how are we able to have hundreds or thousands of wireless devices sending and receiving signals within range of each other without any of those waves going through the air interfering with one another and corrupting data?
In: Technology
It’s just a basic property of waves. They can intersect with each other and at the exact point of intersection they do affect each other, but before or after that point, they are unchanged. Also for any negative effects to occur they need to be very close in frequency. To honest, you get way more interference from your own signal bouncing off something before it gets to the receiver than you do from other sources.
The premise of the question is not correct because the radio waves do interfere with each other.
If you and your neighbours have two separate WiFi networks on the same channel or even a nearby channel for the 2.4 GHz band and devices transmit at the same time can be the case that the access point cant read the packet and it needs to be retransmitted.
The interference will not result in data corruption because you have checksum on the data that is transmitted so you can detect if there is transmission error and then the data is retransmitted.
Wifi devices do listen to what is transmitted and will not star sending a packet if someone else is transmitting at the same frequency at high enough power.
The system works as if you have a group of people that talks. When there is a plus something two people start to talk at the same time but then you stop talking and after a short pause then someone starts to take again but start over again.
The result of interference is lower bandwidth, not data corruption.
The range of WiFi is quite short by design so a lot of separate networks can be quite close to there and work even if there is a limited number of channels.
If you look at mobile phone network then you have a regulates system where each operator has a frequency range the can use. They will then set up the networks so to transmitter direct beside each other do not use the same frequency but you reuse it farther away like [in this picture](https://en.wikipedia.org/wiki/Cellular_network#/media/File:Frequency_reuse.svg). The cellular network also has a quite short range just because of this reuse of the frequency-time and time again. It is called cellular network because you build it of a lot of small cells.
Multiple phones will use the same frequency and communicate with the same tower but you use a clever way to encode the signal so multiple devices can transmit at the same time and the receiver can receive all signal at the same time and get out all the data. It is called CDMA and is a bit like how you can hear two people speaking over each other and still pick out what they say.
First of all, there’s very few cases where there’s literally hundreds of thousands of devices attempting to operate on similiar wavelengths in an area similiar to the effective range of those communications. If you think of a worst case scenario like an absolutely packed mega-event, you’d have maybe 60,000 people in a small enough area where they’d be connecting to the same for example, 4G services.
In any case, all digital wireless communications protocols have built in error detection and correction methods. In short – every time you DO use anything wireless even if it seems like it’s working great, there are corrupted packets that are being discarded. The worse the signal and the noisier the enviornment, the less packets of data that get through unscathed. For the most part, you don’t notice the difference because the theoretical maximum bandwidth of 802.11ac is 6.9Gbps – Are you really going to notice a huge difference if it’s only working at ~1/7th capacity (1Gbps), especially if your home internet connection isn’t even that fast?
Latest Answers