Tab...................................................................................................................................57

4.2.3 Running the SPM Calibration Process..............................................................................................594.2.3.1 The Automatic Calibration Wizard ...............................................................................................604.2.3.2 The Assisted Calibration Wizard .................................................................................................61

4.3 Calibrating Hata Models.............................................................................................................624.3.1 Quality Targets..................................................................................................................................624.3.2 Setting Initial Parameters in the Hata Models ...................................................................................63

4.3.2.1 Defining General Settings ...........................................................................................................634.3.2.2 Selecting an Environment Formula .............................................................................................634.3.2.3 Creating or Modifying Environment Formulas .............................................................................64

4.3.3 Running the Hata Calibration Process ..............................................................................................644.4 Analysing the Calibrated Model .............................................................................................66

4.5 Finalising the Settings of the Calibrated SPM.................................................................71

4.6 Deploying the Calibrated Model .............................................................................................734.6.1 Copying a Calibrated Model to Another Document...........................................................................734.6.2 Deploying a Calibrated Model to Transmitters ..................................................................................74

5 Additional CW Measurement Functions ..........................................775.1 Creating a CW Measurement Path ......................................................................................77

5.2 Drawing a CW Measurement Path .......................................................................................78

5.3 Merging Measurement Paths for a Same Transmitter................................................78

5.4 Smoothing Measurements to Reduce the Fading Effect ...........................................78

5.5 Calculating Best Servers Along a CW Measurement Path ......................................795.5.1 Adding Transmitters to a CW Measurement Path.............................................................................795.5.2 Selecting the Propagation Model ......................................................................................................795.5.3 Setting the Display to Best Server ....................................................................................................805.5.4 Calculating Signal Levels ..................................................................................................................805.5.5 Displaying Statistics Over a Measurement Path ...............................................................................805.5.6 Displaying Statistics Over Several Measurement Paths ...................................................................80

6 Survey Site Form.............................................................................85

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List of Figures

List of Figures

Figure 2.1 Enhanced Slope at Receiver ..................................................................................................................... 18Figure 2.2 Losses due to Clutter................................................................................................................................. 22Figure 2.3 Setting losses per clutter class .................................................................................................................. 23Figure 2.4 Tx-Rx profile .............................................................................................................................................. 23Figure 2.5 Settings when using clutter heights set per class ...................................................................................... 24Figure 2.6 Diffraction caused by surrounding buildings when the receiver is indoors ................................................ 24Figure 2.7 Clutter class settings when using a clutter height file ................................................................................ 25Figure 4.1 The Setup tab of the Import of Measurement Files dialogue..................................................................... 37Figure 4.2 Defined thresholds as they will appear in the Legend ............................................................................... 43Figure 4.3 Distribution of the Measured Signal Strength around a station ................................................................. 44Figure 4.4 Point distribution in the different clutter classes......................................................................................... 45Figure 4.5 Filtering Assistant Launching..................................................................................................................... 48Figure 4.6 Point Selection Tool in the Filtering Assistant............................................................................................ 49Figure 4.7 Point Exclusion Tool in the Filtering Assistant ........................................................................................... 49Figure 4.8 Point Analysis Tool window showing diffraction peaks.............................................................................. 50Figure 4.9 Distribution of the point positions around a station .................................................................................... 51Figure 4.10 The CW Measurement Analysis Tool window ........................................................................................... 52Figure 4.11 Simultaneous display of measurement path and table .............................................................................. 53Figure 4.12 Angular Filter around a station................................................................................................................... 55Figure 4.13 SPM Transmitter effective height method selection .................................................................................. 56Figure 4.14 Calculating the total clutter loss between the transmitter and the receiver................................................ 58Figure 4.15 Comparative behaviour of the clutter weighting functions in the SPM....................................................... 58Figure 4.16 Calibration launching on SPM model......................................................................................................... 59Figure 4.17 Path and Calibration method selection for SPM Calibration...................................................................... 60Figure 4.18 Range definition for SPM parameters during calibration ........................................................................... 60Figure 4.19 SPM Comparative Calibration Results ...................................................................................................... 61Figure 4.20 Table listing the correlation of the SPM variables to the global error ........................................................ 62Figure 4.21 Calibration launching on Hata models ....................................................................................................... 65Figure 4.22 Path and Calibration method selection for SPM Calibration...................................................................... 65Figure 4.23 Range definition for SPM parameters during calibration ........................................................................... 66Figure 4.24 Hata Models Comparative Calibration Results .......................................................................................... 66Figure 4.25 Selecting the calibrated model for all CW measurement paths ................................................................. 67Figure 4.26 Calculating the signal levels on all CW measurement paths ..................................................................... 67Figure 4.27 Selecting on of the verification stations for the statistics ........................................................................... 68Figure 4.28 Comparative statistics of the verification stations ...................................................................................... 68Figure 4.29 Distribution of error around a verification station ....................................................................................... 69Figure 4.30 Opening the CW Measurement Analysis tool ............................................................................................ 70Figure 4.31 CW Measurement Analysis ....................................................................................................................... 71Figure 4.32 Description of the available clutter classes................................................................................................ 73Figure 5.1 The New CW Measurement Path dialogue ............................................................................................... 77Figure 5.2 Sliding Window Property Dialogue ............................................................................................................ 79

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Atoll User Manual

8 Unauthorized reproduction or distribution of this document is prohibited © Forsk 2010

Chapter 1

AtollRF Planning & Optimisation Software

Introduction

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Measurements and Model Calibration Guide

Chapter 1: Introduction

1 IntroductionThe Model Calibration Guide is intended for project managers or anyone else responsible for calibrating the StandardPropagation Model (SPM) or Hata Models (Okumura-Hata and Cost-Hata) using continuous wave (CW) measurements.To that end, the Model Calibration Guide presents you with detailed information on the SPM and guides you through thecalibration process of both types of models.

It is not the intention of this guide to explain in detail how to use Atoll, nor to provide detailed technical information aboutAtoll projects. For information on using Atoll, see the User Manual and the Administrator Manual. For detailed technicalinformation about Atoll projects, see the Technical Reference Guide.

The Model Calibration Guide follows the calibration process from planning the CW survey, to incorporating the CW meas-urements into Atoll, to using the CW measurements to calibrate the SPM.

If this is the first time you are calibrating Atoll’s SPM, you might want to read though the entire Model Calibration Guide.Or, you can go directly to the chapter that interests you:

• The Standard Propagation Model: This chapter describes the Atoll SPM, including the SPM formula and theHata formula on which the SPM is based. Other aspects described include, typical SPM parameter values, makingcalculations using the SPM, and recommendations for using the SPM.

• CW Measurements: This chapter explains the role of CW measurements in calibrating the SPM. It also gives youinformation that will help you successfully plan and carry out a CW survey.

• The Model Calibration Process: This chapter explains the entire calibration process for any model type:

- Creating an Atoll document that to use to calibrate a propagation model.- Importing the measurements from the CW survey into the new Atoll document.- Filtering the imported CW measurements to ensure that you are using only the most relevant data.- Calibrating the SPM or Hata Models, using either the automatic or the assisted method (SPM only).- Finalising and deploying the calibrated model.

This guide also contains an appendix with additional information on using CW measurements in Atoll.

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Measurements and Model Calibration Guide


Chapter 2


Standard Propagation Model


Technical Reference Guide

Chapter 2: Standard Propagation Model

2 Standard Propagation ModelThe Standard Propagation Model is a propagation model based on the Hata formulas and is suited for predictions in the150 to 3500 MHz band over long distances (from one to 20 km). It is best suited to GSM 900/1800, UMTS, CDMA2000,WiMAX, and LTE radio technologies.

2.1 SPM FormulaThe Standard Propagation Model is based on the following formula:

where:

• received power (dBm)

• transmitted power (EIRP) (dBm)

• constant offset (dB)

• multiplying factor for

• distance between the receiver and the transmitter (m)• multiplying factor for

• effective height of the transmitter antenna (m)

• multiplying factor for diffraction calculation. must be a positive number.

• losses due to diffraction over an obstructed path (dB)• multiplying factor for



• effective height of the receiver antenna (i.e., mobile antenna height) (m)


• average of weighted losses due to clutter• corrective factor for hilly regions (=0 in case of NLOS)

2.2 The Correspondence Between the SPM and HataIn this section, the Hata formula on which the SPM is based is described. The correspondence between the SPM and theHata formula is also described.

2.2.1 Hata FormulaThe SPM formula is derived from the basic Hata formula, which is:

where,

• , , , , , Hata parameters

• Frequency in MHz• Effective BS antenna height in metres

• Distance in kilometres• Mobile antenna height correction function

• Clutter correction function

Typical values for Hata model parameters are:

• A1 = 69.55 for 900 MHz, A1 = 46.30 for 1800 MHz

PR PTx

K1 K2 Log d( )× K3 Log HTxeff( )× K4 DiffractionLoss× K5 Log d( ) Log HTxeff

( )×× + + + + +

K6 HRxeff× K7 Log HRxeff

( )× Kclutter f clutter( )× Khill LOS,+ + +⎝ ⎠⎜ ⎟⎛ ⎞–=

PR

PTx

K1

K2 Log d( )

dK3 Log HTxeff

( )

HTxeff

K4 K4

DiffractionLossK5 Log d( ) Log HTxeff

( )×

K6 HRxeff

K7 Log HRxeff( )

HRxeff

Kclutter f clutter( )

f clutter( )

Khill LOS,

Note: The distance in this equation is given in kilometres as opposed to the SPM, where the distance is given in metres.

L A1 A2 flog A3 hBSlog B1 B2 hBSlog B3hBS+ +( ) dlog a hm( ) Cclutter––+ + +=

A1 A2 A3 B1 B2 B3

fhBS

da hm( )

Cclutter



• A2 = 26.16 for 900 MHz, A2 = 33.90 for 1800 MHz• A3 = −13.82• B1 = 44.90• B2 = −6.55• B3 = 0

2.2.2 Correspondence Between Hata and SPM ParametersIn this section, the Hata and SPM parameters are compared.

2.2.2.1 Reducing the Hata and SPM EquationsBecause you are only dealing with standard formulas, you can ignore the influence of diffraction and clutter correction. Itis understood that, with appropriate settings of A1 and K1, and taking only one clutter class into consideration, you can setthe clutter correction factor to zero without reducing the validity of the following equations.

The correction function for mobile antenna height can also be ignored. The mobile antenna height correction factor is zerowhen hm=1.5 m, and has negligible values for realistic mobile antenna heights. The B3 parameter is usually not used andcan be considered to be 0.

The Hata formula can now be simplified to:

where:

• , , , , , Hata parameters

• Frequency in MHz• Effective BS antenna height in metres

• Distance in kilometres

The SPM formula can be simplified to:

If you rewrite the Hata equation using with the distance in metres as in the SPM formula, you get:

This leads to the following equation:

2.2.2.2 Equating the CoefficientsIf you compare the simplified Hata and SPM equations, you see the following correspondence between the coefficients:

2.2.3 Typical SPM Parameter ValuesBy referring to typical Hata parameters, typical SPM parameters can be determined as the following:

K1 depends on the frequency, some examples are:

L A1 A2 flog A3 hBSlog B1 B2 hBSlog+( ) dlog+ + +=

A1 A2 A3 B1 B2

fhBS

d

L K1 K2 dlog K3 hBSlog K5 dlog hBSlog× K6hmeff K7Log hmeff( )+ + + + +=

L A1 A2 flog A3 hBSlog B1 B2 hBSlog+( ) d1000-------------log+ + +=

L A1 A2 flog 3 B1×– A3 3 B2×–( ) hBSlog× B1 dlog B2 hBSlog dlog×++ + +=

K1 A1 A2 flog 3 B1×–+=K2 B1=

K3 A3 3 B2×–=

K5 B2=

K6 0=K7 0=

Project type Frequency (MHz) K1

GSM 900 935 12.5

GSM 1800 1805 22

GSM 1900 1930 23

UMTS 2110 23.8

K2 44.90=

K3 5.83=K5 6.55–=



2.3 Making Calculations in AtollIn this section, the different aspects of making calculations using the SPM are explained in detail:

• "Visibility and Distance Between Transmitter and Receiver" on page 17• "Effective Transmitter Antenna Height" on page 17• "Effective Receiver Antenna Height" on page 20• "Correction for Hilly Regions in Case of LOS" on page 21• "Diffraction" on page 21• "Losses Due to Clutter" on page 21• "Recommendations for Using Clutter with the SPM" on page 22.

2.3.1 Visibility and Distance Between Transmitter and ReceiverFor each calculation pixel, Atoll determines:

• The distance between the transmitter and the receiver.

- If the transmitter-receiver distance is less than the maximum user-defined distance (the break distance), thereceiver is considered to be near the transmitter. Atoll will use the set of values called “Near transmitter.”

- If the transmitter-receiver distance is greater than the maximum distance, the receiver is considered far fromthe transmitter. Atoll will use the set of values called “Far from transmitter.”

• Whether the receiver is in the transmitter line of sight or not.

- If the receiver is in the transmitter line of sight, Atoll will take into account the set of values (K1, K2)LOS. TheLOS is defined by no obstruction along the direct ray between the transmitter and the receiver.

- If the receiver is not in the transmitter line of sight, Atoll will use the set of values (K1, K2)NLOS.

2.3.2 Effective Transmitter Antenna HeightThe effective transmitter antenna height (HTxeff) can be calculated using one of six different methods:

• "Height Above Ground" on page 17• "Height Above Average Profile" on page 17• "Slope at Receiver Between 0 and Minimum Distance" on page 18• "Spot Ht" on page 18• "Absolute Spot Ht" on page 18• "Enhanced Slope at Receiver" on page 18.

2.3.2.1 Height Above GroundThe transmitter antenna height is its height above the ground (HTx in metres).

2.3.2.2 Height Above Average ProfileThe transmitter antenna height is determined relative to an average ground height calculated along the profile between atransmitter and a receiver. The profile length depends on the minimum distance and maximum distance values and islimited by the transmitter and receiver locations. Distance min. and Distance max are minimum and maximum distancesfrom the transmitter respectively.

where,

• is the ground height (ground elevation) above sea level at transmitter (m).

• is the average ground height above sea level along the profile (m).

1xRTT 1900 23

WiMAX

2300 24.7

2500 25.4

2700 26.1

3300 27.8

3500 28.3

HTxeff HTx=

Note: If the profile is not located between the transmitter and the receiver, HTxeff equals HTx only.

HTxeff HTx H0Tx H0–( )+=

H0Tx

H0



2.3.2.3 Slope at Receiver Between 0 and Minimum DistanceThe transmitter antenna height is calculated using the ground slope at the receiver.

where,

• is the ground height (ground elevation) above sea level at the receiver (m).

• is the ground slope calculated over a user-defined distance (Distance min.). In this case, Distance min. is thedistance from the receiver.

2.3.2.4 Spot HtIf then,

If then,

2.3.2.5 Absolute Spot Ht

These values are only used in the last two methods and have different meanings for each method.

2.3.2.6 Enhanced Slope at ReceiverAtoll offers a new method called “Enhanced slope at receiver” to evaluate the effective transmitter antenna height.

The X-axis and Y-axis represent positions and heights respectively. It is assumed that the X-axis is oriented from the trans-mitter (origin) towards the receiver.

This calculation is made in several steps:

1. Atoll determines line of sight between the transmitter and the receiver.

The LOS line equation is:

where,

Notes:

• If , Atoll uses 20 m in calculations.

• If , Atoll takes 200 m.

HTxeff HTx H0Tx+( ) H0Rx– K d×+=

H0Rx

K

HTxeff 20m<

HTxeff 200m>

H0Tx H0Rx> HTxeff HTx H0Tx H0Rx–( )+=

H0Tx H0Rx≤ HTxeff HTx=

Note: Distance min. and distance max are set to 3000 and 15000 m following ITU recommendations (low frequency broadcast f < 500 Mhz) and to 0 and 15000 m following Okumura recommendations (high frequency mobile telephony).

HTxeff HTx H0Tx H0Rx–+=

Figure 2.1Enhanced Slope at Receiver

Los i( ) H0Tx HTx+( )H0Tx HTx+( ) H0Rx HRx+( )–( )

d-------------------------------------------------------------------------------Res i( )–=



- is the receiver antenna height above the ground (m).- i is the point index.- Res is the profile resolution (distance between two points).

2. Atoll extracts the transmitter-receiver terrain profile.

3. Hills and mountains are already taken into account in diffraction calculations. Therefore, in order for them not tonegatively influence the regression line calculation, Atoll filters the terrain profile.

Atoll calculates two filtered terrain profiles; one established from the transmitter and another from the receiver. Itdetermines the filtered height of every profile point. Profile points are evenly spaced on the basis of the profile reso-lution. To determine the filtered terrain height at a point, Atoll evaluates the ground slope between two points andcompares it with a threshold set to 0.05; where three cases are possible.

Some notations defined hereafter are used in next part.

- is the filtered height.

- is the original height. The original terrain height is determined from extracted ground profile.

