How WiFi Works - Computerphile

Wow, I've never thought about the fact that Wi-Fi routers can only transmit one packet at a time to a single receiver. And the final example with two people using the same network and the person with a slow connection results in a slow connection for everyone -- it was just mindblowing!

guys stop posting interesting topics when i am currently watching something else which i am also interested in

I find it best to think about Energy required to receive a single bit. You can increase the transmitted Energy per Bit by either slowing it down, or increasing the Power.

Me: Yeah I know how wi-fi works Steve: Explains how wi-fi really works Me: Ok then, I'm glad I watched it 😄

Yeah, been a network engineer for a decade, studied and worked with multiple wireless data transmission technologies, and whenever anyone asks how wifi works, my stock response is "surprisingly well, when it's not working poorly". What they really want to know is "how can I fix my wifi speed", and most of the time my suggestion is to switch off the 2.4GHz radio in your router and just use the 5GHz one, because there's a lot more free channels so a better chance it will pick one that's not congested. And then if the reception is poor in the furthest reaches of the house, it's really time to invest in a better wifi solution. But at least now if they really want to know how wifi works, I can just point them to this video and save myself the 20 minute explanation!

This was fascinating. I had no idea about this aspect of wifi. I feel like this could use a better title than the generic "how wifi works". I almost didn't click on it because I thought it'd be another basics I already knew. This is more like "how your bad signal can slow everyone's wifi".

This is a great explainer! Do OFDM and MIMO next :)

One thing I didn't think of for a long while. There's usually only one radio receiver in a laptop/phone etc which can only listen to one channel at a time. Yet when you click the WiFi button it has to show you all the different base stations, many of which are on different channels. So your device retunes the radio for about a tenth of a second, per second through each of the different channels to find all the base stations. But while it's doing that, it misses packets on the channel it's actually connected to, so they have to be resent! That's why the announcement is every tenth of a second. So there's a bit of jitteriness on WiFi that you don't get with Ethernet.

Atari ST in the background? Thats some legit cred right there :)

~30 years in IT. Still learned a lot! Thanks for this video!

My favourite way of explaining these concepts is using food dye in water. The more dye, the more power. The further out from the origin point of the dye in the water, the further from the wifi router. Add lots of different food dye colors in represents interference from other devices, which you can overcome by using more power (putting more dye in), but eventually you're so saturated that it would take unreasonable amounts of dye to get something representing color, instead of a gross brown/black.

Great video as always. Please talk about DHT some time!

Very interesting video I'm now playing with the idea that all of my slow IoT objects in my house (Google Home Minis, Ikea outlets, etc.) should say use the 2.4Ghz network while my laptops and phone should be "isolated" on the 5Ghz network as the far away IoT objects might be slowing down the network?

this should have 10 million subs by now - love computerphile.

Thank you for explaining this. I had a few different experimental SSIDs being broadcast by my AP, each tied to a different VLAN. Now that I know that it's more-or-less radio pollution (because I'm not actively using those SSIDs), I've turned them off until I'm ready to resume experimentation.

Thanks for uploading this now, my networks exam is tomorrow! Good luck Imperial Computing second year, hope this video finds you

THANKS for providing all these videos!!!!

Love to see a video on wifi channels if it's not already done

Thank you for that video. I see a trend to use WiFi for everything. Don't use cable, it is something of the past, use WiFi, it is so convenient, event for the desktop of the secretary, that is sitting on their desk and will never move anywhere, even for that huge printer that obviously needs a cable for main power. You demonstrate clearly that using WiFi when it is not needed is a bad idea (i.e. slow)

Dr Steve is a national treasure