Frequency-interleaved spread spectrum with MMSE frequency-domain equalization

Kazuaki Takeda, Fumiyuki Adachi

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


The use of frequency-domain equalization (FDE) based on minimum mean square error (MMSE) criterion can significantly improve the downlink bit error rate (BER) performances of DS- and MC-CDMA in a frequency-selective fading channel. However, the uplink BER performance degrades due to a strong multi-user interference (MUI). In this paper, we propose frequency-interleaved spread spectrum (SS) using MMSE-FDE, in which the subcarrier components of each user's signal are interleaved onto a wider bandwidth. Then, the frequency-interleaved frequency-domain signal is transformed into a time-domain signal by the inverse fast Fourier transform (IFFT). Frequency-interleaving patterns assigned to different users are orthogonal to each other. The proposed scheme can avoid the MUI completely while achieving frequency diversity gain due to MMSE-FDE. It is shown by computer simulation that the use of frequency-interleaving can significantly improve the uplink performance in a frequency-selective Rayleigh fading channel.

Original languageEnglish
Pages (from-to)260-268
Number of pages9
JournalIEICE Transactions on Communications
Issue number2
Publication statusPublished - 2007 Feb


  • Component
  • Frequency-interleaving


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