An approximately MAI-free multiaccess OFDM system in carrier frequency offset environment

Shang-Ho Tsai*, Yuan-Pei Lin, C. C.Jay Kuo

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


The carrier frequency offset (CFO) effect of a new multiaccess orthogonal frequency division multiplexing (OFDM) transceiver is analyzed. We show that multiaccess interference (MAI) due to CFO can be mitigated by choosing a proper set of orthogonal codes. That is, if we use M/2 symmetric or antisymmetric codewords of the M Hadamard-Walsh codewords, MAI can be greatly reduced to a negligible amount. The new OFDM system has been shown to be approximately MAI-free when there is no CFO. The new result developed here shows that the system continues to be approximately MAI-free even in the presence of CFO. Furthermore, we derive a close form for the reduced MAI, which reveals an interesting property of the system. That is, when the number of users increases, the reduced MAI and the inter carrier interference (ICI) due to self-CFO will decrease. Finally, it is demonstrated by simulation that the proposed OFDM scheme with proper code selection outperforms the OFDMA and the multicarrier code division multiplexing access (MC-CDMA) systems in a CFO environment.

Original languageEnglish
Pages (from-to)4339-4353
Number of pages15
JournalIEEE Transactions on Signal Processing
Issue number11
StatePublished - Nov 2005


  • Carrier frequency offset (CFO)
  • Code selection
  • Frequency synchronization
  • MAI-free
  • Multiuser OFDM
  • Multiuser detection (MUD)


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