When filtering starts from the transmitter:

Let us assume that

For each point, there are three different possibilities:

a. If and ,

Then,

b. If and

Then,

c. If

Then,

If, as well,

Then,

When filtering starts from the receiver:

Let us assume that

For each point, there are three different possibilities:

a. If and ,

Then,

b. If and

Then,

c. If

Then,

If, as well,

Then,

Then, for every point of profile, Atoll compares the two filtered heights and chooses the higher one.

4. Atoll determines the influence area, R. It corresponds to the distance from receiver at which the original terrainprofile plus 30 metres intersects the LOS for the first time (when beginning from transmitter).

The influence area must satisfy additional conditions:

- ,- ,

HRx

Hfilt

Horig

Hfilt Tx– Tx( ) Horig Tx( )=

Horig i( ) Horig i 1–( )>Horig i( ) Horig i 1–( )–

Res------------------------------------------------------ 0.05≤

Hfilt Tx– i( ) Hfilt Tx– i 1–( ) Horig i( ) Horig i 1–( )–( )+=

Horig i( ) Horig i 1–( )>Horig i( ) Horig i 1–( )–

Res------------------------------------------------------ 0.05>

Hfilt Tx– i( ) Hfilt Tx– i 1–( )=

Horig i( ) Horig i 1–( )≤

Hfilt Tx– i( ) Hfilt Tx– i 1–( )=

Hfilt i( ) Horig i( )>

Hfilt Tx– i( ) Horig i( )=

Hfilt Rx( ) Horig Rx( )=

Horig i( ) Horig i 1+( )>Horig i( ) Horig i 1+( )–

Res------------------------------------------------------- 0.05≤

Hfilt Rx– i( ) Hfilt Rx– i 1+( ) Horig i( ) Horig i 1+( )–( )+=

Horig i( ) Horig i 1+( )>Horig i( ) Horig i 1+( )–

Res------------------------------------------------------- 0.05>

Hfilt Rx– i( ) Hfilt Rx– i 1+( )=

Horig i( ) Horig i 1+( )≤

Hfilt Rx– i( ) Hfilt Rx– i 1+( )=

Hfilt i( ) Horig i( )>

Hfilt Rx– i( ) Horig i( )=

Hfilt i( ) max Hfilt Tx– i( ) Hfilt Rx– i( ),( )=

R 3000m≥

R 0.01 d⋅≥



- R must contain at least three pixels.

5. Atoll performs a linear regression on the filtered profile within R in order to determine a regression line.

The regression line equation is:

and

where,

i is the point index. Only points within R are taken into account.

d(i) is the distance between i and the transmitter (m).

Then, Atoll extends the regression line to the transmitter location. Its equation is:

6. Then, Atoll calculates the effective transmitter antenna height, (m).

If HTxeff is less than 20 m, Atoll recalculates it with a new influence area, which begins at the transmitter.

7. If is less than 20 m (or negative), Atoll evaluates the path loss using and applies a cor-rection factor.

Therefore, if ,

where,

2.3.3 Effective Receiver Antenna Height

where,

is the height of the receiver antenna above the ground (m).

is the ground height (ground elevation) above sea level at the receiver (m).

Notes:

• When several influence areas are possible, Atoll chooses the highest one.• If d < 3000m, R = d.

Notes:

• If , 1000m will be used in calculations.

• If is less than 20 m, an additional correction is taken into account (step 7).

y ax b+=

a

d i( ) dm–( ) Hfilt i( ) Hm–( )

i∑

d i( ) dm–( )2

i∑

------------------------------------------------------------------------=

b Hm adm–=

Hm1n--- Hfilt i( )

i∑=

dm d R2----–=

regr i( ) a i Res⋅( )⋅ b+=

HTxeff

HTxeffH0Tx HTx b–+

1 a2+--------------------------------------=

HTxeff 1000m>

HTxeff

HTxeff HTxeff 20m=

HTxeff 20m<

Lmodel Lmodel HTxeff 20m=( ) d f, ,( ) Klowant+=

Klowantd

105--------- 0.3 HTxeff 20–( )⋅( )–

20 1 HTxeff 20–( )–( )⋅

9.63 d1000-------------+⎝ ⎠

⎛ ⎞ 6.93 d1000-------------+⎝ ⎠

⎛ ⎞⋅------------------------------------------------------------------------------–=

HRxeff HRx H0Rx+( ) H0Tx–=

HRx

H0Rx



is the ground height (ground elevation) above sea level at the transmitter (m).

2.3.4 Correction for Hilly Regions in Case of LOSAn optional corrective term enables Atoll to correct path loss for hilly regions when the transmitter and the receiver are inline of sight.

Therefore, if the receiver is in the transmitter line of sight and the hilly terrain correction option has been selected:

When the transmitter and the receiver are not in line of sight, the path loss formula is:

is determined in three steps. Influence area, R, and regression line are assumed to be available.

1. For every profile point within the influence area, Atoll calculates height deviation between the original terrainprofile and regression line. Then, it sorts points according to the deviation and draws two lines (parallel to theregression line), one which is exceeded by 10% of the profile points and the other one by 90%.

2. Atoll evaluates the terrain roughness, Δh; it is the distance between the two lines.

3. Atoll calculates .

If ,

Else

If ,

Else

iRx is the point index at receiver.

2.3.5 DiffractionFour methods are available to calculate diffraction loss over the transmitter-receiver profile. These methods are explainedin the Technical Reference Guide.

• Deygout• Epstein-Peterson• Deygout with correction• Millington

Along the transmitter-receiver profile, you can take one of the following into consideration:

• Ground altitude and clutter height (Consider heights in diffraction option). In this case, Atoll uses clutter heightinformation from the clutter heights file if it is available in the ATL document. Otherwise, Atoll considers averageclutter height specified for each clutter class in the clutter classes file description.

• Only ground altitude.

2.3.6 Losses Due to ClutterAtoll calculates f(clutter) over a maximum distance from the receiver.

where,

• L: loss due to clutter defined in the Clutter tab by the user (in dB).• w: weight determined through the weighting function.• n: number of points taken into account over the profile. Points are evenly spaced depending on the profile resolu-

tion.

Four weighting functions are available:

Note: The calculation of effective antenna heights ( and ) is based on extracted DTM profiles. They are not performed properly if you have not imported heights (DTM file) beforehand.

H0Tx

HRxeff HTxeff

Lmodel K1 LOS, K2 LOS, d( )log K3 HTxeff( )log K5 HTxeff( ) d( )loglog K6 HRx⋅ Kclutterf clutter( ) Khill LOS,+ + + + + +=

Lmodel K1 NLOS, K2 NLOS, d( )log K3 HTxeff( )log K4 Diffraction⋅ K5 HTxeff( ) d( )loglog K6 HRx⋅ Kclutterf clutter( )+ + + + + +=

Khill LOS,

Khill LOS,

Khill LOS, Kh Khf+=

0 hΔ< 20m≤ Kh 0=

Kh 7.73 hΔ( )log( )2 15.29 hΔ( )log– 6.746+=

0 hΔ< 10m≤ Khf 2– 0.1924 H0Rx HRx regr iRx( )–+( )⋅ ⋅=

Khf 2– 1.616 hΔ( )log( )2– 14.75 hΔ( )log 11.21–+( )H0Rx HRx regr iRx( )–+

hΔ------------------------------------------------------------⋅ ⋅=

f clutter( ) Liwi

i 1=

n

∑=



• uniform weighting function:

• triangular weighting function:

• , where d’i is the distance between the receiver and the ith point and D is the maximum distancedefined.

• logarithmic weighting function:

• exponential weighting function:

The following chart shows the weight variation with the distance for each weighting function.

2.3.7 Recommendations for Using Clutter with the SPMThe decision of what clutter information you should use with the SPM depends on the type and quality of the availableinformation. Normally you want to use the most detailed and most accurate information. This section gives a few recom-mendations on using the information available to you efficiently with the SPM. The following scenarios are possible:

• No clutter height information is available: You do not have a clutter height file and the height per clutter classis either not defined, or is too roughly defined. In this case, you should define a loss per clutter class and not usethe height per clutter class. For more information, see "Losses per Clutter Class" on page 22.

• No clutter height file is available: You do not have a clutter height file. However, the clutter classes file has rel-atively good data defining the height per clutter class and has a high enough resolution. In this case, you can usethe height per clutter class, but, if you use the height per clutter class, you must not define a loss per clutter class.For more information, see "Clutter Height per Class" on page 23.

• Clutter height file is available: You have a clutter height file available that has accurate data over a resolutionthat is fine enough for your network. In this case, you should use the clutter height file. But, if you use the clutterheight file, you must not use a loss per clutter class. For more information, see "Clutter Height File" on page 24.

More information is given on each option in the following sections.

Losses per Clutter Class

If you specify losses per clutter class, as illustrated in Figure 2.3, you must not consider clutter altitudes in diffraction lossover the transmitter-receiver profile. This approach is recommended if the clutter height information is statistical (i.e.,where the clutter is roughly defined and without a defined altitude).

Figure 2.2Losses due to Clutter

wi1n---=

widi

dj

j 1=

n

∑

--------------=

di D d'i–=

wi

diD---- 1+⎝ ⎠⎛ ⎞log

djD---- 1+⎝ ⎠⎛ ⎞log

j 1=

n

∑

--------------------------------------=

wie

diD----

1–

e

djD----

1–

j 1=

n

∑

--------------------------=



Clutter Height per Class

If you consider clutter height per class, as illustrated in Figure 2.5, you must not define any loss per clutter class. In thiscase, f(clutter) will be "0;" losses due to clutter will only be taken into account in calculated diffraction. This approach isrecommended if the clutter height information is semi-deterministic (i.e., where the clutter is roughly defined with an aver-age altitude per clutter class).

When the clutter height information is an average height defined for each clutter class, you must specify a receiver clear-ance per clutter class. Both ground and clutter height are considered along the entire transmitter-receiver profile exceptover a specific distance around the receiver (clearance), in which Atoll bases its calculations only on the DTM. The clear-ance information is used to model streets because it is assumed that the receiver is in the street.

In Figure 2.4, the ground altitude and clutter height (in this case, average height specified for each clutter class in the clut-ter classes map description) are taken into account along the profile.

Note: Because the Standard Propagation Model is a statistical propagation model, using this approach is recommended.

Figure 2.3Setting losses per clutter class

Figure 2.4Tx-Rx profile



Clutter Height File

If you use a clutter height file, do not define any loss per clutter class, as illustrated in Figure 2.7. In this case, f(clutter) willbe "0;" losses due to clutter will only be taken into account in calculated diffraction. This approach is recommended if theclutter height information is deterministic (in this case, where there is a clutter height file).

It is not necessary to define receiver clearance if the height information is from a clutter height file; the clutter height infor-mation is accurate enough to be used without additional information such as clearance. Atoll calculates the path loss ifthe receiver is in the street (i.e., if the receiver height is higher than the clutter height). If the receiver height is lower thanthe clutter height, the receiver is assumed to be inside a building. In this case, Atoll does not consider any diffraction forthe building (or any clearance) but takes into account the clutter class indoor loss as an additional penetration loss. Never-theless, Atoll does consider diffraction caused by surrounding buildings. In Figure 2.6 on page 24 this diffraction isdisplayed with a green line.

Figure 2.5Settings when using clutter heights set per class

Important: In order to consider indoor losses inside a building when only using a deterministic clutter map (i.e., a clutter height map), you must clear the Indoor Coverage check box when creating a prediction or indoor losses will be added twice (once for the entire reception clutter class and once as indoor losses).

Figure 2.6Diffraction caused by surrounding buildings when the receiver is indoors



Figure 2.7Clutter class settings when using a clutter height file




Chapter 3


Collecting CW Measurement Data



Chapter 3: Collecting CW Measurement Data

3 Collecting CW Measurement DataCW measurements, i.e., measurements made in the field for a single transmitter at a given frequency (continuous wave),are used to calibrate propagation models. Creating CW measurements in Atoll can be made either by importing meas-urements or general data samples (including Planet® data) or by pasting measurement results directly in the document.

When you import measurements, you can save the settings used during the import procedure in a configuration which youcan used the next time you import similar measurements.

Atoll enables very complete management of CW measurements and provides several features allowing you to updategeographical data, define additional fields, or define how the path will be displayed.

This chapter presents the points to be considered when planning a CW survey in order to get the most accurate and usefulmeasurements. Once you have made a CW survey and have collected the CW measurements, importing them into Atolland using them to calibrate a propagation model (SPM or Hata models) is explained in "Setting Up Your CalibrationProject" on page 35.

Atoll offers other possibilities for working with CW measurements. For more information, see "Additional CW Measure-ment Functions" on page 77.

3.1 Before You StartBefore you make a CW survey, it is essential to properly prepare for it. This section describes the data you must havebefore you start your CW survey:

• "Geographic Data" on page 29• "Measurement Data" on page 29.

3.1.1 Geographic DataYou must have up-to-date geographic data when you are planning your CW survey. If you perform a CW survey on anarea for which you do not have up-to-date geographic data of sufficient quality, you will not be able to use the CW meas-urements you have collected to calibrate the propagation model. In any case, up-to-date geographic data will be laterrequired to produce realistic results in coverage predictions.

The types of geographic data you will need are the following:

• Raster geographic data: The SPM or Hata Models can use raster geographic data as input. It can obtain theground elevation information from the DTM (Digital Terrain Model) files and clutter information from either clutterclasses files or clutter heights files.

Clutter classes files describe the land cover (dense urban areas, buildings, residential areas, forests, open areas,villages etc.). In these files, the ground is represented by a grid where each pixel corresponds to a code allocatedto a main type of cover, in other words, to a clutter class. Clutter height maps describe the altitude of clutter overthe DTM with one altitude defined for each pixel. Clutter height maps can offer more precise information than defin-ing an altitude per clutter class because, in a clutter height file, it is possible to have different heights within a singleclutter class.

DTM and clutter class files must be of a sufficiently high resolution to obtain a high-quality and accurate results ina calibration project. The resolution of geographic data should typically be:

- 25 m or less for urban areas- 50 m or less for rural areas.

• Vector data: Vector maps, representing at least major roads, are useful for planning and verifying measurementsurvey routes.

• Scanned maps: Scanned maps are useful for planning and verifying measurement survey routes in urban areas.

3.1.2 Measurement DataIt is strongly recommended to use CW (continuous wave) measurements to calibrate the SPM or Hata models. Althoughit is possible to calibrate the SPM or Hata models using drive test data, it is not the recommended approach:

• Since drive test data are made on a real network, part of the measured signal is actually due to interference.• Using directional antennas implies that the propagation calculation strongly depends on the accuracy of antenna

patterns, and only the measurement points in the direction of the main beam are relevant.• Several frequencies are measured for drive test data, although the SPM or hata models are calibrated only for a

base frequency.• The sampling rate of each measured station is low because a lot of stations are scanned at the same time. There-

fore, the Lee criterion cannot be fulfilled (see "Guidelines for CW Measurement Surveys" on page 30).• Only the signal from the best server is scanned and, therefore, the signal level is measured over only a short dis-

tance from each transmitter. Therefore, the model will only be calibrated for coverage predictions and not for theevaluation of interference.



Therefore, you should plan CW measurement surveys if you need measurements to calibrate the SPM or Hata models.However, before planning and performing CW a measurement survey:

• Determine the number of required propagation models depending on representative area types (urban, suburban,flat_rural, hilly_rural, etc.), and on the number of frequency bands (GSM 900, GSM 1800, UMTS, etc.). One prop-agation model for each "area type–frequency band" pair must be calibrated.

• Select a representative area of each area type, where the measurement survey campaigns will be performed.• For each area type, select at least 8 sites (6 for calibration and 2 for verification), which respect the conditions

described in "Guidelines for CW Measurement Surveys" on page 30.• For each selected site, define a survey route, which respects the conditions described in "Guidelines for CW Meas-

urement Surveys" on page 30.• Ensure that it will be possible to respect all other criteria described in "Guidelines for CW Measurement Surveys"

on page 30 when performing the measurement survey.

3.2 Guidelines for CW Measurement SurveysThe quality of the calibrated propagation model depends strongly on the quality of the CW measurements. Therefore, youcan only meet the quality targets if the CW measurements, on which the calibration will be based, are of good quality, theprovided radio data are correct, and the calibration procedure described in "The Model Calibration Process" on page 35is followed.

This section gives some information for planning a CW measurement survey. Keeping this information in mind when youare planning the survey route will help guarantee high-quality measurements that can serve as input for the SPM (or Hatamodels) calibration project.

In this section, the following are described:

• "Selecting Base Stations" on page 30• "Planning the Survey Routes" on page 30• "Radio Criteria" on page 31• "Additional Deliverable Data" on page 31.

3.2.1 Selecting Base StationsWhen selecting stations to be used in the CW measurement survey, the following guidelines should be respected:

• A minimum of about eight stations should be measured for each propagation model to be calibrated. The exactnumber of stations depends on the terrain.

• Selected stations should fulfil the following conditions:

- The stations should have good RF clearance, in other words, the stations selected should not be obstructedin any direction.

