Automatic Spectrum Analysis for Band Refarming and Network Rollout Application Note Products: R&S TSMx R&S ROMES4 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 Application Note Samuel Tretter 7.2017 1MA293_0e
Table of Contents 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 Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout 2
Introduction 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 Figure 1: Example result of a drive test in interference hunting quite well. So you Munich 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. Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout 3
Involved Products 2 Involved Products Figure 2: R&S TSME, the smallest member of the network scanner family 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. Figure 3: R&S ROMES4 Figure 4: R&S ROMES4NPA 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. Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout 4
Drive Test 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 Figure 5: Example drive test route (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 1 R&S TSMx with 12 V supply (we used an R&S TSME for this application note) 1 notebook with R&S ROMES4 installed 1 R&S ROMES4 license USB stick with the necessary licenses (see chapter 7 for more details) 1 omnidirectional antenna e.g. (R&S ZA1, R&S ZE8) 1 magnetic GPS antenna 1 LAN cable Figure 6: Setup on a car roof 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. Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout 5
Drive Test 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: Notebook LAN R&S TSME SMA RF antenna USB SMA R&S ROMES4 license USB stick GPS antenna Figure 7: Cabling overview Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout 6
Drive Test 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 Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout 7
Drive Test 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. Figure 9: Mode selection for data collection 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 Use 50 Hz and 0.5 Hz Measured points (use 2048 as standard) Figure 10: Measurement configuration Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout 8
Drive Test 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. Figure 11: Setting signal level as display unit for the map 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. Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout 9
Drive Test 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 12: Spectrum and waterfall diagram view. Figure 13: Navigation view Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout 10
Drive Test 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. Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout 11
Analysis of the Measurement Results 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. Figure 14: Open Measurement files for replay 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 Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout 12
Analysis of the Measurement Results 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. Figure 16: Selection of the processing module of the NPA. 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. Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout 13
Analysis of the Measurement Results Figure 17: Test parameter settings for analysis More information about the parameters can be found in the following table: Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout 14
Analysis of the Measurement Results Figure 18: Explanation of parameter settings 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 19: Starting the analysis after configuration Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout 15
Analysis of the Measurement Results 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 righthand 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 userdefined 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. Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout 16
Analysis of the Measurement Results 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 Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout 17
Analysis of the Measurement Results 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. Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout 18
Solutions for Hunting Down Interferers 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. Figure 22: R&S Spectrum Rider FPH 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. Figure 23: R&S MNT100 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 24: R&S MobileLocator Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout 19
Additional Information about Interference Hunting 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/interferencehunting/ 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/ Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout 20
Ordering Information 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 Antenna Emitter, 698 MHz to 2700 MHz Software platform for measurement and replay R&S TSME and R&S TSMA driver Network Problem Analyzer, base package R&S TSME-ZA3 1506.9830.02 R&S TSMW-ZE8 1506.9852.02 R&S ROMES4 1117.6885.04 R&S ROMES4T1E 1117.6885.82 R&S ROMES4NPA 1510.9276.02 Spectrum Analysis module R&S ROMES4N18 1117.6885.74 Rohde & Schwarz Automatic Spectrum Analysis for Band Refarming and Network Rollout 21
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 customersupport@rohde-schwarz.com North America 1 888 TEST RSA (1 888 837 87 72) customer.support@rsa.rohde-schwarz.com Latin America +1 410 910 79 88 customersupport.la@rohde-schwarz.com Asia Pacific +65 65 13 04 88 customersupport.asia@rohde-schwarz.com China +86 800 810 82 28 +86 400 650 58 96 customersupport.china@rohde-schwarz.com Sustainable product design Environmental compatibility and eco-footprint Energy efficiency and low emissions 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. PAD-T-M: 3573.7380.02/02.05/EN/ Rohde & Schwarz GmbH & Co. KG Mühldorfstraße 15 81671 Munich, Germany Phone + 49 89 4129-0 Fax + 49 89 4129 13777 www.rohde-schwarz.com