CONFIDENTIAL
CW Test and Propagation Model Tuning ISSUE 4.0
www.huawei.com
RNP Staff Training Dept.
HUAWEI TECHNOLOGIES CO., LTD.
Huawei Confidential
Foreword CW test (Continuous Wave test) is an important step of Propagation Model Tuning. According to the CW
test data (including latitude / longitude and received signal level) and corresponding Digital maps, we can get the accurate Propagation
Model through tuning.
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Foreword CW test (Continuous Wave test) is an important step of Propagation Model Tuning. According to the CW
test data (including latitude / longitude and received signal level) and corresponding Digital maps, we can get the accurate Propagation
Model through tuning.
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Objectives
After this course, you will will ： Know
principle of propagation model
tuning Know
the procedure of CW test
Know
the procedure of tuning t uning propagation model
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Contents 1 Principle of Model Tuning 2 CW Test Flow 3 Pre-pro Pre-processing cessing of CW Test Data 4 Propagat Propagation ion Model Tuning
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Radio Propagation Model
Propagation model is used to predict the effect of terrain, obstacle and artificial environment on the path loss.
WCDMA common propagation models
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Common Radio Propagation Models Based on Statistics
Okumura/Hata model COST231-Hata model
WaveSight model
For: 1500-2000MHz
WinProp model
COST231 Walfish-Ikegami model
For: 800M-2000MHz
Keenan-Motley model
Ray Tracing model Volcano model
For: 900M－1500MHz
Based on theory analyses
For indoor propagation
SPM model in U-Net
For macro cell on 300M－2000M
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Radio Propagation Model in U-Net
SPM model (Standard Propagation Model): PathLoss = K1 + K2log (d) + K3log (HTxeff ) + K4*Diffraction loss + K5log (d)×log (HTxeff ) + K6*(HRxeff ) + Kclutter *f (clutter)
K1: constant (dB) K2: multiplier factor of log(d) d: distance between Tx antenna and Rx antenna (m) K3: multiplier factor of log(H Txeff ) HTxeff : effective height of Tx antenna (m) K4: multiplier factor of diffraction loss, which must be a positive number Diffraction loss: diffraction loss through the path with barriers (dB) K5: multiplier factor of log(H Txeff )log(d) K6: multiplier factor of HRxeff HRxeff : effective height of Rx antenna (m) Kclutter : multiplier factor of for f(clutter) f(clutter ): average weighted loss caused by clutter With a set of K parameter, we can make prediction for the planning area.
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Typical Radio Propagation Environment Name
Description
Dense Urban
There are dense buildings in the city, normally most of the buildings are more than 10 floors high.
Urban
Normal area in cities. Buildings are not so dense. Normally there are streets or planting areas between them. And few buildings are more than 10 floors high.
Sub-Urban
Buildings are sparsely distributed, and mainly low buildings.
Country
Village. Buildings are distributed very sparsely, and mainly houses.
Special
Including mountain area, sea surface, highway, indoor, tunnel, etc.
Different radio scenario adopts different propagation model.
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Principle of Propagation Model Tuning Target Propagation Environment
Setup a Model
Collect data from field test
Set the model Parameter
Actual PathLoss
Prediction PathLoss
Compare
Meet the precision request?
N
Y
End
Huawei take GENEX U-Net to perform propagation model tuning.
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Propagation Model Tuning working flow 1. Decide the propagation environment 2. Acquire site, setup the simulation site, transmitting continuous wave (CW) signal
GPS Satellite
3. Drive test on the pre-planned route, collecting enough data 4. Post process the data, compare test results with prediction results, and then tune the propagation parameters (K1, K2, …Kclutter)
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Basic Principle of CW Test
Typification
The CW test data must represent the characteristic of electromagnetic wave in this area.
Balance
The CW test data must represent the characteristic of electromagnetic wave by the proportion of different clutters in this area.
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Contents 1 Principle of Model Tuning 2 CW Test Flow 3 Pre-processing of CW Test Data 4 Propagation Model Tuning
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Contents 2 CW Test Flow 2.1 Decide the Propagation Environment 2.2 Site Selection 2.3 Setup Test Platform 2.4 Plan the Drive Test Route 2.5 Drive Test
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2.1 Decide the Propagation Environment
Firstly, decide if it’s necessary to separate the planning area to several propagation environments, such as Dense Urban, Urban, Sub-Urban or Rural Area, etc.
Then for each environment, set proper initial propagation model parameter, and perform dedicate CW test and propagation model tuning.
