How Wi-Fi Works

[andrenotgiant]

This is (good) SEO linkbait. Someone at Verizon got $10k to spend getting it created by saying it will boost organic search traffic to Verizon. Right now (during link-building phase) they keep the page completely separate from rest of site. Later, (after most links are created) they'll change it. Not sure whether the goal is just to generally build authority to VerizonInternet, or to get this URL ranking for wifi keywords. (Seems more likely the former.)

[srtjstjsj]

The promoted embed snippet actually points to a different URL: http://www.verizoninternet.com/bookmark/guides/how-wifi-work... which contains a bunch of site gunk for their "bookmark" blog, where they post a lot of content (and probably some net "neutrality" articles coming soon?)

[vxNsr]

Would it be accurate to assume this is gonna be used as ammo in the net neutrality debate of the next few weeks?

[srtjstjsj]

Are you saying they'll change the content later, and won't lose seojuice for that?

[ejo3]

That page probably cost a lot more than 10K.

[mrb]

As hatsunearu said, the radio modulation described is grossly incorrect. WiFi never uses 8-PSK (encoding 3 bits per symbol). 802.11n and 11ac encode 1/2/4/6/8 bits using a BPSK/QPSK/16-QAM/64-QAM/256-QAM symbol (256-QAM is for 11ac only). The modulation scheme is negotiated based on signal quality. Here is a quick reference: http://mcsindex.com/ (MCS = modulation coding scheme) On Linux you can find the MCS negotiated with "iw dev wlan0 link | grep -i mcs"

14 channels are defined in the 2.4GHz band. For example channel 6 is centered on 2437 MHz. Each channel is 20MHz wide and divided in 52 "data" subcarriers, each occupying a different frequency and spaced out by 312.5 kHz (52 × 312.5 kHz is less than 20 MHz because there are "control" subcarriers and additional spacing.) So 52 different symbols can be sent in parallel at the same time, which is what we call OFDM https://en.wikipedia.org/wiki/Orthogonal_frequency-division_... (basically, I'm simplifying!)

Remember this is for just 1 channel. So with 14 channels each composed of 52 subcarriers, we could have 728 symbols transmitted at the same time. If they are 256-QAM symbols that's basically 728 × 8 = 5824 bits being transmitted at the same time in the air. And they will all be received and demodulated independently. This high level of parallelism of OFDM is how WiFi can achieve very high throughput.

Then, with wide channels of 40 MHz, which basically aggregate two 20 MHz channels, we get a few more data subcarriers because we don't need as many control subcarriers so a few of them become used as data subcarriers. Hence a 40 MHz channel will have not 52 × 2 = 104 but actually 108 data subcarriers. And 802.11ac defines 80 MHz and 160 MHz channels with respectively 234 and 468 data subcarriers.

Let's calculate the maximum usable throughput of a single 802.11ac 160 MHz channel using 256-QAM modulation... It sends 468 symbols at the same time on 468 data subcarriers. Each symbol encodes 8 bits and takes in the best case 3.6us to be transmitted: 3.2us for the actual symbol + a short guard interval of 0.4us (the GI is normally 0.8us but can be a short GI of 0.4us if negotiated). The raw physical bitrate is:

1/3.6e-6 × 468 × 8 = 1.04 Gbit/s

However there is a mandatory error correction which is 5/6 in the best case so the actual usable bandwidth is:

1.04 × 5/6 = 866.67 Mbit/s

[azernik]

Note that, although the 2.4GHz spectrum is formally divided into 12-14 channels (depending on local regulations), these are very narrow channels; in practice there are only 3 non-overlapping 20MHz-wide channels. This is a small fraction of the width of the 5GHz band.

[dzhiurgis]

> 1.04 × 5/6 = 866.67 Mbit/s

This is bang on what most hardware is able to achieve.

I am curious Apple haven't jumped into 512-QAM yet. Partly stopped me from upgrading my fiber to 1Gb/s.

[princekolt]

"How Wi-Fi Works" --> 503 Service Unavailable

Seems about right.

[Kenji]

Hahaha, I was about to post just that. Made me laugh. Reminds me of my time at university... during breaks and boring lectures, WiFi was impossible to use because of the load. You could probably measure how boring a lecture is by recording WiFi latency and stability parameters.

[microwavecamera]

Verizon is trying to give you the authentic experience of how your WiFi works when you're on their network.

[dzhiurgis]

I've got that once it requested WebGL access and I've clicked "Never for this site". Refreshed and worked fine.

[Ajedi32]

Getting a 404 now. Any idea where the page went? (Here's an archive link: https://web.archive.org/web/20170723145452/http://www.verizo...)

[glenneroo]

Are you sure it was a 404? I'm getting a 503 (Service Temporarily Unavailable). Not that it really matters...

[sshanky]

This is beautiful, but probably still too complex for most of their customers. I wonder what their motive in putting this together was, as it must have been very expensive.

[crispyambulance]

Yeah, it is beautiful.

Unlike their overcomplicated phone plans and billing statements which are deliberately obscure and their customer service which they run like a 2-bit boiler room operation.

[joe5150]

it was nearly too complex for my pc! I had hardware acceleration disabled in Chrome and it completely pegged my CPU out. the animations barely worked until I re-enabled it, but then the page ran out of memory. I ended up having to look at it on my phone.

