Wi-Fi Glossary and Terminology - Jargon Buster

hello my name is gary sims and this is gary explains now i'm preparing a series of videos about different aspects of wi-fi so i'm talking about you know kind of wi-fi six and mesh networks and kind of wi-fi extenders the kind of real life throughput you get through all those things and so on and i was actually going to make the first video today about a wi-fi extender here is a simple wi-fi extender and i was going to talk about how they actually work what they achieve where you need to put it and so on but in making that video i discovered i was explaining lots of terminology and i thought to myself it's probably not best to explain the terminology in this video you bet if i had a separate video which i could refer back to in all my wi-fi videos about the terminology five gigahertz qam 64 qam and error encoding and you know channels and 802.11 ax all these things that kind of we talk about and maybe we're not sure exactly about what all of them mean so this video is about looking at all the different terminology of wi-fi trying to understand what it all means so that we have a good grounding for when we want to start talking about mesh networks and wi-fi 6 and all that other great stuff that i've got coming down the pipeline so if you want to find out more please let me explain [Music] okay so let's get cracking what does wi-fi stand for wi-fi is the brand name and trademark of the wi-fi alliance a consortium of companies that oversee the various wi-fi standards the y part stands for wireless good and the well the five part stands for fidelity you know hi-fi wi-fi but actually it turns out the wi-fi doesn't actually stand for anything but with the original brand then when it was launched there was the tagline the standard for wireless fidelity so what is wi-fi wi-fi is the wireless version of ethernet and ethernet of course is what we use where we've got you know switches and hubs and routers and lan cables we plug them all in connecting with our pcs together ethernet is designed defined in 802.3 and wi-fi is defined by 802.11 or a whole series of standards which is why you read about i 802.11a or 802.11.n and so on and we'll speak more about those in a minute ethernet is often referred to as a lan local area network that means it's in your building in your house and therefore wi-fi is often referred to as a w lan a wireless local area network and then just for the completeness of your education once network packets leave your office building your home whatever then they go out onto a wan a wide area network not a local area network in other words they go out onto the internet so we talked about 802.11 and look at all the different standards here uh 802.11.b 1999 2.4 gigahertz maximum theoretical speed up to 22 megabits a second 802.11.a that was 1999 as well 5 gigahertz greater speed 54 megabits a second then we had g n ac a second wave of ac then we had a x and we've also now got ax wi-fi six e now obviously those namings off are they just trip off the tongue you know as you're down the shops you know oh i've got an 802.11.ac router so recently they've been rebranded wi-fi six and then retrospectively wi-fi five wi-fi four wi-fi three right do you have one and wi-fi 6e is the same as wi-fi six but it's into the six gigahertz uh frequency range which in the moment america has the usa has opened up not necessarily been opened up in other parts of the world yet so the rest of the world 2.4 gigahertz and 5 gigahertz quoting loads of figures there down the right hand side 600 megabits a second 1300 megabits a second uh now all those speeds are theoretical and we'll talk more about that later and they do depend on a whole bunch of things like the number of streams and the modulation and the channels and all this kind of stuff and we'll talk more about that later and you may disagree with some of those numbers that's fine because they're all just theoretical anyway they don't really make any real world uh reality we'll talk more about that in a minute okay now the first thing you have to understand about wi-fi and why it really is a bit of a mess is that we're talking about 2.4 gigahertz five gigahertz and six gigahertz and those three frequencies can't talk to each other which is obvious from a law of physics you know a device is transmitting at 2.4 gigahertz it can't be picked up on a device that's listening at five gigahertz so you've got these 2.4 gigahertz only standard 802.11b and 802.11g wi-fi one and wi-fi three then you've got these five gigahertz only ones that's 802.11.a and 11ac wi-fi 2 and wi-fi 5 then you've got wi-fi 6e which is in 6 gigahertz it's another whole new frequency and then you've got some standards that apply to both so you've got 2.4 gigahertz and 5 gigahertz in 802.11.n and in axo wi-fi 4 and wi-fi 6. so first of all you might get yourself a shiny new smartphone you might yourself get a new laptop and actually it turns out that you've got a 2.4 gigahertz wi-fi you know 80211g router in your house and your new device supports five gigabytes but they're not going to talk to each other so that you may read in some things about dual band so dual band often refers to devices that can work on both 2.4 and five gigahertz if you're into wi-fi six or you've got wi-fi for then you kind of are expecting it to work on both now tri-band doesn't refer to two point four five and six at the moment it refers to 2.4 and two regions of the five gigahertz range and we'll talk more about this when i come into mesh networking because you might get tri-band mesh network and we'll