 is that Dan is not planning to thank the president. You'll notice the word again here at the end of the slide. But nonetheless, LifeEye has many subtle details that can be used to your benefit or harm you badly. I remind you of an invitation. Please photograph things, tweet things. For reasons I'm thinking, you can request from the organizing team or more of the team to please use the Fossager instead of the National Fossager, but other than please rebots. Right, hi guys. I'm Daniel and I'm going to go through a talk on why Wi-Fi is, like these days, much worse and of course getting worse and how you can improve it. So it's called making Wi-Fi great. I've got a background in software engineering, but then these days I think if you're interested in physics, if you're interested also in some of the theory behind these things, it can be quite useful. So often, like Wi-Fi, everywhere you'll be in a conference, you'll be in a café, you'll be trying to connect and you can't connect to an access point, you can't connect to your phone, you really have a lot of issues. And in everywhere. The only place pretty much you can get really good Wi-Fi is if you're not in a dense, open environment, so the countryside or somewhere kind of, perhaps with low density. So to understand why this is the case, you'll actually, the list of sources of issues pretty much starts with congestion. So there's so many sources of interference and even if they aren't at like the frequencies that are used in Wi-Fi, they still can interfere. Other kind of main issues really are the actual location of your access point or the access points you're trying to connect to and also the kind of distance therefore. And then there's some other perhaps less key items here, but certainly how these things are set up and also the actual OS as well. So if you have enterprise access point, typically you have a much more robust, much more fine-tuned OS stack including the radio firmware as well. Traffic also, so clearly, even you have traffic say, which is like a traffic that you expect, you also have a traffic which is background, like app like things like other kind of protocols, which are not really what you actually want to route. So those can of course take away radio time from the actual traffic you really want. So we'll later have a look at some of those things. So I'd say one of the main things here is if you have basic kind of like a home access point like an ASUS or whatever, typically these are optimized for consumers and so the kind of difference here is in enterprise hardware you actually typically separate the role of the access points from routing packets. Now one of the other kind of powerful features of enterprise kit typically is also you can plug it in anywhere. So you can plug in power into an Ethernet cable from anywhere and then inject it and run it from an Ethernet cable. So that's also obviously useful in your home environment as well since clearly then you can put your router somewhere in your home in a good location and get good signal strength and good behavior. Typically also when you have like many more APs also in enterprise kits you can also manage them like from a central location and therefore you can see the configuration if they're online, what OS they're running, the MAC addresses, IP addresses, whatever. And then also clearly the vendors who produce enterprise kit, they do a lot of validation. So they have like stable lab environments and RF environments where they can actually test in a very complete way which almost certainly home routers don't get that level of validation. I mean therefore also security is also something to consider as well. Often a lot of these like brands, Cisco, HP so forth, they're actually really expensive so you will almost never find anyone buying and having those at home. So really there's like a new, perhaps in the last 10 years a new kind of wave of devices from both Microchip and UBNT which actually is optimal kind of value for the features and for also the validation and the features that you also get. So moving on to one of the main sources of issues with like Wi-Fi is siting. So clearly if you have your AP nearer wall then you can actually get a lot of signal or loss through like say a concrete wall or like a hard breaks for example here. So when you place your AP in your house or in your environment you really also must consider these scenarios. So putting it perhaps somewhere more centrally where the actual angle for clients wouldn't be through so much kind of break or concrete would help a lot. And of course clearly there wouldn't necessarily be a table or like a fibre point for you to plug it in but that's where if you have power over Ethernet or you also separate your radios and access points therefore from your router then you can like mount it for example on the ceiling over here and so also that's an important thing as well. Now one of the actual reason why this distance is one of the key things simply is the further you get away from your access point you get a like a division like a fraction of the energy from your clients and from your access point. So also this also as well works for frequencies so if you're using a 5 gigahertz access point or radio then the signal is half the actual energy like for a given distance than the 2 gigahertz radio. So you also must take into account that you actually get weaker signals as you're going higher in frequency. So even if say you have a 5 gigahertz access point you actually may get a lot more attenuation. But then