RF Propagation, Ray Tracing and Wireless Scenario Modeling in MATLAB - MATLAB
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    RF Propagation, Ray Tracing and Wireless Scenario Modeling in MATLAB

    Overview

    In this webinar, you will learn about new capabilities in MATLAB for modeling RF propagation channels and scenarios. You will learn how easy it is in MATLAB, to visualize wireless scenarios and model indoor, outdoor and satellite RF propagation performance. You will also learn about new spatial channel modeling techniques, and the use of ray tracing methods. Practical demonstrations will show you how to quickly get started studying and visualizing RF propagation scenarios.

    Highlights

    • Configuring antenna and antenna arrays transmitters and receivers on maps
    • Integrating effects of terrain, building elevations and atmospheric conditions
    • Analyzing the antenna and antenna array performance including propagation effects.
    • Indoor and outdoor RF propagation modeling including ray tracing techniques
    • Satellite scenario modeling and orbit visualizations with new Satellite Communications Toolbox

    About the Presenters

    Dr. Houman Zarrinkoub is a senior product manager at MathWorks responsible for wireless communications products. During his 20-year tenure at MathWorks, he has also served as a development manager and has been responsible for multiple signal processing and communications software tools. Prior to MathWorks, he was a research scientist working on mobile and voice coding technologies in the Wireless Group at Nortel Networks. He has been awarded multiple patents on topics related to computer simulations of signal processing applications. Houman is the author of the book Understanding LTE with MATLAB: From Mathematical Modeling to Simulation and Prototyping. He holds a B.Sc. degree in electrical engineering from McGill University and M.Sc. and Ph.D. degrees in telecommunications from the University of Quebec, in Canada.

    Jacob Halbrooks is the Senior Team Leader for Mapping and RF Propagation at MathWorks. His team develops Mapping Toolbox and contributes map-based propagation and visualization features for Antenna Toolbox and Communications Toolbox. Jacob received a B.S. in Electrical Engineering from Tufts University and an M.S. in Engineering Science from Dartmouth College. His Master’s thesis dealt with laser mode shaping for optical free-space communication.

     

     

    Recorded: 21 Sep 2021

    Hello, everyone. My name is Houman Zarrinkoub. I'm the product manager for the wireless products here at MathWorks. That includes the 5G, LTE, wireless LAN, and satellite communications. And I'm here with my friend, Jacob. Jacob?

    Hey, Houman. My name is Jacob Halbrooks. I'm a development manager at MathWorks. I lead a team that develops tools for mapping and wireless scenarios. I've been at MathWorks for over 15 years and spent most of that time as a software engineer in the SPC group. And I'm excited, today, to show you some demos for our RF propagation and satellite tools.

    Yes, so today's topic is RF propagation, ray tracing, and wireless scenario modeling in MATLAB. And we have put together a agenda for you as follows. We've got to go through some introductory remarks, and following that, we present in essentially four sections, the RF propagation, ray tracing, beamforming and link performance, and satellite scenario modeling. Finally, we conclude with some summarizing remarks.

    Now, as you know in the 21st century, the goal of wireless industry is ubiquitous with wireless connectivity. No matter where you are in the globe with larger to smaller networks of wireless networks, we want to connect you to internet. We can use modalities, such as satellite communication, cellular communication, Wi-Fi, and even personal area technology, like Bluetooth and Zigbee. And MathWorks provide solutions in all these wireless connectivity areas.

    Now, when it comes to examining the performance of these systems, we want to enable users, no matter how much familiarity they have with maps or geographic expertise. We want them to be able to visualize, analyze the diverse art of propagation data on maps, and we want them to go beyond that. Take into account the effects of 3D environment on the virus propagation, the effect of antennas, and terrain, and buildings, and other obstacles, such that they get a good feel of RF propagation wireless connectivity in outdoor and indoor situations.

    Let's go to the first topic, which essentially focuses on RF propagation outdoors. So imagine you want to essentially examine what is the best place to place your antenna rays for wireless connectivity. You have to put it on a building or in different environments.