- An omnidirectional antenna should be used.- The antennas on the measured stations should represent the full variation of antenna heights (typically from

20 m. to 50 m.) in the area covered by the survey. A histogram displaying the antenna heights can be a usefultool in determining what antenna heights should be represented.

- The terrain within a relevant radius around each selected station should be representative of the entire areacovered by the survey. For example, in a relatively flat region, all rural stations selected should be surroundedby relatively flat terrain within a radius of 10 km; a station surrounded with hilly terrain would not give meas-urements representative of the entire area.

- If there is a variety of different types of clutter in the survey area (open, urban, suburban, dense urban, etc.),there should be as equal a distribution as possible of the major clutter categories within a relevant radius ofeach station.

- There should be sufficient roads available to enable easy access with transmission equipment on all sides ofeach station.

3.2.2 Planning the Survey RoutesWhen selecting survey routes to be used in the CW measurement survey, the following guidelines should be respected:

• Measurement surveys should be performed over a long enough distance to allow the noise floor of the receiver tobe reached. Typical distances are:

- Rural areas: approximately 10 km- Suburban areas: approximately 2 km- Urban areas: approximately 1 km

• The measurement routes must be laid out so that they have equal numbers of samples near as well as far fromthe station in all directions.

Note: To avoid problems if the measurements of one or more stations must be rejected, a minimum of 10 stations for each propagation model to be calibrated is recommended.


Chapter 3: Collecting CW Measurement Data

• The survey routes should not cross forests or rivers; such clutter types should be avoided. Even profiles betweenthe transmitter and the receiver should not cross such kinds of clutter, if these types of clutter are not especiallyrepresentative of the area. These points will have to be filtered out during the calibration process.

• When planning the survey routes, any proposed routes should be presented for approval to the project managerin the form of vector maps in a format that can be imported in Atoll.

• The maps used to plan the survey routes should use the same projection system as the scanned maps in the Atollcalibration project. This will allow you to validate the survey routes beforehand.

• The GPS of the CW measurement equipment should be configured to match that of the mapping data.• If possible, before actually making the survey, you should try to ensure consistency between the coordinates given

by the GPS on the survey route with those used in Atoll by making a test drive without taking measurements.

3.2.3 Radio CriteriaWhen planning a CW measurement survey, the following radio guidelines should be followed:

• The area to be covered by the CW measurement survey must be scanned before performing the drive test toensure that there is no interference.

• Only one frequency must be measured during a single survey.• The frequency measured must be clean:

- For GSM, there must be 3 contiguous unused channels (i.e., a clearance of 200 kHz on either side of themeasured signal).

- For UMTS and CDMA2000, there must be one unused carrier. This can be verified by checking whether thereception level is at zero when the transmitter is off.

• The Lee criterion must be satisfied in terms of sampling rate to overcome the effects of fast fading.

At least 36 samples must be collected over a distance of 40λ. But, because the required rate depends on the high-est speed the vehicle would travel during the survey, the vehicle speed must be adapted accordingly. The followingtable provides a list of required rates corresponding to different vehicle speeds in order to respect the Lee criterionfor a frequency 900 MHz.

• The measured signals over the distance of 40λ should be averaged, with the mean signal level (50th percentile)being the one stored.

• The maximum distance between 2 stored measurement points should be equal to one half the resolution of theclutter file used. This is necessary to obtain a good representative sample of each clutter class.

• At least 5,000 points per station must remain after averaging. A typical number of points per measured station isbetween 10,000 and 20,000 points.

3.2.4 Additional Deliverable DataDuring the survey, certain types of information should be collected in addition to measurements. This additional informa-tion will aid in interpreting the collected CW measurement data and will increase the overall quality of not only the CWsurvey but of the subsequent calibration.

The following data should be collected during the survey:

• Measurement data: The radio data collected should meet the following criteria:

- The measurements to be imported should correspond to the average of the measured signals over the dis-tance of 40λ.

- The maximum distance between 2 stored measurement points should be equal to one half the resolution ofthe clutter class file used. This is necessary to obtain a good representative sample of each clutter class.

- The survey should have at least 5,000 points per station. A typical number of points per measured station isbetween 10,000 and 20,000 points.

• A rooftop sketch: A rooftop sketch must be provided indicating the locations of:

- The transmitting antenna- Any rooftop obstacles (including their relative location, distance from transmitter, and height)- Any nearby obstacles (for example, other buildings) within 400 m. of the transmitter (including their relative

location, distance from transmitter, height, and width)

• Panoramic photographs: Panoramic photographs should be taken from each rooftop of each station startingfrom north and turning clockwise. These photographs should show the surroundings in all directions. The azimuthand station number should be recorded for each photograph.

Highest Speed (Km/h) Sampling Rate (samples per sec)

60 45

90 68

120 90

150 113



• Transmission data: The following data should be recorded for all stations:

- Precise coordinates of each station measured during the CW survey- Antenna patterns, downtilt, azimuth (if the antenna is not perfectly omnidirectional), and antenna height- Transmission power, and transmission gain and losses

• Reception data: The following data should be recorded for all stations:

- Receiver height, receiver sensitivity, and reception gain and losses- The voltage standing wave ratio (VSWR) (should be < 1.5).

• Vector maps: Vector maps of each survey route should be collected to be imported into the Atoll calibrationproject prior to the measurement survey.

Each CW measurement file should be accompanied by a "Survey Site Form" indicating:

• Details describing the station• The locations of any spurious measurements where the physical clutter data does not coincide with the mapping

data• Any useful information about incidents that may have occurred.

You can find an example of a survey site form in "Survey Site Form" on page 85.


Chapter 4


The Model Calibration Process



Chapter 4: The Model Calibration Process

4 The Model Calibration ProcessThis chapter explains the propagation model calibration process, from creating or selecting the project you will use to cali-brate the model, to calibrating the model, to deploying the calibrated propagation model. Two types of models can be cali-brated: SPM and Hata Models (Hokumura and Cost-Hata).

Before you can begin the calibration process, you must ensure that you have properly prepared for the process. First, thenecessary CW measurements must be available. For information on planning the CW measurement survey, see "Collect-ing CW Measurement Data" on page 29.

When the CW measurement data is available, you can begin the SPM calibration process:

1. Setting up the calibration project: The first step consists of creating an Atoll document with all of the networkand geographical data necessary to recreate the CW measurement survey area. When the Atoll document hasbeen created with all the necessary data, you can import the CW measurement data and filter them in order toensure that only meaningful data is used for calibration.

- "Setting Up Your Calibration Project" on page 35.

2. Calibrate the SPM: When the CW measurement data has been selected and filtered, you can begin calibratingthe model. You must first set a few initial parameters in the propagation model and then you can begin the cali-bration process, using either the automated or the assisted method. After calibration, Atoll offers several differentways for you to analyse the calibrated propagation model.

- "Calibrating the SPM" on page 55.

3. Finalising the calibrated propagation model: When you have calibrated the propagation model and are satis-fied with the results, you must make a few final adjustments to compensate for values that could not be calibrateddue to missing or incomplete data. The missing values can be extrapolated from existing data or from standardvalues.

- "Finalising the Settings of the Calibrated SPM" on page 71.

4. Deploying the calibrated propagation model: The final propagation model can now be deployed to the trans-mitters for which it was calibrated.

- "Deploying the Calibrated Model" on page 73.

4.1 Setting Up Your Calibration ProjectWhen you set up the calibration project, you must first create or select an Atoll document with the network and geograph-ical data necessary to recreate the CW measurement data survey area. Creating the Atoll document is explained in"Creating an Atoll Calibration Document" on page 35. If you already have an Atoll document that you will use to calibratethe propagation model, you can continue directly with "Importing CW Measurements" on page 36.

When you have imported the CW measurements, your next step is to verify that the CW measurement data you have justimported correspond to the geographical data of the Atoll document you will be using for calibration. This step is veryimportant because Atoll will use the geographical data of the document to evaluate the CW measurement points. If thepoints are not properly situated on the map, Atoll will not be able to apply the correct geographical data, especially clutterto each point. This is explained in "Verifying the Correspondence Between Geo and Measurement Data" on page 43.

In theory, the imported measurement values are supposed to be smoothed by the measurement equipment so that theyare not subject to any fading effect. In the case the fading effects occur on the measured samples, and in order to improvethe input data for calibration, you can average them by defining a smoothing sliding window as explained in "SmoothingMeasurements to Reduce the Fading Effect" on page 78.

Once you are satisfied that the positions of the CW measurement points correspond properly to the geographical data inthe Atoll document, you can filter out the CW measurement data that, for various reasons, can not be used in the calibra-tion process. This is explained in "Filtering Measurement Data" on page 44.

After preparing the CW measurement data, the final step before proceeding to the calibration step is selecting the basestations that will be used for calibration and those that will be used to verify the calibration process, as explained in "Select-ing Base Stations for Calibration and for Verification" on page 55.

4.1.1 Creating an Atoll Calibration DocumentYou can create the Atoll calibration document in one of two ways:

• From a template: You can create a new Atoll document from a template. Atoll is delivered with a template foreach technology you will be planning for. For information on creating a document from a template, see the UserManual.

• From an existing document: If you already have an existing document covering the CW measurement surveyarea, you can make a copy of it to use in the calibration process so that you can calibrate the propagation modelwithout making changes to the original document. For information on making a copy of an existing document, seethe User Manual.



Once you have created the calibration document, you must set a few necessary parameters and import or create thepreliminary data. These steps are explained in the following sections:

• "Setting Coordinates" on page 36• "Importing Geo Data" on page 36.

4.1.1.1 Setting CoordinatesIn Atoll, you define the two coordinate systems for each Atoll document: the projection coordinate system and the displaycoordinate system. By default, the same coordinate system is used for both.

The maps displayed in the workspace are referenced with the same projection system as the imported geographic datafiles; thus, the projection system depends on the imported geographic file.

For more information on the projection and display coordinate systems in Atoll, see the User Manual.

4.1.1.2 Importing Geo DataThe geographic data is an important part of an Atoll document when the document is going to be used for a calibrationproject. Several different geographic data types are used in a calibration project:

• Digital Terrain Model: The DTM describes the elevation of the ground over sea level and is indispensable in acalibration project.

• Clutter Classes: The clutter class geo data file describes land cover or land use. Either clutter classes or clutterheights must be present in a calibration project.

• Clutter Heights: Clutter height maps describe the altitude of clutter over the DTM with one altitude defined perpixel. Clutter height maps can offer more precise information than defining an altitude per clutter class because,in a clutter height file, it is possible to have different heights within a single clutter class.

• Vector Maps: Maps with possible survey routes defined as vectors can be imported to verify the planned surveyroutes against other maps.

• Scanned Images: Scanned images are geographic data files which represent the actual physical surroundings,for example, road maps or satellite images. They are used to provide a precise background for other objects.Although they are not used in calculations, they can be used to verify the accuracy of proposed survey routes.

• WMS Raster-format Geo Data Files: Raster images from a Web Map Service (WMS) server. The image mustbe in TIF format and be referenced in the document; it can not be embedded. You can use a WMS image to adda precise background for other objects, or to add place names, or a map of roadways. WMS images are not usedin calculations.

For more information on any of the geographic data formats that can be used in Atoll, see the User Manual, and the Tech-nical Reference Guide. For information on importing geographic data, see the User Manual.

4.1.2 Importing CW MeasurementsIn Atoll, you can import CW measurement files in the form of ASCII text files (with tabs, semi-colons, or spaces as sepa-rator), with DAT, TXT, and CSV extensions. For Atoll to be able to use the data in imported files, the imported files mustcontain the following information:

• The position of the CW measurement points. When you import the data, you must indicate which columns give theabscissa and ordinate (XY coordinates) of each point.

• The measured signal level at each point.

The imported files can also contain other information, such as point names and field characteristics, that can be used todefine the display of measurement points, for example, to filter points.

You can import a single CW measurement file or several CW measurement files at the same time. If you regularly importCW measurement files of the same format, you can create an import configuration. The import configuration contains infor-mation that defines the structure of the data in the CW measurement file. By using the import configuration, you will notneed to define the data structure each time you import a new CW measurement file.

In this section, the following are described:

• "Importing a CW Measurement Path" on page 37• "Importing Several CW Measurement Paths" on page 38• "Creating a CW Measurement Import Configuration" on page 40• "Defining the Display of CW Measurements" on page 41.

Note: All imported raster geographic files must be use the same cartographic system. If not, you must convert them to a single cartographic system.

Note: The only propagation models that can take clutter heights into account in calculations are the Standard Propagation Model and WLL model.



4.1.2.1 Importing a CW Measurement PathTo import a CW measurement file:

1. Click the Data tab in the Explorer window.

2. Right-click the CW Measurements folder. The context menu appears.

3. Select Import from the context menu. The Open dialogue appears.

4. Select the file or files you want to open.

5. Click Open. The Import of Measurement Files dialogue appears.

6. On the General tab:

a. Enter a Name for the CW measurement. By default, the CW measurement is given the name of the file beingimported.

b. Under Reference Transmitter, select the Transmitter with which the CW measurements were made and se-lect the Frequency.

c. Under Receiver, enter the Height of the receiver, the Gain, and the Losses.

d. Under Measurements, define the Unit used for the CW measurements.

e. If the Coordinates used for the CW measurement data are different than the one displayed, click the Browse

button ( ) and select the coordinate system used.

7. Click the Setup tab (see Figure 4.1). If you already have an import configuration defining the data structure of theimported file or files, you can select it from the Configuration list on the Setup tab of the Import of MeasurementFiles dialogue. If you do not have an import configuration, continue with step 8.

a. Under Configuration, select an import configuration from the Configuration list.

b. Continue with step 9.

Important: CW measurements are usually made using WGS84. By default the coordinate system displayed in the coordinates field is the display system used in the document. If the CW measurements were made using WGS84, be sure to select WGS84, a geographic system as indicated by the globe symbol ( ).

Figure 4.1The Setup tab of the Import of Measurement Files dialogue



8. Under File, on the Setup tab:

a. Enter the number of the 1st Measurement Row, select the data Separator, and select the Decimal Symbolused in the file.

b. Click Setup to link file columns and internal Atoll fields. The CW Measurement Setup dialogue appears.

c. Select the columns in the imported file that give the X-Coordinates and the Y-Coordinates of each point inthe CW measurement path file.

d. In the Measurements box, select the field that contains the value of the measured signal for each definedpoint.

e. Click OK to close the CW Measurement Setup dialogue.

f. If there is other data available in the file, in the table under File, define the Type for each additional column ofdata.

9. Once you have defined the import parameters, click Import. The CW measurement data are imported into the cur-rent Atoll document.

4.1.2.2 Importing Several CW Measurement PathsTo import several CW measurement files:






6. On the General tab:

a. Enter a Name for the CW measurement. By default, the CW measurement is given the name of the file beingimported.

b. Under Reference Transmitter, select the Transmitter with which the CW measurements were made and se-lect the Frequency.

c. Under Receiver, enter the Height of the receiver, the Gain, and the Losses.

d. Under Measurements, define the Unit used for the CW measurements.

e. If the Coordinates used for the CW measurement data are different than the one displayed, click the Browse


Notes: • When importing a CW measurement path file, existing configurations are available in the Files

of type list of the Open dialogue, sorted according to their date of creation. After you haveselected a file and clicked Open, Atoll automatically proposes a configuration, if it recognisesthe extension. In case several configurations are associated with an extension, Atoll choosesthe first configuration in the list.

• The defined configurations are stored, by default, in the file "MeasImport.ini", located in thedirectory where Atoll is installed. For more information on the MeasImport.ini file, see theAdministrator Manual.

Note: You can also identify the columns containing the XY coordinates of each point in the CW measurement path by selecting them from the Field row of the table on the Setup tab.

Note: You can select contiguous files by clicking the first file you want to import, pressing SHIFT and clicking the last file you want to import. You can select non-contiguous files by pressing CTRL and clicking each file you want to import.




7. Click the Setup tab (see Figure 4.1). If you already have an import configuration defining the data structure of theimported file or files, you can select it from the Configuration list on the Setup tab of the Import of MeasurementFiles dialogue. If you do not have an import configuration, continue with step 8.

a. Under Configuration, select an import configuration from the Configuration list.

b. Continue with step 9.

8. Under File, on the Setup tab:







9. If you wish to save the definition of the data structure so that you can use it again, you can save it as an importconfiguration:

a. On the Setup tab, under Configuration, click Save. The Configuration dialogue appears.

b. By default, Atoll saves the configuration in a special file called "MeasImport.ini" found in Atoll’s installationfolder. In case you cannot write into that folder, you can click Browse to choose a different location.

c. Enter a Configuration Name and an Extension of the files that this import configuration will describe (for ex-ample, "*.csv").

d. Click OK.

Atoll will now select this import configuration automatically every time you import a drive test data path filewith the selected extension. If you import a file with the same structure but a different extension, you will beable to select this import configuration from the Configuration list.

10. Once you have defined the import parameters, you can import the selected files:

- When importing several files for the same transmitter: Click Import All. The CW measurement data areimported into the current Atoll document.

