Effective, Efficient Test and Measurement: the Key to Successful 5G Deployments

December 4, 2018

Time: 12 pm EST


With the promise of 5G—including higher data speeds and new services—comes major challenges for operators in terms of network quality, reliability, and availability.

Mission critical applications will demand a network which cannot fail, and ensuring network quality will be at the core of deployment and management. Whether it is the fiber infrastructure, the next generation fronthaul, or the new radio (NR) air interface with mmWave and complex active beam forming antennas, network quality will depend on the rigor of 5G test and measurement during the complete lifecycle.

In this webinar, we will discuss the key field tests required for a successful 5G NR deployment, and how to easily ensure that all physical interfaces, including fiber, coax, and RF, are properly tested when deploying, managing, and maintaining 5G services.

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Check out the full transcript of the Effective, Efficient Test and Measurement: the Key to Successful 5G Deployments webinar.

Ben: Welcome everyone and thank you for joining us for today's webinar: Effective, Efficient, Test and Measurement, The Key to Successful 5G deployments.

Ben: Today's speaker is Kashif Hussein, Director of Solutions Marketing at Viavi Solutions.

Ben: In this webinar, we will discuss the key field tests required for a successful 5G NR deployment, and how to easily ensure that all difficult interfaces including fiber, coax, and RF, are properly tested when deploying, managing, and maintaining 5G services. And now I'm pleased to give it away to Kashif.

Kashif: Hey, thanks, Ben. So today what we are going to do, we are going to cover a few areas. One key thing that we will try to cover is the different physical interfaces that play a heavy role in how in 5GNR things have changed. And with that being said, also we may well try to understand, how do we test these interfaces. Basically when you deploy 5G, are we satisfying the 5G use cases? There is a reason why we are trying to deploy 5G. Our service providers are going to expect 5G, it's not just about data throughput anymore. And we will go through and learn a little about that as well. And if you have any questions, I'll be more than happy to answer those.

Kashif: With that being said, let's go to the next slide. So, first we'll go through the Overview, and then we'll talk about the Technology Dependencies, meaning the fiber aspect of the transport network as well as then we'll talk about the Air Interface and the Testing of Air Interface as well.

Kashif: So the first thing, let's talk about where 5G's at. This is a little bit old data, about like a few months ago, I'd say five, six months ago, and basically this is from GSMA, which is like Global or mobile, actually an association which is responsible which captures all this information. So, as you can see there are a lot of countries, or a lot of regions, where there is a lot of work going on in 5G. There have been some networks that have been deployed, for example in North America Verizon has deployed a 5GTF network in some cities. In EMEA for example, there is a lot of work going on, and I think the first few deployments of 5H that you will see in the next year or the near future will be more on the sub-six Gigahertz, and we'll talk about the different spectrum assets that can be utilized in 5G. Sub-six Gigahertz versus millimeter wave is alright.

Kashif: Multiple countries are doing 5G tests all around the world. There is a lot of work going on in Middle East. Couple of the small deployments of 5G has happened. Of course there are dependencies, on a device perspective, also, which flavor of 5G. 5G is not just a one-time thing, it will be expended over multiple years and we will see what the different releases that come out for 5G.

Kashif: If you look at a little more detail, there's like about 81 operators in 50 countries that are planning on 5G or related trials. In different regions of the world. I know in Japan, for example, Docomo and those guys are also doing significant amount of testing. China Mobile and China Unicom, multiple regions. In North America all the key service providers are looking into 5G, but hasn't, as I said, already deployed it, and depending on what kind of features they are going to deploy, and how they will declare 5G, it needs to be seen.

Kashif: With that, next slide. So, what is actually the rationale for 5G? I mean, is it all about mobile broadband? Not really, right? So, if you look at this picture, there are a couple of things that I've tried to show. If I draw it on an axis, there are three things which will drive the use case for 5G. So from an IoT perspective, meaning Internet of Things, or we also call it MTC, Machine Type Communications, massive Machine Type Communications. Also the latency aspect of it and throughput aspect. If you take a look at the bottom figure, the different applications and how these application will demand a certain service level agreement for these key KPIs. Meaning the throughput, the latency, and the number of users with the capacity of.

Kashif: Of course, not every user or every application behaves the same way. For example, a video download, versus a connective card, versus a virtual surgery, they all have their different requirements and different demands. That's why 5G is much more of a flexible network, and the changes that are coming in 5G are not just on the air interface. You will see that the air interface, transport, meaning mid-haul, front-haul, back-haul, changes are also coming at the same time, from a core network perspective you will also see changes how network slicing and virtualization will play the role. But the key thing is, the different use cases, further enhancement of data rates, in the latency requirements, the reliability aspect of it, we talk about URLLC, Ultra Reliable Low Latency Communication. Those things all play.