    And depending on your cellular frequency, bandwidth, propagation, power, and gains, you want to look at how much coverage do I have, how much signal to interference noise ratio I have, and you want to visualize it on a geographic map to see if my area of coverage is as I expected. Now, as you do that, you want to also bring in the effect of terrain. Now, the Earth is not always flat, and the nature of things on Earth are different.

    Sometimes, you pass through a lake, urban areas, suburban areas, desert, and you want to put that terrain information into your analysis. Of course, as you have a transmitter, you propagate. The signal propagates, and you have various propagation models, which essentially reduced the signal power as a function of distances. And we have multiple of them, Longley-Rice, TIREM, atmospheric, and all kinds of stuff.

    And finally, you want to have the ability to explore different antenna patterns and installation scenarios. All of that is available with our tools in MATLAB that specialize in RF propagation, and you can find them in various products on the MATLAB. With that, I want to hand it over to my friend, Jacob, who's going to show you a demo on coverage maps over terrains.

    Thanks, Houman. So I'm going to start off here in MATLAB and show you where I recommend going to explore the product and start learning the tools. So I typed doc at the command line to open the documentation, and I like to go to the examples.

    So the tools that we're going to be showing, today, are antenna toolbox, communications toolbox, and satellite communications toolbox. So you can select one of those, and then click the Examples tab. And you get a nice gallery of all the featured examples that we show. In my opinion, these are the best place to get started with these tools, and in particular, propagation and channel models.

    So what I'm going to be showing are extracts from some of the featured examples that we ship, so we'll come over to the live editor, where I've adapted some of these examples. And we're going to start off with a simple example to show how easy it is to get started and create a coverage map with just a few lines of code. So we're going to start off creating a transmitter site or TX site. And when we create the TX site, we specify latitude and longitude coordinates.

    Here, we're going to situate the transmitter site in the Boulder, Colorado area. We're also going to display the object that's created just to see the properties that are available on it. We have the location properties. We have a few properties related to the antenna, the antenna type.

    The default is isotropic. You can define its orientation and its height above the ground terrain, and then we have some operational parameters for the transmitter. The frequency and the power are most important.

    So next thing we're going to do is visualize this site on a 3D terrain map, so we call show on the object. And what this does is launch Site Viewer. Site Viewer is a 3D map. So we can pan, zoom, and rotate the map. As we rotate, we see that there's the Rocky Mountains to the West of this transmitter site.

    Now to create a coverage map, we simply call coverage, and pass in the transmitter site, and define the coverage parameters. So in this first map, we're going to use the free space propagation model. This is our most basic propagation model and assumes that line of sight exists everywhere. So it ignores the effects of the curvature of Earth and the effects of terrain, and the result is this idealized coverage map.

    Now, one thing we see is the map imagery is just satellite, so we're not getting any street names or town locations. So to get another sense of the area, we can select a different base map from the base map picker. I like the topographic map, because it combines street maps with some physical map data. And, here, we see this idealized region over several towns.

    This is the best case scenario you could get, if you can get a line of sight with the transmitter site, but you're typically going to be more interested in a realistic coverage map that does take into account the terrain around your base station. So, here, we're going to repeat the call to coverage, but instead, specify the Longley-Rice propagation model. This is a very standard propagation model that includes the effects of terrain, and we'll compute the effects of the obstructions, and also, diffraction effects over the terrain.

    So we regenerate the coverage map, and we see, now, we get a much reduced area that takes in the terrain into account. Now, the imagery and the terrain data that you're seeing in Sight Viewer is available because of an internet connection, and it streams data. The terrain is generated from a USGS data set called GM Ted 2010.

    The resolution is about 250 meters, but you might need better resolution terrain data for your purposes. Or you might need to work on a machine that doesn't have access to the internet. So for this, you can import D Ted format terrain data, and use that both for your analysis and visualization.

    So, here, we're going to specify a D Ted level one file. This is a sample file that we ship in the product, and then call add custom terrain. Add custom terrain processes the D Ted file. It creates tiles that we can use in the Viewer Tool, and this is a one time step.

