smart antenna for softwer define and cognitive radio

1. By
HUSSEIN TUAMA HAZIM
(525018)
ME.CN

2.  Generally, an antenna is a device which is
used for radiating electromagnetic energy
into space or for collecting electromagnetic
energy from space.
 Isotropic: Hypothetic omnidirectional
antenna, a point in space, radiates power in
all directions equally.
 Half wave-dipole: A commonly used
omnidirectional antenna, which radiates and
receives signals almost equally in all
directions.

3.  Traditional directional antennas:
◦ Such as Helix, Yagi-Uda, Aperture horn
and reflector
 Electronically steerable or smart antenna
system
◦ A smart antenna is an antenna array consists of a
set of antenna elements
Reflector Grid

4. In communication environments serious problems such as a multi-path
fading caused by a reflection by any physical structures Fig(a)
When passing through multi-path, the signals are delayed and out of phase
from the signals through direct-path, as in Fig(b) that causes the signal
strength to be weakened at a receiver and hence receiving quality is also
reduced.
Its “Raleigh Fading”.
Its important to configure receiver and transmitter flexibly in response to the
signal environment.
Several techniques: Phased array antenna and Diversity antenna using
active array configurations can adapt the antenna pattern according to the
change of mobile communication environment.

5. Adaptive/Smart Antenna:
A system capable of automatically changing the directionality of its
radiation patterns (beams) in response to its signal environment.
Increases capacity and quality of a wireless system.
An “Adaptive/Smart Antenna” system uses spatially separated
antennas called array antenna and processes received signals
with a digital signal processor after analog to digital
conversion
The name is derived from an “Adaptive Filter” or “Adaptive
Filter Signal Processing”.
Antenna that is combined with a digital signal processor is
also called by the name of “Smart Antenna” or “Software
Antenna” or “Digital Beamforming Antenna (DBF Antenna)”
that all mean an intelligent antenna different from a
conventional omni-directional antenna

6.  Radio Interface
◦ Smart Antenna allows signals to be directed to a
device
 Increase the quality of the signals
 Only installed at the Base Station, not the handset
 Increase the usage of the BS
 Increased frequency reuse
Omni Directional
Directed
(Smart Antenna)

7.  Frequency reuse
◦ It is possible to make each user in a particular
direction the only user as far as the device is
concerned
 Directing communications to the device
 Currently though replies will be omni-directional
Directed
(Smart Antenna)

8. Switched Beam
Adaptive Array Antenna
• Smart Antenna two main types
– Switched Beam
– Adaptive Array Antenna

9.  Radio Interface
◦ Adaptive Array Antennas
 These devices track a communicating device
 The power can be adjusted to exactly what is required for
successful communications
 They can minimise interference by controlling the power in a
particular direction
 The transmission of the signal can be directed to the user and
follow them.
 This removes any interference from other users
 Reduces the effect of signal propagation
 As the signal is directed

10.  Advantages
◦ Integration
 Switched beam can be added to current infrastructure
 Adaptive antenna, require consideration to the network and there use
◦ Range
 Switched beam can increase range between 20 – 200% over a normal cell
 Depending on local conditions
 Switched beam power can not be adapted as the user moves, as the power and
shape are pre-defined
 Adaptive Array can cover larger area due to the directing of the signals to a
device
◦ Interference Suppression
 Switched beam Interference from beams which are away from where they are
expected are ignored
 As the beams are pre-determined at the development stage, interference is still possible
 Switched Beam has problems with interference from device which are close to the
BS
 Adaptive array is more resistant to interference as the signal is narrowed towards
the actual device
◦ Capacity
 Increased with SDMA

11.  Smart Antenna Capacity
◦ Spatial Division Multiple Access (SDMA)
 More efficient use of the allocated frequency
 By controlling
 Amount of interference
 Multi-path Propagation
 Multi-path interference
 Allowing 2 users in the same cell to use the same transmission
slot
 Potentially having a single user per allocation slot
 This is more of a consideration with WCDMA rather than GSM tech
 It has been defined as a essential development for the use of 4G
communications