Antenna arrays with smart signal processing algorithms
Smart antennas
(also known as adaptive array antennas,
digital antenna arrays
, multiple antennas and, recently,
MIMO
) are
antenna arrays
with smart
signal processing
algorithms
used to identify spatial signal signatures such as the
direction of arrival
(DOA) of the signal, and use them to calculate
beamforming
vectors which are used to track and locate the antenna beam on the mobile/target. Smart antennas should not be confused with
reconfigurable antennas
, which have similar capabilities but are single element antennas and not antenna arrays.
Smart antenna techniques are used notably in acoustic signal processing, track and scan
radar
,
radio astronomy
and
radio telescopes
, and mostly in
cellular systems
like
W-CDMA
,
UMTS
, and
LTE
and 5G-NR.
[1]
Smart antennas have many functions: DOA estimation,
beamforming
, interference nulling, and constant modulus preservation.
Direction of arrival (DOA) estimation
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The smart antenna system estimates the direction of arrival of the signal, using techniques such as
MUSIC
(MUltiple SIgnal Classification),
estimation of signal parameters via rotational invariance techniques
(ESPRIT) algorithms,
Matrix Pencil
method or one of their derivatives. They involve finding a spatial spectrum of the antenna/
sensor array
, and calculating the DOA from the peaks of this spectrum. These calculations are computationally intensive.
Matrix Pencil is very efficient in case of real time systems, and under the correlated sources.
Beamforming
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Beamforming
is the method used to create the
radiation pattern
of the antenna array by adding constructively the phases of the signals in the direction of the targets/mobiles desired, and nulling the pattern of the targets/mobiles that are undesired/interfering targets.
This can be done with a simple
Finite Impulse Response (FIR)
tapped delay line filter. The weights of the FIR filter may also be changed adaptively, and used to provide optimal beamforming, in the sense that it reduces the
Minimum Mean Square Error
between the desired and actual beampattern formed. Typical algorithms are the
steepest descent
, and
Least Mean Squares
algorithms. In digital antenna arrays with multi channels, use the digital beamforming, usually by DFT or
FFT
.
Types of smart antennas
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Two of the main types of smart antennas include switched beam smart antennas and adaptive array smart antennas. Switched beam systems have several available fixed beam patterns. A decision is made as to which beam to access, at any given point in time, based upon the requirements of the system. Adaptive arrays allow the antenna to steer the beam to any direction of interest while simultaneously nulling interfering signals.
[2]
Beamdirection can be estimated using the so-called direction-of-arrival (DOA) estimation methods.
[3]
In 2008, the United States
NTIA
began a major effort to assist consumers in the purchase of
digital television converter boxes
.
[4]
Through this effort, many people have been exposed to the concept of smart antennas for the first time. In the context of consumer electronics, a "smart antenna" is one that conforms to the EIA/
CEA-909
Standard Interface.
In 2017, the Israeli Aerospace Industries unveiled an adaptive array antenna called
ADA
, and stated that it is already operational and shall be fitted onto "major platforms" used by the
Israel Defense Forces
.
Limited choice of EIA/CEA-909A smart antennas in the marketplace
[
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]
| This article or section
may need to be rewritten
to comply with Wikipedia's
quality standards
, as Outdated, many more smart antennas are available in the market.
You can help
. The
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may contain suggestions.
(
July 2018
)
|
Prior to the final transition to ATSC
digital television
in the United States on 11 June 2009, two smart antenna models were brought to market:
- RCA ANT2000
? no longer available from retailers
- DTA-5000
? manufactured by
Funai Electric
, marketed under the "DX Antenna" brand name, sometimes associated with the
Sylvania
brand name; no longer available from retailers
And two models are causing consumer confusion:
- Although the
Apex SM550
is capable of connecting to a CEA-909 port for the purpose of drawing electrical power, it is not a true smart antenna.
[5]
- The
Channel Master
3000A and CM3000HD
SMARTenna
series are otherwise-conventional amplified omnidirectional antennas, not steerable smart antennas.
[6]
- ADA
- An adaptive antenna produced by MLM factory of the
Israel Aerospace Industries
[7]
See also
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References
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Further reading
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- Sun, Chen; Cheng, Jun; Ohira, Takashi (2008).
Handbook on Advancements in Smart Antenna Technologies for Wireless Networks
. Premier Reference Source (1 ed.).
IGI Global
.
ISBN
978-1599049885
.
(584 pages)
External links
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