• In a cellular system the radio communication is between the user and a base station, which provides radio coverage within a certain area, called a cell.
• The base stations are omni directional or sectored.
• This is a waste of power as most of it will be radiated in other directions than toward the user.
• The power radiated in other directions will be experienced as interference by other users.
• The idea of smart antennas is to use base station antenna patterns that are not fixed, but adapt to the current radio conditions.
• This can be visualized as the antenna directing a beam toward the communication partner only.

• Smart antenna provides

  Large increase in Capacity
  Increased range
  Potential to introduce new services
  More security
  Reduced Multipath propagation

Sharing the Radio Spectrum

Users communicating via the same base station have been separated in various ways:

• by frequency as in FDMA ( frequency division multiple access),
• by time as in TDMA ( time division multiple access),
• by code as in CDMA ( code division multiple access) and
• by space through SDMA ( space division multiple access) in smart antennas.

Smart Antenna consists of a number of radiating elements, a combining/dividing network and a control unit.

Control unit can be called the smart antenna’s intelligence. It is realized using a digital signal processor (DSP).

Based on this definition of smart antenna, one can define “levels of Intelligence”.