Kashif: Now, the challenges will be, from a perspective of that the air interface is as good as the network behind it is supporting it and typically the network that supports it is our fiber network. Fiber plays a fundamental role, not just in 5G, but in a lot of different communication networks. But even in 5G you will see the amount of throughput we are talking about you will see fiber plays a much bigger role, especially when you talk about the sole densification of it. Then you will have a significant number of cell sights, and fiber has to be connected to all of them in a sense to offer the high throughput rate, fat pipes for transport and what have you.

Kashif: And of course, when we are talking about connective cars and Ultra Low Latency and reliability and the cell coordination aspect of it, as well as that transport has to be much more efficient and stringent in terms of the delay aspect of it. Also in 5G the millimeter rates. Millimeter rates, yes, there is significant amount of the spectrum available in millimeter rate, however, at the same time, if you think about millimeter rate, the RF character sticks are extremely poor, compared to sub-six Gigahertz. So what do we need to do there? What are the implications of that? How do we test that? How millimeter rate will work in conjunction with sub-six Gigahertz?

Kashif: So those things we will talk about as well, and those are some of the things that RF engineers and technicians will have when they go out there and the tests that they have to validate all those things. So the work of engineers is going to expand much more. Of course massive MIMO, I mean we've been seeing MIMO, but now we are talking about beamforming, a special multiplexing in which multi-user MIMO and things like that. I mean beamforming and millimeter wave is a tremendous asset where the coverage gap, because of the characteristics of the millimeter wave can be overcome somewhat.

Kashif: And of course, specific network slicing, we'll talk about that too a little bit. And high-velocity service activation. What does that mean actually? Well it means that depending on a certain demand of an enterprise, which is driving a certain type of an application. Now if you want to turn on the service, I mean if you are trying to upgrade a network from a proprietary products like RNCs and all those things and MMEs and what have you, will be more challenging versus commercial off the shelf products on which you can do software upgrades and things like that. So virtualization concept also plays in where you can quickly enable most services and actually improve your top line. And this is from the perspective of a service provider. So skill of service activation will also pay a significant role. And of course the monetization aspect of it we are not even talking about that because we are talking just about the challenges that are coming with 5G and what engineers, people who will be optimizing the networks, managing the networks, will have to pay attention to.

Kashif: So, how do we achieve all that we talked about? It is not just a one ping rate, one type ping. I mean you will see S\LTE evolve from LT advanced to LT pro then IoT was supported and IoT came into being and in different releases you will see enhancements for example in release 15, the first phase of it, the non-stand alone actually 5GNR solution was delivered. Which takes advantage of the LP core where the control signaling and all that implementation is still passing through the same LT core and the data is basically, the user data can directly or indirectly be passing through the eNodeB, or directly connected to the core in a sense. So in phase 15B, a stand alone operation will be supported, meaning a pure 5G core, and of course there are certain other enhancements that will come with it.

Kashif: But the 15, phase 1, which as we all know, the standards are already approved last year, end of last year, and there is implementation going on, on basically NSA, which primarily supports the EMBBURLLC, and massive MIMO. The things that are not being supported that are keeping I would say IOT, because it will take care of the Oracle use, the old LT base IOT technology rate. However, millimeter wave and massive MIMO and all those things will be supported, wider spectrums are supported up to 52.6 Gigahertz, the standards support that from the get-go. In the past if you look at LTE we were doing up to CBS dan rate, 3.5 Gigahertz and what have you. Here we are talking about already from the get-go 52.6 Gigahertz, and there are significant changes in the numerology and all that stuff that we talk about.

Kashif: So 5G, as it evolves, there are a lot of new things that are coming out that will be supported. Of course, beyond 15, you will see 16, where you will see the support for massive machine type communication and all the other things. W

Kashif: hat other key pain, if you look at it from a service provider perspective, and they are deploying it and engineers will be managing these networks, right? I mean if you think about it, there's a lot of complexity that comes with 5G. And not even taking into account that engineers will have to manage multiple RAMs. You will still have a 4G RAM, and then you are deploying these 5G radios, on top of that you will have to understand millimeter wave, you will have to understand beamforming, you will have to understand how this wider spectrum's new numerologies, subcarrier spacing changes, all these thing have to be understood, tested, and validated in the field.

Kashif: Why does network lifecycle, if you talk about that, if it starts from a feature development, and then it goes into the lab, then into the field verification, trials, what have you, and then you go and do it as a mass deployment. So scaling it up, remember, one of the fundamentals of 5G that we have always talked about is the millimeter wave, and when we talk about millimeter wave we also talk about cell densification, because the conversion millimeter wave is very limited. And when we talk about cell densification, then the management of it, the deployment of it, has to be scaled up, otherwise the business case will not be there. It has to be done much more efficiently, eventually you will be looking at automation and things like that to which you can much faster and then much rapid way deploy these small cells and what have you.

