how do network cables transmit data from thousands of people without interference? Like a phone cable for 5 houses not mixing up calls?
In: Technology
The word you are looking for is “multiplexing”. There are many ways:
In packet networks you are sending small pieces of data called packets (up to some thousands of bytes), each of them has a header that says where it is coming from and where it is going. The devices at the end of the cable have a queue for packets that should go down that cable. You can get clever about how much of the total bandwidth each of the flows is allowed to use and even more clever about whether other flows can get the bandwidth a flow is allowed to use, but does not. With sufficient cleverness you can make it so you can guarantee someone’s packets will be delivered within a given time if they do not send more than a given amount.
You can assign _time slots_ to flows. Split time into some intervals (called frames, I think), split frames into slots, assign each slot to a flow. If that flow does not use it, no one does. That gives you lower efficiency, but very deterministic timing (this is what we used for phone calls before compression was clever, when we knew exactly how much bandwidth any flow would use).
You can take an optical cable and assign different wavelengths (colours) of light to different flows, then use a prism to split them again. I think you can get about 160 different colours into a single cable.
When you really need lots of bandwidth, you would combine these — send 8 (or 160) different colours down a piece of fiber and on each of them use packet multiplexing.
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