A Robust Parametric Technique for Multipath Channel Estimation in the Uplink of a DS-CDMA System

  • Vassilis Kekatos
  • Athanasios A Rontogiannis
  • Kostas Berberidis
Open Access
Research Article


The problem of estimating the multipath channel parameters of a new user entering the uplink of an asynchronous direct sequence-code division multiple access (DS-CDMA) system is addressed. The problem is described via a least squares (LS) cost function with a rich structure. This cost function, which is nonlinear with respect to the time delays and linear with respect to the gains of the multipath channel, is proved to be approximately decoupled in terms of the path delays. Due to this structure, an iterative procedure of 1D searches is adequate for time delays estimation. The resulting method is computationally efficient, does not require any specific pilot signal, and performs well for a small number of training symbols. Simulation results show that the proposed technique offers a better estimation accuracy compared to existing related methods, and is robust to multiple access interference.


Cost Function Channel Estimation Multiple Access Path Delay Multipath Channel 
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  1. 1.
    Proakis JG, Salehi M: Communication Systems Engineering. Prentice-Hall, Upper Saddle River, NJ, USA; 2002.MATHGoogle Scholar
  2. 2.
    Iltis RA, Mailaender L: An adaptive multiuser detector with joint amplitude and delay estimation. IEEE Journal on Selected Areas in Communications 1994,12(5):774-785. 10.1109/49.298051CrossRefGoogle Scholar
  3. 3.
    Madhow U: Blind adaptive interference suppression for the near-far resistant acquisition and demodulation of direct-sequence CDMA signals. IEEE Transactions on Signal Processing 1997,45(1):124-136. 10.1109/78.552211CrossRefGoogle Scholar
  4. 4.
    Logothetis A, Carlemalm C: SAGE algorithms for multipath detection and parameter estimation in asynchronous CDMA systems. IEEE Transactions on Signal Processing 2000,48(11):3162-3174. 10.1109/78.875473CrossRefGoogle Scholar
  5. 5.
    Torlak M, Xu G: Blind multiuser channel estimation in asynchronous CDMA systems. IEEE Transactions on Signal Processing 1997,45(1):137-147. 10.1109/78.552212CrossRefGoogle Scholar
  6. 6.
    Strom EG, Parkvall S, Miller SL, Ottersten BE: Propagation delay estimation in asynchronous direct-sequence code-division multiple access systems. IEEE Transactions on Communications 1996,44(1):84-93. 10.1109/26.476100CrossRefMATHGoogle Scholar
  7. 7.
    Ostman T, Parkvall S, Ottersten BE: An improved MUSIC algorithm for estimation of time delays in asynchronous DS-CDMA systems. IEEE Transactions on Communications 1999,47(11):1628-1631. 10.1109/26.803496CrossRefGoogle Scholar
  8. 8.
    Petrochilos N, van der Veen A-J: Blind time delay estimation in asynchronous CDMA via subspace intersection and ESPRIT. Proceedings of IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP '01), May 2001, Salt Lake City, Utah, USA 4: 2217-2220.Google Scholar
  9. 9.
    Ruifeng Z, Zhenhui T: ESPRIT-based delay estimators for DS-CDMA systems. Proceedings of IEEE International Conference on Communications (ICC '00), June 2000, New Orleans, La, USA 3: 1472-1476.CrossRefGoogle Scholar
  10. 10.
    Bensley SE, Aazhang B: Subspace-based channel estimation for code division multiple access communication systems. IEEE Transactions on Communications 1996,44(8):1009-1020. 10.1109/26.535441CrossRefMATHGoogle Scholar
  11. 11.
    Bensley SE, Aazhang B: Maximum-likelihood synchronization of a single user for code-division multiple-access communication systems. IEEE Transactions on Communications 1998,46(3):392-399. 10.1109/26.662645CrossRefGoogle Scholar
  12. 12.
    Strom EG, Malmsten F: A maximum likelihood approach for estimating DS-CDMA multipath fading channels. IEEE Journal on Selected Areas in Communications 2000,18(1):132-140. 10.1109/49.821727CrossRefGoogle Scholar
  13. 13.
    Tripathi V, Montravadi A, Veeravalli VV: Channel acquisition for wideband CDMA signals. IEEE Journal on Selected Areas in Communications 2000,18(8):1483-1494. 10.1109/49.864012CrossRefGoogle Scholar
  14. 14.
    Ertin E, Mitra U, Siwamogsatham S: Maximum-likelihood-based multipath channel estimation for code-division multiple-access systems. IEEE Transactions on Communications 2001,49(2):290-302. 10.1109/26.905887CrossRefMATHGoogle Scholar
  15. 15.
    Aktas E, Mitra U: Single-user sparse channel acquisition in multiuser DS-CDMA systems. IEEE Transactions on Communications 2003,51(4):682-693. 10.1109/TCOMM.2003.810842MathSciNetCrossRefGoogle Scholar
  16. 16.
    D'Amico AA, Mengali U, Morelli M: Channel estimation for the uplink of a DS-CDMA system. IEEE Transactions on Wireless Communications 2003,2(6):1132-1137. 10.1109/TWC.2003.819031CrossRefGoogle Scholar
  17. 17.
    Fessler JA, Hero AO: Space-alternating generalized expectation-maximization algorithm. IEEE Transactions on Signal Processing 1994,42(10):2664-2677. 10.1109/78.324732CrossRefGoogle Scholar
  18. 18.
    Universal Mobile Telecommunications System (UMTS) : Spreading and modulation (FDD). In Technical Specification 3GPP 25.213. ETSI, Sophia-Antipolis, France; June 2005. http://www.3gpp.orgGoogle Scholar
  19. 19.
    Björck Å: Numerical Methods for Least Squares Problems. SIAM, Philadelphia, Pa, USA; 1996. chapter 9CrossRefMATHGoogle Scholar
  20. 20.
    Rontogiannis AA, Marava A, Berberidis K, Palicot J: Efficient multipath channel estimation using a semi-blind parametric technique. Proceedings of IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP '03), April 2003, Hong Kong, China 4: 477-480.MATHGoogle Scholar
  21. 21.
    Rontogiannis AA, Berberidis K, Marava A, Palicot J: Efficient semi-blind estimation of multipath channel parameters via a delay decoupling optimization approach. Signal Processing 2005,85(12):2394-2411. 10.1016/j.sigpro.2005.02.018CrossRefMATHGoogle Scholar
  22. 22.
    Universal Mobile Telecommunications System (UMTS) : Selection procedures for the choice of radio transmission technologies of the UMTS. In Tech. Rep. 3GPP 101.112. ETSI, Sophia-Antipolis, France; April 1998.Google Scholar

Copyright information

© Vassilis Kekatos et al. 2006

This article is published under license to BioMed Central Ltd. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Authors and Affiliations

  • Vassilis Kekatos
    • 1
  • Athanasios A Rontogiannis
    • 2
  • Kostas Berberidis
    • 1
  1. 1.Department of Computer Engineering and Informatics and Research Academic Computer Technology InstituteUniversity of PatrasRio PatrasGreece
  2. 2.Institute of Space Applications and Remote SensingNational Observatory of AthensPalea PenteliGreece

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