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2.2 Site Selection – Principles
Number of sites: It is usually agreed that a minimum of 5 sites should be tested in large and dense city, and one site is enough for normal city, which mainly depends on antenna height and EIRP.
Representation: Site selection should aim to cover all types of clutter (from the digital map) in the coverage zone.
Multiple models: Define the corresponding zone of each model if the test environment requires multiple models to describe its propagation characteristics.
Overlap: Increase measurement overlap area between each site as much as possible. But reasonable inter-site distance should be ensured.
Obstacle: The data should be filtered in the subsequent processing if obvious obstacle exists.
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2.2 Site Selection – Standards 1. Antenna height of the CW transmitter should be greater than 20m. 2. Antenna of the CW transmitter should be at least 5m higher than the obstacle objects nearby within 50m far. Note: Here the obstacle mainly refers to the highest building on the rooftop where the antenna is installed. The building where the site is located should be higher than average height of surrounding buildings.
m 5
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2.3 Setup Test Platform (1)
CW Transmitter: Tx antenna, feeder, RF signal source and antenna pole
CW Receiver: test receiver, GPS receiver, test software and laptop
Tx antenna
RF Power Signal Booster RF cable 2 Source RF cable 1
CW Transmitter
Power supply
Rx antenna Drive test tool (GPS Build-in)
CW Receiver
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Laptop
2.3 Setup Test Platform (2) TX Antenna
CW Transmitter
CW Receiver
Mobility Power Supplier
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2.3 Setup Test Platform (3)
Record the gain or loss of all the RF parts: a) TX power of the CW transmitter b) Loss of the RF cables c) Gain of TX antenna
d) Loss of the connectors e) Gain of Rx antenna Then with a, b, c and d, we can get the EIRP.
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2.4 Plan the Drive Test route (1)
Rules to plan the route
Landform: The route must cover all main landforms in the area.
Height: The test route must cover landforms with different height in this area if the landforms are up-and-down.
Distance: The route must cover near and far to the site. But normally no need to test in areas more than 2R far away to the site. – R: Future cell radius in this area.
Direction: The route must be consistent on the horizontal and vertical route.
Length: The total distance of one CW test route should be longer than 60km.
Number of test samples: The more, the better. (At least 10,000 samples, and at least 4 hours test time)
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2.4 Plan the Drive Test route (2)
Rules to plan the route
Overlap: Overlap the test route in different sites as much as possible to enhance the reliability of models.
Obstacle: Shadow areas behind walls should be avoided when
antenna signals are obstructed by the wall. Such areas as under viaducts or in tunnels should be avoided. If have to pass through such areas, data should be filtered after test.
If a directional antenna is adopted for a CW transmitter, the test
route should be planned within the main lobe coverage area of the antenna (don’t plan route in area behind the antenna).
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2.5 CW Drive Test – Limitation of the speed
CW drive test data contains results affected by slow fading (shadow fading) and fast fading (Raileigh Fading).
To tune a model, only the effect by slow fading will be accept, but not fast fading.
To get rid of the effect caused by fast fading, enough samples are need in a certain distance.
Lee criteria says the request for sampling: At
least 50 samples on 40λ range, then the difference between mean value of test data and actual value can be less than 1dB –
λ:
wavelength of the RF signal
Then the maximum vehicle speed: V max = 0.8λ*f – f : samples per second of the receiver
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2.5 CW Drive Test - Equipment
Scanner – DTI (GPS build in）
GPS antenna
RF antenna of scanner
Cables for data and power
Laptop
Probe and Dongle
Huawei GENEX Probe has the function for CW test.
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Contents 1 Principle of Model Tuning 2 CW Test Flow 3 Pre-processing of CW Test Data 4 Propagation Model Tuning
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Contents 3 Pre-processing of CW Test Data 2.1 Data Filtering 3.2 Data Dispersion 3.3 Data Binning 3.4 Format Conversion
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3.1 Data Filtering
Six kinds of data should be filtered: 1. Data tested in places where GPS is unable to locate accurately (such as under the viaduct, in the tunnel)
2. Data obtained when the distance to antenna is too near or too far 3. Data obtained with too weak signals 4. Error data caused by inexact antenna pattern 5. Data with a loss exceed over 15~30 dB but no reasonable reason 6. Other data inconsistent with the requirements
during the route planning of CW test
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3.2 Data Dispersion (1)
Principle:
Sampling speed of the receiver is much more higher than that of the GPS. So there are many receiver samples stored together on each GPS sample. Actually these receiver samples should be distributed one by one in time sequence between every two GPS samples.