Notes: • When importing a CW measurement path file, existing configurations are available in the Files

of type list of the Open dialogue, sorted according to their date of creation. After you haveselected a file and clicked Open, Atoll automatically proposes a configuration, if it recognisesthe extension. In case several configurations are associated with an extension, Atoll choosesthe first configuration in the list.



Notes:

• You do not have to complete the import procedure to save the import configuration and haveit available for future use.

• When importing a CW measurement file, you can expand the MeasImport.ini file by clicking thebutton ( ) in front of the file in the Setup part to display all the available import configurations.When selecting the appropriate configuration, the associations are automatically made in thetable at the bottom of the dialogue.

• You can delete an existing import configuration by selecting the import configuration underSetup and clicking the Delete button.

Note: When you click the Import All button, Atoll does not import files that do match the currently selected import configuration. It displays an error message and continues with the next file.



- When importing several files for different transmitters:

i. Click Import. The CW measurement data are imported into the current Atoll document.

ii. Click the General tab to ensure that the information on the General tab, especially the Reference Trans-mitter selected, reflect the current file being imported.

iii. If necessary, click the Setup tab and redefine the import configuration for the current file being imported.

iv. Click Import to import the current file.

v. Repeat these steps for each file being imported.

4.1.2.3 Creating a CW Measurement Import ConfigurationIf you regularly import CW measurement files of the same format, you can create an import configuration the first time youimport the CW measurement files. The import configuration contains information that defines the structure of the data inthe CW measurement file. By using the import configuration, you will not need to define the data structure each time youimport a new CW measurement file.

To create a CW measurement import configuration:






6. Click the Setup tab (see Figure 4.1).

7. Under File, on the Setup tab, define the data structure of the file or files you have selected:







8. On the Setup tab, under Configuration, click Save. The Configuration dialogue appears.

a. By default, Atoll saves the configuration in a special file called "MeasImport.ini" found in Atoll’s installationfolder. In case you cannot write into that folder, you can click Browse to choose a different location.

b. Enter a Configuration Name and an Extension of the files that this import configuration will describe (for ex-ample, "*.csv").

c. Click OK.

Atoll will now select this import configuration automatically every time you import a drive test data path filewith the selected extension. If you import a file with the same structure but a different extension, you will beable to select this import configuration from the Configuration list.


Notes:

• You do not have to complete the import procedure to save the import configuration and haveit available for future use.

• When importing a CW measurement file, you can expand the MeasImport.ini file by clicking thebutton ( ) in front of the file in the Setup part to display all the available import configurations.When selecting the appropriate configuration, the associations are automatically made in thetable at the bottom of the dialogue.

• You can delete an existing import configuration by selecting the import configuration underSetup and clicking the Delete button.




4.1.2.4 Defining the Display of CW MeasurementsYou can define how CW measurements are displayed in Atoll’s map window. CW measurements are organised in foldersaccording to their reference transmitter on the Data tab of the Explorer window.

You can define the display of individual CW measurements but also set the same display parameters for all CW measure-ments or for all CW measurements for the same reference transmitter.

To define the display of a CW measurement path:


2. Click the Expand button ( ) to expand the CW Measurements folder.

3. Click the Expand button ( ) to expand the folder of the reference transmitter.

4. Right-click the CW measurement whose display you want to define. The context menu appears.

5. Select Properties from the context menu. The Properties dialogue appears.

6. Select the Display tab. The following options are available:

- "Defining the Display Type" on page 41- "Using the Actions Button" on page 42- "Defining the Visibility Scale" on page 42- "Defining the Tip Text" on page 42- "Adding CW Measurement Points to the Legend" on page 43.

7. Set the display parameters.

8. Click OK.

Defining the Display Type

Depending on the object selected, you can choose from the following display types: unique, discrete values, value inter-vals, or advanced.

To change the display type:

1. Open the Display tab of the Properties dialogue as explained in "Defining the Display of CW Measurements" onpage 41.

To modify the appearance of the symbol:

a. Click the symbol in the table below. The Symbol Style dialogue appears.

b. Modify the symbol as desired.

c. Click OK to close the Symbol Style dialogue.

2. Select the display type from the Display Type list:

- Unique: defines the same symbol for all CW measurement points.

- Discrete values: defines the display of each CW measurement point according to the value of a selected field.This display type can be used to distinguish CW measurement points by one characteristic. For example, youcould use this display type to distinguish CW measurement points by the clutter type they are on, or by theirreference transmitter.

i. Select the name of the Field by which you want to display the objects.

ii. You can click the Actions button to access the Actions menu. For information on the commands availa-ble, see "Using the Actions Button" on page 42.

- Value intervals: defines the display of each object according to set ranges of the value of a selected field.This display type can be used, for example, to distinguish population density, signal strength, or the altitudeof sites.

i. Select the name of the Field by which you want to display the objects.

ii. Define the ranges directly in the table.

iii. You can click the Actions button to access the Actions menu. For information on the commands availa-ble, see "Using the Actions Button" on page 42.

- Advanced: allows you to display measurement points by more than one criterion at a time. - only available for transmitters; Atoll automatically assigns a colour to each transmitter, ensuring that each

transmitter has a different colour than the transmitters surrounding it.

i. Click the symbol in the table below. The Symbol Style dialogue appears.

ii. Modify the symbol as desired.

iii. Click OK to close the Symbol Style dialogue.

iv. You can click the Actions button to access the Actions menu. For information on the commands availa-ble, see "Using the Actions Button" on page 42.



Using the Actions Button

The Actions button on the Display tab of the Properties dialogue allows you to modify the display type as defined in"Defining the Display Type" on page 41.

To access the Actions menu:


2. Click the Actions button. The Actions menu gives you access to the following commands:

- Select all: Atoll selects all the values in the table.- Delete: Atoll removes selected value from the table.- Insert before: When the selected display type is value intervals, Atoll inserts a new threshold in the table

before the threshold selected in the table.- Insert after: When the selected display type is value intervals, Atoll inserts a new threshold in the table after

the threshold selected in the table.- Shading: Atoll opens the Shading dialogue. When "Value Intervals" is the selected display type, you select

Shading to define the number of value intervals and configure their colour. Enter the upper and lower limitsof the value in the First Break and Last Break boxes respectively, and enter a value in the Interval box.Define the colour shading by choosing a Start Colour and an End Colour. The value intervals will be deter-mined by the set values and coloured by a shade going from the set start colour to the set end colour.

When "Discrete Values" is the selected display type, you select Shading to choose a Start Colour and anEnd Colour.

Defining the Visibility Scale

You can define a visibility range for CW measurement points. A measurement point is visible only if the scale, as displayedon the zoom toolbar, is within this range. This can be used to, for example, prevent the map from being cluttered withsymbols when you are at a certain scale.

Visibility ranges are taken into account for screen display, and for printing and previewing printing. They do not affect whichmeasurement points are considered during calculations.

To define the visibility range:

1. Access the Display tab of the Properties dialogue as explained in "Defining the Display of CW Measurements"on page 41.

2. Enter a Visibility Scale minimum in the between 1: text box.

3. Enter a Visibility Scale maximum in the and 1: text box.

Defining the Tip Text

For most object types, such as sites and transmitters, you can display information about each object in the form of a tooltip that is only visible when you move the pointer over the object. You can display information from every field in that objecttype’s data table, including from fields that you add.

To define tip text for an object type:

1. Access the Display tab of the Properties dialogue as explained in "Defining the Display of CW Measurements"on page 41.

2. Click the Browse button ( ) beside the Tip Text box. The Field Selection dialogue appears.

3. Select the fields which you want to display in the label:

a. To select a field to be displayed in the label for the object type, select the field in the Available Fields list and

click to move it to the Selected Fields list.

b. To remove a field from the list of Group these fields in this order, select the field in the Selected Fields list

and click to remove it.

Note: Predictions and CW measurements are shaded differently. Nevertheless, you can obtain a similar colouring by excluding the last break of the CW path display. To do this, select the ’Filter up to Last Break’ check box.

Note: For most object types, you can also display object information in the form of a tool tip that is only visible when you move the pointer over the object. This option has the advantage of not filling the map window with text. For more information on tool tips, see "Defining the Tip Text" on page 42.



Once you have defined the tool tips, you must activate the tool tip function before they appear.

To activate the tool tip function:

• Click the Display Tips button ( ) on the toolbar. Tool tips will now appear when the pointer is over the object.

Adding CW Measurement Points to the Legend

You can display the information defined by the display type (see "Defining the Display Type" on page 41) in your Atolldocument’s legend. Only visible objects appear in the Legend window. For information on displaying or hiding objects,see the User Manual.

In Figure 4.2, on the Display tab of a signal level prediction, the intervals defined are:

• Signal level >= -65red • -65 > Signal level >= -105shading from red to blue (9 intervals)• Signal level < -105not shown in the coverage.

The entries in the Legend column will appear in the Legend window.

With value intervals, you can enter information in the Legend column to be displayed on the legend. If there is no infor-mation entered in this column, the maximum and minimum values are displayed instead.


2. Check the Add to legend box. The defined display will appear on the legend.

4.1.3 Verifying the Correspondence Between Geo and Measure-ment DataYou can quickly verify the correspondence between the CW measurements and the Atoll geo data by importing the CWmeasurements and a set of vector files representing roads or a scanned map of the area and checking that the CW meas-urement survey routes correspond with the geo data. You can also check whether the measurement path starts or endsat approximately the location of the base station used for the CW measurements.

It is also important to check that the CW measurement survey routes used correspond to the planned survey routes toensure that the CW measurement points are evenly distributed around the station. In case measurement paths do notexactly match the vector roads (due most of the time to inconsistencies between several coordinate systems), you canmove a set of points to the appropriate location.

To move measurement points to another location:

1. On the map, click any point to select it. To select more than one point, press CTRL as you click the other points.To select a entire segment of points, press SHIFT as you click the other extremity of the segment.

2. Click and drag the set of points to the desired position. If you want to exactly put points on a vector line, drag themto it until it is highlighted.

3. Release the points where you would like to place them. In the case of a vector which has to be matched, the shapeof the paths might be modified accordingly after the points have been released.

If the IDs of the CW measurement points do not reflect the order in which the measurements were collected, you can checkwhether the station location is consistent with its relative measurement path by displaying measurement points accordingto measurement levels, as shown in Figure 4.3. For information on setting the display according to measurement levels,see "About Potentially Invalid Measurement Levels" on page 51.

Note: You can also display information about data objects in the form of a label that is displayed with the object. Given the large number of CW measurement points in a CW survey, defining labels that are always visible is not recommended.

Figure 4.2Defined thresholds as they will appear in the Legend



If panoramic photographs of the area surrounding the base station are available, you should verify that there are no nearbyobstacles disturbing propagation. If there is an obstacle close to the base station, you can filter out the obstructed CWmeasurement data using an angle filter or remove the station from the set of CW measurement data if the obstruction istoo wide. For information on defining an angle filter, see "Filtering by Angle" on page 54.

4.1.4 Filtering Measurement DataOne of the most important steps in preparing CW measurement data for use in a calibration project is filtering the meas-urement points. When you are filtering CW measurement data, the goal is to eliminate the points that are the least repre-sentative of the survey area while retaining a number of points that is both representative and large enough to providestatistically valid results.

The filtering process is often, therefore, a series of trade-offs. Although you would normally consider filtering out certaindata if, for example, their values appear high or low, if filtering them all out leaves you with too small a sample, you mightconsider leaving some of them in. By the same token, if filtering out the points on a clutter class means that that clutterclass will no longer be represented at all, you might consider leaving those points on the CW survey path where they arebest represented.

There are several reasons why you would not want to take certain measurement points into consideration:

• The measurement points might appear potentially invalid, they might be in clutter classes that are of no signifi-cance in terms of the propagation model to be calibrated, they may show extreme signal levels, they might be tooclose to the transmitter, or they might suffer from too much diffraction.

• The zones where the measurement points are located might be in an area where the results can not be consideredaccurate (for example, any points coming from behind a directional antenna should not be used in a calibrationproject).

If you wish, you can permanently delete the points you filter out. You can always re-import the original measurement dataif you want to add those points again. Or you can filter them out for the current calibration, but leave them in the measure-ment data.

Filtering CW measurement data is made in several steps. Depending on the CW measurement data available and the indi-vidual calibration project, it is possible that not all steps will be necessary, however, the basic steps are:

1. Filtering by clutter class: The first step in filtering CW measurement data is to filter out points by clutter class.Typically you will want to remove all points on clutter classes that are represented by less than 5% of the totalmeasurement points in the CW survey. For information on filtering by clutter class, see "Filtering on ClutterClasses" on page 45.

2. Filtering by signal strength and distance: The next step is to filter out points that lay outside of a defined rangeof signals and that are either too close to or too far from the reference transmitter. For information on filtering bydistance and signal strength, see "Signal and Distance Filtering" on page 46.

3. Removing sections that are not representative: The final step in filtering CW measurement data consists ofexamining the CW measurement data to remove points that are affected by obstruction or that are potentiallyinvalid, i.e., measurement points affected by diffraction or measurement points that are too high or too low. Forinformation on filtering by distance and signal strength, see "Filtering by Geo Data Conditions" on page 50.

Figure 4.3Distribution of the Measured Signal Strength around a station

Important: If you set filters on the CW Measurements folder, any filters set on individual CW measurement paths will be erased.



4.1.4.1 Filtering on Clutter ClassesThe first step in filtering measurement points is to filter out the points by clutter class. If only a few measurement pathshave points on a given clutter class or only a few points are located on this class, then the clutter class should be filteredout. There are not enough points to give a statistically good sampling of the conditions for that clutter class. In other words,keeping these points will likely cause the clutter class to be incorrectly calibrated, leading to incorrect coverage predictionresults when the calibrated propagation model is used. Therefore, it is highly recommended not to take irrelevant clutterclasses into account during the calibration process, and to deduce the clutter losses afterwards using similar clutterclasses and typical values.

The rule of thumb is 5%: if only 5% of the points on a measurement plan are on a given clutter class, the points for thatclutter class should be removed. However, this should just be used as a guideline. Under certain circumstances, for exam-ple, if that clutter class is not well represented in any survey path, you might want to keep them. You can always try cali-brating the propagation model once with the clutter class and once without and comparing the results.

You should also remove the measurement points located on clutter classes that are not at all representative of the surveyarea. For example, there may be a park along the survey route that is classified as "Forest" in terms of clutter class. If thearea itself is mostly dense urban, keeping the points in the forest clutter class will lead to inaccurate results.

You can view the point distribution statistics for all CW measurements, or all CW measurements for a single referencetransmitter, or for a single CW measurement path. Figure 4.4 shows the distribution of statistics for all CW measurements.

To display the point distribution statistics for CW measurements:

1. On the Data tab of the Explorer window, right-click the CW measurements whose statistics you wish to display:

- All CW measurements: Right-click the CW Measurements folder.- All CW measurements for a single reference transmitter: Click the Expand button ( ) to expand the CW

Measurements folder and right-click the folder of the reference transmitter.- A single CW measurement path: Click the Expand button ( ) to expand the CW Measurements folder and

click the Expand button ( ) to expand the folder of the reference transmitter. Then, right-click the CW meas-urement path.

The context menu appears.

2. Select Display Statistics from the context menu.

If more than one CW measurement path is selected, a dialogue appears where you can choose the statistics ofwhich CW measurement paths you want to display. Select or clear the check boxes to choose the CW measure-ment paths and click OK.

The statistics dialogue appears, with the distribution of the selected CW measurements (see Figure 4.4).

3. Take note of the clutter classes that have few measurement points (with only 5% or lower of the total number ofpoints).

4. Click Close to close the dialogue.

Important: Before the point distribution statistics can be displayed, you must calculate signal levels on the CW measurement points. You can calculate signal levels by right-clicking the CW Measurements folder and selecting Calculations > Calculate Signal Levels from the context menu.

Figure 4.4Point distribution in the different clutter classes



To filter out the measurement points from the under-represented clutter classes:

1. On the Data tab of the Explorer window, right-click the CW measurements whose statistics you have just exam-ined:


Measurements folder and right-click the folder of the reference transmitter.


2. Select Filter from the context menu. The CW Measurement Filter dialogue appears.

3. In the Per Clutter window, under Filter, clear the check boxes of the clutter classes you want to filter out. Only theclutter classes whose check box is selected will be taken into account.

4. If you want to keep the measurement points inside the focus zone, select the Use focus zone to filter check box.

5. If you want to permanently remove the measurement points outside the filter, select the Delete Points OutsideFilter check box.

If you permanently delete measurement points and later want to use them, you will have to re-import the originalmeasurement data.

6. Click OK. The selected CW measurement data will be filtered according to the defined parameters.

The filter settings can also be saved to a filter configuration which can be retrieved afterward.

You can also filter out the measurement points from the under-represented clutter classes on a single CW measurementpath by using the Filtering assistant (see "Using the Filtering Assistant on CW Measurement Points" on page 48).

See "Displaying Statistics Over a Measurement Path" on page 80 and "Displaying Statistics Over Several MeasurementPaths" on page 80 for more information on measurement path statistics.