    You can reuse the terrain that we've labeled South Boulder, here, now, both in this session and future sessions of MATLAB. Now to generate a coverage map using this D Ted data, we, first, launch Site Viewer, again, but this time, specify that terrain label that we gave above. And then we repeat the call to coverage.

    When we call it coverage with this new Site Viewer window, that D Ted terrain data is automatically used in the coverage map, and we can compare it to the old one to see that the general shape is similar. But we have enhanced detail now with the D Ted data. Thanks. Houman, back to you.

    You saw how easy it was to get started with RF propagation in MATLAB. You used TX site, and RX site, and objects, like that. You call functions, like coverage, and so on. And it can easily visualize the RF propagation on the map.

    Let's look at a second topic here, how we can bring in beamforming or multi-antenna techniques into the picture, and assess the performance of the link with those type of MIMO techniques included, so as you can see, as you generate the TX site, in this case, the transmitter and so on, you can change the default antenna and antenna array characteristics to use almost any kind of antenna and antenna array that we ship with our antenna and phased array system toolbox. So we can use rectangular arrays of dipoles, and all you have to do is set the desired signal frequency.

    And you can specify the beamforming pattern or electronically steer the array beam with applying gains. So you can essentially direct your transmission electronically toward the area of your interest. Very easily done within our RF propagation capabilities.

    Now, one important new advance these days in the 5G area is the introduction of millimeter wave frequencies that are becoming more and more prevalent. The 5G, as you can imagine, has typical cellular frequencies below seven gigahertz, and also, millimeter waves above 28 gigahertz. And, of course, other standards also use millimeter wave frequency.

    So when you have millimeter waves, and the propagation losses are very quick and rapid, you need to use arrays and beamsteering to kind of boost the signal. So in this case, we can use array beamsteering to have a line of sight assessment, all the losses, the array design, and simultaneous transmission of multiple sites, which enables you to see if you have the overall area of coverage covered. Now, not only do we allow using antenna, antenna array parameters included with our RF propagation stuff being visualized, but RF propagation or large scale fading considerations is one of the main things you have to worry about in wireless communication.

    Propagation channels are different kinds that are available within our various tools. The scattering MIMO channel exists with our phase ray system toolbox, free space path loss that we use in our calculations of RF propagation. The ray-tracing that we're going to do a lot about soon, it's a new functionality, relatively new, that we have employed within our tools to allow you to treat this narrow beam width transmissions that are emerging in millimeter wave and others as rays, and examine the channel modeling based on the ray concept. And we have other channels, such as winner II, and effects, such as loss due to gases, fogs, and clouds.

    So the RF propagation technology that we have is rather widespread and enables you to model a lot of things. For example, you want to look at the link-level simulation or performance evaluation of a links with narrow beam widths using ray tracing channel models, right? So all you have to do is specify or our calm.ray tracing channel as you see on the MATLAB script above. Set some sample rates or certain frequencies, and essentially, you can examine using ray tracing, whether your link has enough of, essentially, budget to achieve right performance that is visualized here using EVM measurements on the receiving.

    OK, the next topic is, actually, ray tracing, so ray tracing is a technique that is historically applied to optical communication, optical concepts. But now, we have it here in our wireless communication. Because with the emergence of millimeter wave and narrow beam widths, the signal processing is viewed as multiple raids that propagate through the air.

    Now, for example, in urban scenarios, you see here, we have a snapshot. I'm sure, Jacob will go through that of a transmitter and the receiver. And, in this case, the receiver is not in the line of sight with a transmitter. It's hidden behind a building. And as you will see soon with the demo by Jacob, we're going to show you how easy it is to bring all these elevations and this urban, essentially, maps into your analysis and design.

    And then the ray tracing engine that we have in our RF propagation tools find the best one hop or two hop ways that the rays emanating from the transmitter can make its way to receiver if the line of sight is not available. So all you have to do is import and visualize buildings and their specification from OpenStreetMaps, which is an open software. And you calculate the line of sites using building data, and you arrive at point to point ray tracing analysis. And it can find a coverage map using terrain and elevations using ray tracing propagation models.

