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Turbo-synchronization

Turbo-synchronization. Introduction. Communication systems based on the turbo principle Remarkable performances Ideal synchronization. Transmission System. The Turbo Principle. Compute soft information on the transmitted symbols using an iterative receiver. Soft / Hard Information.

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Turbo-synchronization

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  1. Turbo-synchronization

  2. Introduction • Communication systems based on the turbo principle • Remarkable performances • Ideal synchronization Sébastien de la Kethulle de Ryhove – Turbo-synchronization

  3. Transmission System Sébastien de la Kethulle de Ryhove – Turbo-synchronization

  4. The Turbo Principle Compute soft information on the transmitted symbols using aniterative receiver Sébastien de la Kethulle de Ryhove – Turbo-synchronization

  5. Soft / Hard Information • Hard approach • Soft approach Sébastien de la Kethulle de Ryhove – Turbo-synchronization

  6. The Turbo Principle • Applicable to a wide variety of problems: • Decoding: Turbo-decoding • Decoding + equalization: Turbo-equalization • Decoding+demodulation: Turbo-demodulation • … • Turbo detection Sébastien de la Kethulle de Ryhove – Turbo-synchronization

  7. Example: Turbo-demodulation Transmitter Sébastien de la Kethulle de Ryhove – Turbo-synchronization

  8. NSC Encoder Sébastien de la Kethulle de Ryhove – Turbo-synchronization

  9. Grouping and Mapping Sébastien de la Kethulle de Ryhove – Turbo-synchronization

  10. Example: Turbo-demodulation Receiver – Exchange of soft information Sébastien de la Kethulle de Ryhove – Turbo-synchronization

  11. Synchronization • Find estimates for • The carrier frequency • The carrier phase • The sampling time Sébastien de la Kethulle de Ryhove – Turbo-synchronization

  12. Synchronization Classicalreceiver Sébastien de la Kethulle de Ryhove – Turbo-synchronization

  13. Turbo-synchronization Soft receiver Sébastien de la Kethulle de Ryhove – Turbo-synchronization

  14. Soft Synchronization – Example • Traditional DD synchronization • Soft DD synchronization Sébastien de la Kethulle de Ryhove – Turbo-synchronization

  15. Algorithm: Soft Phase Synchronization Initialize/* many possibilities */ do{ Correct the phase of the received sequence Perform one soft det./dec. iteration on the corrected sequence Find a new estimate for using the newly obtained soft information }while ( changes a lot) /* Continue with detection / decoding */ Sébastien de la Kethulle de Ryhove – Turbo-synchronization

  16. BER Performance BER Performance vs. Phase Offset for a Turbo Coded system BER Phase offset [degrees] Sébastien de la Kethulle de Ryhove – Turbo-synchronization

  17. Mean Estimated Phase Offset Mean Estimated Phase Offset [degrees] Phase offset [degrees] Sébastien de la Kethulle de Ryhove – Turbo-synchronization

  18. Estimator Variance Estimator Variance [degrees2] Phase offset [degrees] Sébastien de la Kethulle de Ryhove – Turbo-synchronization

  19. BER Performance BER Phase offset [degrees] Sébastien de la Kethulle de Ryhove – Turbo-synchronization

  20. Estimator Variance Phase offset = 30 degrees Estimator Variance [degrees2] Eb / N0 [dB] Sébastien de la Kethulle de Ryhove – Turbo-synchronization

  21. Performances – Acquisition Preamble: 7 16-QAM symbols BER Eb / N0 [dB] Sébastien de la Kethulle de Ryhove – Turbo-synchronization

  22. Conclusions • Performance enhancement • Synchronization algorithms • Overall system • Encouraging results Sébastien de la Kethulle de Ryhove – Turbo-synchronization

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