Smart antenna


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Smart antenna

  1. 1. <ul><ul><li>Smart Antennas </li></ul></ul>Presented by :- Rajib Kumar Das
  2. 2. Overview <ul><li>Introduction </li></ul><ul><li>Types of Smart antennas </li></ul><ul><li>Smart antenna for vehicles </li></ul>Part I Part II <ul><li>Beamforming algorithms </li></ul><ul><li>DoA algorithms </li></ul><ul><li>MSA implementation </li></ul>
  3. 3. Smart Antenna <ul><li>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. </li></ul>
  4. 4. SA Application <ul><li>Radar </li></ul><ul><li>Radio Astronomy </li></ul><ul><li>Radio Telescopy </li></ul><ul><li>Cellular System </li></ul>
  5. 5. Non Smart antenna system <ul><li>Limited BW available hence interference in system </li></ul><ul><li>Omni directional antennas used at the BS </li></ul><ul><li>This is an interference limited system </li></ul><ul><li>Solution : Sectorized antenna </li></ul>Source
  6. 6. Smart antenna Technology <ul><li>Concept of beam forming </li></ul><ul><li>Reduces interferences in the system & increases capacity </li></ul><ul><li>Each user signal is multiplied by complex weight thereby </li></ul><ul><li>adjusting mag & phase of signal & beam is formed </li></ul><ul><li>Beam forming is of two types </li></ul>BS Source
  7. 7. Switched beam <ul><li>Beams are formed in pre determined direction </li></ul><ul><li>BS switches between different beams based on Rx signal measurement. </li></ul>Source
  8. 8. Adaptive beam forming <ul><li>Beams are not formed in pre determined direction </li></ul><ul><li>Real time processing </li></ul><ul><li>BS forms narrow beam towards desired user </li></ul><ul><li>Improves S/N ratio </li></ul>Source
  9. 9. Types of SA <ul><li>Adaptive array </li></ul><ul><li>MIMO </li></ul>
  10. 10. MIMO <ul><li>Increased data handling capability </li></ul><ul><li>Higher spectral efficiency </li></ul><ul><li>No additional BW requirement </li></ul>Source Advantages
  11. 11. Adaptive arrays antennas <ul><li>Switched beam </li></ul><ul><li>Parasitic array </li></ul><ul><li>Digital beam forming array </li></ul><ul><li>Diversity array </li></ul><ul><li>Phased array </li></ul>
  12. 12. Switched beam forming implementation <ul><li>Implementation using power splitters & phase shifters </li></ul><ul><li>Application: Radar, EW & satellite system </li></ul>Source
  13. 13. Phased array antenna Functional block diagram of phased array mounted on car Source
  14. 14. Phased array antenna Functional diagram of phased array antenna
  15. 15. Digital beam forming array antenna ]. Source
  16. 16. Parasitic array antenna <ul><li>Active element is surrounded by number of parasitic elements </li></ul><ul><li>Switching of parasitic elements done by PIN diode </li></ul><ul><li>3 direction beam steering achieved </li></ul>
  17. 17. SA application on vehicles with array antenna <ul><li>Antennas are usually vertically mounted </li></ul><ul><li>Requirement Omni directional pattern in azimuth plane </li></ul>Cellular car radio antenna [1]
  18. 18. Radiation properties as function of antenna location <ul><li>Roof rim has rotational non symmetric environment </li></ul><ul><li>Deviation of desired omni directional pattern </li></ul><ul><li>Omni directional pattern could be achieved only at </li></ul><ul><li>the center of roof </li></ul>Radiation properties as a function of antenna loc on car[2]
  19. 19. Array antenna on vehicles[1] <ul><li>Multi element phased array technique </li></ul><ul><li>Vertical dimension less than quarter wavelength is possible </li></ul><ul><li>At BS individual BF for individual tracking & signal optimzation </li></ul><ul><li>Conventional methods used at Mobile station </li></ul><ul><li>Thus only one RX/TX front end is required </li></ul>
  20. 20. 3 element antenna with adjustable main beam direction[1] <ul><li>Achievement: Adjustable directive main beam covering </li></ul><ul><li>complete azimuth plane </li></ul><ul><li>Reduction in side lobes </li></ul><ul><li>Gain is 5 dB more than conventional antenna </li></ul><ul><li>Further optimization possible by 4 elements </li></ul>
