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Automatic Spectrum Analysis for Band Refarming and Network Rollout Application Note
Products:
ı R&S®TSMx
ı R&S®ROMES4
ı R&S®ROMES4NPA
RF interference is one of the largest contributors to poor network performance. It shows up in dropped calls
and low data throughput rates. Traditionally, interference hunting means you get a list of sites with bad
performance from an OSS. This defines the areas for interference hunting quite well.
If, however, the problem remains after attempts at mitigation, it could be because other sources often mask
symptoms of RF interference. Usually the strongest masking is due to the overlap between the interference
signal and your network's signals. Analysis could involve complete cities or even countries, an error-prone
task when using traditional spectrum analyzers and/or portable receivers and one that consumes a
significant amount of time and budget.
A more automated solution for larger areas can make the effort involved more manageable. The
Rohde & Schwarz network scanner family (R&S®TSME, R&S®TSMA and R&S®TSMW) plus the network
problem analyzer (NPA) feature of the R&S®ROMES4 measurement software is such a solution. It allows
you to perform a fast drive test with a fleet of cars and collect spectrum data for your targeted or even
complete network area in next to no time. Back at your office, the NPA tells you where to send dedicated
interference hunting teams with an analyzer or receiver to track down the source of interference. This
paper introduces the approach in detail.
Note:
The most up-to-date document is available on our homepage
http://www.rohde-schwarz.com/appnote/1MA293
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Table of Contents
Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout
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Table of Contents
1 Introduction ......................................................................................... 3
2 Involved Products ............................................................................... 4
3 Drive Test ............................................................................................ 5
3.1 Measurement setup ..................................................................................................... 5
3.2 Configuring the devices .............................................................................................. 7
3.3 Starting the measurement .......................................................................................... 8
3.4 Running the measurement .......................................................................................10
3.5 Finishing the measurement ......................................................................................11
4 Analysis of the Measurement Results ............................................ 12
4.1 Replay function ..........................................................................................................12
4.2 Network problem analyzer (NPA) .............................................................................13
4.3 Summary .....................................................................................................................18
5 Solutions for Hunting Down Interferers .......................................... 19
6 Additional Information about Interference Hunting ....................... 20
7 Ordering Information ........................................................................ 21
Introduction
Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout
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1 Introduction
RF interference is one of the largest
contributors to poor network performance.
It shows up in dropped calls and low data
throughput rates. When you invest in a
new infrastructure to improve your
network's performance and then realize
that you get 30% less performance than
expected for your money, that is when you
decide to tackle the problem.
Traditionally, interference hunting means
you get a list of sites with bad performance
from an OSS. This defines the areas for
interference hunting quite well. So you
send out an interference hunting team into the site's sectors and start looking.
If, however, the problem remains after attempts at mitigation, it could be because other
sources often mask symptoms of RF interference. Usually the strongest masking is
due to the overlap between the interference signal and your network's signals.
There is also a second, similar, conceivable scenario: you already completed a
traditional interference analysis, but you still have huge issues with interference
lowering the performance of an existing network. What can you do? You cannot afford
to switch off your network and troubleshoot interference until you have eliminated all
the interferers. But what you can afford to do is to switch off your network for one or
two hours in the night with one absolutely necessary condition: your network must be
up and running when rush hour starts.
This situation leads to the idea to clear out the spectrum before the network is rolled
out to prevent masking by your own network signals. However, this idea comes with a
new challenge. If you have not deployed a network, there is no OSS and of course no
list of sites with bad performance. So interference hunting has to be done in the entire
network area. This could involve complete cities or even countries, an error-prone task
when using traditional spectrum analyzers and/or portable receivers and one that
consumes a significant amount of time and budget.
A more automated solution for larger areas helps reduce the amount of working hours
to a manageable level. The Rohde & Schwarz network scanner family (R&S®TSME,
R&S®TSMA and R&S®TSMW) plus the network problem analyzer (NPA) feature of the
R&S®ROMES4 measurement software is such a solution. It allows you to perform a
fast drive test with a fleet of cars and collect spectrum data for your complete network
area in next to no time. Back at your office, the NPA tells you where to send a
dedicated interference hunting team with a spectrum analyzer or receiver to track down
the source of interference.
