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CODING FOR MULTIPLE ANTENNAS WITH LINEAR AND NONLINEAR (BLAST) INTERFACES

This work explores coding techniques for multiple antennas with linear and nonlinear (BLAST) interfaces. The system model, receivers, iterative receiver, and simulation results are discussed.

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CODING FOR MULTIPLE ANTENNAS WITH LINEAR AND NONLINEAR (BLAST) INTERFACES

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  1. CODING FOR MULTIPLE ANTENNAS WITH LINEAR AND NONLINEAR (BLAST) INTERFACES EZIO BIGLIERI (work done with A. Nordio, G. Taricco, and A. Tulino) DIMACS WORKSHOP, OCTOBER 2002

  2. OUTLINE • SYSTEM MODEL AND BASIC ASSUMPTIONS • LINEAR AND NONLINEAR RECEIVERS • ZERO-FORCING AND MMSE BLAST • ITERATIVE RECEIVER • CODING FOR NONLINEAR RECEIVERS • SIMULATION RESULTS

  3. SYSTEM MODEL • mimo channel with t transmit and r receive antennas • fading constant over N symbol intervals • independent rayleigh fading channel • perfect csi at receiver

  4. TX RX H

  5. SYSTEM MODEL

  6. INTRODUCING AN INTERLEAVER Pairwise error probability with ML detection: E E

  7. INTRODUCING AN INTERLEAVER Spatial interference

  8. INTRODUCING AN INTERLEAVER

  9. INTRODUCING AN INTERLEAVER • OPTIONS FOR REMOVING 1: • r 

  10. INTRODUCING AN INTERLEAVER • OPTIONS FOR REMOVING 1: • r  • Alamouti-type coding

  11. INTRODUCING AN INTERLEAVER • OPTIONS FOR REMOVING 1: • r  • Alamouti-type coding • Introducing a row-interleaver

  12. INTRODUCING AN INTERLEAVER A random row interleaver yields

  13. A LINEAR INTERFACE Metric used:

  14. NONLINEAR INTERFACE reduce spatial interference G + + – L decoder L has zero diagonal elements

  15. NONLINEAR INTERFACE reduce spatial interference G + + – L decoder L strictly upper triangular: Allows t iterations  BLAST L with zero diagonal elements  ITERATIVE RECEIVER

  16. BLAST INTERFACE Use a soft estimate of the transmitted code word X in the form

  17. BLAST algorithm: step 1

  18. BLAST algorithm: step 1

  19. BLAST algorithm: step 1

  20. BLAST algorithm: step 1

  21. BLAST algorithm: step 2

  22. ZF BLAST

  23. ZF BLAST

  24. MMSE BLAST

  25. MMSE BLAST

  26. NONLINEAR ITERATIVE INTERFACE A + + – L decoder estimate of spatial interference L has zero diagonal elements: L = AH - diag(AH)

  27. NONLINEAR ITERATIVE INTERFACE estimate of spatial interference:

  28. CODING FOR NONLINEAR INTERFACES vertical coding: coded symbols are spread across TX antennas encoder . . .

  29. CODING FOR NONLINEAR INTERFACES encoder horizontal coding: each TX antenna is encoded separately encoder . . . encoder

  30. encoder . . . CODING FOR NONLINEAR INTERFACES vertical coding: no preliminary decisions available to increase the reliability of symbols detected and used for cancellation

  31. encoder encoder . . . encoder CODING FOR NONLINEAR INTERFACES horizontal coding: interference cancellation is limited by the weakest code

  32. CODING FOR NONLINEAR INTERFACES horizontal + vertical coding: each TX antenna transmits a subcode of a larger code encoder . . .

  33. SIMULATION RESULTS (8,4,4) Extended Hamming code

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