LTE Design using Mentum Planet
Contents
1 Introduction....................................................................................... 2 2 Design Procedure............................................................................. 2 2.1 Customer Input.............................................................................................3 2.1.1 Planet Project..................................................................................................3 2.1.2 Antennas folder...............................................................................................4 2.1.3 Geo Data Folder.............................................................................................4 2.1.4 Model Folder...................................................................................................4 2.1.5 Site Database.................................................................................................4 2.1.6 GIS Data.........................................................................................................5 2.1.7 Traffic Maps....................................................................................................5 2.1.8 Survey Data....................................................................................................5 2.1.9 Spectrum usage strategy................................................................................5 2.1.10 Potential interference sources......................................................................5 2.1.11 Coverage Requirements...............................................................................5 2.1.12 Antenna Patterns..........................................................................................6 2.1.13 Sector Limitations.........................................................................................6 2.1.14 MIMO/SIMO Information...............................................................................7 2.1.15 DAS Information............................................................................................7 2.1.16 Traffic Input...................................................................................................7 2.2 Setting up LTE project in Mentum Planet...................................................7 2.3 Importing Antenna Files.............................................................................10 2.4 Model Validation and Tuning.....................................................................15 2.4.1 Propagation Model........................................................................................15 2.4.2 Survey Data..................................................................................................16 2.4.3 Importing Survey Data..................................................................................16 2.4.4 Creating a Link Configuration.......................................................................20 2.4.5 Assigning sites to surveys............................................................................21
1
Introduction This document describes the design process for LTE from the initial stage until the deliverables. The process defined in this document was utilized during the LTE design phase for Metro PCS. Mentum Planet was the design tool that was used for running Monte Carlo simulations and predictions. The ACP that was used for optimization was Capresso. The aim of this document is to explain the different stages of design and the settings that were used in the tool in order to serve as a reference for future projects.
2
Design Procedure Below is a brief stepwise description of each process that was required in order to accomplish the targets,
Step 1: Customer Input – In order to begin the project there is a set of inputs that are required in order to set up Planet tool. Each of these inputs will be discussed in detail in the following sections Step 2: Project Creation – The next step would be to create the project on the planet tool. Parameters like operating band, site data base and antenna information are defined during this step. Step 3: Model Validation – Once all the inputs are received and the project is set up, the next step would be to validate the propagation models using the survey CW data. Planet tool was used to perform this verification. Detailed procedure to perform model validation is described within this document Step 4: Network Settings – Before we move forward, necessary network settings like modulations, subscriber settings, services etc are to be defined based on the customer input and some other standard guidelines. Step 5: Configure and place sites – All the sites with respective propagation model settings, antenna assignments, link configuration settings and other parameter settings are to be loaded and configured into the planet tool Step 6: Monte Carlo Simulations – Once all the parameters are set and the steps mentioned above are completed, simulations are run in order to analyze the traffic impact and to understand the network behavior in a real time scenario. Step 7: Generating Layers – The next step is to generate layers such as RSRP, RSRQ, Throughput, Best server etc based on the loadings generated in the Monte Carlo simulations Step 8: The final step is to optimize the network using an ACP (Automatic Cell Planner) tool. The tool described in this document is Symena’s Capesso.
2.1
Customer Input The very initial stage in a design project would require a lot of inputs from the customer. These inputs can be requested in many different formats. Explained below are each of the inputs and the format in which they were requested
2.1.1
Planet Project One of the important inputs that are required is an existing planet project for previous design. If the customer is unable to provide with the project itself then the different files that are required to build a project may be provided. A planet project file has an extension of *.planet and it is accompanied by a group of folders which are required in order to open the project file. The group of folders along with the project file is shown below in Figure 1: Folder structure of a Planet project. The process of creating a new project will be discussed in latter section.
The folders which have to be populated (mandatory requirement) in order to be able to open the project are ‘Antennas’ folder, ‘GeoData’ folder and ‘Model’ folder
Figure 1: Folder structure of a Planet project
2.1.2
Antennas folder Contains the antenna files received from the customer. Planet accepts *.paf files for antennas. However *.dpa can be imported, which will generate a *.paf files.
2.1.3
Geo Data Folder This folder contains all the geo data that is associated with the project. Planet requires the following sub-folders to be present within this folder: Clutter, Clutter Height, Custom Data, Heights, Vectors - Clutter Height and Clutter folders should be populated in order to open the project.