talk more about then but this is going to get more complicated when we get six gigahertz support are we gonna talk about you know four band or are they gonna replace the word tri-band to include six and get rid of the two it's gonna be complicated so you really have to get your head around this there is a different radio frequency they're not compatible they can't talk to each other and some of them are only tied to that frequency and some of them work across different frequencies so hopefully we can kind of sort out that mess but really 802.11n and ax are the way to go because at least you're kind of getting support for both frequencies built into the devices so let's do a pop quiz i've taken these numbers actually from actual devices so i've got one device here that says it supports 802.11 bgn what what does that mean i'll give you the answers in a minute you try and answer so i've got another device it's 8011 a n c so the letters are different except for the n is common what what does that mean now the iphone 12 for example supports wi-fi six 802.11 ax what does that mean what does it does it support 80 to 11b does it does do that and i went back to samsung's website and the galaxy s8 supports 80 to 11 abg n ac what does that mean what what supported more so let's have a look at the answers hopefully you've got the answers now from my previous slide so if it supports bgn it means it's only 2.4 gigahertz it supports 11b 11g and 11n but without the 5 gigahertz hertz parts of uh 11 n okay so it's only the 2.4 gig now if you've got an 80211 anc device that means it's 5 gigahertz only it supports 80 to 11a 11 n but only the 5 gigahertz part and 80211 ac so there's no 2.4 gigahertz around now the iphone 12 supports wi-fi 6 8 11 ax what does that mean it means it supports everything it's got 2.4 gigahertz and 5 gigahertz it covers a b g n ac and ax so that's great so as i said earlier if you are getting into wi-fi six at least you know you're going to kind of get everything uh in the box and the galaxy s8 of course is a few years old now so it was doing pretty well for its time 802.11 a b g n a c that means it supports 2.4 gigahertz b g and n it also supports five gigahertz a n and s a c so let's say the n is common and ac will be the fastest because it's the fastest version of what you get for five gigahertz but basically it will connect to just about anything else at the time of course now since then we've had we've had ax wi-fi six added so i how did you do in that quiz i hope you did well do tell me in the comments below to tell me whether you're able to work all that out so which is better 2.4 gigahertz or 5 gigahertz this is one of the questions we you'd have to ask yourself as you're kind of thinking about wi-fi equipment and and what you're buying so 2.4 gigahertz wi-fi is better at covering larger areas and that's because at that frequency the radio waves can go through solid objects more easily so you know if you build yourself a superman led lined room it's not gonna go outside of that but if you're talking about walls if you talk about partitions then 2.4 gigahertz will do better but five gigahertz is faster so you can get more data into a five gigahertz signal and so you're going to get greater speeds but because it's five gigahertz you're gonna get a smaller coverage uh because it passes through a solid object much much harder they bounce off rather than pass through or get dispersed and so the advantage of course of dual band devices and dual band access points is you can switch between the two frequencies so if you've got an access point that's giving you 2.4 wi-fi network and a 5 gigahertz wi-fi then you can connect to the different ones if you walk further away from it maybe you can switch to the 2.4 and still get connection but you're going to drop your speed now this is also important to know because i've been reading around on kind of you know websites like amazon or whatever and reading people who've bought routers and they've complained oh this this ac router doesn't go nowhere near as far as my old 2.4 gigahertz which is rubbish and they give it two stars and it's because they don't realize of course five gigahertz doesn't go as far as two points the nature of physics you can change the laws of physics he says in his very bad scottish scotty accent so that's a point to remember they are different and they have got different um kind of qualities so don't go around putting two styles on amazon websites because you didn't understand that of course ac is never going to go as far as you know a an n or a b or a g signal now the frequency bands so we're talking about 2.4 gigahertz five gigahertz are split into little slices little groups of frequencies next to each other and they're called channels now 2.4 gigahertz wi-fi covers around about 100 megahertz depends exactly what country you're in and those channels are five megahertz wide so you go great five megahertz wide that's really good but the thing about 2.4 gigahertz wi-fi for b and g is that they transmit on 20 22 megahertz bandwidth so therefore they overlap each other so if you're in channel one and you've got another piece of wire equipment in channel three then they're gonna clash because that's only 15 megahertz between them so really you've actually only got three channels that can be used without overlapping channels one six and 11. you might have 13 in in some countries so um most access points thankfully will configure to that automatically so that when they kind of have a look around they'll see if there's another device broadcasting on channel 6 