also... Yes exactly so the actual noise floor is really one of the key things. So if I move on to the signal to noise ratio so if you actually look at the spectrum here what you'll find is you'll find like a level of background noise here which is it's going to lower band here like minus 96 dBm here and then in this case at like 5 gigahertz channel 36 you're seeing like about 65 dBm signal here and so when there's more attenuation with higher frequencies like say at like 5 gigahertz what you'll find is you'll generally have a lower noise floor because other sources of interference from your neighbors and so are also attenuated better which gives you an advantage. And so that's also why you can also use like wider channels. So channel width is also something you can adjust when you're setting up your access points, the radios. Yep so normally much of the like our consumer radios and access points are 100 milliwatts transmit that generally is the regulatory limit. Question here. 5 gigahertz, yeah channel 36, yeah. Because actually so you actually haven't got that much channel like that 80 megahertz channel width possible at 2 gigahertz on Wi-Fi. And that's pretty powerful because at 2.4 the standard is 42 milliwatts so it's like probably get something at 138 at least in Europe that would be about 2.4 gigahertz. Yes, correct, yeah exactly, yeah. That certainly would be violating the limits of 100 milliwatts really which would be the limits at 2 gigahertz. Anyway so how do you actually translate this signal to the ratio to the actual throughput that you can achieve with your devices? So what actually happens is when your AP is talking to your devices the actual signal noise ratio and channel width dictates the maximum speed of data transfer so the actual fire rate. So what you see is here we have a signal noise ratio of 32 decibels here so they can noise flow to the actual signal strength here and that translates in this table here to a certain modulation coding scheme MTS-7 which is a certain kind of strategy for encoding signals and so 11ac 80 megahertz channel width so we know it's MTS-7. So how does MTS-7 translate to the actual speed that you'll get over the air? So there's a second table in the standards which says for MTS-7 you'll use 64 cam modulation and at 80 megahertz with a short guard interval you'll get a 325 megabits a second raw fire rate so maybe you'll see perhaps half of that in practice but so this illustrates how the actual signal noise ratio and channel width on your Wi-Fi. Now, so if you select, yeah, so later we were saying so earlier we were saying that 5 gigahertz you have more link headroom for your signals but then why did the channel, the more interference with other channels so if you have voice over IP phones or if you're just browsing or something like that in certain environments like in an internet kiosk or in simpler scenarios then it definitely makes sense to choose narrow channels so in this case in this conference Wi-Fi channel width has been selected for 40 megahertz at like 5 gigahertz and 20 at 2 gigahertz so there isn't any wider channels like 40 megahertz at like 2 gigahertz because of too much congestion so really what you want to do when you're putting your router at home is you want to conduct a spectral scan to understand what interference is already there what other access points are transmitting and so what channel can you select what you can do is of course you can have a very poor approximation using an app on your phone and here what you will see is in a well defined environment typically all access points at like 2 gigahertz will be on channels 1, 6 and 11 and so if you choose a channel which is in between these and overlaps with say like channels 1 and 3 then you'll get a lot of co-channel interference so at home if you select channel 1, 6 or 11 you'll typically get better behavior obviously you might want to do a scan because the existing APs may be on other channels typically let's see so typically if you enable auto channel selection on your access points it'll actually select something that has minimal RF energy which perhaps an average could be like channel 8 or 9 or something like that or in this case that one's in fact 2 channels wide so yeah 8 or 9 but then you'll get interference from many more access points in fact from 8 access points if any of these transmits then it'll interfere with your access points so better choosing say 1 or 6 or 11 and also turning off the automatic selection one just went deeper into why is it the fact that they if you have a group on the same channel each of them have to interfere though there are a smaller number of channels that's fine but are they understand about the access points that do this because they're now landing yeah well so one of the kind of things is in the .11 standards when you have let's see when you're sharing channels with other APs you enable something called RTS and CTS and so when one of your devices wants to then transmit it then sends a request to the access point which then broadcasts a message to all devices actually on that channel and also other SSIDs as well saying a device wants to cross transmit now allow a certain time window so all devices on that channel will then allow that device then to transmit and therefore you have much better sharing of channels sorry of like time on that channel and that definitely scales much better than if you either don't enable the RTS CTS feature or if you are in between channels basically and then have less clear communication with all the