    Not only we have done that. But recently, in the last release of MATLAB, the last two releases, we have done a lot to make the ray tracing, which I can imagine. We go through all possible rays that connect one transmitter to receiver. That takes a long time.

    We have been able to speed up those calculations and arrive at fast ray tracing analysis, and we have here some kind of a comparison between the classical methods compared to shooting bouncing ray method. And you see, we have huge speed ups, and I'm sure Jacob will talk about that as well. Not only you can apply ray tracing for outdoor propagation, but also, for indoor propagation aspects.

    Here, you see we have a very simple diagram of an indoor room, where you have in the middle of some table and chairs. And you put the antenna, a transmitter antenna somewhere on the ceiling. And with using Cartesian coordinates rather than latitude and longitude, we can specify the location of the antenna in Cartesian coordinates, the location of the receiver on the table in Cartesian coordinates. And you can perform ray tracing with, essentially, four or five lines, like that. That's wonderful to see that not only we can do outdoor, but also, indoor ray tracing. It's time for me to hand off to my friend, Jacob, again, for urban and indoor analysis using ray tracing.

    All right, great, Houman. I'm going to get to show examples for everything you just talked about here. So we're going to start out with the urban example, and launch Site Viewer with a building's property set to a OSM file name. So you mentioned OpenStreetMap as a source of data. I encourage folks to go to openstreetmap.org.

    You'll be able to go anywhere in the world and download a data file for any region, so we've done that for the Canary Wharf area of London. So we're going to launch Site Viewer, and we see when the Site Viewer gets launched. We get the 3D building geometries right inside Site Viewer.

    These are placed on top of the terrain data that's included in Site Viewer as well. So within this area of high rises, our primary area of interest will be this park region, and we're going to place a transmitter site on a utility pole and show that. And the idea is we want to service the park and the surrounding neighborhood.

    Before we proceed to the site specific analysis, I want to highlight how you can use these tools for easy what if analysis. And this will give some insight into 5G communications, and particularly, what happens at high gigahertz frequencies. So we're going to set our transmitter frequency to three gigahertz, and then create a simple propagation map using free space model. And just see what kind of region does this cover, and we see the coverage map covers a major portion of the London City.

    But now, we're going to increase the frequency to 28 gigahertz, and this is important. Because the channel bandwidth requirements for 5G require using higher frequencies, even into millimeter wave territory. So now, when we increase the transmitter frequency, regenerate our coverage map, we see there's a lot more signal loss that occurs at these higher frequencies.

    The coverage region zones weigh in to an area just a little bit larger than the buildings region that we imported, and the range here is in the one hundreds of meters. So that helps explain why you got these 5G frequencies. The distances between base stations is, like, 250 meters, 500 meters.

    All right, but in addition, at these high frequencies, the losses due to obstruction are very significant, and a common coverage map you want to create to start off with is actually the coverage map within line of sight. And we can use ray tracing to do this. We're going to start off creating a ray tracing propagation model, and I'm going to comment a little bit about this method. So there's two types of ray tracing models that are tool support. One is the image method, and one is the SBR.

    SBR stands for Shooting and Bouncing Rays. This is a less precise model than the image method, but its advantage is that it's much faster and enables modeling up to 10 order reflections. And that's a challenge for the image method, so we recommend the SBR propagation model here.

    We set maximum reflections to zero, which means the analysis is only going to consider the direct rays from the transmitter site, and we call coverage passing in this propagation model that we've configured. And we specify the signal strengths, and the max range here is 250 meters. So that'll provide the bounds of the coverage region.

    All right, we zoom in to where the coverage is. And as we expect in the area around the transmitter side, we light up anywhere that there's a line of sight between the transmitter site and the area on the map. And we see clear shadowing behind obstructions, so that gives us a point to area analysis.

    But we often want to dig in a little bit to point to point analysis, and in this case, what we want to do is figure out what can we do to serve the area of the street on the South side of the park that does not have any line of sight access to the base station. Can we still get a signal there? So first, we're going to place a receiver site there and use LOS function to show that, indeed, it is blocked. There is no line of sight.