4.1.4.2 Signal and Distance FilteringThe goal of the calibration process is to produce an accurate propagation model which can be used to reliably calculatethe propagation of each base station within the area. To respect this goal, the propagation model’s own constraints withrespect to signal levels have to be taken into account. There are limitations in the measurement equipment, which alsohave to be considered.

In this section, filtering out CW measurement points based on the signal strength or their distance from the reference trans-mitter is explained:

• "Typical Values" on page 46• "Using Manual Filtering on CW Points" on page 46• "Creating an Advanced Filter" on page 47• "Using the Filtering Assistant on CW Measurement Points" on page 48.

4.1.4.2.1 Typical ValuesThe values to be used to filter CW measurements depend on a lot of factors. In this section, some typical values are given.These values are by definition general. Atoll provides a filtering assistant that can be used for each CW measurementpath; it is highly recommended to use the filtering assistant to define a specific signal and distance filters for each CWmeasurement file. For information on the filtering assistant, see "Using the Filtering Assistant on CW Measurement Points"on page 48.

When filtering out CW measurement points by signal strength, generally, signal levels above -40 dBm are filtered out,because they would be inaccurate because of receiver overload. When you filter on the minimum signal level, the sensi-tivity of the receiver and tolerance have to be considered. Therefore, signals below “Receiver Sensitivity + Target StandardDeviation” have to be filtered out to avoid the effect of noise saturation in the results. A typical value for the minimum signallevel filter can be then considered to be:

-120 + 8 = -112 dBm

When filtering out by distance from the reference transmitter, measurement data at a distance of less than 200 m from thestation should be discarded because these points are too close to the station to properly represent the propagation overthe whole area. A typical maximum value is 10 km for rural areas.

4.1.4.2.2 Using Manual Filtering on CW PointsWhen you filter CW measurements on signal strength or distance, you can filter the values in either all CW measurementpaths, in all the CW measurement paths for one reference transmitter, or in a single CW measurement path.

Warning: Remember that, by selecting the Delete Points Outside Filter check box, you are defining a property of the CW measurement path. Once you have defined this property, points that you filter out using other methods, for example, using the Filtering Assistant (see "Using the Filtering Assistant on CW Measurement Points" on page 48) will also be permanently deleted.

Note: The Clear All button resets the existing filters.



To filter out CW measurement points on signal strength or distance:

1. On the Data tab of the Explorer window, right-click the CW measurements whose points you want to filter:





3. Under Filter, define the settings for signal strength and distance:

- Distance between CW measurement point and reference transmitter: Enter the Min. Distance and Max.Distance. Atoll will keep only CW measurement points which are within this range.

- Measured signal: Enter the Min. Measurement and Max. Measurement. Atoll will keep only CW measure-ment points whose value is within this range.

You can also use this dialogue to filter on the following criteria:

- Clutter class: For information on filtering by clutter class, see "Filtering on Clutter Classes" on page 45.- Angle with the antenna azimuth: For information on filtering by the angle with the antenna azimuth, see "Fil-

tering by Angle" on page 54.- Additional fields: For information on filtering with additional fields, see "Creating an Advanced Filter" on

page 47.



6. Click OK. The selected CW measurement data will be filtered according to the defined parameters.


You can also filter out CW measurement points on signal strength or distance on a single CW measurement path by usingthe Filtering assistant (see "Using the Filtering Assistant on CW Measurement Points" on page 48).

4.1.4.2.3 Creating an Advanced FilterAtoll enables you to create an advanced filter using several fields and expressions with which you can filter CW measure-ment points. You can create an advanced filter to filter the values in either all CW measurement paths, in all the CW meas-urement paths for one reference transmitter, or in a single CW measurement path.

To filter out CW measurement points using an advanced filter:

1. On the Data tab of the Explorer window, right-click the CW measurements whose points you want to filter:





3. Click the More button. The Filter dialogue appears.

4. In the Column row, select the name of the column to be filtered on from the list. Select as many columns as youwant.

5. Underneath each column name, enter the criteria on which the column will be filtered as explained in the followingtable:

Caution: If you permanently delete measurement points and later want to use them, you will have to re-import the original measurement data.


Formula Data are kept in the table only if

=X value equal to X (X may be a number or characters)

<> X value not equal to X (X may be a number or characters)

< X numerical value is less than X

>X numerical value is greater than X

<=X numerical value is less than or equal to X



6. Click OK to filter the data according to the criteria you have defined.

Filters are combined first horizontally, then vertically.


You can also filter out CW measurement points using an advanced filter on a single CW measurement path by using theFiltering assistant (see "Using the Filtering Assistant on CW Measurement Points" on page 48).

4.1.4.2.4 Using the Filtering Assistant on CW Measurement PointsAtoll makes available a Filtering Assistant to help you filter the CW measurements points of each CW measurementpath. Because each CW measurement path is made under different circumstances, you can only use the Filtering Assist-ant on individual CW measurement paths, and not on groups of CW measurement paths, even if they are for the samereference transmitter.

Nevertheless, if you can provide several measurement paths for a same transmitter and want to use the filtering assistantfor all of them, you can merge all or part of these in a unique table. See "Merging Measurement Paths for a Same Trans-mitter" on page 78.

To use the Filtering Assistant:

1. On the Data tab of the Explorer window, click the Expand button ( ) to expand the CW Measurements folder.The CW Measurements folder opens.

2. Click the Expand button ( ) to expand the folder of the reference transmitter. The reference transmitter folderopens.

3. Right-click the CW measurement path. The context menu appears (see Figure 4.5).

4. Select Filtering Assistant from the context menu. The Filtering Assistant dialogue appears (see Figure 4.6).

The Filtering Assistant dialogue displays measurements by 10log(d), where "d" represents the distance. Thisenables you to check whether measurement points are homogeneously distributed for the relevant signal leveland distance according to a linear function.

The Filtering Assistant enables you to filter by entering the values for Min. Distance, Max Distance, Min. Meas-urement, and Max Measurement. Or, you can filter by drawing a rectangle in the graph. You can select the pointsto keep or you can select areas with few points to exclude the points. After including or excluding points, you canverify the number of points remaining and their percentage of the whole.

5. Under Clutter, clear the check box of any clutter class that is either under-represented or unrepresentative of thesurvey zone. For more information, see "Filtering on Clutter Classes" on page 45.

>=X numerical value is greater than or equal to X

*X* text objects which contain X

*X text objects which end with X

X* text objects which start with X


Formula Data are kept in the table only if

Figure 4.5Filtering Assistant Launching



6. Filter the measurement points by selection. Typically, you will first select the points to include, respecting minimumdistance and minimum and maximum values, and then you will exclude the anomalous points from that selection.

To select points to include:

a. Click on the graph where you want to start the rectangle that will contain the points to keep.

b. Drag to the opposite corner. The selection rectangle appears outlined in red.

When you release the mouse, the values reflected by the current selection are displayed in the fields on theleft.

c. Right-click the rectangle. The context menu appears.

d. Select Filter Selected Points from the context menu (see Figure 4.6). All points outside the rectangle are fil-tered out.

The Number of Points field displays the number of points kept as well as their percentage of the whole.

To select points to exclude:

a. Click on the graph where you want to start the rectangle that will contain the points to exclude.

b. Drag to the opposite corner. The selection rectangle appears outlined in red.

When you release the mouse, the values reflected by the current selection are displayed in the fields on theleft.

c. Right-click the rectangle. The context menu appears.

d. Select Excluded Selected Points from the context menu (see Figure 4.7). All points inside the rectangle arefiltered out.

Figure 4.6Point Selection Tool in the Filtering Assistant

Figure 4.7Point Exclusion Tool in the Filtering Assistant



The Number of Points field displays the number of points kept as well as their percentage of the whole.

7. Click OK to apply the filters and close the dialogue.

4.1.4.3 Filtering by Geo Data ConditionsAfter you have made an initial selection of CW measurement points based on clutter classes and signal strength anddistance, you can filter points based on geo data conditions.

There are several reasons why you should remove certain CW measurement points from a CW measurement path:

• Areas that suffer from diffraction: Areas that suffer from a large amount of diffraction should be filtered outbecause they are not representative of the entire area. For more information, see "About Diffraction" on page 50.

• Sections that are not representative of the survey area: Certain measurement points may not be representa-tive of the entire area. For more information, see "About Specific Sections" on page 50.

• Areas around the reference transmitter where obstacles prevent proper propagation: Some measurementpoints should be removed because their reception is affected by obstructions between the measurement point andthe reference transmitter. As well, measurement points that are behind a non-omni-directional antenna should beremoved. For more information, see "About Specific Sections" on page 50.

• Areas with potentially invalid points: Measurement points with a signal level that is significantly higher or lowerthan the CW measurement points around them should be removed, as they could be invalid. For more information,see "About Potentially Invalid Measurement Levels" on page 51.

You can select and remove CW measurement points in several ways:

• You can delete CW measurement points from the data table: "Deleting a Selection of Measurement Points"on page 53

• You can draw a filtering zone: "Using Filtering Zones on CW Measurement Points" on page 54• You can filter out the points by their angle with the reference transmitter: "Filtering by Angle" on page 54.

4.1.4.3.1 About DiffractionCW measurement points that suffer from a large amount of diffraction should be filtered out because they are not repre-sentative of the entire area. For example, if there are three diffraction peaks in the profile between the station and themeasurement points there’s a greater chance of errors and thereby a negative influence on calibration.

You can use the CW Measurement Analysis Tool and the Point Analysis Tool to quickly review each measurementpath for measurement points that have too many diffraction points. The profile between the site and the CW measurementpoint is displayed in the Point Analysis Tool window (see Figure 4.8).

For more information on using the CW Measurement Analysis Tool and the Point Analysis Tool to display diffractionpeaks, see "Using the CW Measurement and the Point Analysis Tools" on page 69.

4.1.4.3.2 About Specific SectionsUnder certain conditions, certain sections of CW survey routes must be removed before calibration. The values of the CWmeasurements in these sections could have been influenced by conditions in the profile between the measurement pointand the reference transmitter. For example:

• A section where the profile between the transmitter and the receiver includes a forest area (unless this configura-tion is representative of the survey area)

• A section where the profile between the transmitter and the receiver passes over water (unless this configurationis representative of the survey area)

• A section of measurement points on a bridge• A section of measurement points in a tunnel• A section where the profile between the transmitter and the receiver is obstructed near the transmitter• A section of CW measurement points behind an antenna that is not omni-directional.

Notes:• When moving the mouse over the graph, the related distance, measurement, and point index

are displayed in the left of the dialogue.• The Clear All button resets the existing filters.

Figure 4.8Point Analysis Tool window showing diffraction peaks



These points can be selected and deleted or filtered out by:

• Selecting them in the data table: For information, see "Deleting a Selection of Measurement Points" on page 53• Creating an exclusion zone: For information, see "Using Filtering Zones on CW Measurement Points" on page 54• Filtering them out by their angle to the antenna: For information, see "Filtering by Angle" on page 54.

4.1.4.3.3 About Potentially Invalid Measurement LevelsSome CW measurement points might have a signal level that is significantly higher or lower than the CW measurementpoints around them. These points should be removed as they could be invalid and would, therefore, have a negative effecton the accuracy of the calibration project.

Atoll enables you to verify the signal level of the CW measurement points:

• "Displaying CW Measurement Points by Signal Level" on page 51• "Using the CW Measurement Analysis Tool" on page 52.

Once you have verified the signal level, potentially invalid measurements can be selected and deleted or filtered out by:

• Selecting them in the data table: For information, see "Deleting a Selection of Measurement Points" on page 53• Creating an exclusion zone: For information, see "Using Filtering Zones on CW Measurement Points" on

page 54• Filtering them out by their angle to the antenna: For information, see "Filtering by Angle" on page 54.

Displaying CW Measurement Points by Signal Level

You can check whether propagation is homogeneous for all measurement paths by displaying each CW measurementpoint on a single path by signal level and displaying a grid around the reference transmitter (see Figure 4.9). This way youcan check on the map whether the propagation loss is spatially homogeneous. Any sudden drop in signal level or anyareas where the received signal does not match your expectations will be immediately visible.

To display the signal level of CW measurement points on the map:

1. Click the Data tab of the Explorer window.

2. In the CW Measurements folder, clear the display check box beside all CW measurement paths except the oneyou want to display.

This will limit the number of points displayed to the ones you want to examine.

3. Define the display settings of the CW measurement path:

a. Select the Display tab.

b. Set the Display Type and select signal strength from the Field list. For more information, see "Defining theDisplay Type" on page 41.

Figure 4.9Distribution of the point positions around a station



4. Add the CW measurement points to the legend, as explained in "Adding CW Measurement Points to the Legend"on page 43.

5. Select View > Legend Window. The Legend window appears.

6. Define the grid around the reference transmitter:

a. Right-click the reference transmitter in the map window. The context menu appears.

b. Select Grid from the context menu. The Radial Grid dialogue appears.

c. Define a radial grid around the reference transmitter that covers the survey area.

d. Click OK.

By examining the displayed CW measurement points on the map, you can see on the map whether the propaga-tion loss is spatially homogeneous.

Using the CW Measurement Analysis Tool

You can use the CW Measurement Analysis Tool to analyse variations in the signal level on all points on the CW meas-urement path. The CW Measurement Analysis Tool indicates any sudden drop in signal level or any areas where thereceived signal does not match your expectations.

To analyse data variations using the CW Measurement Analysis Tool window.



3. Click the Expand button ( ) to expand the folder with the CW measurement path you want to analyse.

4. Right-click the CW measurement path. The context menu appears.

5. Select Open the Analysis Tool from the context menu. The CW Measurement Analysis Tool window appears(see Figure 4.10)

6. You can display the data in the CW measurement path in two ways:

- Click the values in the CW Measurement Analysis Tool window.- Click the points on the CW measurement path in the map window.

The CW measurement path appears in the map window as a line connecting the reference transmitter and the CW

measurement point, which is indicated by the pointer ( ).

7. You can display a second Y-axis on the right side of the window in order to display the values of a second variable.You can select the secondary Y-axis from the list on the right-hand side on the top of the CW Measurement Anal-ysis Tool window.

8. You can change the zoom level of the CW Measurement Analysis Tool window in the following ways:

- Zoom in or out:

i. Right-click the CW Measurement Analysis Tool window.

ii. Select Zoom In or Zoom Out from the context menu.

- Select the data to zoom in on:

i. Right-click the CW Measurement Analysis Tool window on one end of the range of data you want tozoom in on.

ii. Select First Zoom Point from the context menu.

iii. Right-click the CW Measurement Analysis Tool window on the other end of the range of data you wantto zoom in on.

iv. Select Last Zoom Point from the context menu. The CW Measurement Analysis Tool window zoomsin on the data between the first zoom point and the last zoom point.

9. Click the data in the CW Measurement Analysis Tool window to display the selected point in the map window.Atoll will recentre the map window on the selected point if it is not presently visible.

Figure 4.10The CW Measurement Analysis Tool window



4.1.4.3.4 Deleting a Selection of Measurement PointsWhen you have identified unreliable or irrelevant sections, you can remove them by deleting them from the data table.

To delete measurement points from the data table:


2. In the CW Measurements folder, right-click the CW measurement path with the points you want to delete. Thecontext menu appears.

3. Select Open Table from the context menu. The data table appears.

4. Right-click the column name for the Id column. The context menu appears.

5. Select Sort Ascending or Sort Descending from the context menu. The contents of the data table are sorted bythe Id of the CW measurement point.

Because the CW measurement points on the map are ordered sequentially by their Id, ordering the contents ofthe data table by Id makes it easier to select and delete contiguous selections of CW measurement points.

6. In the data table, click the first point of the sequence to be deleted, press SHIFT and click the last point of thesequence.

7. Press DEL to delete the CW measurement points permanently from the data table.

Tip: If you open the table for the CW measurement path you are displaying in the CW Measurement Analysis Tool window, Atoll will automatically display in the table the data for the point that is displayed in the map and in the CW Measurement Analysis Tool window.

Tip: When you select a CW measurement point on the map, Atoll automatically selects the same point in the data table. So, by arranging the map window and the data table so that both are visible, you can locate the first and last points of the selection in the data table by clicking them on the map.


Figure 4.11Simultaneous display of measurement path and table



4.1.4.3.5 Using Filtering Zones on CW Measurement PointsWhen you have identified unreliable or irrelevant sections on a CW measurement path, you can filter them out by creatinga filtering zone over the points you want to exclude. A filtering zone applies only to the CW measurement path on which itis made. This filter is added to any other filters applied to the CW measurement path.

To define a filtering zone on measurement points:




4. Right-click the CW measurement from which you want to exclude some points with a filtering zone. The contextmenu appears.

5. Select Filtering Zones > Draw from the context menu. The Properties dialogue appears.

6. Draw the filtering zone to cover:

a. Click once on the map to start drawing the zone.

b. Click once on the map to define each point on the map where the border of the zone changes direction.

c. Click twice to finish drawing and close the zone.

The filtering zone is delimited by a red line. The points of the path inside the filtering zone are filtered out of the displayand the data table. They are not taken into consideration in any calculations.

