Open Access

Space-Time Joint Interference Cancellation Using Fuzzy-Inference-Based Adaptive Filtering Techniques in Frequency-Selective Multipath Channels

  • Chia-Chang Hu1,
  • Hsuan-Yu Lin1,
  • Yu-Fan Chen2 and
  • Jyh-Horng Wen1, 3
EURASIP Journal on Advances in Signal Processing20062006:062052

Received: 7 March 2005

Accepted: 19 July 2005

Published: 15 February 2006


An adaptive minimum mean-square error (MMSE) array receiver based on the fuzzy-logic recursive least-squares (RLS) algorithm is developed for asynchronous DS-CDMA interference suppression in the presence of frequency-selective multipath fading. This receiver employs a fuzzy-logic control mechanism to perform the nonlinear mapping of the squared error and squared error variation, denoted by ( , ), into a forgetting factor . For the real-time applicability, a computationally efficient version of the proposed receiver is derived based on the least-mean-square (LMS) algorithm using the fuzzy-inference-controlled step-size . This receiver is capable of providing both fast convergence/tracking capability as well as small steady-state misadjustment as compared with conventional LMS- and RLS-based MMSE DS-CDMA receivers. Simulations show that the fuzzy-logic LMS and RLS algorithms outperform, respectively, other variable step-size LMS (VSS-LMS) and variable forgetting factor RLS (VFF-RLS) algorithms at least 3 dB and 1.5 dB in bit-error-rate (BER) for multipath fading channels.


Authors’ Affiliations

Department of Electrical Engineering, National Chung Cheng University
Department of Communications Engineering, National Chung Cheng University
Institute of Communication Engineering, National Chi Nan University