Kashif: Enough to goes to that loop of assurance and optimization feeding into new features coming in what have you and things like that. Now, there is going to be a skill gap in the beginning. Understanding the technology, how it will test it, my test equipment that is out there will not support the, for example, the 3GGBNR interface, the existing ones, because the statistical analysis that you do, or how do you track overshoot interference and all that stuff, that is going to be a little bit different. Especially when you have DBB, dynamic TDD and things like that, and interference in those will be very different, how do you capture that versus what was in the past.

Kashif: So those things are coming, and we are working, we as a company, I meant, working with service providers and of course, NEMS, right? When I say NEMs, meaning people like Erickson, Samsung, and those guys, trying to understand how these technologies are being delivered so we can help service providers do this much more efficiently.

Kashif: So complexity in validating millimeter wave is another challenge and of course all of this has to be done with CAPEX and OPEX in mind. At the end of the day it is a business, and we have to manage of an operational expense and as well as a capital expenditure. So those things are key pain points for service providers. And to resolve these pain points, one of the fundamental thing is the rigorous 5G test. If I test my products in the lab environment, and showing that everything that is delivered out there in the field has been validated and simulated and emulated within the right 5G test criteria, I will have a much more confidence to get to a better time to market.

Kashif: So, if I do that, then in that case, guess what? My customer satisfaction will be higher, my CAPEX can be managed, meaning I won't be spending and wasting money. Operationally I can do the right thing. So that's the reason network testing in general, it doesn't matter if it's just 5G network testing or any network testing, otherwise you will have significant customer turn, which will impact your bottom line and top line as well. So those are the things we have to understand, why testing is required. If 5G testing is not done properly when you are launching a network, and while you are managing it, it will impact your overall business case for the network.

Kashif: So lets get into some of the meat of the technology. One thing that's always overlooked in most cases by I would say by engineers working in the field, especially on beta interface site, that whenever a throughput problem happens, or any metric related problem happens, the first thing anybody blames is the RF, like there's an interference problem, the site of the problem, what have you, but at the end of the day your RF interface is going to be as good as your connected network to that cell site is. Which is usually, typically a fiber network. There is significant deployment going on in the world right now on 5G on fiber because of 5G. And I've just put some data points, once you guys go have the slide you can click on it, the link will show you, I mean significant. We're talking about billions and billions of investment that is happening in multiple parts of the world, to deploy more and more fiber.

Kashif: Guess what? When we talk about 5G, there's going to be 20-30 times the number of the small cells, especially if we are talking about millimeter wave and higher frequency waves, because the coverage areas will be small, and both of those things have to work in conjunction with each other, I mean, meaning the larger footprint cells, the macro cells, versus the small cells rate.

Kashif: 5G is likely to fully utilize the dedicated fibers and wavelengths that are out there, because of the throughput that we have been talking about so much. And of course, the more fiber you will have, the more endpoints you will have, the more failure potential out there, so validating those things will be extremely important. And the big challenge as customers have, there's a lack of fiber experts. Just because the light turned on on the digital unit, or on the radio unit that connected the fiber, that does not mean it is working well. There can be small impurities in fiber connections that can literally reduce the performance to one third or even less than that. So we have to account for that as well. So that's why I'm bringing, my background is RF but I'm bringing fiber more in to the discussion because I am seeing those challenges out there, and people are facing them and they are going out in the field.

Kashif: There's a question for everyone. This is a generic network diagram looking at from the coal, to the metro access, and premises. Where do you think the final inspection happens to be? I mean, a simple answer is, literally everywhere. Because everywhere there's a fiber connection and if there is a fiber connection you need to test that.

Kashif: So now let's get into the transport aspect of it. So, today, if you look at the front haul, you have a CPRI front haul, CPRI based front hauls are already known for their stringent delay and data requirements, and even they are quite inefficient when it comes down to throughput. So, CPRI is not going to scale for 5G. For 5G when you are talking about the challenges for 5G transport are, you need ultra low latency. You have simplization issues, you will have and you have to support massive machine time, massive machine time communication, tied to security, gigabit throughput. All of these things have to be considered from a transport perspective, and of course for URLLC there is latency requirement of .5 milliseconds.

Kashif: So those thing have to be understood and considered. And because of that there are industry initiative, for example the next generation front haul, you have the 5G cross haul forum, and all those guys are looking at it and looking at different solutions. How do we split from the other seed to the physical layer, and depending on the type of application, what would be the right option that we can use. Meaning, the demand for latency is much lower for best effort type traffic, meaning for eMBB type traffic. What's this when you have a connected car, so higher order option, when I'm talking about higher order options, meaning options seven/eight, like those rate, much lower bandwidth and latency requirements, lower order options for when joint coordination.

