Današnja pitanja i odgovori nam se javljaju zahvaljujući SuperUseru - podjele Stack Exchange-a, zajednice-driven grupiranja Q & A web stranica.
Fotografija ljubaznošću rust.bucket (Flickr).
Pitanje
Čitač SuperUser Hooli želi znati što zaustavlja mobilni širokopojasni pristup od doživljavanja problema "smetnje":
Assuming that mobile broadband uses radio waves to transmit data, could the number of users connected to a 3G/4G network create an incredible amount of “interference” that would prevent it from working? Why does it work?
Što je to što zaustavlja mobilni širokopojasni pristup doživljavanja problema "smetnji"?
Odgovor
Jcbermu za SuperUser suradnika ima odgovor za nas:
3G uses CDMA (Code Division Multiple Access).
With CDMA, several transmitters can send information simultaneously over a single communication channel. The users share a band of frequencies employing spread-spectrum technology and a special coding scheme where each transmitter is assigned a code.
Suppose you have a room in which people wish to talk to each other simultaneously. To avoid confusion, people could:
- Take turns speaking (TDMA or Time Division Multiple Access)
- Speak at different pitches (Frequency Division)
- Use different languages (CDMA)
CDMA is like people speaking the same language; they can understand each other but reject the other languages. Similarly, in CDMA each group of users is given a shared code. Many codes occupy the same channel, but only users associated with a particular code can communicate.
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