EE 609 :TERM PAPER

1
EE 609 TERM PAPER

• Smart Antennas

Presented by - RITESH PAL BINAY RAJ
2
Overview
Part I

• Introduction
• Types of Smart antennas
• Smart antenna for vehicles

Part II

• Beamforming algorithms
• DoA algorithms
• MSA implementation

3
Smart Antenna

• Smart antenna refers to a system of antenna
  array with smart signal processing algorithms
  that are used to identify spatial signal
  signature such as the DOA of the signal, and use
  it to calculate beam forming vectors, to track
  and locate the antenna beam on the mobile/target.

4
SA Application

• Radar
• Radio Astronomy
• Radio Telescopy
• Cellular System

5
Non Smart antenna system

• Limited BW available hence interference in
  system
• Omni directional antennas used at the BS
• This is an interference limited system
• Solution Sectorized antenna

Source http//www.altera.com/endmarket/wirelessant
enna
6
Smart antenna Technology
BS

• Concept of beam forming
• Reduces interferences in the system increases
  capacity
• Each user signal is multiplied by complex weight
  thereby
• adjusting mag phase of signal beam is
  formed
• Beam forming is of two types

Source http//www.altera.com/endmarket/wirelessant
enna
7
Switched beam

• Beams are formed in pre determined direction
• BS switches between different beams based on Rx
  signal measurement.

Source http//www.smartanteenas.googlepages.com
8
Adaptive beam forming

• Beams are not formed in pre determined
  direction
• Real time processing
• BS forms narrow beam towards desired user
• Improves S/N ratio

Source http//www.altera.com/endmarket/wirelessant
enna
9
Types of SA

• Adaptive array
• MIMO

10
MIMO
Advantages

• Increased data handling capability
• Higher spectral efficiency
• No additional BW requirement

Source www.webopedia.com
11
Adaptive arrays antennas

• Switched beam
• Parasitic array
• Digital beam forming array
• Diversity array
• Phased array

12
Switched beam forming implementation

• Implementation using power splitters phase
  shifters
• Application Radar, EW satellite system

Source http//www.smartanteenas.googlepages.com
13
Phased array antenna
Functional block diagram of phased array mounted
on car
Source http//www.smartanteenas.googlepages.com
14
Phased array antenna
Functional diagram of phased array antenna
15
Digital beam forming array antenna
.
Source http//www.smartanteenas.googlepages.com
16
Parasitic array antenna

• Active element is surrounded by number of
  parasitic elements
• Switching of parasitic elements done by PIN
  diode
• 3 direction beam steering achieved

17
SA application on vehicles with array antenna
Cellular car radio antenna 1

• Antennas are usually vertically mounted
• Requirement Omni directional pattern in azimuth
  plane

18
Radiation properties as function of antenna
location
Radiation properties as a function of antenna loc
on car2

• Roof rim has rotational non symmetric
  environment
• Deviation of desired omni directional pattern
• Omni directional pattern could be achieved only
  at
• the center of roof

19
Array antenna on vehicles1

• Multi element phased array technique
• Vertical dimension less than quarter wavelength
  is possible
• At BS individual BF for individual tracking
  signal optimzation
• Conventional methods used at Mobile station
• Thus only one RX/TX front end is required

20
3 element antenna with adjustable main beam
direction1

• Achievement Adjustable directive main beam
  covering
• complete azimuth plane
• Reduction in side lobes
• Gain is 5 dB more than conventional antenna
• Further optimization possible by 4 elements

21
Two element optimized antenna
2 element pattern optimized antenna 2
22
Diversity car antenna for cellular radio
Signal quality with different antenna
combination1

• Problem of multiple path propagation in channel
• Signal quality improves with number of elements

23
Part II
24
Why Smart Antennas ?

• Enhance System performance
• Increases channel capacity
• Enhances Spectrum efficiency
• Range coverage
• Track multiple users
• Reduce Interference
• Delay spread
• Multipath fading

25
Why Smart Antennas ? (contd..)

• Reduce system complexity
• Reduce co channel interference
• Tx mode
• Rx mode

26
Terminologies

• Fading
• Mean path loss
• Slow fading
• Difficult to predict
• Fast fading
• Multipath propagation
• Phase variations
• Rayleigh distribution
• Channel spread
• Doppler spread
• Angle spread
• Delay spread

27
Switched Beam Vs Adaptive Array
28
Block diagram of Smart Antenna
Source 8
29
Beamforming
30
Beamforming Schemes

• Delay sum
• Unity response
• Disadvantage Interference
• Null steering
• Cancels plane wave from known direction
• Handles strong interference
• Disadvantage Multiple interference
• Digital Beamforming
• Higher sampling rates
• Capacity enhancement upto 200

Source 4
31
Adaptive Beamforming Algorithms

• Sample Matrix Inversion (SMI)
• Replaces covariance matrix of spatially sampled
  signals by estimated value iteratively
• Least Mean Square (LMS)
• Weights are subjected to constraints
• Constant Modulus Algorithm (CMA)
• Assumes that interference causes amplitude
  fluctuation in o/p
• Neural Network approach
• Applicable when ref sig is available
• Iteratively minimizes the MSE between ref sig and
  modified array o/p

Source 5
32
DoA Algorithms

• DFT and Maximum Entropy Method (MEM)
• Uses signal subspace
• MUltiple SIgnal Classification (MUSIC)
• Estimates DoA in noise subspace
• More accurate

Source 8
33
Smart Antenna Design Implementation
A planar array configuration Dx 54.562 mm, Dy
54.747 mm, dx 7.500 mm, dy 7.500 mm, xo
0.794 mm, yo 1.164 mm, W 2.247 mm, L 2.062
mm, t 0.300mm, ?r 11.7, ? 0.04, f
20GHz.
Source 6
34
Radiation Pattern
E-plane
H-plane
Source 6
35
Conclusion

• Advantages accrued
• Applications
• PL
• Adhoc networks
• High data rate 3G
• Applicable scheme for
• TDMA
• CDMA

36
References

• 1 R Kronberger,H Lindermerier,J Hopf Smart
  antenna applications on vehicles
• with low profile array antenna Proc IEEE Vol 53
  pp1-3 September 2003.
• 2 R Kronberger,H Lindermerier,J Hopf Design
  method for antenna array on cars Proc IEEE Vol
  101 pp11-15 September 2003.
• 3 http//www.smartanteenas.googlepages.com
• 4 http//www.iec.org
• 5Michael Chryssomallis Smart antennas IEEE
  antenna and propagation magazine Vol 42 No 3 pp
  129-138, June 2000.
• 6Salvatore Bellofiore, Constantine,Jeffry and
  Andreas Smart antenna systems for mobile
  communication networks IEEE Antennas and
  propagation magazine
• Vol 44 No 3 pp 145-154, June 2002.
• 7 AJ Paulraj,D Gesbert Smart antennas for
  mobile communication IEEE Antennas and
  propagation magazine Vol 57 No 5 pp 1-14, June
  2000.
• 8JM Samhan,RM Shubair and MA Alquadi Design
  and implementation of an adaptive smart antenna
  Proc IEEE Vol 57 pp6-7 September 2006.

37
Questions ??