Kashif: So those are the things that are being looked at. The point is that I'm trying to make, you will see changes and flexibility on the transport side as well. And it will not be the same thing as I just have a remote radio up there and a BBU. Some of the functionality of the BBU will be moving towards our U radio unit, basically to overcome these challenges of latency and what have you. So we will see those things as well. Although interfaces, physical interface may be fiber, and you will be looking at RF over fiber in that case in a different way, right, when we talk about that. You're using the ethernet protocol by sending out the information over internet protocol just to manage all those things that we just talked about.

Kashif: Now, just to close on the fiber and the transport discussion. If you look at the lifecycle of managing a cell site, from the construction, from turning on new wavelengths, maintenance, or upgrading it, or expansion of it, there are multiple tests that you have to run to ensure everything is working the way it is supposed to be. Now inspection and cleaning is one test that has to be done in all the phases of a network's lifecycle. And here I'm talking about the wireless network. Insertion losses also needed when you are doing construction builds or system upgrades, or optical return loss, same way, similar way, maintenance and restoration as well added into that. And of course there is the failure you are trying to identify and the issues, and OTDR comes in to play. In fact, from a metro transport perspective, internet turn up testing or transport testing basically and from synchronization perspective, the PDP tester, and network timing test and those things have to be done.

Kashif: This is just a map of during the different lifecycle stages. Often it's the test that you need to do on fiber to ensure your fiber network is healthy.

Kashif: Now let's go and talk about air interface. On the air interface side, significant changes have been made on 3GPPNR, and it'll continue to evolve, I mean in the next few releases that you will see. So now we are from the get-go supporting higher frequency operations and spectrum flexibilities provided, and we'll talk a little about those details too.

Kashif: We'll have flexible numerology, we'll see what that means. Basically you will have subcarrier spacing, which goes from 15 kilohertz all the way to I think it's 240 kilohertz, you will see that. I mean, of course semi static and dynamic TDD is also getting introduced, I mean before TDD was on very specified slots, now we are talking a dynamic TDD where your uplink and downlink can occupy right next to each other, and you don't have to wait for the end of the frame. Beamforming and multi antenna management, that's something new that is coming out and they play a different role in the sub-6 Gigahertz versus greater than 6 Gigahertz. Then we can talk about also the non-stand alone as well as the dual connectivity, because remember, you will still be coordinating traffic latching on to the 4G core while you are on NSA, and the coordination has to be done in that case too.

Kashif: So those are the things that we have to understand, and how things will be changing for us and going into 3GNR.

Kashif: At a high level, just to show you the difference, the picture on the right hand side that I just wanted to share with everybody, I mean, why the limiter wave plays such an important role. Why do we talk about the throughput rate, just to give you a visual idea, the amount of the spectrum that is available in the millimeter wave, anything from, let's call it 34 Gigahertz and up, or like 30 Gigahertz and up, and you look at it, there's a significant amount of the spectrum available. If you look at everything below 6 Gigahertz, the total spectrum is somewhere around 1 Gigahertz total, whereas the millimeter wave we are talking about, you have about 1420 Gigahertz of the spectrum available.

Kashif: So there's a significant, lots and lots of the spectrum available. And when you look at the picture below, just to give you an idea how the two networks will coexist, of course a millimeter wave, shorter coverage, will be much more focused on areas where you have hotspots, where you are providing throughput, maybe other applications are going through, maybe a connected car, what have you, and of course there will be an umbrella network, because I mean you have tremendous throughput and bandwidth and all that stuff, but there has to be a coexisting of, sub 6 Gigahertz and millimeter wave together.

Kashif: As we know millimeter wave frequencies will offer a significant large amount of spectrum providing a higher throughput and stuff like that. Massive MIMO can help, as I've originally mentioned, to improve the coverage, but the sub six Gigahertz network will play a lighter role in order for this thing to be successful. This is just to give you the high level over view.

Kashif: Now what changes are being made? So I talked about flexible numerology. If you look at it the sub carrier spacing, I mean the formula is at the bottom, so you have a 15 kilo ... so what is that FR1 and FR2, so let me tell you. FR1 is the sub-six Gigahertz, which is Frequency Range one, and Frequency Range 2, which is about 6 Gigahertz, we'll be talking about. There are a few nuances and differences between FR1 and FR2. A lot of stuff has stayed the same, so that it is backwards compatible, so that LTE network numerology and the 15 kilohertz sub carrier spacing allows that for that. And so can see in the downlink is the same as LTE, you'll be using CP-OFDM. Uplink you will CB-OFDM, and of course DFT-OFDM will be used in higher frequency ranges.

