I'm a newbie on wireless technologies and I'm trying to understand how they work.
One thing I don't understand is this: How come transmissions from different devices don't interfere with each other all the time?
For example, I'm living in a dense metropolitan area. There's a router on my desk, and a laptop connected to it via WiFi. I would bet that in the 100 meter radius surrounding me, there are at least 100 more routers, and at least 200 more devices (laptops or cell phones) that are connected to the aforementioned routers. They are all communicating with each other at the same time. How can my humble laptop and my humble router send messages to each other? When my router send a message, how can my laptop pick it up from all the noise on these frequencies?
This question applies to phone networks as well. How can a phone reliably communicate with its tower when there are 500 phones nearby who are communicating with the same tower? How do they know which data belongs to which phone?
Thanks for satisfying my curiosity!