You can create several filtering polygons for each path.

4.1.4.3.6 Filtering by AngleWhen you have sections of the CW measurement path that are obstructed by obstacles in the profile close to the trans-mitter between the CW measurement point and the reference transmitter or when the antenna is not completely omni-directional, you can filter out CW measurement points that are outside of a set angle from the reference transmitterantenna beam.

To define a filter by angle:

1. On the Data tab of the Explorer window, right-click the CW measurements whose points you want to filter byangle:





3. Under Azimuth/Point Angle, select one of the following:

- Relative: Select Relative if the antenna is directional. The entered angles will then be offset from theantenna’s azimuth.

- Absolute: Select Absolute if the antenna is omnidirectional. Because an omnidirectional antenna has no azi-muth, the entered angles will then be offset from the north.

4. Define the negative and positive angles of the aperture:

a. Min. Angle: Enter a minimum angle from 0 to -180 degrees.

b. Max. Angle: Enter a minimum angle from 0 to 180 degrees.

In the example in Figure 4.12, a filter from -140 to 140 degrees relative to the antenna azimuth has been createdto filter out CW measurement points in the 80 degrees directly behind the antenna.

Note: When you have created several filtering polygons for a path, you can delete all of them at the same time by selecting the Delete Filtering Polygons check box in the CW Measurement filter dialogues.





7. Click OK.


You can also filter out CW measurement points using a filter by angle on a single CW measurement path by using theFiltering assistant (see "Using the Filtering Assistant on CW Measurement Points" on page 48).

4.1.5 Selecting Base Stations for Calibration and for VerificationOnce you have imported and filtered the CW measurement data, you can select the base stations that you will use forcalibration and those you will use for verification. Selecting the correct base stations for calibration and verification is animportant step in the process of calibrating the propagation model.

In "Selecting Base Stations" on page 30, it is recommended to have at least eight base stations. With a total of eight basestations, two base stations will be required for verification.

If not enough base stations are available (in other words, if there are less than eight base stations per propagation modelbeing calibrated), you should use all the base stations for calibration. You can verify the calibration later by using the samemeasurement paths as in the calibration process.

When selecting base stations for calibration and for verification, you should keep the following guidelines in mind:

• For calibration: Select paths that cover the entire area so that all the area characteristics can be taken intoaccount during the calibration process.

• For verification: Select several paths (the number depends on the total number of available paths) that are withinthe covered area and not at the outer boundaries. Ensure that the areas covered by the verification paths are alsocovered by the calibration paths.

4.2 Calibrating the SPMWhen the CW measurement data have been imported into the Atoll calibration project and prepared as explained in"Setting Up Your Calibration Project" on page 35, you can calibrate the SPM. Atoll offers both an automatic and anassisted calibration wizard.

4.2.1 Quality TargetsThe quality of the final calibrated propagation model depends strongly on the quality of the CW measurements used in thecalibration process. Therefore, you will only be able to meet the following quality targets if the CW measurements used inthe calibration process are of good quality, the provided radio data are correct, and the described calibration procedure isfollowed.

Figure 4.12Angular Filter around a station




Calibration Sites:

• Global mean error on calibration sites: < 1 dB• Global standard deviation on calibration sites: < 8 dB• Mean error on each calibration site: < 2.5 dB• Standard deviation on each calibration site: < 8.5 dB

Verification Sites:

• Global mean error on verification sites: < 2 dB• Global standard deviation on verification sites: < 8.5 dB

4.2.2 Setting Initial Parameters in the SPMBefore starting the calibration process, you have to set a few parameters in the SPM.

In this section, the following initial SPM parameters are explained:

• "Parameters Tab" on page 56• "Clutter Tab" on page 57.

4.2.2.1 Parameters TabTo set or verify settings on the Parameters tab of the SPM’s Properties dialogue:

1. Click the Modules tab in the Explorer window.

2. Click the Expand button ( ) to expand the Propagation Modules folder.

3. Right-click the copy of the SPM that you want to calibrate. The context menu appears.


5. Click the Parameters tab (see Figure 4.13).

6. Verify the following settings on the Parameters tab:

Tip: After you have set initial parameters, you can retain the original copy of the SPM by creating a copy of the SPM and calibrating the copy instead. This allows you to restart calibration from the original version if you should need to. You can create a copy of the SPM by right-clicking the SPM on the Modules tab of the Explorer window and selecting Duplicate from the context menu.

Figure 4.13SPM Transmitter effective height method selection



Near Transmitter:

- Maximum Distance (m): Under Near Transmitter, ensure that Maximum Distance (m) is set to "0." If thisparameter is not set to "0," it will be forced to "0" during the automatic calibration process because the algo-rithm can not calibrate a dual-slope model.

Effective Antenna Height:

- Method: The Method you choose depends on the relief of the survey area to be used in calibration. The auto-matic calibration process adapts antenna height (as set in the transmitter properties) during calculationsaccording to the characteristics of the profile between the transmitter and the receiver. You can either set themethod yourself now, or it can be set automatically during the automatic calibration process.

Diffraction:

- Method: You can select the method use to calculate diffraction. The Millington method can only calculate onediffraction edge. All other diffraction methods can calculate three diffraction edges.

Other Parameters:

- Hilly Terrain Correction: The correction for hilly terrain correction cannot be modified by the automatic cali-bration process and therefore you must set it beforehand. If you decide to manually adjust these parameters,the following configurations are recommended:

For hilly terrain:

- Effective Antenna Height: Under Effective Antenna Height, select "5 - Enhanced slope at receiver" asthe Method.

- Hilly Terrain Correction: Under Other Parameters select "1 - Yes" to activate the Hilly Terrain Correc-tion.

For flat terrain:

- Effective Antenna Height: Under Effective Antenna Height, select "1 - Height above average profile"as the Method.

- Hilly Terrain Correction: Under Other Parameters select "0 - No" to deactivate the Hilly TerrainCorrection.

- Kclutter: Ensure that Kclutter is set to "1." Kclutter is the multiplicative factor of loss if the losses defined perclutter class are used inn the SPM formula.

- Limitation to Free Space Loss: Select "1 - Yes" to activate Limitation to Free Space Loss. Activating Lim-itation to Free Space Loss ensures that unrealistic values are not taken into account during the automaticcalibration process.

- Profiles: Select "0 - Radial" from Profiles. Activating radial optimisation ensures that profile extraction is pre-cise enough for the purposes of calibration while ensuring that calculation time is significantly improved.

- K6: Ensure that K6 is set to "0." Because the K6 coefficient is a direct multiplicative factor of the receiver heightin the formula used to calculate path loss, it can influence propagation results in an unrealistic way.

- K7: The K7 coefficient has little influence on the performance propagation model and can usually be set to "0."It is a direct multiplicative factor of the log of the receiver height in the formula used to calculate path loss; anincorrect setting can influence propagation results in an unrealistic way.

Other Ki values will be calibrated during the automatic calibration process.

4.2.2.2 Clutter TabTo set or verify settings on the Clutter tab of the SPM’s Properties dialogue:





5. Click the Clutter tab (see Figure 4.14).

6. Verify the following settings on the Clutter tab (for more information on the settings available on the Clutter tab,see "Recommendations for Using Clutter with the SPM" on page 22):

Clutter Taken into Account, you can set the following parameters under Heights:

- Clutter Taken into Account in Diffraction: Given the impact that clutter heights have when calculating lossby diffraction, this method should only be used when the height information available is very precise.

If clutter height files or high resolution (5m) clutter class files are available, select "1 - Yes" to have clutter takeninto account in diffraction. If you select "1 - Yes", you must set Kclutter to "0" on the Parameters tab of the Prop-erties dialogue, to ensure that the calibration will not calculate clutter losses.

If there is no clutter heights file available and the clutter class files are low resolution, select "0 - No" to nothave clutter taken into account when calculating diffraction. The effect of clutter on propagation will be takeninto account using clutter losses, which will be calculated during the calibration process. The calculated clutterlosses can be associated with a weighting function, which can be chosen after the calibration process.



- Receiver on top of clutter: Select "0 - No", unless you are calibrating a model to be used for fixed WiMAXand LTE receivers. This option is only used for fixed receivers which are located on top of buildings.

Under Clutter Taken into Account, you can set the following parameters under Range:

- Max. distance: This parameter indicates the distance from the receiver for which clutter losses will be con-sidered via a weighting function, with an effect on the influence of clutter on total losses which diminishes withdistance from the receiver. Set this value within the typical range [150 m; 500 m] depending on the model typeyou are currently calibrating, where the lower value corresponds to a dense urban model whereas the uppervalue is compliant with a more rural model.

The effect of this value is to simulate the real diffraction along the path which a result of the several obstacleslocated in front of the receiver. If you set this value to "0", clutter classes will be considered like in Hata modelswhere only the clutter class on which is located the receiver is considered in the path loss evaluation.

- Weighting Function: Select the weighting function which is the mathematical formula used to calculate theweight of the clutter loss on each pixel from the pixel with the receiver in the direction of the transmitter, up tothe defined maximum distance.

In the example in Figure 4.14, the defined maximum distance indicates that only the clutter losses on the firstsix pixels will be taken into account when calculating the total loss. How the losses on each pixel within themaximum distance are taken into account when calculating the total loss depends on the weighting function.There are four possible weighting functions:

- Uniform- Triangular- Logarithmic- Exponential.

Figure 4.14 displays how the clutter loss of each pixel will be taken into consideration. In Figure 4.14, the valueof each pixel is displayed as a function of its distance from the receiver. With the uniform weighting function,the clutter loss of each pixel within the maximum distance is simply added. With the other three functions, theclutter loss of each pixel diminishes according to a mathematical formula. For more information on the weight-ing functions and on the mathematical formulas used, see the Technical Reference Guide.

Figure 4.14Calculating the total clutter loss between the transmitter and the receiver

Figure 4.15Comparative behaviour of the clutter weighting functions in the SPM

Note: If clutter losses are not taken into account by the propagation model, clutter loss weighting will not have an effect.

U

RxTx

DU DU DU U U U U

Maximum Distance

DU = Dense UrbanU = Urban



Under Parameters per clutter class, you can set the following parameters for each clutter class:

- Losses: Clutter losses will be calibrated.- Clearance: Clutter clearance is only used when clutter height information from the clutter class file is used for

a clearance distance from the receiver when calculating diffraction.- Rx Height: Ensure that the Rx Height is set to "(default)." The default receiver height is defined on the

Receiver tab of the Predictions folder Properties dialogue.

4.2.3 Running the SPM Calibration ProcessThere are two different calibration processes available. The goal of both processes is to reduce the mean error and stand-ard deviation of measured values versus calculated values. Independently of how you calibrate the standard propagationmodel, it must be able to give correct results for every CW measurement point from the same geographical zone, includingCW measurement points that were not used to calibrate the standard propagation model. The difference between the proc-esses lies in how they accomplish the task:

• Automatic: Using acceptable data ranges that you set for the K1 to K6 variables, the automatic calibrationprocess attempts to reduce the mean error and standard deviation of measured values versus calculated values.The automatic calibration process selects the method for calculating diffraction.

• Assisted: The assisted calibration process enables you to display the correlation of the K1 to K6 variables to themean error. There are some parameters that have more influence on error than others. You will usually proceedby adjusting the value of the variable that correlates the most with the mean error to reduce the mean error andstandard deviation.

Both methods have their advantages. The automatic calibration process is simpler and more straight-forward. As well, theresults are constrained by limits you set. On the other hand, any solution given by the automatic calibration process is apurely mathematical solution. So, before using a propagation model calibrated using only the automatic calibration proc-ess, you should ensure of its relevance in a realistic environment.

The assisted calibration process relies on your input to set the values for the K1 to K6 variables. It gives you more controlover the calibration process but, because there is no defined range set, it can lead to a mathematical solution that bearslittle relation to the physical environment. For this reason, the assisted calibration process is better suited to advancedusers who can apply their experience to the calibration process.

The recommended approach is to combine both calibration methods, by first using the automatic calibration process andthen fine-tuning the results of the calibrated propagation model using the assisted calibration method.

Both calibration processes are started using the same method.

To start the calibration process:




4. Select Calibration from the context menu (see Figure 4.16). The Calibration Wizard window appears.

5. Select the CW measurement paths that you decided to use for the calibration process (see Figure 4.17). For infor-mation on selecting CW measurement paths, see "Selecting Base Stations for Calibration and for Verification" onpage 55.

6. Select the calibration method:

- Automatic Calibration: When you select the automatic calibration method, you set the acceptable ranges forvariables and Atoll attempts to find a solution that minimises the error between measurements and predictionsand their standard deviation.

Figure 4.16Calibration launching on SPM model



- Assisted Calibration: When you select the assisted calibration method, you can adjust each variable of thepropagation model using a correlation matrix which indicates which variables have the greatest impact on themean error.

When you select the assisted calibration method, you can select the check boxes of LOS or NLOS to indicatewhether you want to work with the LOS or NLOS sets of variables or with both.

7. Click Next.

- If you selected Automatic Calibration, continue with "The Automatic Calibration Wizard" on page 60.- If you selected Assisted Calibration, continue with "The Assisted Calibration Wizard" on page 61.

4.2.3.1 The Automatic Calibration WizardAfter you have selected the automatic calibration method in "Running the SPM Calibration Process" on page 59, you cancontinue with the automatic calibration wizard:

1. For each parameter and method (i.e., HTx and diffraction method) you want to calibrate, select the check box ofthe parameter in the Parameter column.

2. Define the range of each Ki parameter to be calibrated:

a. Click the Ki parameter in the Parameter column.

b. Click the Define Range button. The Define Range dialogue appears.

c. Set the Min. Value and Max. Value for the variable.

Here are default and recommended ranges for Ki parameters:

Figure 4.17Path and Calibration method selection for SPM Calibration

Note: The filters defined in the properties of each CW measurement path will be taken into account in the calibration process.

Figure 4.18Range definition for SPM parameters during calibration



d. Click OK.

3. Click Next to start the calibration process.

After the calculations have completed, a results window appears with the previous parameters and methods andcurrent parameter values and methods (see Figure 4.19).

The previous and the current statistics are also displayed in terms of the root mean square, the standard deviationand the mean error (error = predicted - measured).

4. Click Commit to apply the results of the calculation process (i.e., calibrated Ki, methods, and clutter losses) to theinitial propagation model.

4.2.3.2 The Assisted Calibration WizardAfter you have selected the assisted calibration method in "Running the SPM Calibration Process" on page 59, you cancontinue with the assisted calibration wizard.

The table under Variables in the Assisted Calibration dialogue displays for each parameter to be calibrated (K1, K2, K3,K4, K5, K6 and K7) the correlation of the variables (log(d), log(HTxeff), Diff, log(d)log(HTxeff), HRxeff, log(HRxeff) with theglobal error. The variable with the highest absolute correlation is the variable that is the most correlated with error. In otherwords, this variable has the highest impact on the error and modifying this variable with have the greatest improvementon the global error. When you select an entry under Variables, the graph on the right shows the regression line corre-sponding to the variable for all the points (see Figure 4.20). The X-axis corresponds to the variable (in ascending order forall paths) and the Y-axis indicates the corresponding error.

Ki Minimum MaximumK1 0 100

K2 20 70

K3 -20 20

K4 0 0.8

K5 -10 0

Important: Leave the K6 parameter unselected. You can set the K7 parameter to "0" as well as it has little influence on the performance propagation model.

Figure 4.19SPM Comparative Calibration Results



When the correlation coefficient is close to one, the graph showing the regression is a vertical line; this indicates that theglobal error depends strongly on the variable. When the correlation coefficient is close to zero, the points are scatteredaround a horizontal line; this indicates that the correlation between the error and the variable is limited. It means that if thevariable if modified, this will not improve the error.

To use the assisted calibration wizard to reduce the mean error:

1. In the table, select the variables that you want to modify to reduce the mean error. To select more than one vari-able, press CTRL as you click the other variables.

2. Click the Identify button. The assisted calibration wizard attempts to bring the correlation as close to zero as pos-sible. Under Statistics, you can compare the Root Mean Square, the Average, and the Standard Deviationbefore and after.

If you want to adjust the losses per clutter class to reduce the mean error, the maximum distance, as defined underRange on the Clutter tab of the propagation model’s Properties dialogue, must be set to "0". If the maximumdistance is set to any other distance, Atoll will ask you if you want to force the maximum distance to "0" beforeletting you modify the losses per clutter class.

Calibration is complete when the Root Mean Square, the Average, and the Standard Deviation are as close tozero as possible.

3. Click Statistics to view a report on the statistics of the propagation model, using the current parameter values.

Under Model Parameters, the settings defined in General and Clutter tabs of the propagation model’s Propertiesdialogue are summarized: formulas, methods, distances, diffraction method, and losses per clutter class.

Under Global Statistics, the number of CW measurement points which match any filter criteria is given, alongwith the mean, standard deviation, and minimum and maximum values for variables such as the error, error (LOS),error (NLOS), log(d), log(HTxeff), Diff, log(d)log(HTxeff), and HRxeff.