Kashif: Duplexing will be same FDD and TDD and the FR2, it will be only TDD and you will see dynamic and semi static in some cases to save the power that we like or what have you. Bandwidth up to 400 Megahertz but the initial deployments will be around 100 Megahertz. That is quite significant if you think about it, and it can be scaled up with carrier application in the future you will see.

Kashif: On the right hand side what I'm trying to show you if you will look at 1 millisecond subframe up LT, which has as you can see the 14 slots in there, and as you go into the higher sub carriers, sorry, I mean the high bandwidth sub carriers, your slot duration gets reduced, and you'll have many slots which will be very useful for a ULCC type application as you will see.

Kashif: Going into the next slide, 14 symbols, or slots, which is the same, however, when the sub carrier space is going to increase, the length of the slot is going to reduce. The idea behind all these slides is to share with you the differences that are coming your way and then how you will test will also be changing. Your signal analysis will be changing. I'll talk about if you have a dynamic TDD, how do you add and define interference before we were able to test for interference easily. Now, it may not work here in that case because you don't know where the uplink and the downlink are starting.

Kashif: So anyway, slot aggregation will allow the data heavy transmission and many slots, like I mentioned before, will be defined for shorter data transmission for URLLC type application rate, so you can quickly send data without waiting for the end of the whole duration, you can start transmitting earlier, so that will improve your latency. So this are the changes that are coming.

Kashif: On the MIMO side, when we talk about Massive MIMO, significant number of internet elements, when we're talking about 10s to hundred, like 64 x 64 or 128 rate, improved coverage, signal amplification by beamforming. You'll use the phase shift in amplifying RF signal. I mean basically, you're pretty much limited and its greater than 6 Gigahertz, so using beamforming you can take advantage of that, and of course for high cell capacity, by providing a spacial multiplexing permit and simultaneous fusers you can take advantage of that in the sub 6 Gigahertz as well. I mean, that's basically what technology will allow us to do that.

Kashif: So when we talk about beamforming, so beamforming is the ability to generate and shape multiple beam using a much larger antenna array and by manipulating the phase and amplitude of the arrays. And what the UE does it will identify the SSB which is the synchronization signal block. Basically, what happens, there is a beam index, which is a part of the, and you will see in the test to screen rate that basically the SSB index will be used to identify that particular beam by the UE and if it matches a certain criteria from a threshold perspective on the RF signal and all that stuff, basically the UE will identify in the PRACH, basically the random access procedure, this is basically the beam I want to attach to. And of course that's how the coordination between the two will work, and of course there is a constant cycling going on with the measurement and determination and reporting of it, and of course if there is a failure then there is a failure procedure as well that has been identified. So that, if you have to go to a new beam, that can be done.

Kashif: The point is, all these 5G tests, you can test all these things even today, with products that are out there and Ill talk about that in a minute, but beamforming is something new for engineers and they will have to learn how to deal with that, validate it, the beams the way they are supposed to be defined, and if there is any consideration they can do from a network prospective they can to improve the overall performance of the network.

Kashif: Okay, so now let's go into the testing of the air interface. So, just like any other technology in the past, RF Characterization and Conformance Test is one thing that you will always do to elevate the channel, power, occupied bandwidth, and of course adjust channel leakage, validating that you are not basically going into a spectrums where you shouldn't be and what have you.

Kashif: So basically you're validating data from the environment, today you can do that with a cell advisor 5G a product that we came out with, you can validate the mission mask and all those things as well. That's the fundamental 5G test we do and we are launching new technologies and stuff like that. And of course, Persistence Spectrum and Spectrogram. Why do they play a significance? The fundamental reason is, now, think about it I'll give you a use guess. For example, dynamic TDD, I was just talking about dynamic TDD, in the case of dynamic TDD, you don't know where your uplink and downlink is, so before you had a gated CP chain, which allowed you basically, to know where the uplink will be and the downlink will be, so as a result, so when somebody is transmitting on the downlink you know that's at the starting point so that data coming in is not an interference.

Kashif: However, now with dynamic TDD it will be difficult so having persistence and a real time spectrum analyzer, which captures every signal, without slowing down or without omitting any results for those certain frequencies, you can see a true shape of it, if there is an interference signal that shows up, you can identify that and you can see just because of the function of the real time spectrum analyzer, you can see a bit of an interference caused by an uplink or some other source on the uplink. So persistence plays a vital role in identifying interference in those situations.

Kashif: Of course in 5G carrier aggregation up to eight carriers, you can validate that, you can, for example on the right hand side, you can see the different channel frequencies that we have, in respect to the PCIs and of course you can validate the SSB index. So you can see how each and every carrier is behaving, also the constellation diagrams so that you can see the EBM, and validate all those things. So far you can perform some signal analysis, you can look at your radio power performance on all carriers, if they are up to par, if there is a problem with one of the carriers then you need to go and troubleshoot and figure out, if it's bad because of any network anomaly or it's actually because of the RF environment itself, or there's a source of interference in there so that will be a next step to peeling the onion and basically going into it and looking at it.