nearby and it will switch to channel 11 but wi-fi 2.6 gigahertz is bad in that sense there's only three channels and so therefore we can get a lot of congestion and more than that you've also got wi-fi uh sorry bluetooth appears in the same channel range so here's that picture you can see here's channel one here's channel two channel three and they're only five so really only one and then six kind of don't have this overlapping clash that the other ones the other ones do so one three uh and eleven and also you can get bluetooth snack in here as well completely different protocol completely different system but it occupies the airwaves so you might get you know you'll get interference and things won't go as far as they should do microwave ovens also operate at 2.4 gigahertz as well baby monitors so you can actually get a lot of stuff going on in this frequency range and it can kind of clog up your 2.4 gigahertz uh you know airwaves now five gigahertz uses 25 channels that are spaced 20 megahertz apart so there's 25 channels now but to choose between not just three and they are spaced properly apart in fact if you look at the diagram here you can actually see that it's channel 36 and 40 well actually they are that's four lots of you know five five megahertz so they are still five megahertz apart but we only use 36 and then 40 44 and then 48 so in reality they're 20 megahertz apart and there's no overlapping so that gives us a lot more range when we're talking about any congestion we're getting five gigahertz the other people can have their devices nearby and it's not going to be so crowded and you'll be your router your devices we've got to pick a nice clean channel that's not going to get any other signals going on top of course that means you'll get better throughput ultimately of course that's the aim now if you look at these channels here we've got four of them like i said all spaced uh nicely apart if you look at this next row here there's actually 40 megahertz channels so what's actually happening here is that these two channels 100 and 104 are being joined together and then this 108 112 are being joined together of course you're basically therefore using two channels so you get double the throughput so that's great so 40 megahertz and even the possibility of 80 megahertz was added into later versions of wi-fi particularly in the five gigahertz uh channel and in fact even 160 megahertz is a thing nowadays taking up all these channels here i did some testing on that until you write that back in the very last slide in fact so you can actually join together and every time you add in more channels you increase the uh you increase the throughput increase the speed which is great so a wider channel gives you the greater possibility of throughput but a couple of things it does reduce the number of overlapping channels so we were starting with 25 hooray great and then suddenly we've joined them all together as you know eight uh 160 megahertz channels or eight eight little channels joined together to be one where now you've only got three so you've gone back to the days of you know wi-fi at 2.4 gigahertz so if you've got busy area you've got neighbors if you're in an apartment in blocks then you're gonna you're gonna get this problem that neighbors might be using the same channels and therefore it's not gonna work and also an interesting thing every time you increase the width of the channel you do actually increase the noise and when you've got greater noise that means the signals can't get through which means therefore you get errors and so actually you reduce the throughput so actually there's a bit of a balancing act going on between which is better a wider channel or with a what you know more noise or if you've got good signals then you're okay but if it's bouncing around if it's going through a wall then maybe that's gonna be noisier and you can actually reduce your throughput so that the router and your device negotiate we'll talk more about this in a minute to try to get the best throughput now there's a really complicated subject which we'll just touch on but you need to know it because you will see these terms now radio waves of course are they're analog they're radio waves and wi-fi of course is digital wi-fi is not uh analog so we need a way of converting digital information to transmit it over a radio and then convert it back into digital information so modulation is basically digital to analog conversion trying carrying in a radio wave and then converting it back to digital again if you remember the old old days of kind of modems you know when you dial up modems or maybe you've watched an old an old movie you know and you've seen um you know young sheldon or whatever you've watched and you can hear the old dude that's my impression of it thank you thank you thank you thank you everybody now if you think about that that's basically doing analog to digital conversion digital analog conversion by using audible frequency so it's taking each tone and it's making it mean something now modern day modulation is way way more complex than that you can multiply that complexity by a million or probably even more now there are different ways of modulating the signal to carry that digital information phase shift keying psk both in its binary method and other methods are used by wi-fi and also so is clam so let's just talk a little bit about quan for a second now won't go too much into it but it's a very sophisticated method of dividing up the the segment of four different areas we won't go into it much but the lower the quan the higher