    We can see where the line of sight obstruction point is here, but now, we're going to set the maximum reflection paths of our propagation model to one. So we're going to search for all the possible paths, where there might be a reflection off of the building and reach the receiver site. We use the ray trace function to visualize the propagation paths, and we see there is a single propagation path from the transmitter side to the base station, where the signal reflects off of the building.

    Now, I'm going to show how you can add some more realism into the analysis by adding additional impairments, so we can compute the signal strength along this path. But by default, it's still using a free space, a model along the distance of the path. The most important thing is to use realistic materials. Because every time you reflect off of a surface, there's a loss and polarization change associated with that reflection, and we can include that in our propagation model.

    So here, we're going to set the buildings material and the terrain material, both to concrete, and use the sig strength function to compute how that impacts the received power at the receiver site. We see with perfect reflection about minus 70 dBm received power, and then with concrete, it goes down by about 8 dB to minus 79 dBm. We can also add the impact of rain losses into the analysis here.

    So here, we're going to add the gas propagation model and the rain propagation model to our ray tracing model, and call ray trace and six strength, again, to see how that impacts our received power. And we see it goes down, again, this time by about 1.5 dB. Now, one thing we can do to see if we can get more power is to adjust our propagation model to look for more paths. So we're going to look.

    In this case, include max num reflections of two. We see in the visualization that there's now four total propagation paths, and three of them are highly clustered. And the received power has gone up by about 3 dB to minus 77 dBm, and now, we're going to regenerate our coverage map. Our previous one only showed coverage for line of sight area.

    Now, we're going to set max num reflections to four, and I've previously run this analysis. It takes a few minutes to run, and I've saved the results. And we load them in.

    But the nice thing we see now is that all the areas that were previously shadowed, we now see a signal being received in those areas, and we can see bands, depending on how many reflections it takes to get to that point on the map. Now, I'm going to show how you can use a phased array antenna to improve the link quality for a point to point link. So the first thing I'm going to do here is a design an eight by eight uniform, rectangular array using phased array system toolbox, and visualize that on the map.

    So this is, by default, we point the antenna mechanically South, and now, we're going to use the ray trace function to get the ray tracing analysis. And use that to steer the beam. So previously, we used ray trace to visualize the propagation paths. Here, we get a return argument, and we get all the same information available to you at the command line.

    So all the geometric and propagation information that went into the visualization is now at your fingertips here in this ray object, and what we're going to use is the angle of departure to steer the phased array antenna along the single reflection path that we saw earlier to get an optimal link. So we can see in the visualization, the phased array antenna has been electronically steered along that propagation path. And now, as a result, the total received power goes up by about 20 dB to minus 57 dBm corresponding to the peak gain along the border site.

    All right, now, I'm going to move over to an indoor example, showing how we can do the same sort of analysis in a indoor scenario. The indoor scenario is defined by this office.stl file, so we support stl files. And also, if you have your model, as a MATLAB triangulation object, you can also use that for your analysis.

    So we're going to launch Site Viewer, specifying this office stl file, and we see the 3D model now appear in Site Viewer. And we can use all the same mouse gestures as we did previously to pan, zoom, and rotate. So we see we have a nice office area here with the partition.

    I'm going to set the transparency to one just to get a little more realism in the visualization and not have some blockage here in the view. All right, so now, we're going to create a TX site and RX site. We're going to use all the same functions, as you saw in the previous demos, for outdoor scenarios. The difference here is that all the analysis is done with respect to the model origin, so this is using Cartesian coordinates instead of geographic latitude and longitude.

    So when we create our TX site and RX site, instead of latitude, longitude, we define antenna positions in xyz coordinates. We still show them in the room. We have a TX site that models an access point that's mounted on the wall, and then the receiver site corresponds to a user device that's on a desktop. And we're going to do the same sort of analysis as we did in the city.

    We're going to call LOS to see that the partition does, indeed, block the line of sight between the transmitter side and receiver site. We're going to call ray trace to see that we can get a single reflection path that can reach the receiver. We're going to set maximum reflections to two. Call retrace, again, and see that, now, we have many propagation paths that are available for the signal to travel.

