Hello everybody, welcome back. My name is Tyler McMinn with Aruba. And this is the Aruba Mobility Essentials course Part 1. We are on our 8th video in the Part 1 series, covering RF Channels. In the last video, we hit the rules of 3 rules of 10 talking about RF power and how that's described. So definitely go back and check that one out if you missed it, and this one, we're going to cover what RF Channels are and how we can use those to our advantage. So let's get started. [MUSIC] All right, so RF Channels. Let's jump in and take a peek here. What is a channel? Well, a channel is a range of frequencies that we use for our radio frequency communication. So if you look at this range of frequencies here, this channel space the 2.4 GHz, has several channels that are being utilized. Channels themselves, which usually are next to each other, not always, but usually like channel 1, channel 2, channel 3, they're going to be part of this overall frequency band that we're using. So this band is a chunk of frequency that's been allocated either because you've paid money to license it, or if you're in the world of wireless here, you're using the industry scientific medical bands which are free to use at certain power levels. So channels usually next to each other are part of that frequency band. And then bands and channels have rules defined by whatever the regulatory is that governs them. This means in the United States, we have the FCC that's going to dictate what band width is available. What channel width is being used, like this channel is 5 MHz away from channel number 2, but the actual channel if you utilize it is a channel width of 20 MHz or we could use a wideband channel and eat up 40 MHz of distance if we want to. A wider channel means faster throughput, and we'll talk about that more in the next video. But the FCC is ultimately the one that kind of governs those. They also dictate your transmission power. So if you were on channel 1, even in a 20 MHz band, but you were broadcasting way stronger signal than you are legally supposed to, you run the risk of interfering with users that otherwise you wouldn't be interfering with. So the 2.4 GHz is part of that industry scientific ban. The 2.4 is part of it, the 5 GHz is part of it. There's also the 900 MHz which is often utilized for outdoor deployments. The IEEE itself defines 14 viable channels and that 2.4 GHz space, but not everybody uses that. In fact, only Japan, as far as I know utilizes the 14th channel there. In Europe, they have channels one through 13, and in the United States, we utilize channels 1 through 11. So the regulatory domain that you're in is going to dictate what channels are allowed. One thing to note if you're on channel 1, 6, and 11, these three channels have a specific designation as a non overlapping channel. In other words, if you had an access point on channel 1 and right next to it, like right on top of it, you put another access point on channel 6, and right on top of that, you put another access point on channel 11. They're all going to overlap in the same radio space, there's really not going to be a difference in coverage of these three access points. But users on channel 1 are not going to suffer any interference with users on channel 6, they can all coexist just fine with users on channel 11. And the reason why they can is simply because they're on different channels. So if you're broadcasting over here in channel 11, you're going to see your broadcast go as low as channel 9, but they're not going to cause any interference with the channel space being used by channel set. So it's like having an FM radio signal right on top of an AM radio, they're not going to interfere with each other. Because 2.4 was so adopted, it was used in other devices not just access points. It was used with Bluetooth using frequency hopping, cordless phones, these dect phones from back in the day, microwave ovens, believe it or not, they use the 2.4 frequency to vibrate water molecules in your burrito or your cup of tea. So a microwave could end up blowing up pretty much a large swath of this spectrum, at least in the area before it attenuates and dies out. Probably the biggest issue with 2.4 is that there are only three non-overlapping channels. So it's recommended leave your channel settings on automatic, your access points will typically work it out amongst themselves depending on how they're set up, but they'll typically work it out on which channel as the least utilized and adjust accordingly. The 5GHZ is broken up into the U-NII-1, the U-NII-2 and I guess the U-NII-2 extend it should be included as well as the U-NII-3. The two big ones are the U-NII-1 and the U-NII-3. And I mean big in the sense that the most number of devices will support these