Kashif: The next slide, the beamforming aspect of it. So for example the SSB index, which is actually the synchronization signal block, which is a combination of the synchronization signal and basically your physical downlink beam modulator, and you can validate that each and every unique beam, because a UE will attach to, it will see these SSB indexes and it will report back that this is the beam I want to attach to and you can validate it there all coming from a different signal level what have you. So the RSRP or signal to interference to noise ratio and all those things you can analyze to validate these beams are actually coming out the way they are supposed to be or any integration, acquired, or what have you.

Kashif: So that's pretty much all from a beam perspective, now also you can validate the coverage, the cell site coverage using the CellAdvisor 5G, I just talked about, so you can see the physical ID, the beam index, the beam bobber, signal to noise ratio, you can see the propagation at 28 Gigahertz in this case, or different signals, what have you, and of courses the beam availability and overall cell coverage.

Kashif: So, what I just talked about, in a sense, validating, whether your 5G signal is being transmitted, it is not interfering with anybody else, all your beams are coming out, all your different carriers, if you are doing carrier aggregation, that's working as well, and your beams are working too. So you're validating, you're getting a complete picture of the RF interference in this case. These 5G tests are done over the air, and these are all over the air tests that I was sharing with you.

Kashif: Next slide, so now, just to summarize, and closing the whole thing, you will have a coexistence off the 4G and the 5G network, and to ensure that everything is working as designed and we are getting the maximum out of it, we'll have to make sure that of our fiber networks, which are foundational are tested properly, of a transport network is meeting the SLA requirements that we have, and of course all the RF environment is tested properly. And to make it easy, all these things have to have a proper work flow where steps are done consistently, the quotes are generated easily, so you have a solution that can do for you.

Kashif: Basically, if I have a certification, rapid fault wall isolation, back haul transmission SLAs, front haul latency specification, things like that, you can do all these tests, in some case, even virtual proof scan delivered that too, and be off of those virtual solutions as well.

Kashif: Basically by using CellAdvisor 5G and our MTS-2000 you can run an end to end test for any 5G cell site that you may have out there.

Kashif: With that, questions? I'm open for questions, Ben

Ben: Great. Thank you so much for that presentation, Kashif. So, first of all, just as a reminder to the audience to enter any questions that you have for Kashif will be answered. First question here, "When do you think that the commercial 5GNR networks will be deployed, and what's the rationale for them?"

Kashif: So the thing is, the biggest hurdle is typically, I mean and we saw the same thing with 4G and 3G, is the timeline for the devices. You see today for example, Verizon just launched, I mean they announced it publicly that the 5G network that they'll deploy it's a fixed wireless network, and those are customer premise equipment attached to the outside of the building, and they are basically transmitting signal and trying to figure out, I'm going to assume that they are trying to figure out a direct line of sight to that so the best available service can be delivered. Now, I'm mean moving forward with that, you have to imagine that user UEs have to come out, of course they will be all new UEs, which will have to have support 5G compatible radios, radio front ends, I mean remember we talked about MIMOs as well taking advantage of MIMO in this case, Massive MIMO we are talking about, so the number of antennas have to be increased as well.

Kashif: So all these things are quite complicated, from a radio side, you have enough power always available because you are at a base station, devices are usually limited in power. So all those things have to be considered, and once those UEs are start coming out commercially, I'm expecting based on the road maps that we are seeing, somewhere around 2019, there will be a few of them, but 2020 we expect a lot more, and by that time, I mean, the other challenge is, today the standards are being solidified, things are changing and there dynamically moving, and you will see these new devices coming out. Once the devices are out there then you will see true deployment of 5GNR. You will see trials, you will see some of the applications of 5G but the true 5G in my mind will come around somewhere commercially around late 2019, 2020 and it will continue as new features are deployed, new applications are implemented, we will see those.

Ben: Wonderful, and then Kashif, you didn't talk too much on the network slicing, and there's a lot of discussion on that. Could you go into that?

Kashif: Network slicing, to think about it this way, we originally talked about the different applications of 5G. So what if I want to offer a service for massive machine type communication in an industrial park or something like that. Now that industrial park, my requirement may be, very high latency requirement for example, I mean because the robots are working, they are talking to each other what have you, the coordination have to happen. Now the SLA requirements will be more different for that kid of environment. My throughput might not be so much, because I really, these are bytes of data that are constantly being transmitted between these robots, what have you, on how they are performing, how the next step will be, a cycle will be.

