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Overview of Wireless Communications

10. IETF Part1

the Internet Engineering Task Force. The IETF is one of five main groups that are a part of what we call the ISOC, or Internet Society. And you'll see a little breakdown chart here in just a bit to better explain the hierarchy of where the IETF fits into the Internet Society. But what they're doing is that basically the IETF is the one that does a lot of the designs and creates a lot of what we call the "requests for comments" that eventually become standards that we use in different types of internet communication. So in the ICEOC, by the way, besides the IETF, they have the Internet Architecture Board. They also have the group that assigns names and IP addresses. They call it ICANN. or the Internet Corporation for Assigned Names and Numbers. And even in that organization, it's broken down by different regions of the world. They have the Internet Engineering Steering Group and the Internet Research Task Force. Now, for those of you seeking certifications, you don't really need to know about all of the different pieces of ice hockey. But when you're out there and you're working in the production world, it is important that you understand what some of these regulations are and how they're changing, because we have to work with them. So the goal here is to let you know about these different organisations so that you will hopefully, in your life of working with wireless, continue to stay up to date with things as they change.

11. IETF Part2

Now, one of the RFCs I was just talking about the request for comments; these, you know, start off as ideas that get published, and then other groups can add their thoughts to these RFCs. And if everybody likes this new thought, then, you know, it basically gets an update. But as it gets updated, it gets a different number, and so you can trace back many of the RFCs almost generationally through the ways in which they have evolved. But anyway, RC 39, Section 35, is designed to give us the purpose of what the IETF is supposed to do. And what they're supposed to do in their part of iSock is give us high-quality, relevant technical and engineering documents that influence the way people design, use, and manage the internet, and in such a way to make the internet work better. Now, the documents will include protocol standards; they'll talk about the best current practises and include some informational documents of different kinds, basically around how we do communications. Now, I know I talked about the internet, but a lot of what the ITF does and designs is going to be standards that we use inside our networks. As an example, consider how we'll use IP addresses both within our network and when connecting to the Internet. And so that's where we see a lot of the work that the ITF has done for us.

12. ISOC Hierarchy

So again, at the top level we have the Internet Society, ISOC, and from there you'll see that we branch down to the names and numbers with ICANN, and that's pretty much where we stopped there. They are the ones who would improve new domain names or the types of IP addresses you use if you wanted to use them. And then on the design of the new updates and what we can do better with our communications, we'll start through the Internet Architecture Board, and from there, they're going to have a research task force working underneath them, as well as the Internet Engineering Steering Group. Really. Again, like I said, you don't have to memorise all of this for those of you seeking certifications in this particular course, but it's just information, and I think that is crucial for you to understand so that you know where all this stuff comes from. Anyway, the Internet Engineering Steering Groupis the ones that are basicallyin this hierarchy over the IETF. Does the IETF do it? I said, well, in essence, they're trying to make the Internet better. So that might be with applications, general protocols, operations management, or different types of routing protocols. I mean, IETF, we're the ones that helped us with the OSPF routing protocol and transport layer information. Again, Internet standards, best practices, security information, real-time applications such as voice over IP, and the type of information structure to support that And as they put all of these different ideas together, which, as I said, will eventually become our standards, you're going to see them published as these requests for comments.

13. Wi-Fi Alliance

The WiFi Alliance is a nonprofit organisation of about 550 different vendors that is devoted to improving the equipment that we use with wireless communications. The goal of the WiFi Alliance is to actually examine the different vendors' equipment and make sure that they work together, work out the way the standard was set, and that they would interoperate with any other vendor. And so when they test that equipment, you'll often see the little Wi-Fi Certified logo, which basically tells you that it's going to work with the majority of other networking vendors. I mean, that's your Cisco, Juniper, and Aruba. It just goes on and on with all of the different types of people or companies that are building equipment and knowing that they interoperate.