Between two GPS sample, vehicle speed is regarded uniform, so the time intervals between every two adjacent receiver samples are same. 1 GPS Sample and n Receiver Samples
●
….
●
●
●
….
Receiver Samples ●
●
●
●
Many Receiver samples share one geography data
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3.2 Data Dispersion (2)
Data Process:
Equally distribute the receiver samples to the route section between two GPS points in time sequence so that there will be sufficient points in every 40λ range on test route. 1 GPS Sample and n Receiver Samples … .
●
●
●
… .
Disperse … .
●
●
●
Original GPS sample
●
●
●
●
●
Fitting GPS data
●
●
●
●
●
●
●
… .
Each receiver sample has its own geography data
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3.3 Data Binning (1)
Objective:
Keep the impact of slow fading but eliminate the fast fading
According
to Lee criteria: At least 50 samples on 40λ range, then
the error between the mean value of the data on this 40λ range
and the actual value can be less than 1dB.
Methods:
Method 1 (Grid Binning): Divide the whole area into 40λ*40λ grids, take the average value for data located in each grid, and take the center of each grid as the new location.
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3.3 Data Binning (2)
Methods:
Method 1 (Grid Binning): Divide the whole area into 40λ*40λ grids, take the average value for data located in each grid, and take the center of each grid as the new location.
Method 2 (Distance Binning): Divide the drive test route into sections with 40λ length, take the average value for data located on each section, and take the center of each section as the new location. ….
….
●
….
●
●
●
….
●
●
●
….
●
●
●
….
●
●
….
….
40λ
Tool: Huawei Genex Probe, or CW Data Editor
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Before Binning After Binning
3.4 Format Conversion
The data exported by Genex Probe is a .txt file with format: X (Longitude)
Y (Latitude)
Power (dBm)
Data imported to U-Net is a .dat file
Format conversion can be implemented manually (save as .dat file)
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Contents 1 Principle of Model Tuning 2 CW Test Flow 3 Pre-processing of CW Test Data 4 Propagation Model Tuning
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Contents 4 Propagation Model Tuning 4.1 Basic Knowledge 4.2 Model Tuning by U-Net
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Procedure of Model Tuning
CW data
SPM Model Set Model
Perform Appropriate Filtering
SPM Calibration
YES NO
Parameter
Is Filtering Necessary
Analysis Results
NO
Goto Next Parameter
Error Satisfactorily Low? YES
Original Data is
All Parameters finished Calibration?
Unreasonable. Need to retest.
YES End Page 35
NO
Criteria to evaluate the model (1)
The main idea to evaluate the model is to compare the predicted value to the actual test value for a certain area, then get a statistics result of the errors. Suppose the error of sample i is:
E (i) [ dB]
P measured P predicted
[ dBm]
[ dBm]
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Criteria to evaluate the model (2) E Mean Deviation
RMS Deviation
Standard Deviation
Correlation Coefficient
Corr .Coeff .
dB E RMS
dB
1 n
dB i 1
1
E i
n
n
n
E 2 i
dB i 1
E i E E dB n 1 i1 dB dB 1
(( P ( P
n
2
(i ) P measured ).( P Pr edecited (i) P predicted ))
measured
measured (i ) P measured ) . 2
( P Pr edecited (i ) P predicted ) 2
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Criteria to evaluate the model (3)
A model is reasonable if the statistics of the error between the predicted results and the actual results meet the following requests:
Mean Deviation
2dB E 2dB
Standard Deviation
Correlation Coefficient
Corr .Coeff . 0.8
8dB
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Contents 4 Propagation Model Tuning 4.1 Basic Knowledge 4.2 Model Tuning by U-Net 4.2.1 Establish a Project 4.2.2 Establish a Propagation Model 4.2.3 Create the Transmitter 4.2.4 Import the CW test data & Digital Map correction 4.2.5 CW data Filtering 4.2.6 Implement the Tuning 4.2.7 Evaluate the Turned Model
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Model Tuning Operation flow on U-Net Establish a Project Establish a Model
Create Transmitter Import CW data & Map correction CW data Filtering Implement Tuning Evaluate the Model
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4.2.1 Establish a Project for Model Tuning
Create a new project Select
―UMTS‖ in the dialog of ―Project type‖ selection
Set the coordinate system Set
the coordinate system according to the digital map.
―WGS84 UTM Zones‖ is widely used.