Kashif: I mean just giving it a hypothetical situation, so in a situation like that, if you think about it, that specific network slice, my quality of service end to end has to meet a certain criteria. Now in that case I can complete a network slice for that, where my RF requirements, my transport requirements, all that stuff, now this concept of network slicing in validating will be a little bit different than what we see today.

Kashif: I mean taking another example, in a same network, you can have massive coverage for the whole neighborhood, and then there are connected cars which are driving with already stringent requirement a URLLC type thing, where a vehicle is talking to another vehicle. That can be another network slice, within the same network. Again, the SLAs are different, the KPIs will be measured differently, their failures can be much more catastrophic than you know, if I'm not getting my email today.

Kashif: So those things need to be considered and those network slices need to be tested, and the assurance aspect will be extremely important in that case. And how quickly we can respond to those failure reasons. Okay?

Ben: Thank you. And what about interference management in 5G. Would it be any different than it would be in 4G?

Kashif: Yes, somewhat. Let's think about it this way. We just talked about the TDD aspect of it, if you think about it. What is interference? The presence of a signal that is actually is not helping the transmission of data or voice. Any signal in the same frequency or band, when I'm downloading data, can cause interference. Interference can be internal to the network, external to the network, can be because of intermods and what have you. What makes it more complicated is the skill of the network deployment that will be happening. Imagine the amount of coordination that needs to be done between the cell sites, because if I am transmitting, and this guy's transmitting, a macro cell, it's transmitting and it's taking the same slots, coordination is the key.

Kashif: On top of it, we are talking about the TDD, the dynamic aspect of it. And I talked about it a little bit. Where, I mean at what point I go from uplink to downlink and downlink to uplink, the signal that is on the uplink side, I mean that I was expecting it's not there, so the downlink is it like sort of interference, how do I separate those two out? So that kid of analysis will be required. And that will be quite challenging. Having the right tools, having a real-time spectrum analyzer that's persistent can truly help benefit their rate and it can reduce the time it takes to identify interference sources and defense will become, as more and more sources will be out there, the potential for interference will keep increasing.

Ben: Thanks. What are the three most important air interface KPIs for 5GNR? How are they different from 4G KPIs?

Kashif: One thing that you'll have to understand, of course this question will go much more for NEMs, how they are defining the networks and the standard body. However, it will again be the same thing, depending on the type of application that you are driving. If your application, we talked about that, right? I mean the slice of that application that you are driving, the SLA requirement will be completely different for example, for a URLLC application your jiggle, your latency, those will be the top priority versus if I am just downloading metabytes of data, if my demand is that, in that case throughput is the key. But throughput may mean nothing in an industrial IOT complex.

Kashif: So these, the KPIs will vary with respect to the application. And they will be further I will say refined with the 3CGPP specs as they keep moving forward. But again, it will be application specific, throughput is not going anywhere, latency isn't to going anywhere, but they'll be much more application specific and the requirements for application may be maybe 0.5 milliseconds on which I have to meet the URLLC latency requirement. Once this, I can be up to 10 milliseconds or 20 milliseconds waiting on another network.

Kashif: So it all depends on the application, but as we see in 4G throughput stands there or course if your RF environment is poor, so for example, if I'm having too many drop connections, if I'm having interference problems in the network then of course I'm not going to meet my throughput requirements. Of course my transmissions will be higher. I'm not calling those as KPIs, but the fundamentals of the RF environment, they have to be there for those KPIs to be met. You cannot have high throughput if you have RF issues in the network, if you're constantly retransmitting, if you are constantly dropping packets, if you have too much delay and jitter in your network, you can not meet the KPIs.

Kashif: The KPIs stays there, but the character sticks, and the different things that we look at to get to the 2nd layer or the 3rd layer of a KPI will still have to be analyzed, and according to the application you will see new KPIs coming out. Ben: And do you have a case example for FR2 TDD interference in either sub six Gigahertz or MM wave?

Kashif: The use case, like I said, in that situation, of course the networks are not really deployed as such at that extent that we will see. But in the lab environment, when you test these things you can actually see the impact of that. So no, I don't have a use case that has come out already, however there are use cases that we do believe, for example you go to the TDD band rate and they're always talking about the real time spectrum analyzer, so in those higher frequencies you have to understand there is also a point of intercept on these real time spectrum analyzers, and that point of intercept allows you how much off a signal can you capture.

Kashif: So if I go to, for example, 240 Kilohertz of curious carrier spacing my slot size significantly reduces. If I, and let me go back to my slide. In one of the slides I mention that actually. Right here, so I remember that, but for example, a 120 Kilohertz, there's a slot slant is about 125 microseconds, so at 125 microseconds, my spectrum analyzer has to be sharp enough to see that signal. If my spectrum analyzer has a POI, point of intercept of 125 microseconds then an interference that is caused at that FR2 band, or in millimeter wave, or even in FR1, I should be able to see that spectrum problem, basically the RF issue in that spectrum.