Under Statistics per Clutter Classes, number of points, mean, and standard deviation for each clutter class aregiven.

Under Correlation Matrix, is a matrix of all parameters.

4. When you are satisfied with the results, click Commit to update the Ki factors of the propagation model with thechanges.

4.3 Calibrating Hata ModelsWhen the CW measurement data have been imported into the Atoll calibration project and prepared as explained in"Setting Up Your Calibration Project" on page 35, you can calibrate the Okumura-Hata and Cost-Hata Models. Atoll offersboth an identical automatic calibration wizard.

4.3.1 Quality TargetsThe quality of the final calibrated propagation model depends strongly on the quality of the CW measurements used in thecalibration process. Therefore, you will only be able to meet the following quality targets if the CW measurements used in

Figure 4.20Table listing the correlation of the SPM variables to the global error

Note: If you are not satisfied with the changes made when you clicked Identify, you can undo them by clicking Reinitialise.



the calibration process are of good quality, the provided radio data are correct, and the described calibration procedure isfollowed.

Calibration Sites:

• Global mean error on calibration sites: < 1 dB• Global standard deviation on calibration sites: < 8 dB• Mean error on each calibration site: < 2.5 dB• Standard deviation on each calibration site: < 8.5 dB

Verification Sites:

• Global mean error on verification sites: < 2 dB• Global standard deviation on verification sites: < 8.5 dB

4.3.2 Setting Initial Parameters in the Hata ModelsBefore starting the calibration process, you have to set a few parameters in Hata Models.

The Okumura-Hata model is suited for predictions in the 150 to 1000 MHz band over long distances (from one to 20 km).It is best suited to GSM 900, IS-95 cdmaOne, and CDMA 1xRTT radio technologies.

The Cost-Hata model is suited for coverage predictions in the 1500 to 2000 MHz band over long distances (from one to20 km). It is best suited to DCS 1800 and UMTS radio technologies.

Hata models in general are well adapted to the urban environment. You can define several corrective formulas and asso-ciate a formula with each clutter class to adapt the Hata model to a wide variety of environments. You can also define adefault formula to be used when no land use data is available. Additionally, you can consider diffraction losses based onthe DTM.

In this section, the following initial Hata Model parameters are explained:

• "Defining General Settings" on page 63• "Selecting an Environment Formula" on page 63• "Creating or Modifying Environment Formulas" on page 64.

4.3.2.1 Defining General SettingsTo set general parameters on the Okumura-Hata propagation model:

1. Click the Modules tab of the Explorer window.

2. Click the Expand button ( ) to expand the Propagation Models folder.

3. Right-click the Hata Model to set-up. The context menu appears.


5. Click the Parameters tab. You can modify the following settings:

- Add diffraction loss: The Okumura-Hata propagation model can take into account losses due to diffraction,using a 1-knife-edge Deygout method, and using the ground altitude given in the DTM. For detailed informa-tion on the Deygout method, see the Technical Reference Guide. The calculations take the curvature of theearth into account. Select "1 - Yes" if you want the propagation model to add losses due to diffraction. You canweight this diffraction for each Hata environment formula (See "Creating or Modifying Environment Formulas"on page 64)

- Limitation to free space loss: When using a Hata-based propagation model, it is possible to calculate a the-oretical path loss that ends up being lower than the free space loss. In Atoll, you can define any Hata-basedpropagation model to never calculate a path loss that is lower than the calculated free space loss per pixel.Select "1 - Yes" if you want the propagation model to limit the path loss calculated per pixel to the calculatedfree space loss.

6. Click OK.

4.3.2.2 Selecting an Environment FormulaThe Okumura-Hata propagation model can use an environment formula appropriate to each clutter class when calculating.You can assign a default formula that Atoll can use for all clutter classes for which you have not assigned an environmentformula or if you do not have clutter classes in your Atoll document.

To select environment formulas:



3. Right-click Okumura-Hata. The context menu appears.

Tip: After you have set initial parameters, you can retain the original copy of the Hata Model by creating a copy of the considered Hata Model and calibrating the copy instead. This allows you to restart calibration from the original version if you should need to. You can create a copy of an Hata Model by right-clicking the appropriate model folder on the Modules tab of the Explorer window and selecting Duplicate from the context menu.




5. Click the Configuration tab.

6. Under Formulas assigned to clutter classes, select the Default formula row. Under this grid, choose the appro-priate formula in the formula scrolling list.

Atoll uses the default environment formula for calculations on any clutter class to which you have not assignedan environment formula or if you do not have clutter classes in your Atoll document.

7. For each clutter class under Formulas assigned to clutter classes, select the corresponding row. Under thisgrid, choose the appropriate formula in the formula scrolling list and an additional loss (in dB). This additional lossacts as correction on the loss calculated by the chosen formula.

For information on modifying the selected formula, see "Creating or Modifying Environment Formulas" on page 64.

8. Click OK.

4.3.2.3 Creating or Modifying Environment FormulasSeveral environment formulas are available with the Okumura-Hata propagation model to model different environments.You can modify existing environment formulas used by the Okumura-Hata propagation model or create new environmentalformulas.

To create or modify an environment formula:



3. Right-click Okumura-Hata. The context menu appears.


5. Click the Configuration tab.

6. Click the Formulas button. The Formulas dialogue appears. You can do the following:

- Add: To create a new formula, click the Add button and modify the parameters of the formula.- Delete: To delete a formula, select the formula and click the Delete button.- Modify: To modify an existing formula, select the formula and modify the parameters.

7. Click OK to save your changes and close the Formulas dialogue.

8. Click OK.

4.3.3 Running the Hata Calibration ProcessThe goal of the automatic calibration process is to reduce the mean error and standard deviation of measured valuesversus calculated values. Independently of how you calibrate the standard propagation model, it must be able to givecorrect results for every CW measurement point from the same geographical zone, including CW measurement points thatwere not used to calibrate the standard propagation model.

To start the calibration process:



3. Right-click the copy of the Hata Model that you want to calibrate. The context menu appears.

4. Select Calibration from the context menu (see Figure 4.21). The Calibration Wizard dialogue appears.

Note: Additional losses can be evaluated using the Automatic Calibration Wizard. For information on the Automatic Calibration Wizard, see "Running the Hata Calibration Process" on page 64.

Notes: • You can weight the diffraction loss by setting the diffraction multiplying factor within the range

[0;1].• Constant values and diffraction multiplying factor can be evaluated using the Automatic Cali-

bration Wizard for each environment formula. For information on the Automatic CalibrationWizard, see "Running the Hata Calibration Process" on page 64.



5. Select the CW measurement paths that you decided to use for the calibration process (see Figure 4.22). For infor-mation on selecting CW measurement paths, see "Selecting Base Stations for Calibration and for Verification" onpage 55.

6. Click Next.

7. For each parameter you want to calibrate, select the check box of the parameter in the Parameter column.

8. Define the range of each parameter to be calibrated:

a. Click the parameter in the Parameter column.

b. Click the Define Range button. The Define Range dialogue appears.

c. Set the Min. Value and Max. Value for the variable.

Figure 4.21Calibration launching on Hata models

Figure 4.22Path and Calibration method selection for SPM Calibration



Here are default and recommended ranges for the calibrated parameters:

d. Click OK.

9. Click Next to start the calibration process.

After the calculations have completed, a results window appears with the previous parameters and methods andcurrent parameter values and methods (see Figure 4.24).

The previous and the current statistics are also displayed in terms of the root mean square, the standard deviationand the mean error (error = predicted - measured).

10. Click Commit to apply the results of the calculation process (i.e., calibrated Ai, diffraction multiplying factors andAdditional Losses) to the initial propagation model.

4.4 Analysing the Calibrated ModelOnce the propagation model has been calibrated using either the automatic or the assisted method, Atoll offers severalmethods to verify the calibration or to analyse its quality.

The first step is to calculate path loss matrices on the CW measurement paths using the calibrated propagation model, asexplained in "Calculating Path Loss Matrices Using the Calibrated Model" on page 67. Once you have path loss matrices

Figure 4.23Range definition for SPM parameters during calibration

Parameter Minimum MaximumA1 0 100

B1 0 100

Diffraction Factor 0 1

Figure 4.24Hata Models Comparative Calibration Results



that have been calculated using the calibrated propagation model, you can analyse the calibrated model using the follow-ing methods:

• "Displaying Statistics on CW Measurement Paths" on page 67• "Using Display Settings to Analyse the Calibration" on page 68• "Using the CW Measurement and the Point Analysis Tools" on page 69.

Calculating Path Loss Matrices Using the Calibrated Model

The first step in analysing the quality of the calibration process is to calculate signal losses on the CW measurement pathsusing the newly calibrated propagation model. These path loss matrices will then be used to verify the accuracy of thecalibrated propagation model.

To calculate path loss matrices on the CW measurement paths:


2. Select the propagation model you calibrated:

a. Right-click the CW Measurements folder. The context menu appears.

b. Select Properties from the context menu. The Properties dialogue appears.

c. Select the Propagation tab and select the name of the propagation model you calibrated from the PropagationModel list (see Figure 4.25).

d. Click OK.

3. Calculate signal levels for all CW measurement points:

a. Right-click the CW Measurements folder. The context menu appears.

b. Select Calculations > Calculate Signal Levels from the context menu. Atoll calculates the signal levels forall CW measurement paths.

Displaying Statistics on CW Measurement Paths

You can display the statistics on both the CW measurement paths used for calibration and on those used for verification.By comparing these statistics to the quality targets (see "Quality Targets" on page 55), you can see whether the calibrationprocess was successful.

To display the statistics of a CW measurement path:



3. Select Display Statistics from the context menu. The Statistics dialogue appears (see Figure 4.27).

4. In the Statistics dialogue, select the check boxes of the CW measurement paths of either the CW measurementpaths used for calibration or the those to be used for verification and click OK. The CW Measurements dialogueappears (see Figure 4.28).

The CW Measurements dialogue gives the average and standard deviation for all points, grouped by clutter class.You can compare these statistics to the quality targets listed in "Quality Targets" on page 55.

Figure 4.25Selecting the calibrated model for all CW measurement paths

Figure 4.26Calculating the signal levels on all CW measurement paths



Using Display Settings to Analyse the Calibration

You can analyse the quality of the propagation model calibration on the map, by examining areas where the error(predicted minus measured) is very high.

To display the CW measurement points on the map according to the error:


2. In the CW Measurements folder, clear the display check box beside all CW measurement paths except the onesyou want to display.


Figure 4.27Selecting on of the verification stations for the statistics

Figure 4.28Comparative statistics of the verification stations



3. Define the display settings of the CW measurement path:

a. Select the Display tab.

b. Set the Display Type to "Value Intervals" and select "Error (P-M)" from the Field list. For more information,see "Defining the Display Type" on page 41.

4. Add the CW measurement points to the legend, as explained in "Adding CW Measurement Points to the Legend"on page 43.

5. Select View > Legend Window. The Legend window appears.

Using the CW Measurement and the Point Analysis Tools

By simultaneously using the CW Measurement Analysis Tool and the Point Analysis Tool, you can analyse the follow-ing elements of a CW measurement path:

• The measured signal level• The predicted signal level• Diffraction• The error• The profile between the reference transmitter and the receiver.

To use the CW Measurement Analysis Tool and the Point Analysis Tool to analyse elements of a CW measurementpath:


2. In the CW Measurements folder, clear the display check box beside all CW measurement paths except the oneyou want to display.


3. Right-click the CW measurement path you want to analyse. The context menu appears.

4. Select Open the Analysis Tool from the context menu. The CW Measurement Analysis Tool opens.

Figure 4.29Distribution of error around a verification station



5. Select View > Point Analysis Tool. The Point Analysis Tool appears.

As you move the pointer ( ) along the CW measurement path on the map or in the CW Measurement AnalysisTool window, the following information appears in the CW Measurement Analysis Tool window (seeFigure 4.31):

- The measured signal level- The predicted signal level- The error- The graph

You can select an additional characteristic of the CW measurement path from the list on the right.

The Profile tab of the Point Analysis Tool window displays the profile between a reference transmitter and theselected CW measurement point. As well, Atoll displays the strength of the received signal from the selectedtransmitter as well as any diffraction peaks.

Figure 4.30Opening the CW Measurement Analysis tool

Important: The propagation model used to generate the results on the Profile tab of the Point Analysis Tool window is the model defined in the properties of the reference transmitter.

Note: You can also move through the CW measurement points by dragging the vertical line in the CW Measurement Analysis Tool window that indicates the current CW measurement point.



4.5 Finalising the Settings of the Calibrated SPMThe objective of the calibration process is to reduce the error between path loss values predicted by the propagation modeland real path loss values measured during the CW measurement survey. After calibration is complete, however, there arestill a few adjustments that will need to be made before the propagation model can be used.

If clutter classes are taken into consideration in the SPM, the first step in finalising the calibrated propagation model isensuring that a clutter loss is defined for all clutter classes. There are usually a few clutter classes that are not representedin the area covered by the CW measurement survey, or that are not sufficiently represented and were, therefore, filteredout. Nevertheless, losses must be defined for these clutter classes in order for the propagation model to be effective overall areas. This is explained in "Defining Clutter Losses for Uncalibrated Clutter Classes" on page 71.

Once you have losses defined for each clutter class, you must define how the clutter losses will be weighted. The lossesdefined per clutter class refer only to receiver pixel, not to total loss. When you calculate the total clutter loss, you have totake into consideration the loss on pixels between the transmitter and the receiver. However, the influence of clutter dimin-ishes with distance from the receiver. Defining how clutter loss will be weighted is explained in "Clutter Tab" on page 57.

The final step is ensuring that a model standard deviation has been set for each clutter class. As with clutter losses, nostandard deviation will have been calculated for clutter classes that were not represented or not sufficiently representedin the CW measurement survey. To ensure accurate calculations with the calibrated propagation model, you must ensurethat all clutter classes have a defined model standard deviation. This is explained in "Defining the Model Standard Devia-tion for Uncalibrated Clutter Classes" on page 73.

Defining Clutter Losses for Uncalibrated Clutter Classes

Clutter classes that were not represented, or were not sufficiently represented and were, therefore, filtered out, will nothave had clutter losses defined by the calibration process. The clutter loss for these clutter classes will remain at "0."However, when clutter losses are used, leaving the clutter loss at "0" could lead to large errors when you use the calibratedpropagation model in areas where these clutter classes are present. Therefore, undefined clutter losses must be extrap-olated from other sources.

You can extrapolate undefined clutter losses from:

• Propagation models calibrated on other areas: If you calibrated a copy of the same propagation model usingCW measurements made on a different area, some, if not all, of the clutter classes that are uncalibrated in yourcurrent propagation model may have been calibrated in the copy calibrated on the other area.

• Typical losses: You can extrapolate missing clutter losses from typical losses. It is important to remember thatthe relative difference (between losses per clutter class) is more important than the absolute value of clutter lossesbecause the absolute value is dependent on the constant K1. As well, you must calculate and use a scaling factorbetween calibrated losses and typical losses. Additionally, clutter losses should be normalised on the most repre-

Figure 4.31CW Measurement Analysis



sentative clutter class in order to be able to compare them. In other words, if the best represented clutter class is"Urban," then the clutter losses for "Urban" should be shifted to "0" for that clutter class and the calibrated clutterclass losses should be shifted to respect their relative difference from the clutter losses for "Urban" and the con-stant K1 should be modified to compensate for the shift. For example, if "Urban," the best represented clutter class,has a loss of "-3" and "Suburban" has a loss of "-7," when you shift "Urban" it to "0," you will have to shift "Sub-urban" by a corresponding amount, i.e., the normalised loss for "Suburban" will be "-4." As well, if the value of K1was 22, when you shift the clutter losses by 3, you will have to shift the value of K1 by a similar value, to give youa value of 19, in order to compensate for the shift in clutter class losses.

The following table gives typical clutter losses, normalised for the Urban clutter class.

To extrapolate undefined clutter losses from other propagation models:

1. On the Modules tab of the Explorer window, right-click the copy of the propagation model calibrated on anotherarea. The context menu appears.


3. Under Parameters per clutter class, on the Clutter tab, note the losses for all clutter classes that remained uncal-ibrated in the copy of the propagation model you are currently calibrating.

4. Open the Properties dialogue of the propagation model you are currently calibrating.

5. Under Parameters per clutter class, on the Clutter tab, enter the losses for the clutter classes that remaineduncalibrated.

To extrapolate undefined clutter losses from standard values:

1. Using values that are present in both the calibrated propagation model and in the typical values, calculate the scal-ing factor between the two sets of values.

To calculate the scaling factor, you use values existing in both the propagation model and in the typical values, forexample:

2. Calculate the delta between the normalised clutter class loss in the typical values (i.e., "Urban") and the clutterclass loss that is undefined in the calibrated propagation model (i.e., the ).

3. Multiply this delta by the scaling factor between the project losses and the standard losses to calculate the clutterloss for the project:

4. Add the delta of the project to the normalised clutter loss to obtain the value of the clutter class loss that is unde-fined in the calibrated propagation model.