Figure 1: Example result of a drive test in
Munich
Involved Products
Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout
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2 Involved Products
The R&S®TSMx scanner family offers all that is
required for mobile usage. Multitechnology
measurements and multiband support provide full
flexibility and an optimal price/performance ratio for
both drive tests and walk tests. The scanners
measure up to eight radio access technologies
simultaneously and seamlessly in wireless
communications bands from 350 MHz to 4.4 GHz
(R&S®TSMW: 6 GHz). It is possible to cascade
multiple scanners for 4x4 MIMO measurements.
Usually network operators already use an
R&S®TSMx network scanner to monitor and
optimize the network or for benchmarking. In this
specific application, we use the RF power scan
function to measure the spectrum of free
configurable frequency ranges and link it to GPS
coordinates.
R&S®ROMES4 is the universal software platform for Rohde & Schwarz network engineering, network analysis and network optimization systems. In combination with other test and measurement equipment such as wireless communications scanners and test phones, it provides solutions for all essential tasks involved in coverage measurements, interference identification, performance measurement and quality analysis in mobile networks. In this application note, the R&S®ROMES4 software is used to configure the RF power scan measurements and to collect the spectrum data from the area that was driven. It offers a spectrum view and a waterfall diagram, which is useful for intermitting signals.
The sheer volume of data recorded in a large drive
test makes individual and manual analysis
impossible. The R&S®ROMES4NPA network
problem analyzer helps you analyze the
measurement data according to specific, modifiable
criteria that depend on the modules selected.
Modules such as the network quality analyzer, the
coverage analyzer and the DLAA/MIMO analyzer
output a list of all detected trouble spots and display
them on a map using Google Maps, OpenStreetMap
or user-defined map data. They also provide detailed
information about the root cause of the problem. In
this paper, we will focus on the use of the spectrum
analysis module.
Figure 2: R&S®TSME, the smallest
member of the network scanner
family
Figure 3: R&S®ROMES4
Figure 4: R&S®ROMES4NPA
Drive Test
Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout
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3 Drive Test
Our new test approach is changing the
way of doing spectrum clearing – in
three easy steps:
1. Collect spectrum data: Drive around
with the scanner and R&S®ROMES and
use the RF power scan to measure the
spectrum on a given frequency range.
You can use any number of cars
depending on how fast you want to be
and how big the area is.
2. Analyze the data: Back in the office,
you can specify the interference criteria
(min. power level, bandwidth, etc.) and
based on this, the software will analyze
your collected data automatically with the network problem analyzer, generating a list
of all signals that met your criteria as interferers. It tells you where the signal was
detected and how long it was measured by the scanner.
3. Locate and mitigate interference: With a detailed target list, the interference hunting
teams or the regulator can start locating and mitigating the sources of interference.
3.1 Measurement setup
ı 1 R&S®TSMx with 12 V supply (we
used an R&S®TSME for this
application note)
ı 1 notebook with R&S®ROMES4
installed
ı 1 R&S®ROMES4 license USB stick
with the necessary licenses (see
chapter 7 for more details)
ı 1 omnidirectional antenna e.g.
(R&S®ZA1, R&S®ZE8)
ı 1 magnetic GPS antenna
ı 1 LAN cable
ı Either spare batteries for the laptop or a 12V/220V converter
Start by installing the two antennas on the roof of the car and routing the cable through
the window. You can use a cloth to protect the cables from rubbing against the glass
edge during the drive. Connect the antenna cables to the R&S®TSME inside the car.
Figure 5: Example drive test route
Figure 6: Setup on a car roof
Drive Test
Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout
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Connect the scanner to the 12 V cigarette adapter. Use a LAN cable to connect your
notebook to the R&S®TSME. Now plug the R&S®ROMES4 license USB stick into your
notebook's USB port.