other devices on those existing APs so that's relatively straightforward so antennas so typically you will see some routers having dual band antennas and how it works interestingly is you have a loading coil in the middle and then one part of the antenna which is optimised for a certain frequency this is a quarter of the wavelength here and then this is a second different wavelength here and so you'll how it looks like on a graph is that you will see the the antenna resonates at two different frequencies here and so that's how you have multiple multi-band antennas just in case you were curious but then always there's a bit of a trade-off so you lose efficiency at other frequencies so the routers that you see in the market with like three antennas those have much worse behaviour than having say internal antennas which are not dual band so obviously the routers that you have in the market they ask us with the three big antennas it looks really powerful, it feels good but then actually it's almost certainly much worse what you can do is the actual spacing of the antennas is more than half the wavelength so you've got to make sure they're spaced out but then they're normally fixed so that's fine and then the other thing you can do is you can arrange them in an orthogonal kind of way which you never actually see so I couldn't get a picture I couldn't find a picture online to show you but if you imagine these are the three antennas at the back of your router one kind of back and one sideways then you actually have you then polarise in different orientations the signal which then allows you to to communicate with say devices which in fact have perhaps only one antenna in one kind of axis so that definitely improves the communication there so in fact we can see this in enterprise APs because here these are arranged in different axes so yeah and here we have we have I think four antennas two are five gigahertz and two are two gigahertz and they've resonated across different frequencies notably the antennas they aren't sticking out looking really powerful or anything they're just on board which makes things simple really and there isn't any real benefit in having them off-board if they are say like just omnidirectional so one of the other key issues in wifi is the hidden node issue so what you have is say you have an access point then you have like two small say like phones or laptops with different ends like different areas and typically like clients are 30 mW so an access point maybe 100 mW maybe higher at like five gigahertz so clients X and Z can't hear each other right five minutes okay so X and Z can't hear each other so there's actually a protocol here earlier I mentioned the RTS and CTS so you can enable that and even you can tune it enable it for frames reduced for small packets also you can actually you can filter out background traffic by isolating each of the radios the like two gigahertz radio and five gigahertz radio on separate bridge ports this is all kind of going to be online anyway so you can look at this later there's some details which we can admit so what do I use actually I'm about to use anyway a new microtik half AC2 it's actually very very similar to this one here and so this is one of the existing ones and actually quite small so it's not really big or fancy or flashy but then actually they are very very practical very very configurable the new model which is available soon it actually can route it to gigabits a second because it has like dual an internal pathway with like two one gig links to the CPU actually which is like the normal capacity so some more information here you can kind of look through one of the key things when you're buying a router is or access point is having an OS which is then updated on a regular basis and has like security updates and so forth many consumer ones don't actually like they have maybe six months or a year of updates and then that's it so it's better to have something which is a long term so actually this one is about actually $104 and it's available from our local microtik distributor Aldegas Networks so we're going on here you can put up your hands very good so this is my recipe for configuration later you can have a look through the F-Online so they need to go through this there isn't time and then I can do a quick demo of doing a live spectral scan to show you how to optimally select the channels so let me just do this okay let's just log in here okay I need to make sure I'm on the 5 gigahertz channel here yep good okay one second okay so now it's running a like a heat map here and we can see in fact from like 2.412 is like channel 1 2.472 is channel 11 here so you can see how much RF energy there is and here this environment is very very noisy but generally speaking this is channel 6 here so you can see white is the most strongest signal strength greater than minus 35 dB 11 is also more congested in here it's kind of hard to say but maybe there's less congestion here so you of course might say channel 1 so that was a quick demonstration on how to assess yeah exactly in SSH you can also do that with other kind of approaches with the GUI as well so here's a little kind of summary of my tips on how to tune your Wi-Fi and also deploy a good like good network here and yep finally I didn't cover things like spectral regulation or security or new gigahertz 11x equipment you can get this online it's this URL here drop me a note if you have any questions or are like doing anything interesting with Wi-Fi yep and any questions any questions