ETRI Journal

Electronics and Telecommunications Research Institute (한국전자통신연구원)
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Convolutionally-Coded and Spectrum-Overlapped Multicarrier DS-CDMA Systems in a Multipath Fading Channel

  • Oh, Jung-Hun (Department of Electronics Engineering, Kookmin University) ;
  • Kim, Ki-Doo (Department of Electronics Engineering, Kookmin University) ;
  • Milstein, Laurence B. (Department of Electrical and Computer Engineering, University of California)
  • Received : 2000.12.08
  • Published : 2001.12.30
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Abstract

Multicarrier DS-CDMA is an effective approach to combat fading and various kinds of interference. In this paper, we present an overlapped multicarrier DS-CDMA system, wherein each of the rate 1/M convolutionally-encoded symbols is also repetition coded and transmitted using overlapped multicarriers. However, since the frequency spectrums of successive carriers are allowed to overlap, the transmission bandwidth is more efficiently utilized. The effect of the overlapping percentage between successive carriers of a multicarrier DS-CDMA system on the performance is investigated to determine the overlapping percentage showing the best performance. We suggest two methods for sub-band overlapping variation. One is to allow variation of sub-band overlapping percentage when the total number of subcarriers is fixed. The other is to increase the number of sub-bands (the number of repetitions R) with fixed sub-band bandwidth. Given a total number of subcarriers MR, we show that the BER variation is highly dependent on the roll-off factor ${\beta}$ of a raised-cosine chip wave-shaping filter irrespective of convolutional encoding rate 1/M and repetition coding rate 1/R. We also analyze the possibility of reduction in total multi-user interference by considering the variation of both the roll-off factor ($0<{\beta}{\leq}1$) and the sub-band overlapping factor ($0<{\lambda}{\leq}2$), and show that the proposed system may outperform the multicarrier DS-CDMA system in [3].

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References

  1. IEEE Comm. Magazine no.Dec. Overview of Multicarrier CDMA Hara, S.
  2. IEEE Trans. Comm. v.44 On the Performance of Multicarrier DS CDMA Systems Kondo, S.;Milstein, L.B.
  3. Convolutional and Turbo Coded Multicarrier Direct Sequence CDMA, and Applications of Turbo Codes to Hybrid ARQ Communication Systems Rowitch, D.N.
  4. Proc. VTC'96 Effect of Correlation between Subcarriers of an MCM/DSSS Comm. System Ziemer, R.E.;Nadgauda, N.
  5. Proc. VTC'97 Performance of Multicarrier DS CDMA Systems in the Presence of Correlated Fading Xu, W.;Milstein, L.B.
  6. ETRI J. v.21 no.4 The Performance Improvement of a Multicarrier DS-CDMA System Using Both Time-Diversity and Frequency Offset Kim, K.D.;Oh, J.H.;Milstein, L.B.
  7. IEEE Trans. Comm. v.44 Performance of Orthogonal Multicarrier CDMA in a Multipath Fading Channel Sourour, E.;Nakagawa, M.
  8. Int’l Conf. on Telecommunication Offset Multicarrier DS/CDMA System Han, J.H.;Milstein, L.B.;Kim, S.W.
  9. Proc. 4th PIMRC’93 Multicarrier CDMA in Indoor Wireless Radio Network Yee, N.;Linnartz, J.P.;Fettweis, G.
  10. Proc. 4th PIMRC’93 On the Performance of Convolutionally-Coded CDMA/OFDM for Mobile Communication System Fazel, K.;Papke, L.
  11. Proc. GLOBECOM’93 Orthogonal Multicarrier Technique Applied to Direct Sequence Spread Spectrum CDMA Systems Chouly, A.;Barajal, A.;Jourdan, S.
  12. IEEE Trans. Veh. Technol. v.44 no.May Multitone Spread Spectrum Multiple Access Communications System in a Multipath Rician Fading Channel Vandendorpe, L.
  13. IEEE J. on Selected Areas in Comm. v.SAC-5 no.2 Fading Channel Issues in System Engineering Stein, S.
  14. Digital Communications Proakis, J.
  15. Mobile Communications Engineering: Theory and Applications Lee, W.C.Y.
  16. IEEE Trans. Comm. v.19 no.Oct. Convolutional Codes and Their Performance in Communication Systems Viterbi, A.J.