1 / 13

Inter-carrier interference cancellation in OFDM systems

Inter-carrier interference cancellation in OFDM systems. By: Dharamveer Meena Vinodkumar Pralia. Basic OFDM system. Multi-carrier modulation Multiple frequency channels are orthogonal to each other. OFDM modulated signal.

bevis
Download Presentation

Inter-carrier interference cancellation in OFDM systems

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Inter-carrier interference cancellation in OFDM systems By: Dharamveer Meena Vinodkumar Pralia

  2. Basic OFDM system • Multi-carrier modulation • Multiple frequency channels are orthogonal to each other.

  3. OFDM modulated signal • N symbols mapped to bins of IFFT. • IFFT bins correspond to the orthogonal sub-carriers.

  4. Baseband OFDM transceiver system

  5. Drawbacks • Frequency offset • Local oscillator frequencies • Doppler shift • Result: Loss in Orthogonality • Inter-carrier interference

  6. Frequency offset model • y(n) : received sequence • e: normalized frequency offset • N:number of sub carriers • w(n) : complex AWGN

  7. Standard OFDM systems • Received signal: • ICI coeffiecient: • Carrier to interference ratio:

  8. Solutions to combat ICI • Self-cancellation scheme • Maximum likelihood estimation • Extended Kalman Filter

  9. Extended Kalman Filtering • A linear approximation of a non linear system Linear : Nonlinear :

  10. Offset estimation scheme • State-Space Model: • Recursive steps:

  11. Offset correction scheme : symbol data QAM - M Restored : received data symbol distorted by frequency offset : estimated normalized frequency offset : number of subcarrier

  12. References • P. H. Moose, “A Technique for Orthogonal Frequency Division Multiplexing Frequency Offset Correction,” IEEE Transactions on Communications, vol. 42, no. 10, October 1994. • J.Armstrong, “Analysis of new and existing methods of reducing intercarrier interference due to carrier frequency offset in OFDM,” IEEE Transactions on Communications, vol. 47, no. 3, pp. 365 – 369, March 1999. • C. Muschallik, “Improving an OFDM reception using an adaptive Nyquist windowing,” IEEE Transactions on Consumer Electronics, vol. 42, no. 3, pp. 259 – 269, August 1996.

  13. Thank You

More Related