2.1.4
Model Folder This folder contains the files related to the propagation models. The propagation models in Planet have an extension *.pmf
2.1.5
Site Database The site database can be requested in an excel sheet with columns – Site ID, Latitude, Longitude, Azimuth, Existing electrical Tilt, Existing Mechanical Tilt, Feeder type, Feeder length, Current Losses, Antenna height, Antenna Type, Propagation Model per sector to be used, Antenna Sharing with current technology and MIMO/SIMO expectations on each site. All this information can be compiled into an excel sheet. A sample customer input questionnaire is embedded in the end of this section.
2.1.6
GIS Data Terrain and clutter information is a necessary input which is required from the customer. The terrain and clutter files have an extension *.grd and *.grc respectively and they are placed within the Geo Data folder, under subfolders Heights and Clutter respectively. These two files are provided by the customer. Vector files like highway, streets and water bodies are also to be provided. The vector files can be provided in Mapinfo format (*.tab files)
2.1.7
Traffic Maps Traffic map in Planet is a *.grd file which is placed under the ‘TrafficMaps’ folder under the project folder structure. It is essential to know the units of the traffic map in order to be able to use it within a project. The general unit would be Erlangs/hr/sq km.All this information is to be provided by the customer.
2.1.8
Survey Data The customer has to provide with the most current survey (CW) data , so that this information could be used to tune propagation models. The number of propagation models will be directly proportional to the number of morphologies that the customer wants to define. In the MetroPCS project for Dallas the morphologies used were, Dense Urban, Sub Urban, Commercial Industrial, Rural and Residential with trees. Each of these morphologies will have a corresponding propagation model that will be tuned based on the CW data for that model. The survey data has to be provided in sets of data files which will be equal to the number of morphologies. Each of the morphologies will have a set of drive data. The survey drive data should ideally be provided as processed data which would contain set of Mapinfo files – The header information that contains the antenna, latitude, longitude, EIRP power, etc for the survey is contained within the *.tab file and is automatically read by planet when the survey is opened
2.1.9
Spectrum usage strategy Spectrum information such as number of carriers, carrier bandwidth, band of operation, UL and DL center frequencies are to be provided by the customer. This information will be required during the LTE project set up in Mentum Planet.
2.1.10
Potential interference sources Any sources of interference that can affect the call quality should be listed and provided.
2.1.11
Coverage Requirements One of the most important input information is the coverage requirements for the design. This includes information such as, a) Cell edge coverage probability
b) Penetration losses for different coverage targets c) Polygon for the expected service area The penetration losses for various coverage targets and the coverage requirements can be provided in a tabular format as shown below
Table 1: Coverage Requirement and Penetration Losses
2.1.12
Antenna Patterns Antenna patterns are to be provided in order to be used in conjunction with each of the sectors. The antenna files can be provided as *.dpa, *.pln, *.nsm or *.pat format. If the antenna files are provided in any of these formats then they have to be imported in planet in order to convert them to *.paf files which can be directly opened in planet. The process of importing antenna files will be discussed in other sections of this document.
2.1.13
Sector Limitations Sector limitation is an important input that is provided by the customer, as this helps the design team define azimuth and tilt limitations when the ACP is used. Limitations on azimuth, tilts, height and other changes are to be provided.
2.1.14
MIMO/SIMO Information The sites that will be using MIMO are to be identified by the customer in order to use this information in the design process.
2.1.15
DAS Information If there are any DAS sites in the network that will be a part of LTE deployment then information related to these DAS sites should be presented. Information such as DAS location, number of sectors, number of splits per sector, site configuration (active/passive), losses per branch, antenna type etc is essential in order to have accurate design data.
2.1.16
Traffic Input The traffic map for the entire market is to be provided in one of the following units, • Erlangs per subscriber • Erlangs per km2 The traffic map for planet has an extension *.grd and has to be placed under the ‘TrafficMaps’ folder within the project.
2.2
Setting up LTE project in Mentum Planet In this section we will discuss the process for creating a new LTE project in planet. A step by step process will be provided. STEP 1: Create a project folder on the computer at a desired location (Ex: C:/Planet Projects/ Project1_Rev1). Save the Geo data files in the project folder within ‘GeoData’ folder as mentioned in Section 2.1.3 (Ex: C:/Planet Projects/ Project1_Rev1/GeoData ). The GeoData folder should consist of the following subfolders under which the respective files should be placed - Clutter, Clutter Height, Custom Data, Heights, Vectors.
