Antennas-8 - Smart Antennas
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Transcript of Antennas-8 - Smart Antennas
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Dr.-Ing. Getahun Mekuria
Department of Electrical and Computer Engineering (ECE)
Addis Ababa Institute of Technology (AAiT)
Addis Ababa University (AAU)
ECEG 6308
Analysis and Design of Antenna
Smart Antennas
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Non-Smart Antennas
Omni-directional Sectorized
• When omni-directional antennas are used at the base
station, the transmission/reception of each user's signal
becomes a source of interference to other users locatedin the same cell.
• An effective way to reduce this type of interference is to
split up the cell into multiple sectors and use sectorized
antennas.
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Non-Smart Antennas – Sectorized Antenna
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Non- Smart Antennas
• Sectorized antennas transmit and receive in a limitedportion of the cell, typically one-third of the circular area,
thereby reducing the overall interference in the system.
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Smart Antennas -Introduction
• A smart antenna is a Phased or Adaptive Array thatadjusts to the environment
• A smart antenna system combines multiple antenna
elements with a signal processing capability tooptimize its radiation and/or reception pattern
automatically in response to the signal environment.
• Smart Antennas are arrays of antenna elements that
change their antenna pattern dynamically to adjust to thenoise, interference in the channel and mitigate multipath
fading effects on the signal of interest.
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Smart Antennas –Advantages (Mobile Nets)
• Greater coverage area for each cell site• Better rejection of co-channel interference
• Reduced multipath interference / increased directionality
• Reduced delay spread as fewer scatterers are allowed
into the beam• Increased frequency reuse with fewer base stations
• Higher range in rural areas
• Improved building penetration
• Location information for emergency situations
• Increased data rates and overall system capacity• Reduction in dropped calls
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Smart Antennas –Advantages (Mobile Nets)
• Greater coverage area for each cell site• Extended Battery Life
• Better rejection of co-channel interference
• Reduced multipath interference / increased directionality
•
Reduced delay spread as fewer scatterers are allowedinto the beam
• Increased frequency reuse with fewer base stations
• Higher range in rural areas
• Improved building penetration
• Location information for emergency situations• Increased data rates and overall system capacity
• Reduction in dropped calls
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Smart Antennas –Types
• Switched Beaforming
•
Adaptive Beaforming
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Smart Antennas –Types
Switched Beaforming (Phased Array, Multibeam):• Consists of either a number of fixed beams
with one beam turned on towards the desired
signal or a single beam (formed by phase
adjustment only) that is steered towards the
desired signal.
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Smart Antennas –Types
Adaptive Beaforming:• An array of multiple antenna elements with the
received signals weighted and combined to
maximize the desired signal to interference and
noise (SINR) ratio. This means that the main
beam is put in the direction of the desired signal
while nulls are in the direction of the interference.
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Smart Antennas –Types Switched/Phased Array
Beamforming
Adaptive Beamforming
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Smart Antennas –Types
SDMA (Spatial Division Multiple
Access) Beamformer
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Smart Antennas –Types – Pros and Cons
Switched Beam Forming Adaptive Beam FormingPros Simple to implement,
Low cost.
High capacity with
reduced interference,
Best suited for line of
sight environment
Cons Limited configuration
flexibility, There must be at
least one strong direct
component for DOA
estimation
Medium complexity, High
cost, There must be at
least one strong direct
component for DOA
estimation
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Smart Antennas –Geometries
(a) Linear array, (b) Circular Array, (C) 2D grid array, and (d) 3D grid array
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Smart Antennas – Architecture
Smart Antenna
Receiver system
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Smart Antennas – Architecture
Smart Antenna
Receiver system
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Smart Antennas – DOA Estimation Algorithms
Hardware Implementation of Smart Antennas
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Smart Antennas – DOA Estimation Algorithms
• MUSICMultiple Signal Classification
• ESPRIT
Estimation of Signal Parameter via Rotational
Invariant Technique