Import digital map
Import antenna pattern data
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4.2.2 Establish a Model to be turned (1)
Create a new SPM model by duplicate
Create a new ―copy of standard propagation model‖ by duplicating on a exist ―standard propagation model‖. Then rename is if necessary.
Set initial parameters for the new model
General Parameter
Common Parameter – Select the effective antenna height. – Select calculation method of diffraction loss
Clutter Parameter
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4.2.2 Establish a Model to be turned (2)
Initial K parameters of SPM model in normal Urban city Frequency (MHz) K1 K2 K3 K4
K5 K6
450
900
935
1805
2110
4.3
12.1
12.6 44.9 5.83 0.5
22
24.3
-6.55 0
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4.2.3 Create the CW Transmitter Two way to create CW transmitter:
By head file —— Suitable for batch importing the transmitters
Head file is a text file with extension name information for a CW transmitter
.hd ,
it contains basic
e.g.：test.dat DATE test 741790 32 54 0 0 0 23.04499751 113.7509966 Survey 0 GPS 0 0 0 0 hard
Be aware to import the antenna before the head file
Be aware to import the CW data manually after the head file
Manually create —— It is more flexible for single CW transmitter As
normal U-Net project, one by one set the antenna, site and transmitter, etc. Pay attention to the latitude and longitude, EIRP, all the feeder loss and connecter loss.
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4.2.4 Import the CW data
Pre-process on the CW test data
For model tuning, U-Net only need latitude, longitude ant the corresponding measurement power. Combine all data for one transmitter to one .txt file, then import to U-Net or by copy and paste
Import the CW data
Method 1: Right click on the “CW measurements‖ in “Explorer‖，then select ―New‖, then paste the CW data into the sheet. (By this method there should not any blank tail in each row, otherwise U-Net will give a fail result.)
Method 2: Similar to method 1, select ―Import‖ from the context menu, then browse to the CW data file. By this method, we can import several files simultaneously.
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4.2.4 Digital Map correction
Reason:
GPS locating in CW test usually adopts WGS-84 and UTM projection. However, some digital maps in some country (e.g. China) do not use such projections. Correct digital maps if CW test data does not correspond to them.
Correction method:
Correct four parameters on rectangular coordinates in a digital map to realize the optimal match with the test data.
The four rectangular coordinates parameters are stored in files “index.txt‖
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4.2.5 CW data Filtering (1)
Data filtering:
By distance: – Recommended：delete data in range r<0.1r or r>2r ( typically r = 1500m)
By signal strength: – Recommended: delete data with Signal>-40dBm 或Signal<-110dBm
By Clutter: – Recommended: delete clutters with number of samples less than 300
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4.2.5 CW data Filtering (2)
Select ―Filtering Assistant...‖ on properties of the data. Page 48
4.2.5 CW data Filtering (3)
In the clutter list, the un-checked clutter will be deleted.
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4.2.6 Implement Tuning (1.1)
U-Net 2.1 (Build 2050)： Right click on the model, select ―Automatic Calibration‖
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4.2.6 Implement Tuning (1.2)
U-Net 2.2.1 Build2613 ： Right click on the model, select ―Calibration…‖, then select ―Automatic Calibration‖
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4.2.6 Implement Tuning (2) 注释翻译
Select the parameters to be tuned. Normally only tune K1 and K2 must be tuned. Page 52
4.2.6 Implement Tuning (result)
Check if the Standard Deviation less than 8dB
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4.2.6 Implement Tuning (an example)
K Parameter
Reference
K1
23.2
K2
44.90
K3
5.83
K4
0.5
K5
-6.55
K6
0
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4.2.7 Evaluate the model (1) Parameter
Minimal
Typical
Maximum
K2
20
44.9
70
K3
-20
5.83
20
K4
0
0.5
0.8
K5
-10
-6.55
0
K6
-1
0
0
Check if any K parameter exceed out of the scope.
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4.2.7 Evaluate the model (2)
U-Net 2.1 Bulid 2050
Calculate prediction with the tuned model
• Compare the test results to the prediction ones. • Red is test value, blue one is prediction value.
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4.2.7 Evaluate the model (2)
U-Net 2.2.1 Bulid 2613
CW
CW
Calculate prediction with the tuned model
• Compare the test results to the prediction ones. • Red is test value, blue one is prediction value.
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4.2.7 Evaluate the model (3) 1. Create a link budget project by RND to estimate the cell radius 2. Compare the result to radius in similar cities 3. If they are quite different, it means something is wrong with the tuned model, we must find the reason.
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Summary
Principle of model tuning
Procedure of CW test
Procedure of model tuning by U-Net
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