the robustness because you're trying to get less data into that signal so you get lower throughput but it it might survive more the journey from you know the transmitter to to the receiver so 16 qam on a 20 megahertz channel might give you 28.9 megabits per second as the theoretical maximum again remember we'll talk about theoretical maximums in a minute whereas 256 clams so the same signal same 20 megahertz but you're just modulating that signal differently you can get up to 86.7 megabits per second so you see the difference so how you modulate that signal can do that digital to analog conversion the way you fiddle with that radio wave can actually give you a greater throughput and in fact 124 crap cram on 160 megahertz channel can reach over one gigabit per second and that's when you get now into wi-fi six and i've even heard that in wi-fi seven there's going to be 409 six cram 4k clam so you can imagine the kind of speeds they're trying to get into those but it's also worth noting that inside this modulation system they also have to include uh error correction forward error correction that can cope with corrupt bits so as the packets come along you check to see whether everything is as it should be you've got extra bits to repair it so a one two forward error correction has a maximum speed of 28.9 but if you don't need the error correction if the signal is good and clean without that noise then you actually get away with a three four three four means that you put in one bit after every three bits rather than one bit after every bit which is the one two and then you can get a maximum speed of 43.3 because more of the bits are being used for actual data and not being used for error correction that's still using 16 clams so clean signals at high clams high channel widths without too much error correction is going to get you the best the best speeds now obviously high noise interference distance will cause ascendant receiver to switch to lower modulation method and use more error correction bits now let's quickly touch on uh mimo memo how do you mount that mimo mimo multiple in and multiple output a stream is what actually carries the wi-fi data between your device and your router now in wi-fi 4 we had the idea of multiple streams so really two radios being used at the same time to split your data into two paths and send one of it down one channel and one of it down another channel and the top theoretical speed of the router is determined by the speed of the stream multiplied by the number of streams so very crudely the number of antennas you had the better it was although nowadays that isn't actually such a good uh measure and it's also worth noting that mimo allows also applies to 4g and 5g but it's not shared with the wi-fi memo so don't think if it says 4g 4 4 x 4 memo that that also applies to your wi-fi there'll be different radio systems in whatever device it is that you're using now the first n routers had one stream let's say with a single band 2.4 gigahertz so therefore it could achieve 150 megabits a second have you got four streams in your router then you can get four times 150 megabits a second so now you suddenly got a 600 megabits a second throughput so a huge change there and when we get to wi-fi five that has a single stream speed of 433 megabits a second so a single ac stream was actually the equivalent of three streams back in 802.11n so that's quite a difference as well and when you hear them talking about an ac 1900 router well that might mean it uses three five gigahertz streams for a total of 1 300 megabits a second four tire three times 433 plus also two type four times 2.4 gigahertz in the end streams for another 600 mega bits per second so when you add those together you get 1 900 megabits a second but here's the point your single device your smartphone your laptop can't use all of that okay so this is where we're seeing it's for the overall throughput if you've got two laptops a laptop and a smartphone a laptop a smartphone and you know an amazon fire stick or a google chrome cars and they're all talking over the network they can all talk down these different things and the there are different radios different antennas inside the wi-fi uh router so it can handle them all coming in at the same time and that's different to what you're gonna get from just one device so if you are shopping for a router don't see the big number you know 1900 2400 whatever ax 2400 now went to wi-fi says oh this is great my my new iphone is going to go so fast no no it won't it's the overall throughput because it's talking about if you've got things happening in the 2.4 gigahertz band and in the 5 gigahertz band at the same time now there are some devices with special sdks you can use them to actually do this kind of thing but your average normal device is not going to start putting things out across two lots of you know different frequency bands two point four and five gear and multiple streams not gonna happen okay so just be aware of that so a four x four four times four memo mimo router supports four streams that's four x because four x four is because it's four for ascending and four for receiving now a smartphone like you know let's say the latest uh side you know iphone or something or a laptop might be two times two mimo so to get the maximum speed the app must start two parallel downloads to get two times if it just does one download it will be limited to one stream the api the the android whatever the sdk can't suddenly split your data into two streams you can split the data into two series an app developer you can