CDMA Transmission with Complex OFDM/OQAM

We propose an alternative to the well-known multicarrier code-division multiple access (MC-CDMA) technique for downlink transmission by replacing the conventional cyclic-prefix orthogonal frequency division multiplexing (OFDM) modulation by an advanced filterbank-based multicarrier system (OFDM/OQAM). Indeed, on one hand, MC-CDMA has already proved its ability to fight against frequency-selective channels thanks to the use of the OFDM modulation and its high flexibility in multiple access thanks to the CDMA component. On the other hand, OFDM/OQAM modulation confers a theoretically optimal spectral efficiency as it operates without guard interval. However, its orthogonality is limited to the real field. In this paper, we propose an orthogonally multiplex quadrature amplitude modulation (OQAM-) CDMA combination that permits a perfect reconstruction of the complex symbols transmitted over a distortion-free channel. The validity and efficiency of our theoretical scheme are illustrated by means of a comparison, using realistic channel models, with conventional MC-CDMA and also with an OQAM-CDMA combination conveying real symbols.

[1]  Pierre Siohan,et al.  Design techniques for orthogonal Modulated filterbanks based on a compact representation , 2004, IEEE Transactions on Signal Processing.

[2]  R. Chang.  Synthesis of band-limited orthogonal signals for multichannel data transmission , 1966 .

[3]  Jean-François Hélard,et al.  Multicarrier CDMA techniques for future wideband wireless networks , 2001, Ann. des Télécommunications.

[4]  Pierre Siohan,et al.  Channel estimation methods for preamble-based OFDM/OQAM modulations , 2008, Eur. Trans. Telecommun..

[5]  Maurice G. Bellanger,et al.  OFDM/OQAM for Spread-Spectrum Transmission , 2007, MCSS.

[6]  Helmut Bölcskei,et al.  Orthogonal Frequency Division Multiplexing Based on Offset QAM , 2003 .

[7]  Jean-Philippe Javaudin,et al.  Pilot-aided channel estimation for OFDM/OQAM , 2003, The 57th IEEE Semiannual Vehicular Technology Conference, 2003. VTC 2003-Spring..

[8]  Claude Berrou,et al.  Coded orthogonal frequency division multiplex [TV broadcasting] , 1995, Proc. IEEE.

[9]  B. Floch,et al.  Coded orthogonal frequency division multiplex , 1995 .

[10]  Jinghong Guo.  Performance of a wavelet-based OFDM-CDMA high speed power line communication system , 2005, 2005 International Power Engineering Conference.

[11]  S. Kaiser,et al.  Multi-Carrier CDMA Mobile Radio Systems - Analysis and Optimisation of Detection, Decoding, and Channel Estimation , 1998 .

[12]  Jean-Paul M. G. Linnartz,et al.  Multi-Carrier Cdma In Indoor Wireless Radio Networks , 1994 .

[13]  Pierre Siohan,et al.  Analysis and design of OFDM/OQAM systems based on filterbank theory , 2002, IEEE Trans. Signal Process..

[14]  B. Saltzberg,et al.  Performance of an Efficient Parallel Data Transmission System , 1967, IEEE Transactions on Communication Technology.

[15]  B. Hirosaki,et al.  An Orthogonally Multiplexed QAM System Using the Discrete Fourier Transform , 1981, IEEE Trans. Commun..

[16]  Bijan Jabbari,et al.  Spreading codes for direct sequence CDMA and wideband CDMA cellular networks , 1998, IEEE Commun. Mag..

[17]  K. Fazel,et al.  On the Performance of Convolutionally-Coded CDMA/OFDM for Mobile Communication System , 1993 .