Another option is to use an R&S®TSMA with a tablet like an iPad or MS Surface
instead of the R&S®TSME with a notebook.
The setup should be built up as follows:
USB
Notebook RF antenna R&S®TSME LAN SMA
R&S®ROMES4
license USB stick GPS antenna
SMA
Figure 7: Cabling overview
Drive Test
Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout
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3.2 Configuring the devices
The next step is to configure the network settings of the notebook. To prevent sources
of error, deactivate unused network adapters. Configure the IPv4 settings as shown in
the screenshot. These settings work if your R&S®TSME is configured with the default
network settings (IP address 192.168.0.2). If not, adjust the IP address for your
notebook.
Figure 8: Network adapter settings
Drive Test
Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout
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3.3 Starting the measurement
The RF power scan mode measures the spectrum of free configurable frequency
ranges and links it to GPS coordinates. It also offers a waterfall diagram (see Figure 12
on page 10), which is useful for intermittent signals.
It is now time to start measuring. Switch on the R&S®TSME and wait until it has
booted. After that, you can start the R&S®ROMES4 measurement software. Choose
the RF power scan mode by double clicking "TSME RF Power Scanner" in the
"Available Devices" section. If it is not shown in the GUI, close R&S®ROMES4 and
check the network connection.
The list in the new window shows the surveilled bands. You can add, edit or delete
bands. The graphic below explains the configuration. A maximum sweep rate of 50 Hz
and a frequency resolution of 2048 points are good standard values. Of course, you
can find your own compromise between resolution (more points) and speed (less
points). After setting the bands, click OK.
Band name
Band
Frequency
Use 50 Hz and
0.5 Hz
Measured points (use
2048 as standard)
Figure 9: Mode selection for data collection
Figure 10: Measurement configuration
Drive Test
Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout
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In order to display the signal on the map, you have to switch on the GPS. Click "Add
GPS Navigation" in the next window and then "Stay on the current sheet" in the
following window. To choose the signal level as the displayed test parameter on the
map, right click the map and select "Configure". Double click "Level (Peak) [1]" under
"RF Power Scan""Sweep 1""Current Peak Marker" in the "Available Signals" field.
Close the window with "OK". Now your measurement data is linked to your GPS data.
We recommend that you save your settings, which are called workspace, by clicking
"File""Save workspace". This makes it easy to recall your settings and share them
with other teams.
Figure 11: Setting signal level as display unit for the map
Drive Test
Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout
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3.4 Running the measurement
You can now start the measurement by clicking the "Toggle Recording" button (red
circle in the top menu bar) and selecting where you want to save the measurement
data. Be careful not to use the red square.
In the tab menu at the bottom of the window, you can select between spectrum and
waterfall diagram ("Spectrum (2)") and a map showing your position ("Navigation (3)").
Now it's time to start your drive.
.
Figure 13: Navigation view
Figure 12: Spectrum and waterfall diagram view
Drive Test
Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout
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3.5 Finishing the measurement
When you have finished your drive, click the "Stop" button (red square in the top menu
bar). Add a comment in the comment window or click "Cancel" if you don’t want to add
a comment. Your measurement files are saved automatically.
Analysis of the Measurement Results
Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout
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4 Analysis of the Measurement Results
There are two ways to review your measured data. First, you can replay the
measurement to manually evaluate your data. The second option is to use the network
problem analyzer, which automatically generates a list of all interference sources.
4.1 Replay function
To use the replay function, open the R&S®ROMES4 replay software. Click "Open
Measurement File" and select your measurement data. Select "Discard current
workspace" in the next window to load the measurement settings of your drive test.
Click OK in the "Device Filter" window.
You have the same GUI as during your drive test. You can choose the tab (spectrum
or map) in the bottom tab menu. Use the "start/pause" button and the speed control
slider in the top menu as shown in the screenshot to control the replay.