14. IEEE

Now the IEEE, as I've talked about before, is the one that comes up with some of the standards. Remember, they're not building equipment. They're just coming up with the guidelines and the standards that we should build our equipment to. They have about 4000 members in 100 groups spread across 60 countries. And as they create these, how else can I say it's just written documents? They're not making equipment, but they're describing how the technical processes and equipment should function. So we hope that the vendors are following those ideas. Such as when we were excited about high throughput 802 to 11 years ago. The IEE really hadn't finished that document before vendors started putting that equipment out. And there was a problem in the early days where not everything was compatible as they worked together because we didn't really have a set standard once it was standardized. Then, of course, vendors made their equipment work with that standard, and the WiFi Alliance would be able to verify that they worked within those guidelines and worked with other people's equipment.

15. The Hierarchical Model

With this hierarchical model, Cisco is frequently mentioned. And, you know, whether it was Cisco that came up with this idea or some other guidelines, they're the ones that really promote it. But the idea here is to talk about the structure and building of your networks. And the three areas they have are the access layer, the distribution layer, and the core layer. So let's talk a little bit about what happens with wireless communications because, if you think about it, they are in what we would call the access layer. So these are little laptops because that's where we access the network. Anything that is a communication endpoint simply means that the device is either sending or receiving communications, but nothing is passing through it like a router or switch would. So that's the access layer where we access it. And if I have these computers that are doing WiFi, then they need a device, such as the access point, to be able to associate with. And that means that they're entering the access layer. They're accessing your network because obviously, at some point, you're going to enter the wired network. So that's one component, albeit a critical component, of the design. But then we have to worry about how we get from, let's say, one area of our network to, let's say, another area of our network that's also an access layer. Maybe they're not even wireless. Maybe it's a server farm or virtual machines or whatever else you might have; access to them, especially in larger networks, has to go through a distribution layer. The distribution layer—typically, we would think of a router—is So these circles with an X are routers, or we can even have a switch that does routing based on IP addresses. But the distribution layer is our method of being able to get from one point to the other to distribute our traffic throughout the network. It's also one of the classically, thefirst place that we would introduce security. But we've done a lot more now tohave security types of technology or security methodsavailable, even at the access layer. Security is obviously important these days, given the number of hacks reported in the news. So it's policy-based connectivity. And then the core was all about high-speed switching. The goal of the Core was to not worry about security. We wanted to move things at the highest speed possible. We frequently see today that we would connect from the core to, say, a private cloud within your network. And that could be, again, a virtualized server farm or something else. We see the Core as our way to get out to the Internet. The idea being that on these "edges," or what we call the "edge," we have other security apparatuses that are protecting the core from the traffic that gets there. But once we get to the core, then we want to have, like I said, the highest speed possible with nothing stopping us. So a lot of what we call edge services, which are not depicted here in this little picture, connect to the core in most of the typical types of designs.

16. Carrier Signals

When we talk about carrier signals, we're talking about ways in which we can transmit our data. Now, when it comes down to it, all we're sending is a bunch of ones and zeros, part of what we call binary communications. And those ones and zeros, when put together and read by an application or whatever it is that we're using for the communications, will help us understand what the message is. Now, those ones and zeros could be sent by light, through fibre optics. It could be sent by an electrical current through a copper wire. It's just a method of being able; you have to have a method or some sort of medium to carry the ones and zeros. In this case, we're going to use radio frequency.That means that our transmitters need to have a way of being able to send the ones and the zeros from one location to another. Again, the idea is that the receiver will understand the pattern of information and will be able to decipher the ones and zeros being sent so we can put that data together. Now, if a signal fluctuates or if it's altered even slightly, then the signal can hopefully still be interpreted so that the data can still be properly sent and received. This is called the carrier signal. In fact, what you're going to see is that sometimes we've purposely seen fluctuations in that signal to help identify the ones in the zeros.

