Subcarrier Spreading for ICI Mitigation in OFDM/OFDMA Systems

Two of the major challenges facing OFDM/OFDMA systems are their sensitivity to frequency selective fading and ICI due to CFO or Doppler shift, especially when the subcarrier spacing becomes smaller. We propose an OFDM transceiver design that employs frequency redundant subcarrier mapping to mitigate frequency selective fading and subcarrier spreading to achieve ICI self cancelation. Both our theoretical analysis and simulation show that such a code-spread-interleaved-redundant OFDM system design offers significant (over 10dB) improvement in CIR and robust BER performance in different channel conditions.