5. Repeat these steps for each clutter loss that is undefined in the calibrated propagation model.

For example, a project has the following clutter losses:

Dense Urban = 5Urban = (0)Suburban = 2

The clutter loss for Urban is undefined. To extrapolate from the known values using typical values, you must firstcalculate the scaling factor, using the values existing in both the standard values:

Clutter Class LossDense urban From 4 to 5

Woodland From 2 to 3

Urban 0

Suburban From -5 to -3

Industrial From -5 to -3

Open in urban From -6 to -4

Open From -12 to -10

Water From -14 to -12

Important: Before you can extrapolate undefined clutter losses, you must ensure that the losses from the other propagation model are normalised on the same clutter class as the clutter class used for normalisation in the propagation model you are calibrating.

Note: Remember that it is the relative difference between losses per clutter class that is important.

Dense Urban, project( ) Suburban, project( )–( ) Dense Urban, typical( ) Suburban, typical( )–( )⁄

Δstandard

Δproject Δs dard scaling factor×tan=



In this case:

Using the scaling factor, you can calculate the delta between the Urban loss and the Dense Urban in the project:

Or:

Subtracting the result of "1.5" from "5" gives us a clutter loss of "3.5" for Urban in this project.

Defining the Model Standard Deviation for Uncalibrated Clutter Classes

During the calibration process, model standard deviations were calculated for all calibrated clutter classes. You should usethese values to update the model standard deviation for each clutter class in the clutter class properties. Clutter classesthat were not represented, or were not sufficiently represented and were, therefore, filtered out, will not have had a modelstandard deviation defined by the calibration process. You should update the model standard deviation for these clutterclasses if you calibrated a copy of the same propagation model on a different area that covered different clutter classes.

4.6 Deploying the Calibrated ModelOnce you have calibrated the propagation model, you can use it to make coverage predictions in Atoll documents thatcover the calibration area and that use the same frequency band that was used to calibrate the propagation model. WithAtoll you can copy the calibrated propagation model and paste it into another document. Atoll also enables you to quicklydeploy the calibrated propagation model to a defined group of transmitters in a document.

4.6.1 Copying a Calibrated Model to Another DocumentYou can copy a calibrated propagation model from the calibration document to another Atoll document.

To copy a calibrated propagation model to another document:

1. Open the following Atoll documents:

- The Atoll document with the calibrated propagation model- The Atoll document into which you want to copy the calibrated propagation model.

2. Click the Window menu and select the Atoll document with the calibrated propagation model.

Figure 4.32Description of the available clutter classes

Dense Urban, project( ) Suburban, project( )–( ) Dense Urban, typical( ) Suburban, typical( )–( )⁄

5 2–( ) 4 4––( )⁄( ) 38---≈

Δproject Δstandard scaling factor×=

Δproject 4.5 0–( ) 38---× 1.5≈=

Important: Remember that the calibrated propagation model is valid only for the area and frequency band on which it was calibrated. If you use it on another



3. Copy the calibrated propagation model:

a. On the Modules tab of the Explorer window, click the Expand button ( ) to the left of the Propagation Mod-els folder to expand the folder.

b. Right-click the calibrated propagation model. The context menu appears.

c. Select Copy from the context menu. The calibrated propagation model is copied to the clipboard.

4. Click the Window menu and select the Atoll document into which you want to copy the calibrated propagationmodel.

5. Paste the calibrated propagation model:

a. Select the Modules tab of the Explorer window.

b. Press CTRL+V. The calibrated propagation model is pasted into the Atoll document.

You can verify that the calibrated propagation model has been pasted successfully by clicking the Expand button( ) to the left of the Propagation Models folder to expand the folder. The calibrated propagation model is nowvisible in the Propagation Models folder.

4.6.2 Deploying a Calibrated Model to TransmittersYou can now deploy the calibrated propagation model to all transmitters corresponding to the calibration area andfrequency band. You can assign the calibrated propagation model in several different ways but, when you are assigningit to a large number of transmitters, it is easiest to use the Transmitters table.

To deploy a propagation model using the Transmitters table:

1. Filter out the transmitters outside of the area over which you will be deploying the calibrated propagation modelby creating a filtering polygon that selects all the transmitters within the area:

a. On the Geo tab of the Explorer window, click the Expand button ( ) to the left of Zones folder to expand thefolder.

b. Right-click the Filtering Zone folder and select Draw from the context menu. The pointer changes to the

polygon drawing pointer ( ).

c. Click on the map to start drawing the filter polygon. Click each time you change the angle on the border defin-ing the outside of the polygon.

d. Close the polygon by clicking twice. The transmitters outside of the selected zone are filtered out. On the Datatab of the Explorer window, the Transmitters folder appears with a special icon ( ), to indicate that thefolder contents have been filtered. Only the transmitters within the filtering zone will now appear in the Trans-mitters table.

2. Open the Transmitters table:

- On the Data tab of the Explorer window, right-click the Transmitters folder and select Open Table from thecontext menu. The Transmitters table appears.

3. If necessary, sort the entries in the Transmitters table by frequency band:

- In the Transmitters table, click the title of the Frequency Band column to sort the entries by frequency band.

4. Select the calibrated propagation model for all records that will use it:

a. In the Main Propagation Model column, select the calibrated propagation model.

b. Starting with the record you have just changed, click and drag to select all records that will have the samepropagation model.

c. Select Edit > Fill > Down. The entry under Main Propagation Model changes to the value in the first recordof the selected transmitters.

d. If you want to assign the calibrated propagation model to the extended propagation model as well, repeatthese steps with the entries in the Extended Propagation Model column.

Note: If the result was not what you expected, select File > Undo and repeat the steps.


Chapter 5


Additional CW Measurement Functions



Chapter 5: Additional CW Measurement Functions

5 Additional CW Measurement FunctionsIn "Collecting CW Measurement Data" on page 29, preparing a successful CW measurement survey was explained.Importing CW measurement data into an Atoll document is explained in "The Model Calibration Process" on page 35, aswell as preparing imported CW measurement data for a calibration project.

Atoll offers additional possibilities for working with CW measurements. These are described in this chapter:

• "Creating a CW Measurement Path" on page 77,• "Drawing a CW Measurement Path" on page 78,• "Merging Measurement Paths for a Same Transmitter" on page 78,• "Smoothing Measurements to Reduce the Fading Effect" on page 78,• "Calculating Best Servers Along a CW Measurement Path" on page 79.

5.1 Creating a CW Measurement PathIn Atoll, you can import CW measurements as described "Importing a CW Measurement Path" on page 37 if they are inplain text or comma-separated value (CSV) format. However, if the data are stored in tabular format in, for example, aspreadsheet or word-processing document, you can import them by copying and pasting them directly into Atoll.

To create a CW measurement path:



3. Select New from the context menu. The New CW Measurement Path dialogue appears (see Figure 5.1).

4. Enter a Name for the CW measurement path.

5. Under Reference Transmitter, select the Transmitter with which the CW measurements were made and selectthe Frequency.

6. Under Receiver, enter the Height of the receiver, the Gain, and the Losses.

7. Under Measurements, define the Unit used for the CW measurements.

8. If the Coordinates used for the CW measurement data are different than the one displayed, click the Browse


9. From the document with the CW measurements, select the X and Y coordinates and CW measurements to beimported and copy them.

10. In the New CW Measurement Path dialogue, click the Paste button.

11. Click OK.

Once you have created the CW measurement path, you can modify the values of the path in the table. You can open theCW measurement table by right-clicking it in the CW Measurements folder on the Data tab of the Explorer window andselecting Open Table from the context menu.

Figure 5.1The New CW Measurement Path dialogue




5.2 Drawing a CW Measurement PathWhen you have created or imported a CW measurement path, you can use the mouse to add points to it. You can eitheradd the CW measurement points one by one, or you can draw a path segment with the points separated by a defineddistance.

To add points to a CW measurement path:




4. Right-click the CW measurement path to which you want to add points. The context menu appears.

5. Select Add > Points from the context menu. The pointer changes ( ).

6. Click the map at each location where you want to add a CW measurement point.

7. When you have finished, press ESC or double-click.

To add a path segment to a CW measurement path:




4. Right-click the CW measurement path to which you want to add points. The context menu appears.

5. Select Add > Path from the context menu. The Path Creation dialogue appears.

6. Enter the Step between each point and click OK. The pointer changes ( ).

7. Draw the path of the path segment by clicking on the map to draw the starting point and each time the path seg-ment changes direction.

8. When you have finished, press ESC or double-click.

5.3 Merging Measurement Paths for a Same TransmitterIn the case several measurement paths refer to the same transmitter, it might be useful to merge all the data in a uniquetable so that the filtering wizard may be used on it.

To merge several measurement paths of a same transmitter:



3. Right-click the folder of the reference transmitter for which you want to merge the referring paths. The contextmenu appears.

4. Select Merge Measurement paths from the context menu.

5. Choose if you want to merge all the considered paths or only a part of them.

6. Click OK. The selected CW measurement paths will be merged in a unique table.

5.4 Smoothing Measurements to Reduce the Fading Ef-fectWhen the fading effect is not limited by the measurement equipment itself, you can smooth the measured signal strengthby averaging them during the calibration pre-process over a sliding window with a view to minimise the errors and standarddeviations. In other words, you can define the width of a sliding window within which, for each measured point, the meas-ured data is arithmetically averaged.

This part of the calibration pre-process has to be done before the data filtering described in "Filtering Measurement Data"on page 44.

To Smooth the values of an existing CW measurement path:

1. On the Data tab of the Explorer window, click the Expand button ( ) to expand the CW Measurements folder.The CW Measurements folder opens.

2. Click the Expand button ( ) to expand the folder of the reference transmitter. The reference transmitter folderopens.

3. Right-click the CW measurement path. The context menu appears



4. Select Smoothing > Smooth Measurements from the context menu. The Measurement Smoothing dialogueappears (see Figure 5.2).

5. Enter the width of the smoothing window (in meters) and click OK. This parameter defines the number of samplesto be considered when averaging the path data.

In the path table, the smoothed values overwrite the initial ones in the M column. The initial measurement data arereported in new column called (M (Initial)).

5.5 Calculating Best Servers Along a CW Measurement PathUnder certain circumstances, you might need to calculate which is the best server along the CW measurement path. Thisis particularly the case along, for example, rail lines using radio technology for communication. Atoll enables you toapproximate a best server coverage prediction by adding one transmitter to the CW measurement path of another one andcalculating signal levels.

The process consists of the following steps:

1. Adding transmitters to a CW measurement path: The first step is to add additional transmitters to the CWmeasurement path along which you want to calculate best servers. See "Adding Transmitters to a CW Measure-ment Path" on page 79.

2. Selecting the propagation model for the CW measurement path: You must select the propagation model tobe used to calculate signal levels. See "Selecting the Propagation Model" on page 79.

3. Defining the CW measurement path display: You must set the display of the CW measurement path in orderto display the measurement points by best server. See "Setting the Display to Best Server" on page 80.

4. Calculating signal levels: Once you prepared the CW measurement path, you can calculate the signal levels.See "Calculating Signal Levels" on page 80.

5. Displaying comparative statistics between measurement and predicted values: After having calculated thesignal levels over measurement paths you can display global statistics or statistics per clutter class, per transmitteror per measurement path. See "Displaying Statistics Over a Measurement Path" on page 80 and "Displaying Sta-tistics Over Several Measurement Paths" on page 80.

5.5.1 Adding Transmitters to a CW Measurement PathTo add a transmitter to a CW measurement path:



3. Click the Expand button ( ) to expand the folder of the reference transmitter along whose CW measurement pathyou will calculate signal levels.


5. Select Calculations > Add a Transmitter from the context menu. The New Prediction dialogue appears.

6. Select the transmitter to add from the Transmitter list and click OK. The transmitter will be added to the CW meas-urement path data table.

5.5.2 Selecting the Propagation ModelTo add a transmitter to a CW measurement path:



Figure 5.2Sliding Window Property Dialogue

Note: You can restore the initial values in any CW measurement path by selecting Smoothing > Restore Initial Values.



3. Click the Expand button ( ) to expand the folder of the reference transmitter along whose CW measurement pathyou will calculate signal levels.



6. On the Propagation tab of the Properties dialogue, select the Propagation Model.

7. Click OK.

5.5.3 Setting the Display to Best ServerYou must set the display properties of the CW measurement path to discrete values by best server. For information onchanging object display properties, see the User Manual.

5.5.4 Calculating Signal LevelsTo calculate the signal levels:




4. Right-click the CW measurement path to which you want to calculate the signal levels. The context menu appears.

5. Select Calculations > Calculate Signal Levels from the context menu.

Atoll calculates signal levels, updating the values in the data table for that CW measurement path and updatingthe map according to the settings selected in "Setting the Display to Best Server" on page 80.

5.5.5 Displaying Statistics Over a Measurement PathAssuming signal levels have been calculated along a measurement path, you can display the statistics between the meas-urements and the predicted signal levels on a specific measurement path.

To display the statistics for a specific measurement path:




4. Right-click the CW measurement path to which you want to display comparative statistics. The context menuappears.

5. Select Display statistics from the context menu.

Atoll opens a popup in which the global statistics between measurements and predictions are given over all thefiltered (or not) points through the mean error, its standard deviation, the root mean square and the error correla-tion factor. The statistics are also given per clutter class

5.5.6 Displaying Statistics Over Several Measurement PathsAssuming signal levels have been calculated along a measurement path, you can display the statistics between the meas-urements and the predicted signal levels over several measurement paths.

To display the statistics for the entire set of the measurement paths:




4. Select if you want to display the statistics for all the considered paths or only a part of them.

Atoll opens a popup in which the global statistics between measurements and predictions are given over all thefiltered (or not) points through the mean error, its standard deviation, the root mean square and the error correla-tion factor.

The statistics are also given per clutter class, per transmitter and for each measurement path.

To display the statistics for a part or all the measurement paths referring to a unique transmitter:



3. Right-click the folder of the reference transmitter to which you want to display comparative statistics. The contextmenu appears.




5. Select if you want to display the statistics for all the considered paths or only a part of them.

Atoll opens a popup in which the global statistics between measurements and predictions are given over all thefiltered (or not) points through the mean error, its standard deviation, the root mean square and the error correla-tion factor.

The statistics are also given per clutter class, per transmitter and for each measurement path.




Chapter 6


Survey Site Form



Chapter 6: Survey Site Form

6 Survey Site FormThe survey site form should indicate:

• Details describing the station• The locations of any spurious measurements where the physical clutter data does not coincide with the mapping

data• Any useful information about incidents that may have occurred.



Survey Site FormStation Details

Site ID: ZHF993 Survey Site No: 1

Address 18 Smith street

Site Access Details Ask for James Brown at reception desk in regards to getting access to the site on the roof.

Co-ordinates: E: 26,38773 N: 50,59358

Map GPS x

Transmitters: Nominal power 43 dBm

Cable length / type 5m 1/4"

Cable losses max /UMTS 3 dB

location Outdoor, on the roof

Omni Antenna Type K800 1111

Gain 2 dBi

installation On mast / tripod ?

EIRP min. 40 dBm

Ant. Height 20,4 + 3 23,4 m

Type of site Roof top

General Site Comments(Enter construction details, etc.)

• Site under construction (mast without antennas)• Lift• Power supply 220V available from shelter• No obstruction for propagation

Notes:• Pay attention to the separation between the test antenna and any live antennas. Vertical separation, if the antennas

are aligned, is not really a problem, but horizontal separation could be problematic, so it should be avoided.

• Site photos: Take photos of the sites both from the ground and from the site itself. You also need a set of panoramicphotos, starting from 0° (North) and moving clockwise by 45° increments. You can use a laser telemeter to measurethe height of the site.

• Site Drawing: Make an accurate (as far as possible) drawing of the site. Indicate where North lies in relation to the site.



Site Photos

Global view:

Rooftop:



Panoramic Photos

↑ North ↑ East

↑ South ↑ West



Survey Details

Measurement Files: Number: Comments:1

2

3

4

5

6

7

8

9

10

Frequency Band GSM DCS UMTSChannel Used 56 563 1

Frequency 935.200 1815.200 2170

Channel Bandwidth 200 khz 200 khz 200 khz

Interference free control? X X X

TX transmitter Output before survey 40 dBm 40 dBm 40 dBm

-Before antenna- Output power after 39.8 dBm 39.8 dBm 39.8 dBm

VSWR 1.3 1.3 1.3

Survey Comments:(Information about issues that will necessitate data filtering, etc.)

Notes:• Take note of any areas on the survey path which are not suitable data collection areas (avoid them if possible), for

example, tunnels, bridges, raised motorways, etc. Keep in mind that the planning tool assumes that you are at groundlevel; any raised or lowered areas produce errors.

• Before making the survey drive, measure the RF output at the antenna, after the cable.

• Measure the RF output at the antenna again after the survey drive, to ensure that the transmitter is still working.




Atoll RF Planning & Optimisation Software

Measurements and ModelCalibration Guide

v e r s i o n 2.8.2

AT282_MCG_E0

Documents

Atoll 2.8.2 Model Calibration Guide E0