  1. Xie Z, Short RT, Rushforth CK: A family of suboptimum detectors for coherent multiuser communications. IEEE Journal on Selected Areas in Communications 1990, 8(4):683-690. 10.1109/49.54464View ArticleGoogle Scholar
  2. Widrow B, Mantey PE, Griffiths LJ, Goode BB: Adaptive antenna systems. Proceedings of the IEEE 1967, 55(12):2143-2159.View ArticleGoogle Scholar
  3. Jim CW: A comparison of two LMS constrained optimal array structures. Proceedings of the IEEE 1977, 65(12):1730-1731.View ArticleGoogle Scholar
  4. Honig M, Madhow U, Verdú S: Blind adaptive multiuser detection. IEEE Transactions on Information Theory 1995, 41(4):944-960. 10.1109/18.391241View ArticleMATHGoogle Scholar
  5. Poor HV, Wang X: Code-aided interference suppression for DS/CDMA communications. II. Parallel blind adaptive implementations. IEEE Transactions on Communications 1997, 45(9):1112-1122. 10.1109/26.623076View ArticleGoogle Scholar
  6. Kecman V: Learning and Soft Computing: Support Vector Machines, Neural Networks, and Fuzzy Logic Models. MIT Press, Cambridge, Mass, USA; 2001.MATHGoogle Scholar
  7. Wu X, Ge L, Liang G: Adaptive power control on the reverse link for CDMA cellular system. Proceedings of 5th IEEE Asia-Pacific Conference on Communications and 4th Optoelectronics and Communications Conference (APCC/OECC '99), October 1999, Beijing, China 1: 608-611.Google Scholar
  8. Chang P-R, Wang B-C: Adaptive fuzzy power control for CDMA mobile radio systems. IEEE Transactions on Vehicular Technology 1996, 45(2):225-236. 10.1109/25.492846View ArticleGoogle Scholar
  9. Chang P-R, Wang B-C: Adaptive fuzzy proportional integral power control for a cellular CDMA system with time delay. IEEE Journal on Selected Areas in Communications 1996, 14(9):1818-1829. 10.1109/49.545704View ArticleGoogle Scholar
  10. Jamshidi M: Fuzzy logic software and hardware. In Fuzzy Logic and Control: Software and Hardware Applications. Prentice-Hall, Englewood cliffs, NJ, USA; 1993.Google Scholar
  11. Gan W-S: Designing a fuzzy step size LMS algorithm. IEE Proceedings - Vision, Image and Signal Processing 1997, 144(5):261-266. 10.1049/ip-vis:19971417View ArticleGoogle Scholar
  12. Harris RW, Chabries DM, Bishop FA: A variable step (VS) adaptive filter algorithm. IEEE Transactions Acoustics, Speech, Signal Processing 1986, 34(2):309-316. 10.1109/TASSP.1986.1164814View ArticleGoogle Scholar
  13. Kwong RH, Johnston EW: A variable step size LMS algorithm. IEEE Transactions on Signal Processing 1992, 40(7):1633-1642. 10.1109/78.143435View ArticleMATHGoogle Scholar
  14. Song S, Lim J-S, Back SJ, Sung K-M: Variable forgetting factor linear least squares algorithm for frequency selective fading channel estimation. IEEE Transactions on Vehicular Technology 2002, 51(3):613-616. 10.1109/TVT.2002.1002509View ArticleGoogle Scholar
  15. Proakis JG: Digital Communications. 4th edition. McGraw-Hill, New York, NY, USA; 2000.MATHGoogle Scholar
  16. Honig ML, Miller SL, Shensa MJ, Milstein LB: Performance of adaptive linear interference suppression in the presence of dynamic fading. IEEE Transactions on Communications 2001, 49(4):635-645. 10.1109/26.917770View ArticleMATHGoogle Scholar
  17. Honig ML, Goldstein JS: Adaptive reduced-rank interference suppression based on the multistage Wiener filter. IEEE Transactions on Communications 2002, 50(6):986-994. 10.1109/TCOMM.2002.1010618View ArticleGoogle Scholar
  18. Rapajic PB, Vucetic BS: Adaptive receiver structures for asynchronous CDMA systems. IEEE Journal on Selected Areas in Communications 1994, 12(4):685-697. 10.1109/49.286675View ArticleGoogle Scholar
  19. Abdulrahman M, Sheikh AUH, Falconer DD: Decision feedback equalization for CDMA in indoor wireless communications. IEEE Journal on Selected Areas in Communications 1994, 12(4):698-706. 10.1109/49.286676View ArticleGoogle Scholar
  20. Madhow U, Honig ML: MMSE interference suppression for direct-sequence spread-spectrum CDMA. IEEE Transactions on Communications 1994, 42(12):3178-3188. 10.1109/26.339839View ArticleGoogle Scholar
  21. Haykin S: Adaptive Filter Theory. 3rd edition. Prentice-Hall, Englewood Cliffs, NJ, USA; 1996.MATHGoogle Scholar
  22. Zadeh LA: Fuzzy sets. Information and Control 1965, 8(3):338-353. 10.1016/S0019-9958(65)90241-XMathSciNetView ArticleMATHGoogle Scholar
  23. Chen Y-L, Lin Y-S, Wen J-H, Chang W-M, Liao J: Combined fuzzy-based rate and selective power control in multimedia CDMA cellular systems. Proceedings of 58th IEEE Vehicular Technology Conference (VTC '03), October 2003, Orlando, Fla, USA 4: 2506-2510.Google Scholar
  24. Patyra MJ, Grantner JL, Koster K: Digital fuzzy logic controller: design and implementation. IEEE Transactions on Fuzzy Systems 1996, 4(4):439-459. 10.1109/91.544304View ArticleGoogle Scholar
  25. Costa A, De Gloria A, Faraboschi P, Pagni A, Rizzotto G: Hardware solutions for fuzzy control. Proceedings of IEEE 1995, 83(3):422-434. 10.1109/5.364488View ArticleGoogle Scholar
  26. Aboulnasr T, Mayyas K: A robust variable step-size LMS-type algorithm: analysis and simulations. IEEE Transactions on Signal Processing 1997, 45(3):631-639. 10.1109/78.558478View ArticleGoogle Scholar
  27. Lin J, Proakis JG, Ling F, Lev-Ari H: Optimal tracking of time-varying channels: a frequency domain approach for known and new algorithms. IEEE Journal on Selected Areas in Communications 1995, 13(1):141-154. 10.1109/49.363137View ArticleGoogle Scholar
  28. Jakes WC: Microwave Mobile Communications. John Wiley & Sons, New York, NY, USA; 1974.Google Scholar
  29. So CF, Ng SC, Leung SH: Gradient based variable forgetting factor RLS algorithm. Signal Processing 2003, 83(6):1163-1175. 10.1016/S0165-1684(03)00037-9View ArticleMATHGoogle Scholar
  30. Borah DK, Hart BT: Frequency-selective fading channel estimation with a polynomial time-varying channel model. IEEE Transactions on Communications 1999, 47(6):862-873. 10.1109/26.771343View ArticleGoogle Scholar


© Hu et al. 2006