1. Smart Antennas
Presented by :-
Rajib Kumar Das

2. Overview Part I Part II 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

6. Smart antenna TechnologyBS
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

7. Switched beam
Beams are formed in pre determined direction
BS switches between different beams based on Rx signal measurement.
Source

8. Adaptive beam forming Real time processing
Beams are not formed in pre determined direction
Real time processing
BS forms narrow beam towards desired user
Improves S/N ratio
Source

9. Types of SA
Adaptive array
MIMO

10. MIMO Higher spectral efficiency No additional BW requirement
Advantages
Increased data handling capability
Higher spectral efficiency
No additional BW requirement
Source

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

13. Functional block diagram of phased array
Phased array antenna
Functional block diagram of phased array
mounted on car
Source

14. Phased array antenna
Functional diagram of phased array antenna

15. Digital beam forming array antenna].
Source

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 car[2]
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 vehicles[1]
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 direction[1]
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 combination[1]
Problem of multiple path propagation in channel
Signal quality improves with number of elements

23. Part II

24. Why Smart Antennas ? Enhance System performance Reduce Interference
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 Channel spread 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
Unwanted users
Source : [8]

29. Beamforming

30. Beamforming Schemes Delay & sum Null steering Digital Beamforming
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 = mm,
Dy = mm, dx = mm, dy = mm,
xo = mm, yo = mm, W = mm, L = 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 Applicable scheme for 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]
[4]
[5]Michael Chryssomallis “Smart antennas” IEEE antenna and propagation magazine” Vol 42 No 3 pp , June 2000.
[6]Salvatore Bellofiore, Constantine,Jeffry and Andreas “ Smart antenna systems for mobile communication networks “IEEE Antenna’s and propagation magazine”
Vol 44 No 3 pp , June 2002.
[7] AJ Paulraj,D Gesbert “Smart antennas for mobile communication” IEEE Antenna’s and propagation magazine Vol 57 No 5 pp 1-14, June 2000.
[8]JM Samhan,RM Shubair and MA Alquadi “Design and implementation of an adaptive smart antenna” Proc IEEE Vol 57 pp6-7 September 2006.

37. Questions ??