Smart antenna
Smart antennas(also known as adaptive array antennas,digital antenna arrays,multiple antennas and, recently,MIMO) areantenna arrayswith smartsignal processingalgorithmsused to identify spatial signal signatures such as thedirection of arrival(DOA) of the signal, and use them to calculatebeamformingvectors which are used to track and locate the antenna beam on the mobile/target. Smart antennas should not be confused withreconfigurable 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 scanradar,radio astronomyandradio telescopes,and mostly incellular systemslikeW-CDMA,UMTS,andLTEand 5G-NR.[1]
Smart antennas have many functions: DOA estimation,beamforming,interference nulling, and constant modulus preservation.
Direction of arrival (DOA) estimation
[edit]The smart antenna system estimates the direction of arrival of the signal, using techniques such asMUSIC(MUltiple SIgnal Classification),estimation of signal parameters via rotational invariance techniques(ESPRIT) algorithms,Matrix Pencilmethod 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
[edit]Beamformingis the method used to create theradiation patternof 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 simpleFinite 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 theMinimum Mean Square Errorbetween the desired and actual beampattern formed. Typical algorithms are thesteepest descent,andLeast Mean Squaresalgorithms. In digital antenna arrays with multi channels, use the digital beamforming, usually by DFT orFFT.
Types of smart antennas
[edit]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 StatesNTIAbegan a major effort to assist consumers in the purchase ofdigital 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-909Standard Interface.
In 2017, the Israeli Aerospace Industries unveiled an adaptive array antenna calledADA,and stated that it is already operational and shall be fitted onto "major platforms" used by theIsrael Defense Forces.
Limited choice of EIA/CEA-909A smart antennas in the marketplace
[edit] | This article or sectionmay need to be rewrittento comply with Wikipedia'squality standards,as Outdated, many more smart antennas are available in the market.(July 2018) |
Prior to the final transition to ATSCdigital televisionin 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 byFunai Electric,marketed under the "DX Antenna" brand name, sometimes associated with theSylvaniabrand name; no longer available from retailers
And two models are causing consumer confusion:
- Although theApex SM550is capable of connecting to a CEA-909 port for the purpose of drawing electrical power, it is not a true smart antenna.[5]
- TheChannel Master3000A and CM3000HDSMARTennaseries are otherwise-conventional amplified omnidirectional antennas, not steerable smart antennas.[6]
- ADA- An adaptive antenna produced by MLM factory of theIsrael Aerospace Industries[7]
See also
[edit]- Antenna (radio)– Electrical device
- Array processing– Area of research in signal processing
- History of smart antennas
- Phased array– Array of antennas creating a steerable beam
- CEA-909– ANSI standard for 8VSB/ATSC smart antennas
- WiMAX– Wireless broadband standard
- Diversity combining– the combining of multiple received signals into a single improved signal
- Active antenna– Electric antennae
- Reconfigurable antenna– Antenna capable of modifying its frequency and radiation properties dynamically
- Digital antenna array– Smart antenna with multi channels digital beamforming
References
[edit]- ^"StackPath".March 2019.Archivedfrom the original on 2023-12-04.Retrieved2023-04-08.
- ^Gross, Frank (2005).Smart Antennas for Wireless Communications: With MATLAB.Professional Engineering (1 ed.).McGraw-Hill Professional.ISBN978-0071447898.(288 pages)
- ^"Array Processing Tutorial"(PDF).The University of Texas at Austin.Archived(PDF)from the original on 2021-12-02.Retrieved2019-11-25.
- ^"Microsoft Redirect".dtv2009.gov.Archived fromthe originalon 2007-12-14.Retrieved2022-05-22.
- ^The Official AVS 'Smart Antenna' Topic - Page 4Archived2018-07-01 at theWayback Machine.AVS Forum.
- ^Channel Master CM 3000 Suburban Outdoor Amplified Omnidirectional SMARTenna TV Antenna (CM3000A)at the Wayback Machine.
- ^"ADA GNSS Anti-Jamming System".Archivedfrom the original on 2017-06-30.Retrieved2017-06-27.
Further reading
[edit]- Sun, Chen; Cheng, Jun; Ohira, Takashi (2008).Handbook on Advancements in Smart Antenna Technologies for Wireless Networks.Premier Reference Source (1 ed.).IGI Global.ISBN978-1599049885.(584 pages)
External links
[edit]- Smart Antenna Research GroupArchived2013-10-20 at theWayback Machineat Stanford
- Virginia Tech, Mobile and Portable & Radio research group