I'm not convinced the manipulable 3D modem rendered in-browser in realtime really added a lot of value for me, but it's pretty cool I guess.

[Rjevski]

Maybe the fact that as an internet provider it's their duty to explain how what they're selling works? Granted, "internet" doesn't mean Wi-Fi however their equipment includes a wireless access point so it's fair for them to provide documentation about how that works.

[notgood]

Just a reminder that Verizon its the biggest lobbyist against Net Neutrality[0] and if you do support it then it's probably wise to stay away from their services as far as possible.

[0] https://www.dailydot.com/layer8/lobbyists-net-neutrality-fcc...

[jonathanbull]

Mirror: http://webcache.googleusercontent.com/search?q=cache:http://...

[dotancohen]

These guys should do a followup "How Load Balancing Works".

[gruez]

google cache doesn't do the page justice. most of the value is in its visualizations.

[bdcravens]

Speaking of how wifi works, I learned something interesting about wifi and Verizon's partner in many things, Comcast: Last night I notified my home Internet acting funny, and learned that the admin interface for my Comcast router had username "admin", password "password". SMH.

[rayiner]

I mean, I just got a 10-gig router,[1] and the stock username/password was "ubnt"/"ubnt." It's always the installer's job to set up a new username/password.

[1] https://community.ubnt.com/t5/EdgeMAX-Stories/EdgeRouter-Inf...

[mnm2]

... which is "okay", since you can only access it (the admin web console) from within your wlan/lan (and not the internet) and ofc you can/should change it during setup

[greedo]

My ISP just set me up with gigE fiber. The installer was a bit clueless, didn't really want to provide me with the gateway IP for the router. Then I looked at the wifi settings; a 2.4Ghz and 5 Ghz setup, both with SSIDs that included the provider's name as a prefix. The password was a 9 digit password, all numerical...

I called the support line and got through quickly to an admin who could change the password and SSID for me (unless you pay for a public IP, the mgmt interface is locked down). I mentioned that having such a short, all numerical password would mean that any access point they set up would be trivial to crack. Just wardrive looking for similarly named access points, and you'd be able to jump on their connection in just a few minutes. He didn't seem to care, which is too bad.

[joshumax]

If you want to hear something else scary, I dumped the firmware on my modem a little while back and started exploring it:

https://twitter.com/joshumax/status/860712276717748225

[oskenso]

Also there was a time when Verizon's modem/router had generated passwords based on the SSID https://aruljohn.com/fios/

[JustSomeNobody]

Why can't it be "admin", "<random string of x number of nums chars etc>". Could even print it in the bottom of the device.

[peterwwillis]

It's bad practice to assume things are set up properly by someone else. This applies to more than just computers, fwiw.

[deepsun]

Does anyone know, if I'm on a WPA2-PSK wi-fi, do other devices that are also on the same network can "sniff" my traffic. For unprotected networks it's obvious, but what about protected?

[detaro]

Yes, if you know the PSK (=password) and can capture the initial handshake (which is easy, since you can just force-disconnect a client so it has to do a new one) you can decrypt it. (If I remember correctly, Wireshark has this built in, so you can try it for yourself if you are curious)

[GrayShade]

As far as I know, they can [1]. Once you're connected to the network you can sniff out everything from clients that connect after you.

The standard response to this is that you're safe since the eavesdropper needs to know the shared key. You can look into setting up WPA2-Enterprise if you're worried about that. FreeRADIUS doesn't seem particularly hard to configure.

[1] https://superuser.com/a/156969

[ryan-c]

Yes, other devices on the same network (using WPA2-PSK) can sniff your traffic. It's possible to prevent this with WPA2-Enterprise.

[pier25]

I had to disable the ad blocker to get the nice web gl graphics.

From a front end perspective I think this it's awesome. No so sure about the content though.

[arikrak]

I was looking at this and thought it looked nice but then my computer froze so maybe they overdid the 3D graphics a bit?

[dotancohen]

Try the Google cache, it now has the images but not the animations: http://webcache.googleusercontent.com/search?q=cache:http://...

[blocker_chain]

Lol I had the same thoughts

[hatsunearu]

the radio stuff is pretty wrong; one glaring one is that PSK is pretty much not used anymore, it's all OFDM.

[rayiner]

OFDM is orthogonal to PSK (hah). PSK is a modulation--a way of representing bits on a carrier wave. Another type of modulation is QAM. OFDM is a way of combining multiple sub-carriers (each modulated with PSK or QAM) into one signal in order to deal with multi-path distortion: https://www.csie.ntu.edu.tw/~hsinmu/courses/_media/wn_11fall....

[nvahalik]

Can someone explain the natural resonance of walls of talked about with regards to 5Ghz?

[Piccollo]

Why did CSS stop working

[founderguy]

Pretty sure that domain isn't owned by Verizon. Looks like an authorized seller creating content to try to build authority.

[andrenotgiant]

Looks like it is actually owned by Verizon, see email contact on WHOIS http://whois.domaintools.com/verizoninternet.com

[Web1Dollar]

wi-Fi is a best device! but is can work slow than wire. https://www.webhostingonedollar.com/ visit for getting more detail about hosting plan.

[KozmoNau7]

TL;DR: It doesn't.

[srtjstjsj]

website crashes chrome on windows after a few seconds.

[Yizahi]

In my experience it doesn't. My every attempt at improving this shit ends up in laying more wires everywhere.