    But the last thing we're going to do here is show how you can use the output of ray trace to create a channel model. So previously, I showed how you could use that information to steer a phased array antenna. We're going to use the same ray trace function, but we're going to take its output rays and pass it right into this compact ray tracing channel function. And that's going to return a channel object.

    We're going to use the show profile function to visualize the power delay profile, and what that is, is a MATLAB plot that shows a visual representation of the signals arriving at the receiver site, the delay in the power that reaches them. And you could go on to use this channel model to do link level simulation, and generate waveforms, and pass those waveforms through this channel to see the impact of the multi-path on your signal as it filters through. So that concludes this part of the demo. Houman, I'll pass it back to you.

    Before we move on, Jacob, so all of this is in MATLAB, right? As long as you have antenna toolbox or communication toolbox in MATLAB, all these indoor, outdoor maps are accessible to you. All these functions are functions from those two boxes, so you can do indoor, outdoor RF propagation analysis visually superimposed on the map all in MATLAB.

    That's right with the exception of this channel model. That's available only in communications toolbox.

    Toolbox, that's great. Let me go back to another important topic that we're going to discuss next thanks to your demo, and finally, we're going to talk about, OK, we did outdoor propagation, indoor propagation in terrestrial on the Earth. How about satellite scenario modeling? Can we examine the scenarios and visualize the trajectories of moving things in satellites around the Earth?

    As of March of this year, 2021, we have a satellite communication toolbox. It's a new foray we are doing into the satellite communications area, and this toolbox essentially has four uses. It enables you to do orbit propagation and visualization, and scenario modeling, and access and link analysis. We're going to go through that. Link budget analysis.

    You know, because, if the base station or your transmitter is far away from the surface of the Earth with the propagation losses, do you have enough budget in your link to have a viable link? And then, when you have a viable link, and you see the satellite, can you generate waveforms that can transmit and receive between the ground station and satellite? And using end to end simulation with a combination of transmitter operation, channel modeling, propagation modeling, and receiver, you can have realistic bit error rate and other metrics to see if the link is viable.

    All right, so what do we have in satellite communication toolbox that makes scenario modeling easy? One of them is satellite scenario. You can see here, there's a satellite scenario object that can be easily generated in MATLAB. If you have satellite communication toolbox, you can put satellites, associate them with initial conditions at different parts of the satellite scenario, and you play it. And when you play it, it will actually go, and move the satellites in the orbits, and the specification of where the initial conditions of satellites are it from come a tle file. So it can do either two body capillary, or SGP four, or STP four.

    Orbit propagators define orbits from orbital elements or Ephemeris data. Now, after you put that satellite scenario, and satellites, and run the simulation, you can perform access or communication link analysis. You can model transmitter and receivers with antennas mounted on gimbals, a visual light field of view. You can see how much each satellite has a field of view.

    You can measure access or communication link, and it can find out, in this case, in this example-- you can find out, in this example, if I have a ground station in one part of the world, in this case, India, and it wants to communicate with another part of the world, in this case, Australia, and satellites are zooming around the Earth. What is there two hop link scenario I have to exploit in order to make that link possible? So the India transmits to satellite one, satellite one, satellite two, satellite two to Australia, and all these dynamic assessments can be done.

    Here, in the latest release of MATLAB in 2021b, we noticed, if your constellation of satellites that you're visualizing goes very dense, in this case, you have 1,000 constellation, a constellation of 1,000 satellites. Of course, managing all the orbits and so on could slow down the process. So we have put into effect some acceleration techniques using second generation that enables you to essentially up to 20 times speed up your simulation.

    So we are doing everything we can, such that the speed by which you run these large constellations is fast, and it can do it with reasonable time. As of this released 2021b, also, Jacob, and friends have put the ability for you to visualize others aesthetically, or in an animated fashion, the antenna radiation patterns that is visualizing the antenna gains and directivity as is applied on your satellite. So as you see, we can see if I use these static or animated stuff. How does my propagation vary, and how much gain will I have?