Kashif: Not many spectrum analyzers can do that by the way. So when you are buying a spectrum analyzer and looking into it, that okay can I use this real time spectrum analyzer to troubleshoot interference, cost at, in an FR1 band, keep an eye on these figures. What is the point of intercept for these things at?

Ben: Awesome, thank you. Do the units use all directional antenna to test the beam?

Kashif: I don't understand. To read that using one antenna, because its very much directional in a sense, what we are talking about these high frequencies. So you can say yes, today they are, I mean these are one antennas they use to validate today and sources of interference and what have you.

Ben: I see. Thank you. So what's the role of scanners in 5G, and will it be able to measure beams of MIMO antennas and determine beam coverage in cells?

Kashif: Absolutely, I mean we are already doing that, I mean, the slide that I showed you of the beam analysis in fact, Cell Advisor 5G which is actually a signal analyzer it is way more than a scanner but it has a scanner built into it as well. It can do fiber tests, it can do coax tests, it can do transport as well, and signal analysis on top of it, it has a scanner function. And it can scan every beam for 5G testing. So what I'm showing you here actually is a data coming out of Cell Advisor 5G, where it is looking at the synchronization signal, block actually, and taking that index, which is per beam basis rate, so it can actually scan anything that is being transmitted and can show you what is the signal strength of these beams, how they are behaving, what is the signal to interference to noise ratio, sign out is also there on all that stuff. Yes of course, I'm sure other scanners will be coming out too, but the only one I know right now which can do that, over 100 Megahertz of the spectrum today, Cell Advisor 5G does that.

Ben: Wonderful. And how will handover get affected between MM wave and sub 6 Gigahertz?

Kashif: That's a very interesting question, actually. It truly will depend how the scheduler and how the NEMs will implement that. So every NEM will have, there will of course there will be some standard requirements that you'll have to have above a certain signal threshold when you are coming out of the coverage area, just like we had a previous technology. Those thresholds and criteria will be defined by standards but of course there will be a secret sauce that every NEM will have it, for them to trigger a hand off between going from the macro cell to the millimeter wave and of course from millimeter wave to those things. I don't have the details of that because of course we'll have to work with the NEM vendors, how they have implemented it, what are the standards they are the triggers that will be made available, the thresholds will come out and if those thresholds will be met.

Kashif: Think about it this way, the technology, the way we implement in the future will be very much similar to that however, the criteria will be different.

Ben: Great. And with reference to massive MIMO, will each antenna element have a sub pilot physical element, and would it lead it as pilot contamination, if so, how can we detect pilot contamination?

Kashif: Sorry, I don't understand the question. Honestly, I'm trying to understand. So every SSB the way it is built, you will have basically ... So first understand SSB. SSB which is the synchronization signal block, it is composed of a synchronization signal which is a component of the PSS and SSS. And that information is present in every SSB. So based on that along with the broadcast channel, so using that information, it is being transmitted. Yeah, is it going to be always on, just like before? If that's the question, of course you will be transmitting within those slots. So of course whenever there is a signal unnecessarily present of course it will be a source of interference. But in 3GPPNR, 5GNR basically, there is some work that is being done to make it in a sense, much more efficient, where we can reduce the presence of always-on signals. So overall, it reduces the interference, it also reduces in a sense makes it much more energy efficient.

Ben: Thank you. And does your 5G test analyzer have a separate down converter for 28 Gigahertz built in, or is it separate?

Kashif: No, it's not separate, it's built in. It's actually built in. You don't have to buy a separate piece of 5G test hardware that you have to latch on or anything like that. It is built in. It will be a factory delivered product in a sense.

Kashif: And it's not down converting it, it actually is analyzing 28 Gigahertz in there. Ben: Okay, great. And I think there was one question there. So is there interference between beams, and how do you measure?

Kashif: What I'm showing you right here. I mean, sorry, that man I was sharing with my screen, if you go to the Beam Performance page, it actually gives you that information. Of course a signal from this you're not demodulating data, and if it is up there, then in that case it is a source of interference, but because of the coordination that keeps going back and forth between the UE and the GMB, which is like the next generation node B, and whatever data is transmitted, and that coordination allows us to minimize actually the interference caused by unnecessary signals in that case. So that function will continue there.

Ben: Wonderful. Well, that seems to conclude our questions for now, unless we have any from the audience. If not, I just want to thank you so much, Kashif, for your presentation today, and for everyone for attending today.

Kashif: Thank you all.

Ben: So we do have a fairly long question from the audience but I think what we'll do with that since we're pretty low on time is we will follow up with that question. So thank you all so much for your time today.