Speed control slider
Figure 15: Control of measurement replays
Figure 14: Open Measurement files for replay
Analysis of the Measurement Results
Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout
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4.2 Network problem analyzer (NPA)
For spectrum clearing, we use the R&S®ROMES4N18 spectrum analysis module to
automatically detect strong transmitters in the bands that should be empty since the
network isn't rolled out yet. After you configure the settings (bandwidth, duration,
power, etc.), the analysis algorithm will find potential narrowband and wideband
interferers for you. This makes it easy to verify that your spectrum is clear or that an
existing spectrum can be used for refarming purposes.
When you open the NPA software, you can add all your measurement files from
different cars or different drive tests on different dates. The R&S®ROMES4
measurement software splits the measurement data up into 1 GB files. The first file has
the measurement name without an additional number and the subsequent files are
numbered consecutively.
Open the folder with your measurement files by clicking "File""Add Data
Source""Add Folder". Your measurement files will be shown in the list on the left.
Then, you have to choose which NPA module you want to use for to analyze the data.
In this case, it is RF Power Scan. Click "Analysis""Processor Configuration". Scroll
down the list to "RFPowerScan Analysis Processor" and drag it into the middle column
of the window.
The next step is to configure the parameters for interference detection. Click "New
Configuration" and enter a name for it in the right-hand column. Expand the
configuration in the middle column. Click "RFPowerScan Analysis Processor". In the
right-hand column, you can set the parameters for interference detection. When done,
you can save the processor configuration under a particular name and reuse it at a
later stage. It is also possible to define different processors for different types of
interference hunting activities.
Figure 16: Selection of the processing module of the NPA.
Analysis of the Measurement Results
Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout
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More information about the parameters can be found in the following table:
Figure 17: Test parameter settings for analysis
Analysis of the Measurement Results
Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout
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Continue by selecting all of your measurement files in the left-hand list. Then right-click
them. Click "Run Analysis" and select your configured analysis. It will take a few
minutes.
To display the results, again select all measurement files in the left-hand list. Then
right-click them. Click "Open Analysis Result""Analysis Result Overview". To see the
detailed information, click "Spectrum Raster & Problems".
Figure 18: Explanation of parameter settings
Figure 19: Starting the analysis after configuration
Analysis of the Measurement Results
Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout
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Now you can see the analysis results. In the upper part is the map and in the lower
part is the list of found interferers. You can enlarge the widgets by clicking on the right-
hand circle in the left corner of each widget. In the top menu bar, you can export the
results as a .pdf file to your printer or to Excel.
To get an overview of the geographical distribution of the interferers, the NPA
visualizes them on a map using Google Maps, OpenStreetMap or your own user-
defined maps of your network. The values can be set according to your optical
preferences. For example, the following settings can be used:
a) Zoom control
b) Spectrum clearance issues: move the transparency slider to the right
c) Spectrum raster: set to "Peak Power".
d) Track shape: move transparency slider to the right and disable arrows
e) Background: select your favorite map, e.g. OpenStreetMap
Figure 20: Result of the analysis for a drive test in Munich. The orange pins indicate interference
sources.
Analysis of the Measurement Results
Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout
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To obtain more information about single interferers, enlarge the list widget. You will get
a list with all the information needed to decide if you want to send out an interference
hunting team. Clicking the list entries will highlight them on the map.
The following information is found in the list:
a) Latitude/Longitude: geographic coordinates
b) Title: type of interferer
c) Frequency: frequency of the signal
d) Bandwidth: bandwidth of the signal
e) Peak Power: peak power of the signal
f) Duration: how long the signal was measured
Figure 21: List of all found interferers with additional information
Analysis of the Measurement Results
Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout
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4.3 Summary
To sum up, Rohde & Schwarz can offer a solution that can be configured in just a few
minutes. It doesn’t require technicians for the drive test and supports as many cars in
parallel as you want to save time or test very large areas. It saves costs since many
operators already own a scanner and can therefore use existing resources. You get a
detailed list of potential interferers to address directly or to forward to a regulator.
Solutions for Hunting Down Interferers
Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout
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5 Solutions for Hunting Down Interferers
Now you know from the generated list where your interference hunting teams have to
go. But of course knowing the locations isn't enough to find and switch off the bad guys
that are causing you problems. The interferers can be small and located in buildings,
e.g. DECT phones or broken components. This means that once you have an idea of
where to look, you have to find them with a walk test.