    You saw previously that, if you have a nice, narrow beam, a beamforming case in your transmission, it can really increase your link budget there. So we can visualize it as the simulation goes live in these systems. Also, imagine that you have a ground station, and you have a satellite of interest. And then there's a constellation closer to Earth or a different location from that satellite of interest. Who is the transmission interfere with that nice target satellite?

    We have the ability to model interference from a constellation on a communication link and do it in conjunction with the target satellites. Or intervals and visualizations allow you to see at what point every of these interference signals are affecting it. And, of course, we can compute the C over N and C over N plus I. So we can look at the carrier to noise, carrier noise interference issue, and compute lane closures, affecting and taking into account the effect of interference. I think, right now, Jacob has his third and final demo to show how satellite access and link works to a ground station using satellite communications toolbox. Jacob, take it away.

    Great. All right, so I'm going to start off, here, creating a satellite scenario. And when you create a satellite scenario, you need to specify the start time, stop time, and sample time. In this case, we see the stop time is hours past the stop time, so that defines a scenario and a duration of six hours.

    The most important part of a satellite scenario are the satellites, and as Houman mentioned, there's multiple ways you can initialize these in your scenario. You can define them using orbital elements. If you have ephemerous data defining the trajectories of the satellites, you can import those. But probably, the most common way to add satellites is using tle files.

    Here, we have a tle file called Leo Satellite Constellation. This is a sample file that includes 40 satellites in low-Earth orbit, so we simply specify that tle file a satellite. And we have 40 satellites now in our scenario.

    So for this example, what we want to do is model imaging satellites, and the goal is to understand when they'll have the opportunity to take photographs of a particular ground location. So to model the cameras, we're going to use conical sensor. The conical sensor is a field of view based sensor, and it can model a basic antenna. Or it can model an optical sensor-like camera, or even a laser. So it can model any type of a variety of type of sensors.

    So we're going to loop over our satellites, and for each one, add a conical sensor, representing the camera. We're going to add a ground site similar to TX site and RX site. That's a location on Earth that you defined with latitude and longitude coordinates.

    In addition, we're going to specify a min elevation angle, so what that does is define the minimum elevation that the satellite needs to appear in the sky above the horizon for that ground station to be able to see it. And that angle could be due to surrounding terrain and man made structures. So the type of analysis, where we want to analyze when a satellite and ground station can see each other, is called access analysis. So we're going to, again, loop over all of our sensors and add an access analysis from each sensor to the geographic site.

    Now, with our scenario set up, we want to visualize it. So we're going to launch the Satellite Scenario Viewer, and that's going to visualize everything that was added to the scenario. So all 40 satellites are here. We get their trajectories, and we see that the geographic site is here.

    And we see this the line connecting the geographic site and the satellite. That's a visual representation of the access between those, and we can also show a field of view visualization here. So what we're going to do is create one field of view corresponding to satellite four, which is the satellite with access to the geographic site here at the start of the scenario. And we see this green contour drawn on the Earth that represents the intersection of the Earth and the field of view cone from the satellite sensor.

    And as we would expect, the geographic site is within that field of view, and that's why there is access there. But we want-- the next thing we want to do is go beyond this static snapshot at the start of the simulation, and actually, run and animate the simulation. First, we're going to declutter the visualization a little bit. We're going to hide the field of view and hide all the trajectory lines. We're going to make the access lines appear a little bit better, paint them green now, and we're going to call play.

    So play will do all of the orbit propagation of all 40 satellites in there. You saw, right away, it ran through it and got to the animation. So what's going to happen is, anytime a satellite flies overhead from the geographic site, the line appears, showing there's access. It's going a little slow for me, so I'll go ahead and speed that up.

    And you can see that run, and you get a nice play bar at the bottom, where you can control where in the simulation you're viewing. All right, so I'm going to show that this access analysis is available not just in the viewer, but also, at the command line. So whenever we show you information in the visualization, we want to get that data into your hands, so that you can solve engineering problems with it. So what you do is use the access intervals function to get all of the same information as when you saw those green access statuses appear in the visualization, so you get this table of intervals. And each interval defines when a satellite has passed overhead, and there's an access available.

