Automatic Spectrum Analysis for Band Refarming and · PDF fileAutomatic Spectrum Analysis for Band Refarming and Network Rollout Application Note Products: ı R&S®TSMx ı R&S®ROMES4

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

2

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


3

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


4

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


5

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


6

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


7

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


8

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


9

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


10

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


11

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


12

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



13

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.



14

More information about the parameters can be found in the following table:

Figure 17: Test parameter settings for analysis



15

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



16

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.



17

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



18

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


19

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


20

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/

http://www.rohde-schwarz-usa.com/IH.html

http://www.mobile-network-testing.com/solutions/mobile-operators/interference-hunting/

http://www.mobile-network-testing.com/solutions/mobile-operators/interference-hunting/

http://www.mobile-network-testing.com/

https://blog.mobile-network-testing.com/

Ordering Information


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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

Europe, Africa, Middle East +49 89 4129 12345 [email protected] North America 1 888 TEST RSA (1 888 837 87 72) [email protected] Latin America +1 410 910 79 88 [email protected] Asia Pacific +65 65 13 04 88 [email protected]

China +86 800 810 82 28 |+86 400 650 58 96 [email protected]

Sustainable product design

ı Environmental compatibility and eco-footprint

ı Energy efficiency and low emissions

ı Longevity and optimized total cost of ownership

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.

Rohde & Schwarz GmbH & Co. KG

Mühldorfstraße 15 | 81671 Munich, Germany

Phone + 49 89 4129 - 0 | Fax + 49 89 4129 – 13777

www.rohde-schwarz.com

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Documents

Automatic Spectrum Analysis for Band Refarming and · PDF fileAutomatic Spectrum Analysis for Band Refarming and Network Rollout Application Note Products: ı R&S®TSMx ı R&S®ROMES4