STEP 2: Upon creation of the Geodata folder and placement of respective files within the folders, the next step is to start creating the planet project. Open Mentum Planet software and click on File>>New Project. A window as shown in Figure 2 will appear. Provide the project path (where the Geodata folder was created) and then click on ‘Next’.
Figure 2: Project Wizard Dialog
STEP 3: The window to enter project name will appear as shown below in Figure 3. The default project name will be same as the folder name. Any other custom name can be assigned to the project. After entering the project name, click on the ‘Next’ button.
Figure 3: Project Name Dialog
STEP 4: After entering the project name, the next step is to assign the technology for which the design is being done. Since the design is being done for LTE, select ‘LTE FDD’ option and then click on the ‘<<’ button to select the technology. This is shown in Figure 4. Upon selecting the technology, click on ‘Next’
Figure 4: Technology Selection Dialog
STEP 5: The next window shows the default settings for the LTE project. This should be left unchanged. ‘LTE_FDD.xls’ will be the selected file name. Click on ‘Next’. STEP 6: In the next step the location of all the geo data files should be provided. Provide the respective path for Geodata. The names of the heights file and clutter file should get populated automatically. If they do not get populated then check the files extensions or select appropriate files from the drop down. This is shown in Figure 5. Click on ‘Next’.
Figure 5: Geodata Location Dialog
STEP 7: In the next dialog box, select the appropriate co-ordinate system. This can either be defaulted to the co-ordinate system used by the terrain files in the Geo Data folder or can be manually configured. The co-ordinate system used by Ericsson is the WGS 84, so choose the option “Select from list” and then choose the WGS 84 system, as shown in Figure 6. Click on ‘Next’.
Figure 6: Co-ordinate System Dialog Box
STEP 8: Upon completion of all the steps above, click on ‘Finish’ in the final dialog box. This will create appropriate folders within the project folder as shown in Figure 1 and explained in Section 2.1.1.
2.3
Importing Antenna Files Once the project is created, the next step is to place sites and assign attributes to each of the sectors. One of the most important attribute is the antenna assignment. In order to assign antennas to the sites, it is essential first to make sure that the antenna files are all in place and are imported into the tool correctly. In this section we will be discussing the process to import antenna files into Planet. Note: Only antenna files that do not have *.paf extension need to be imported. Antenna files with *.paf extension can be loaded directly into planet. STEP 1: Place all the antenna files provided by the customer in the ‘Antennas’ folder that was generated within the project folder (Ex: C:\PlanetProjects\Project1_Rev1\Antennas). The files should be in one of the formats mentioned previously in Section 2.1.2
STEP 2: In planet go to Edit>>Antennas. A blank window as shown in Figure 7 will appear. In this window go to File>>Import File. Now choose all the antenna files that have to be imported from the location in Step 1 and click on ‘Open’. The number of antenna files that were successfully imported will be displayed. Click on ‘OK’.
Figure 7: Antenna Editor Dialog Box
STEP 3: The imported antenna files will appear as shown in Figure 8. One of the most important aspects in Planet is to define antenna groups before assigning the antenna to a sector. For example, if the antenna files are provided per tilt – Meaning, each tilt has a separate file for the same antenna – In that case all these files should be grouped into one and then the group name should be assigned to the sector. The tool will then automatically choose the pattern based on the tilt assigned to that sector. As seen in Figure 8, as an example, the antenna model 742351 (1900 MHz) with seven tilts has been imported. The following steps will describe the grouping process for this antenna. The antenna files may be provided with grouped antenna files already. In such a case this step can be skipped.
Figure 8: Antenna Import Dialog
STEP 4: Once the antennas are imported the grouping of antennas needs to be done as explained in previous step. Click on the antenna file and under the ‘General’ tab check ‘Electrical tilt” option. This will create an electrical tilt option on the left hand side, under the antenna name. Now update the antenna’s electrical tilt to the respective tilt under ‘Physical Antenna’ (Enter ‘1’ for tilt of 1 degree , 2 for 2 degrees etc.). This is shown in Figure 9.
Figure 9: Antenna Grouping
STEP 5: Repeat Step 4 for all the remaining tilt files related to the antenna (in this example for tilts 1 to 7) as shown in Figure 10. This will create a physical antenna for each file. The next step is to group all these physical antennas into a single file.
