Basics of CDMA

In Code Division Multiple Access (CDMA) systems the narrowband message signals are multiplied by spreading signals. All users in CDMA uses same carrier frequency and can transmit simultaneously. The spreading signals are pseudo random code. The features of CDMA are as follows:


  1. Many users of a CDMA systems share same frequency.
  2. Unlike TDMA and FDMA, CDMA has a soft capacity limit. Increasing the number of users in CDMA systems increases the noise.
  3. Multipath fading in CDMA is reduced.
  4. Channel data rates are very high in CDMA.
  5. CDMA provides better handoffs, mostly it gives soft handoffs.
  6. Self jamming is a problem in CDMA.
  7. The near-far problem occurs in CDMA if the user at receiver has a high detected power than desired one.
  8. CDMA is used in Wideband only.

The features of TDMA and FDMA are discussed separately in other posts. Click on simultaneous links to access the features of FDMA and TDMA.

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