Multiple access

Frequency Division Multiple Access (FDMA)
- Divides the bandwidth of a channel into several smaller frequencies bands.
- ex: TV
Crosstalk

Causes interference on the other frequency and may disrupt the transmission
Time Division Multiple Access (TDMA)
- Divides the transmission time into several slots
- Each user is assigned the entire frequency for the transmission
Advantages of TDMA
- Uses the bandwidth more efficiently
- Allows both data and voice transmissions to be mixed using the same frequency
Code Division Multiple Access (CDMA)
- Uses direct sequence spread spectrum (DSSS) with a unique digital spreading code (PN code)
- Before the transmission occurs high-rate PN code is combined with the data to be sent
- the longer the code the more users.
CDMA Advantages
- Can carry up to three times the amount of data as TDMA
- Transmissions are much harder to eavesdrop on
- A would-be eavesdropper must also know the exact chip in which the transmission starts

Author

Anonymous

64271

Card Set

Multiple access

Description

Describe how different factors affect the design of a radio system

Updated

2011-02-05T16:55:54Z

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