bands. The amazing thing about the 5 GHz is that it has so many channels. If you open up the whole thing for use, it's a total of 25 non-overlapping channels that can be utilized. This additional spectrum means that I can use wider channels rather than just the normal 20 MHz I can go 40 MHz or even 80 MHz wide and see gigabit speeds on my radios and for my clients. Available non-overlapping channels bayberry you can depend on the a the four down in the U-NII-1 and the four major ones and the U-NII-3 and there are way more channels, even with just those eight then the three you get in the 2.4 GHz. And one of the thing I'll add to this is because the 2.4 is a lower propagation signal, it goes further than the 5 GHz, which is a higher signal. It's going to die out at the same power level, is going to attenuate faster than the 2.4. You'll generally need to have more access points that are running 5 GHz than you would run in just 2.4. But we usually buy for the 5 GHz, we deploy with a 5 GHz in mind because it is the most often used. It's used by corporate devices rather than guests. Usually throw the guests on the 2.4 because there's just not a lot of spectrum so they're going to be slow but their guests, we designed for the 5 GHz and the distances between them. There are other bands being proposed, for example, the 60 GHz is available today. It's used by the 802.11 ad standard for Point-to-Point connections. We actually do have at Aruba, an access point called the AP-387, that's the model number that provides 60 GHz and 5GHz radio coverage. The 60 GHz is used as a backhaul only radio to be able to bridge between two buildings allowing you to connect buildings at a small campus that are up to a quarter mile away from each other. These 6 GHz is also proposed, this was proposed in 2020, the FCC approved the use of over 1200 MHz of channel space here. So remember those channels 1, 6, and 11 and the 2.4? That's the equivalent of the entire 2.4 spectrum that we use for years compared to the 6 GHz that's being opened up. I kind of alluded to this earlier, in the 2.4, you would generally stick to your 20 MHz channels because you only have three of them to be utilized. And if you go with a 40 MHz wide channel, you're basically you can only have one AP and your neighbors aren't going to be very happy with you. But in the 5 GHz, we have the opportunity to spread our channels out across multiple bounded channels. Bonding channels was a feature introduced in 802.11n, and it combines multiple channels into one broad channel. Not only do you get the 54 megabits from channel 1, and the 54 megabits here, but you also get the barrier space in between giving you a an estimated roughly around 150, 125 megabits of throughput, almost three times the amount of bandwidth of a single 20 MHz channel. Yeah, nonetheless, it's not really practical in the 2.4 and functional on the 5 gig because you have the amount of frequency to support it. With the newer standards not just a 802.11n, but ac/ax, they take that 40 MHz and they expand upon it into 80 and even 160 MHz channels. What that looks like is your U-NII-1 channels 36, 40, 44, and 48 that's the 20 MHz designation. 40 MHz you would do 36 plus or 44 plus or whatever and be able to utilize two 40 MHz channels. You could use two more over here in the U-NII-3 and you've got plenty of coverage to be able to repeat your APS in a bit of a honeycomb design, where you could say channel 36, we'll just stick with the 20 MHz channel 40, Channel 44. I could reuse channel 36 here and continue to build out this would be channel 44, this would be channel 40. And you can see how those channels can get some separation to minimize our co-channel interference. You can even go 80 MHz if you take advantage of the U-NII-2 bands and get at least three non-overlapping channels with 80 MHz. 160, it gets a little more tricky, and it's worth noting here that the U-NII-2 extended why a lot of countries don't necessarily support it, why a lot of devices do not necessarily support it, is because you need to extended competes with radar. The FCC says by law access points need to disable those channels and shift away from them within 30, 60 seconds of sensing any kind of radar, cause the radar gets precedence in that five gigahertz space. So, 80 MHz is generally the go to channel with that we would utilize, but in more congested areas, offices, conference rooms, classrooms, you might find that going with 40 MHz avoids a lot of co-channel interference that you might run into. After all, the wider the channel more opportunity you have to interfere with other devices. In the next video we're going to cover MIMO and co-channel interference. So thank you very much, I hope you guys enjoyed this video, I'll see you in the next one.