    We see in the first two rows, the source is this satellite one camera. We get a start time, and end time, and duration for each of those intervals. So the interval number, one and two, and star orbits show that satellite one flew overhead from the site twice in that six hour simulation.

    Let me ask you a question, Jacob.

    Sure.

    So go back to that table if you don't mind. So this is for a satellite constellation, right? And you saw, sometimes, the link access is achieved or not. So if we go based on the modern, large constellation, 1,000, 10,000, and if we repeat the operation, we can see that, at almost any point, there is access available for one of those 1,000. That's the thesis behind this satellite communications , right? And if you have enough large constellation, at any point, you can be seen.

    Right, and you might have more requirements. You might need to be able to have three satellites in the sky at any time. And, yeah, you can use these tools to figure out, like, are there any times, where you have less than that?

    Exactly. Thank you.

    All right, so now, we're going to go beyond access analysis, which is just can I see you to communication link analysis, where we actually have to use some RF propagation. And that requires a transmitter and receiver. So what we're going to do is pick the first satellite here, and just analyze a link between that satellite and our ground site. We're going to add a gimbal to the satellite, and what that does is it gives a rotatable body on the satellite that we can mount our transmitting antenna on and allow it to be pointed and rotated.

    So we have our gimbal on the satellite, and now, we're going to design a parabolic reflector antenna. This is available from Antenna Toolbox. It's a highly directional antenna that's common for satellites, and we're going to add a transmitter to our gimbal with that antenna with a frequency of 28 gigahertz.

    We're also going to add a receiver to our ground site. Here, we're going to add a isotropic antenna to the receiver, and first, we want to validate our setup here. So we want to visualize the antenna that we added to the satellite and see where is it pointed. So we call pattern on the TX site, and we see, here, there's a pattern.

    I'm going to set the camera, so that we can get a better side view of it. And we notice that the antenna is pointed down towards the Earth. We call this nadir-pointing. It's not pointed at the geographic site.

    So the next question is to ask, well, is there a link available? Because it's not on the bore site. It's off bore site. Is there enough antenna gain to close the link?

    So what we're going to do is create a link object, connecting the TX and the RX. So this is a link. That's the down link from the satellite transmitter to the ground station receiver. We call link status and ask for the ebno. So ebno is our figure of merit to define the link quality, and we see that there is no link status.

    Our required ebno know was 10. We've got under negative eight, but the next thing we're going to do is called point at to align the antenna with the ground station. And we see this in the visualization now. They're nicely aligned, and once we do that, we're on the bore site. Our link status is now closed.

    It is true, and the last thing we're going to do, just as with access, you want to get a table of the intervals. We can do the same thing for the link intervals to say, when during that my simulation can I close a link? And that concludes the demo. Back to you, Houman.

    Thank you very much. So you see that we can do outdoor propagation, indoor propagation, terrestrial, as well as satellite propagation and analysis. And all you have to do is only MATLAB. But you have to use either Communications Toolbox, or Antenna Toolbox, and, of course, Satellite Communication Toolbox for a satellite scenario modeling. And we can learn more by visiting the corresponding product pages that I have put for you here, but in the wireless communication solution page, you can learn more about the overall wireless solutions we have available for you.

    With that, I would like to summarize using new capabilities in MATLAB for modeling RF propagation channels and scenarios. You can configure antenna array elements on transmitters and receivers, and visualize that effect on the maps. We can integrate the effects of terrain, building elevation, and atmospheric conditions into your analysis.

    We can analyze the antenna array performance onto the propagation effects, budget and closure. And you can model indoor and outdoor RF propagation scenarios, including ray tracing techniques. And for satellite communication, you can model and simulate satellite scenarios, and visualize orbits using the new Satellite Communications Toolbox.

    With that, on behalf of myself and my friend, Jacob, I want to thank you. And after a short pause, we open the floor for the questions that you may have. Thank you very much.

    Thank you.

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