Figure 10: Antenna Editor - Tilts Dialog
STEP 6: Planet requires that the grouping is done under the file with the lowest tilt in order for the grouping to work correctly. In order to group the tilts start by right clicking on the physical antenna ‘eTilt2’ and select ‘Copy physical antenna’ as shown in Figure 11. STEP 7: Now right click on the band name that is displayed under the lowest antenna tilt file (in this case file which has tilt of 1 degree) and then select ‘Paste (new Physical antenna)’. This will append the antenna pattern for electrical tilt of 2 degrees under the same antenna file. Shown in Figure 12. STEP 8: Repeat Step 7 for all the remaining antenna files and make sure that the pasting process is always done under the antenna file with lowest tilt. The resultant structure would appear as shown in Figure 13. Upon completion, make sure that all other parameters related to the antenna are correct and the patterns show variation with tilts when observed under the ‘Master Antenna’ tab. Once everything is verified, click on ‘Apply’. This will create a *.paf file for all the antenna files that were imported, within the Antennas folder. However, only the antenna file in which grouping was done will be useful in the project, which will be the file that had the lowest tilt. In this case the new file name will be 742351_1950-MHz_M45pol_010dt.paf. It is a good practice to rename this file to just the antenna name in order to avoid any confusion.(Ex: Antenna_742351.paf).
Figure 11: Copying Physical Antenna
Figure 12: Antenna Grouping
Figure 13: Grouped Antenna File
STEP 9: Once all the antenna files related to the project are imported, grouped and a respective *.paf file is available for each antenna type, these antenna files can be assigned to the sectors. The process of assigning antenna files to sectors will be described in the following sections.
2.4
Model Validation and Tuning Model validation is an important step in the design process. The propagation models provided by the customer (if any) are validated against the tuned propagation models based on the survey data. The survey data provided by the customer as described in Section 2.1.8 is used in Mentum software in order to tune a propagation model. This tuned model is then compared to the propagation models provided by the customer and the best propagation model is chosen.
2.4.1
Propagation Model A propagation model defines how a radio wave propagates in a given environment. Each of the morphologies has a corresponding propagation model assigned to it. For example, Urban area, Sub Urban area, Rural area, Residential area, etc are different environments. Each of these environments is modelled using a propagation model in order to predict the radio wave propagation. Every sector is then assigned a propagation model in order for it to be able to generate predictions.
In planet the propagation models provided by the customer should be placed under the ‘Model’ folder (Ex: C:\Planet Projects\Project1_Rev1\Model). The tool will automatically pick up these propagation models when they are assigned to the sectors. The propagation model files have a *.pmf extension. 2.4.2
Survey Data Another set of information that is required to tune a propagation model is the survey drive test data. Survey data is collected as a part of CW (Continuous Wave) testing, that is done by the customer whenever a new frequency is expected to be deployed. During this process, first areas within a geographic location are identified which match the closest to the chosen environments. For example downtown area is generally chosen in order to model the ‘Dense Urban’ environment. An omni-directional antenna (for the frequency under test) is mounted on one of the buildings or existing sites. A team then collects some drive data within these areas, tuned to the frequency under test, and this drive data is later used to tune the model for the respective environment. Based on the number of environments the customer should provide a set of survey drive data that is associated with each of the environments. The survey data is usually processed and is provided as *.tab files (accompanied by *.dat, *.map and *.id files – Mapinfo format). These files also contain the header information for each drive. Header information consists of data like Antenna model used, Antenna gain, Lat/Long of the location, height at which antenna was mounted etc. This header information is important as it is accounted for when the model tuning is done. The header information is usually under the *.tab file and is automatically picked by Planet.
2.4.3
Importing Survey Data The easiest way to import survey data is to copy all the survey data within the ‘Surveys’ folder in the planet project folder (Ex: C:\Planet Projects\ Project1_Rev1 \Surveys). This is demonstrated in Figure 14
Figure 14: Surveys Folder structure
Each of the subfolders (as seen in Figure 14) will have the survey drive data associated with that environment. By creating these sub folders we are automatically enabling the Planet tool to group the surveys within the tool itself. Once these subfolders are created and the data is placed within the folders, planet should be restarted in order to reflect this data. Upon restart the surveys will appear in Project Explorer under the ‘Operational Data’ option, under ‘Surveys Data’ -> ‘Surveys RSSI’. This is shown in Figure 15.
Figure 15: Surveys in Planet
Upon expanding the survey data, each of the surveys associated within the environments will be displayed. These surveys will first appear with an icon meaning that it does not have complete header information. See Figure 16.
