How does wifi work?

[Timvandervinne]

i am in high school now and if i want to pass the exam i need to do a presentation about wifi, but i dont know much about it a little but not much. can someone explain wifi in a maner that 14/15 year old kids can understand it because that is the audience to wich i am presenting. and can someone explain what happens to my messages or my foto's that i send after my router recieves them

[ShadowCaptain]

4 minutes ago, Timvandervinne said:

SNIP

Are you not taught this in class? you should pay attention

also this is easily googleable and you can read all abuot it - i just googled it and its right there in black and white.... no offence, but we are not here to do your homework

Here

 

http://www.scientificamerican.com/article/how-does-wi-fi-work/

[WhiteWolf117]

everything is 1s and 0s it uses radio waves the send the 1s and 0s crestś of the waves being 1s (i think) troughs being 0s

[vanished]

Its a wireless communication like radio (am/FM), Bluetooth, or your cellphone.  Or gamma rays, or the light you see.  For more detail, see https://en.m.wikipedia.org/wiki/Wi-Fi

[Timvandervinne]

Just now, ShadowCaptain said:

Are you not taught this in class? you should pay attention

also this is easily googleable and you can read all abuot it - i just googled it and its right there in black and white.... no offence, but we are not here to do your homework

Here

 

http://www.scientificamerican.com/article/how-does-wi-fi-work/

no i am not thaught about wifi in class  but when i google it does explain it to me but 14/15 year olds will never get it.

[KezzaMcFezza]

Wifi works by information being sent out of the computer through a antenna or something. It is broken down into packets for encryption and the packets will travel to any other wifi antenna around. Rage makes a difference as the packets sent out are in a spherand have to be dispersed out more. Meaning the closer the signal is the better. Then when it is received by the other computer the packets are assembled back into what a computer reads and calls data.

 

Maybe this might help

[ShadowCaptain]

Just now, Timvandervinne said:

no i am not thaught about wifi in class  but when i google it does explain it to me but 14/15 year olds will never get it.

You are not being taught about wifi.. so why do you have to do an exam/presentation on wifi? thats weird

You should be able to understand wikipedia articles no problem, at least to some degree

come back and ask questions if you get stuck

[Glenwing]

11 minutes ago, Timvandervinne said:

i am in high school now and if i want to pass the exam i need to do a presentation about wifi, but i dont know much about it a little but not much. can someone explain wifi in a maner that 14/15 year old kids can understand it because that is the audience to wich i am presenting. and can someone explain what happens to my messages or my foto's that i send after my router recieves them

WiFi, like other forms of wireless communication (i.e. radio), is based on light. You can imagine sending digital information over a distance without wires by using a flashlight and flickering it on and off; on means 1 and off means 0. WiFi just does this with a wavelength of light which is outside the range of light visible to the human eye, like a dog whistle makes sound outside the audible range of the human ear.

 

The wavelength of light used by WiFi is much shorter than the one used by radio, it's much closer to microwave-class wavelength (which is where the concern about WiFi causing cancer comes from, though this has never been demonstrated yet). It's also why microwave ovens interfere with WiFi, they flood that spectrum with noise (in addition to the fact that they form a faraday cage, so WFi signals cannot pass directly through them).

[Moonzy]

17 minutes ago, Timvandervinne said:

i am in high school now and if i want to pass the exam i need to do a presentation about wifi, but i dont know much about it a little but not much. can someone explain wifi in a maner that 14/15 year old kids can understand it because that is the audience to wich i am presenting. and can someone explain what happens to my messages or my foto's that i send after my router recieves them

hmm...

its like two person talking to each other

theres a transmitter and a receiver on both ends (mouth and ears)

if there are more people talking, the harder it is to hear what the one you're supposed to hear is talking about (interference)

 

but wifi doesnt use sound waves, it uses electromagnetic waves

and they dont communicate analogously like human do, they communicate with 1s and 0s

 

additional info:

like humans, wifi can only communicate to one person at a time, each person take turn to talk

[Timvandervinne]

1 minute ago, ShadowCaptain said:

You are not being taught about wifi.. so why do you have to do an exam/presentation on wifi? thats weird

You should be able to understand wikipedia articles no problem, at least to some degree

come back and ask questions if you get stuck

yes it was my choise to do a presentation about wifi, and i do understand it but my classmates are pretty stupid, not being cocky but i am smarter than anyone in my class

[Razor512]

If you need a very simplified explanation of how the data is transmitted, this video is about as simple as you can get; useful for when you get to the 2 most popular aspects of WiFi in your presentation.