17. Communication Fundamentals Part1

So, when we look at the various types of communications, all of which use radio frequency, we'll break down the fundamentals so that you understand the terminology used in the communications. So wireless communications use what we would call a module to transmit data. And we'll go over many of the different types of signalling methods, but they all involve radio frequency. And when we define radio frequency, there are two things that we want to look at: the wavelength and the amplitude. Now, when we look at what is sometimes called a classic sine wave, for those of you who remember all the fun math and things like that, we look at the frequency of the signal by looking at the peaks of that signal as a part of the wavelength. And this is what they call it at the top, 360 degrees, if you think about it from zero to 360. But they say that at the wavelength, at the peaks, however frequently that occurs over a period of time, that would be the wavelength, which we'll refer to later as the frequency. Now, the next part of this is the amplitude. The amplitude really is the strength of that signal. So, if you've ever been to an ocean and seen waves coming in, and let's say you were out there getting ready to go swimming, surfing, or whatever, you'd start timing the waves, hoping for some kind of frequency. Of course, it depends on whether many other things are true, but I'm just trying to make an analogy: we can almost measure how frequently these waves come in. Now, the people on the surfboards are wanting a lot of amplitude, which is really the height of that wave. I'm sure if you've done any travelling to different oceans that you've seen that in different areas of the world, a lot of the waves have different amplitudes. Some you can watch on the "extreme sports" types of channels. In some oceans, it looks like just little ripples are coming in. It is still what we would call the wavelength of the frequency of those waves. They just didn't have as much amplitude or strength. If you're just that person swimming in the ocean and you get this monster 20-foot-tall wave while you're out here swimming around in the water, you might be a little bit more afraid of that amplitude than you would have been if you were at some other beach.

18. Communication Fundamentals Part2

So we just had a diagram of this idea of frequency when we looked at it in a chart format. And basically, frequency is the way we describe the behaviour of waves. A wave would be something that travels away from the source that generates them, which could be an antenna. Maybe I'll make this look like an antenna here. The frequency is defined as how fast those waves travel, or more precisely, how many waves are generated in a one-second period of time. So remember when we were talking about this and we saw this transmission as the transmission was moving? We were measuring the distance, basically the distance between the peaks. And we're going to keep measuring that to see how many of those peaks we have over a certain amount of time. In this case, more than one second. And so that becomes the frequency for some transmissions we may see. And I'm just going to draw over the top of this more frequent wave. and so that would be at a different frequency. And that's very important to us, as you'll see when we talk about the different frequencies and what we're looking for. Now, of course, I've made some sort of artistic mess for you, but hopefully that works in describing the idea of what frequency is.

19. Communication Fundamentals Part3

One of the other things that we look at withthe types of communications is what we call phase. phase is important to us. And when we talk about some of these bythe way, when we talk about some of thesedifferent things like the the amplitude and the frequency,those are pretty concrete terms, we can measure those. Phase is a little bit more relative of a term, and it is basically the relationship between two waves that have the same frequency. Now, when we talk about that as a frequency, that means that we have the same number of waves in the same amount of time. But maybe we had one new frequency start at this (we'll call it zero) and then somebody else used the same frequency, but this was a little bit later. So you could try measuring from zero to 360 degrees from the first frequency where that new peak hit in comparison to the first transmission. And that becomes important for a couple of big reasons. One of the main reasons is that if they weren't out of phase, one frequency could basically change the other frequency by doing things like increasing the amplitude, or it's part of the physics. But the idea here is that sometimes, if you were to be, say, 180 degrees out of phase, that second frequency could cancel out the first one. They'd actually cancel each other out, and that then would be a big problem in our communications. So, as a way to think about it, imagine if this dotted transmission was 180 degrees out of phase. That means that the peak would actually have we wouldhave seen the peak up here for this particular one. And that would then cancel out this part of the first frequency, or the first transmission, I should say, being 180 degrees out of phase. Because of the strength of this versus the end of the other part of this, the bottom of this trough would basically cancel out and make the type of transmission that's being seen almost zero. And so that's why face is a big part of how we have to look at the way we set things up. One way to think about it is that maybe some of you have heard of noise-canceling headphones. And what a noise-canceling headphone does is try to, when it detects outside sounds, generate a signal that is basically 180 degrees out of phase so that you don't hear that noise. Because we have a signal that is cancelling it out.

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