start off two streams and start downloading them and you get that increased throughput or if you're using a system that sends requests over multiple streams uh peer-to-peer kind of stuff then that's gonna work but if you're just doing a download one download then it's gonna be limited to that one stream okay and i did a lot of testing on this and this is going to be something of some of the future videos about showing the difference performance you get one stream two streams and the fact you have to start multiple multiple downloads to get that to actually get that throughput okay so we're almost coming towards the end well done for sticking through to here worth mentioning this thing here you may hear about mcs the modulation and coding schemes very important when the client device and the access point chat together they negotiate the speed of the connection okay and they might you know one might transmit something towards the other if it doesn't get the response it goes oh that didn't work very well i'll change to a different coding scheme to a different modulation see if that see if that works and this is called the mcs and there's a big table that you can see that um it shows you all the different mcs uh variations and it's big i'll show you in fact show it to you here look at that there you go that's absolutely huge and that just tells you all the different things that can happen across all of the different types of encodings and the different wi-fi standards and the different uh you know forward error correction oh it's just it's just massive let's have a look at a tinier one this is for just a part of what you can get for wi-fi five so down the left here we have the mcs index and notice it's naught through to nine and then north through to nine again in fact the table goes on beyond this because this first one is about the number of streams here's one one stream and here's when you get to two streams okay so you can see what happens and here's the different clams that we were talking about what clam level are they connecting to okay and then also across here which width of the channel 20 megahertz 40 megahertz 80 megahertz 160 megahertz and then you can see these are the theoretical different speeds that can be achieved if you connect at these different types of connections now what i'm going to show you here is here is on the mac you can actually get that information so look at this here it's saying that it's connected to channel 36 over five gigahertz uh and with an 18 megahertz channel connection okay so that's told me what the two devices have negotiated and it says therefore it's a 1200 megabits a second it's using wi-fi six eight to eleven dot ax and the mcs index would be eleven so i can go and look that up in that big table and find all these parameters in there and it's using two uh two times two uh memo that's what it's doing so there you go now that's not that information is not so easy to get hold of another operating system the mac gives it to you there quite easily which is why i have i've shown you okay a couple of last slides now the physical layer defines how many ones and zeros can be sent over the wireless link okay and so that's when you talk about these theoretical speeds of you know over one gigabit but although not all those ones and there's actual data that you want to send some of them as i've said include that error correction code so you can see for example that by changing the error correction which are additional ones and zeros and you're changing that data you can send and then on top of that you've got things like tcp that itself sends different you know acknowledgements and so on back and forth so there's extra data flowing back that's not your data okay and then there are other protocol overheads for example if you were downloading something over http then there's going to be some stuff that goes on there so noise interference error correction tcp overheads all means that the actual speeds that you get in real life are much lower than all those big numbers that they quote on the side of the box so don't i want to warn you because i will it's a disappointment when you say oh look 1900 this is going to be great is not okay so you have to and we talk more about this in other videos you have to understand that the real world data rates are much lower so here's an example using wi-fi 6 with a huawei p40 clicks to an honor router 3 using two times two memo which was an mcs of nine you can look that up in that table if you want to just google it mcs table which means it had a theoretical physical data connection speed of 1921 megabits a second that's five gigahertz 160 megahertz channel with 256 qam what did i get i got 902 megabits a second so 1921 all the way down to 902 that's just 40 7 of the theoretical speed okay so always take these physical theoretical numbers with a pinch of salt and i cover the more about this in later videos wi-fi six mesh networks and so on okay that's it this is probably quite a long video already so i won't keep you any longer you know the drill like and subscribe et cetera et cetera see you in the next one [Music] you

Channel: Gary Explains

Views: 18,361

Keywords: Gary Explains, Tech, Explanation, Tutorial, Wi-Fi, Wi-Fi 5, Wi-Fi 6, MIMO, 2x2 MIMO, 802.11a, 802.11b, 802.11g, 802.11n, 802.11ac, 2.4GHz, 2.4 GHz, 5 GHz, 5GHz, 2.4 GHz Wi-Fi, 5 GHz Wi-fi, Wi-fi jargon buster, Wi-Fi Tutorial, Wi-Fi Explained, QAM, Wi-Fi Channels, 40 MHz channel, 80 MHz Channel, Wi-Fi Glossary, Wi-Fi Terminology

Id: XEhjHaijPPg

Length: 28min 6sec (1686 seconds)

Published: Thu Apr 01 2021