 

 

 

 

 

If you need to extend the time of the presentation, you can get into the software aspects of it, and focus on why you never get the advertised throughput from your WiFi router.

 

This will open the door for you to touch on why you normally only get around 50-60% of the PHY rate for pretty much all of the WiFI standards.

You can explain how WiFi is still very much a collision domain which relies heavily on control frames to effectively share the air time and minimize the negative impacts to the noise floor. e.g., request to send, clear to send, and acknowledge. this adds a bunch of overhead, then within each frame containing the data you actually want to send, there is more overhead due to the OSI model, as well as the various checksums that are done to check for errors, and re-transmit data as needed (which it needs to do often). The need for lots of management, eats up around half of the throughput, which is why you typically see an N300 connection topping out at around 120-150Mbps in the real world.

 

Usually if the error rate goes beyond some arbitrary level (typically set by whoever was writing the code for the WiFi radio), then it will use a lower modulation, in addition to using other methods to lower the PHY rate until the error rate drops below that arbitrary level.

 

If it is programmed poorly, then the effects can be pretty catastrophic, as in a heavily congested environment, the WiFI radio will not find any rate where it is happy with the error rate, and thus drop as low as the standard will allow, e.g., with this WNR3500Lv2 in an area with well over 150 access points at the time. Channel 2 had the fewest APs and thus the auto selection, picked it, but since auto channel select does not pick based on actual throughput, it picked the worst channel.

 

 

The best being channel 8 which was fairly crowded.

 

 

I you look at some modern router reviews, you will often see many high end ones using roughly the same hardware, but some will perform significantly faster than others. that is often due to better software. e.g., the devs were less overzealous with reducing the PHY rate, and overall finding ways to get the most out of the hardware. At that point, things get extremely complex, and there are very few people who are extremely good at it. e.g., look at what happens when a NAS manufacturer tries to design a router. http://www.smallnetbuilder.com/wireless/wireless-reviews/32960-synology-rt1900ac-router-reviewed

[skywake]

12 hours ago, Timvandervinne said:

can someone explain wifi in a maner that 14/15 year old kids can understand it because that is the audience to wich i am presenting.

For 15 year olds? For a start I'd explain the difference between an access point, modem and router. Specifically that what people typically call a "router" is actually a combination of devices. I'd then explain how you can have multiple access points on one network with the same service set identifier or SSID. Basically the name. When you have multiple access points with the same SSID and security settings your devices can move between them easily. Your school almost certainly has multiple access points.

 

Then I'd move onto how it works. Basically WiFi runs on radio waves which are part of the electro-magnetic spectrum. A spectrum which you can basically divide into three broad categories: ionising radiation, light and radio. On the most basic level WiFi and mobiles are fairly similar and in a sense they're just a bi-directional and multi-user version of over-the-air digital TV and Radio broadcasts. They run over a chunk of spectrum (typically 20-160Mhz) and send a digital signal across the spectrum. The more spectrum and stronger the signal the more data can be transmitted.

 

Ontop of all of this there's an optional layer of security. This is to stop people from connecting to the network who you don't want to connect and to stop people from reading transmitted data. Basically it works by doing a calculation a string of text to generate a "key" that "unlocks" the access point. Once you've connected your data is then encrypted using your key and a sequence of numbers. 

 

Early on a lot of access points used WEP which was easily broken. It used a key that was generated using a 10 character long password and a short sequence of "random" numbers. It was possible to crack it in a couple of minutes. WPA made it harder to crack by allowing longer passwords and also using your SSID in the encryption. So don't use the default SSID! They also rotate through a larger sequence of numbers meaning there is less chance of repeating patterns.

[matrix07012]

15 hours ago, ShadowCaptain said:

Are you not taught this in class? you should pay attention

They don't teach it too much. They only say: "It uses radio waves to transmit data"

[ShadowCaptain]

59 minutes ago, matrix07012 said:

They don't teach it too much. They only say: "It uses radio waves to transmit data"

Fair enough, but if you have the internet, you have no excuse not to learn something you need to write about. the information is all there, youtube videos, online resources, books etc