-
Figure 16: Expanded Surveys
In order to correct the header information, each of the survey header information should be corrected. This is done by double clicking on the survey, which will display the header information dialog window. See Figure 17.
Figure 17: Survey Header Information Dialog
As seen in Figure 17, this particular survey has missing Antenna information because of which the survey is being marked with incorrect header information. In order to rectify this, the survey should be assigned with an antenna. In order to verify the antenna model that was used during the test, the *.tab file associated with the survey can be opened in notepad and the antenna model can be verified. A *.paf file for that particular antenna model is required in order to assign it to the survey. A *.paf file should be placed in the ‘Antennas’ folder under the project folder. If the antenna file is in a different format than *.paf, then it should be imported using the procedure explained in Section 2.3. Since the antennas used in survey do not have any variable tilts usually, grouping may not be required. Upon placing the antenna file under ‘Antennas’ folder, in Planet, under Project Explorer, select ‘Project Data’, right click on ‘Antenna Files’, then click on refresh in order to reflect the new antenna file in the list. See Figure 18
Figure 18: Refreshing Antenna Files
Once this is done, go back to the header information dialog and from the drop down list under ‘Antenna Information’, choose the appropriate Antenna File. Follow this process for all the surveys. The icon will now appear as as shown in Figure 19. This means that a site is not assigned to the survey. Each and every survey should be associated with a site.
Figure 19: Surveys after updating header information
2.4.4
Creating a Link Configuration A link configuration defining the feeder and other losses should be created in order to assign it to a survey site. STEP 1: Under Project Explorer, select ‘Project Data’ and right click on ‘Link Configurations’ – click on ‘New’. A dialog box shown in Figure 20 will appear.
Figure 20: Link Configuration Dialog
STEP 2: Provide an appropriate name to the Link Configuration and change the uplink and downlink losses to zero. The BTS noise figure in ‘Uplink/reverse’ tab should also be changed to zero. This is because there are generally no losses associated in a survey. 2.4.5
Assigning sites to surveys STEP 1: Once the surveys are imported, they have to be associated with a physical site, in order for the tool to be able to run predictions and compare it with drive data. In order to create a site click on the ‘Place Site’ button , from the tools. Place the site anywhere in the map by clicking once on the map. The Lat/Long and other information for this site now should be updated in order to match the survey data. Get the Lat/Long, height and EIRP information for a survey from its header. STEP 2: In Project Explorer select ‘Sites’- you will see that a new site has been created. Double click on this site to open the ‘Site Editor’ dialog. The site editor dialog is shown in Figure 21. STEP 3: Since the survey site does not have sectors two of the sectors can be deleted by right clicking on the sectors 2 and 3 and then click on delete. This is shown in Figure 22. The same should be done for the antennas under the ‘Antennas’ option. The Lat/Long information for the site should be updated as per the survey header information, under ‘Location’. A new site name matching the survey name should be assigned.
Figure 21: Site Editor Dialog
Figure 22: Deleting Sectors
STEP 4: Click on the sector symbol to display the different tab options as shown in Figure 21. Under the ‘Link’ tab, select the Antenna File associated with the survey by clicking on Edit and then choosing the appropriate Antenna file. (This antenna should match the antenna chosen in the header information). Select the link configuration that was created for the surveys, as explained in Section 2.4.4. The cable length should be set at 0m. Under ‘Predictions’ update the ‘Distance’ to 25 km and ‘Number of radials’ to 800. These settings are shown in Figure 23.
Figure 23: Link Settings: Site Editor
STEP 5: Under ‘Powers’ tab the PA power should be entered based on the following calculation, PA power = EIRP from header – Antenna gain - Losses For example if the EIRP for a survey under the header is 49.59 and the antenna being used has a gain of 8 dBi then the PA power is 49.59-8 -0 = 41.59. Click on Apply and then close the dialog. Make sure that the calculated EIRP matches the EIRP in the header information. STEP 6: Once the site is created it can be assigned to a survey. In order to assign the site just drag the survey to the sector of the site, to which you want to assign the survey. This is shown in Figure 24. Once the site is assigned the icon of the survey gets highlighted showing that the survey now has an assigned site. ( ). The same process should be followed for all the surveys. Each survey will have a site assigned, unless more than one survey share a common site location. In this case both the surveys will have the same sites assigned.
Figure 24: Assigning a site to survey