  21. 21. Two element optimized antenna 2 element pattern optimized antenna [2]
  22. 22. Diversity car antenna for cellular radio <ul><li>Problem of multiple path propagation in channel </li></ul><ul><li>Signal quality improves with number of elements </li></ul>Signal quality with different antenna combination[1]
  23. 23. Part II
  24. 24. Why Smart Antennas ? <ul><li>Enhance System performance </li></ul><ul><ul><li>Increases channel capacity </li></ul></ul><ul><ul><li>Enhances Spectrum efficiency </li></ul></ul><ul><ul><li>Range coverage </li></ul></ul><ul><ul><li>Track multiple users </li></ul></ul><ul><li>Reduce Interference </li></ul><ul><ul><li>Delay spread </li></ul></ul><ul><ul><li>Multipath fading </li></ul></ul>
  25. 25. Why Smart Antennas ? (contd..) <ul><li>Reduce system complexity </li></ul><ul><li>Reduce co channel interference </li></ul><ul><ul><li>Tx mode </li></ul></ul><ul><ul><li>Rx mode </li></ul></ul>
  26. 26. Terminologies <ul><li>Fading </li></ul><ul><ul><li>Mean path loss </li></ul></ul><ul><ul><li>Slow fading </li></ul></ul><ul><ul><ul><li>Difficult to predict </li></ul></ul></ul><ul><ul><li>Fast fading </li></ul></ul><ul><ul><ul><li>Multipath propagation </li></ul></ul></ul><ul><ul><ul><li>Phase variations </li></ul></ul></ul><ul><ul><ul><li>Rayleigh distribution </li></ul></ul></ul><ul><li>Channel spread </li></ul><ul><ul><li>Doppler spread </li></ul></ul><ul><ul><li>Angle spread </li></ul></ul><ul><ul><li>Delay spread </li></ul></ul>
  27. 27. Switched Beam Vs Adaptive Array
  28. 28. Block diagram of Smart Antenna Source : [8] Unwanted users
  29. 29. Beamforming
  30. 30. Beamforming Schemes <ul><li>Delay & sum </li></ul><ul><ul><li>Unity response </li></ul></ul><ul><ul><li>Disadvantage : Interference </li></ul></ul><ul><li>Null steering </li></ul><ul><ul><li>Cancels plane wave from known direction </li></ul></ul><ul><ul><li>Handles strong interference </li></ul></ul><ul><ul><li>Disadvantage : Multiple interference </li></ul></ul><ul><li>Digital Beamforming </li></ul><ul><ul><li>Higher sampling rates </li></ul></ul><ul><ul><li>Capacity enhancement upto 200 % </li></ul></ul>Source : [4]
  31. 31. Adaptive Beamforming Algorithms <ul><li>Sample Matrix Inversion (SMI) </li></ul><ul><ul><li>Replaces covariance matrix of spatially sampled signals by estimated value iteratively </li></ul></ul><ul><li>Least Mean Square (LMS) </li></ul><ul><ul><li>Weights are subjected to constraints </li></ul></ul><ul><li>Constant Modulus Algorithm (CMA) </li></ul><ul><ul><li>Assumes that interference causes amplitude fluctuation in o/p </li></ul></ul><ul><li>Neural Network approach </li></ul><ul><ul><li>Applicable when ref sig is available </li></ul></ul><ul><ul><li>Iteratively minimizes the MSE between ref sig and modified array o/p </li></ul></ul>Source : [5]
  32. 32. DoA Algorithms <ul><li>DFT and Maximum Entropy Method (MEM) </li></ul><ul><ul><li>Uses signal subspace </li></ul></ul><ul><li>MUltiple SIgnal Classification (MUSIC) </li></ul><ul><ul><li>Estimates DoA in noise subspace </li></ul></ul><ul><ul><li>More accurate </li></ul></ul>Source : [8]
  33. 33. Smart Antenna Design Implementation A planar array configuration: D x = 54.562 mm, D y = 54.747 mm, d x = 7.500 mm, d y = 7.500 mm, x o = 0.794 mm, y o = 1.164 mm, W = 2.247 mm, L = 2.062 mm, t = 0.300mm,  r = 11.7,  = 0.04, f = 20GHz. Source : [6]
  34. 34. Radiation Pattern E-plane H-plane Source : [6]
  35. 35. Conclusion <ul><li>Advantages accrued </li></ul><ul><li>Applications </li></ul><ul><ul><li>PL </li></ul></ul><ul><ul><li>Adhoc networks </li></ul></ul><ul><ul><li>High data rate : 3G </li></ul></ul><ul><li>Applicable scheme for </li></ul><ul><ul><li>TDMA </li></ul></ul><ul><ul><li>CDMA </li></ul></ul>
  36. 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 129-138, 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 145-154, 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. 37. Questions ??