To locate them, Rohde & Schwarz offers a complete
interference hunting portfolio for all needs and
budgets. Starting with the R&S®Spectrum Rider FPH
handheld spectrum analyzer in combination with a
Yagi antenna, you get a solution that offers signal
strength mapping, interference analysis and
interference location for common, continuous
interference sources. It is designed as a user-friendly
option for technicians in the field who also do
interference hunting and has a very competitive
price.
However, when you want to equip a real interference
hunting team that is doing a lot of interference
hunting, you will realize that there are also more
complicated signals, which are intermittent. The
solution for this is the R&S®MNT100 portable
receiver with an R&S®HE400 directional antenna.
These devices are so fast that they will locate
intermittent signals without any problem. The speed
upgrade saves time finding normal interferers, which
means less man-hours or more solved problems in
the same amount of time.
In urban areas with many high buildings, the
challenge is to avoid hunting reflections instead of
the interferer itself. This is a challenge even for
experienced interference hunters using quality
equipment such as the R&S®MNT100. The
intelligent interference hunting tool
R&S®MobileLocator will find the interference source
using fully automatic PC-based radiolocation,
ensuring that reflections are ignored.
Figure 22: R&S®Spectrum Rider FPH
Figure 23: R&S®MNT100
Figure 24: R&S®MobileLocator
Additional Information about Interference Hunting
Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout
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6 Additional Information about
Interference Hunting
If you are interested in White Papers, Application Notes and videos about interference
hunting & monitoring, check out our related knowledge page:
http://www.rohde-schwarz-usa.com/IH.html
If you are interested in interference hunting solutions from Rohde & Schwarz, check
out our related topic page:
http://www.mobile-network-testing.com/solutions/mobile-operators/interference-
hunting/
If you are interested in the solutions that Rohde & Schwarz offers for mobile operators,
infrastructure vendors, installation companies, testing service providers and regulators,
check out our MNT website:
http://www.mobile-network-testing.com
If you are interested in following a high quality blog about today's mobile network
testing, check out our blog:
https://blog.mobile-network-testing.com/
Ordering Information
Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout
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7 Ordering Information
Designation Type Order No.
Ultracompact Drive Test Scanner R&S®TSME 1514.6520.02
RF Power Scan R&S®TSME-K27 1514.6813.02
Antenna Mount, magnetic, with
integrated GPS antenna
R&S®TSME-ZA3 1506.9830.02
Antenna Emitter, 698 MHz to
2700 MHz
R&S®TSMW-ZE8 1506.9852.02
Software platform for
measurement and replay
R&S®ROMES4 1117.6885.04
R&S®TSME and R&S®TSMA
driver
R&S®ROMES4T1E 1117.6885.82
Network Problem Analyzer, base
package
R&S®ROMES4NPA 1510.9276.02
Spectrum Analysis module R&S®ROMES4N18 1117.6885.74
Table of Contents
Rohde & Schwarz
The Rohde & Schwarz electronics group offers
innovative solutions in the following business fields:
test and measurement, broadcast and media, secure
communications, cybersecurity, monitoring and
network testing. Founded more than 80 years ago,
this independent company has an extensive sales
and service network and is present in more than 70
countries.
The electronics group is among the world market
leaders in its established business fields. The
company is headquartered in Munich, Germany. It
also has regional headquarters in Singapore and
Columbia, Maryland, USA, to manage its operations
in these regions.
Regional contact
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This application note and the supplied programs
may only be used subject to the conditions of use
set forth in the download area of the
Rohde & Schwarz website.
R&S® is a registered trademark of Rohde & Schwarz GmbH & Co.
KG; Trade names are trademarks of the owners.
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Mühldorfstraße 15 | 81671 Munich, Germany
Phone + 49 89 4129 - 0 | Fax + 49 89 4129 – 13777
www.rohde-schwarz.com
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