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Spørsmålet
SuperUser leser Hooli vil vite hva som stopper mobilt bredbånd fra å oppleve "interferens" -problemer:
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?
Hva er det som stopper mobilt bredbånd fra å oppleve "interferens" -problemer?
Svaret
SuperUser bidragsyter jcbermu har svaret for oss:
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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