Pilot-assisted channel estimation based on MMSE criterion for DS-CDMA with frequency-domain equalization

The bit error rate (BER) performance of DS-CDMA in a frequency-selective fading channel can be significantly improved by the use of frequency-domain equalization (FDE). Accurate estimation of the channel transfer function is necessary for FDE. Direct application of pilot-assisted channel estimation (CE) degrades the BER performance, since the frequency spectrum of the pilot chip sequence is not constant over the spreading bandwidth. We propose a pilot-assisted frequency-domain CE based on a minimum mean square error (MMSE) criterion. The BER performance with MMSE-CE in a frequency-selective Rayleigh fading channel is evaluated by computer simulation. It is found that MMSE-CE always provides a good BER performance, irrespective of the choice of pilot chip sequence. For a spreading factor, SF, of 16, the E/sub b//N/sub 0/ degradation with MMSE-CE from the ideal CE case is as small as 0.4 dB at BER=10/sup -4/ (a 0.28 dB loss due to the pilot insertion is included).

[1]  Hiroyuki Atarashi,et al.  Variable Spreading Factor Orthogonal Frequency and Code Division Multiplexing (VSF-OFCDM) , 2002 .

[2]  Abbas Jamalipour,et al.  Wireless communications , 2005, GLOBECOM '05. IEEE Global Telecommunications Conference, 2005..

[3]  W. C. Jakes,et al.  Microwave Mobile Communications , 1974 .

[4]  Fumiyuki Adachi,et al.  Decision Feedback Channel Estimation for OFDM with STTD , 2004 .

[5]  E-L. Kuan,et al.  Overview of Multicarrier CDMA , 2004 .

[6]  F.K. Jondral,et al.  Comparing equalizers and multiuser detectors for CDMA downlink systems , 2004, 2004 IEEE 59th Vehicular Technology Conference. VTC 2004-Spring (IEEE Cat. No.04CH37514).

[7]  T.A. Thomas,et al.  Cyclic-prefix CDMA with antenna diversity , 2002, Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367).

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

[9]  Andrea Goldsmith,et al.  Wireless Communications , 2005, 2021 15th International Conference on Advanced Technologies, Systems and Services in Telecommunications (TELSIKS).

[10]  Fumiyuki Adachi,et al.  Joint Frequency-Domain Equalization and Antenna Diversity Combining for Orthogonal Multicode DS-CDMA Signal Transmissions in a Frequency-Selective Fading Channel , 2004 .

[11]  Ramjee Prasad,et al.  Design and performance of multicarrier CDMA system in frequency-selective Rayleigh fading channels , 1999 .

[12]  Kiho Kim,et al.  Beyond 3G: vision, requirements, and enabling technologies , 2003, IEEE Commun. Mag..

[13]  Hao Yuan,et al.  A novel channel estimation method for OFDM transmission technique under fast time-variant fading channel , 2003, The 57th IEEE Semiannual Vehicular Technology Conference, 2003. VTC 2003-Spring..

[14]  Fumiyuki Adachi,et al.  Performance of multicode DS-CDMA using frequency domain equalisation in frequency selective fading channel , 2003 .

[15]  Fumiyuki Adachi,et al.  Wideband DS-CDMA for next-generation mobile communications systems , 1998, IEEE Commun. Mag..

[16]  S.K. Wilson,et al.  On channel estimation in OFDM systems , 1995, 1995 IEEE 45th Vehicular Technology Conference. Countdown to the Wireless Twenty-First Century.

[17]  J.E. Mazo,et al.  Digital communications , 1985, Proceedings of the IEEE.

[18]  K. Takeda Frequency-domain equalization for antenna diversity reception of DS-CDMA signals , 2003 .