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  • Research Article
  • Open Access

Blind Reduced-Rank MMSE Detector for DS-CDMA Systems

EURASIP Journal on Advances in Signal Processing20032002:356983

  • Received: 18 March 2002
  • Published:


We first develop a reduced-rank minimum mean squared error (MMSE) detector for direct-sequence (DS) code division multiple access (CDMA) by forcing the linear MMSE detector to lie in a signal subspace of a reduced dimension. While a reduced-rank MMSE detector has lower complexity, it cannot outperform the full-rank MMSE detector. We then concentrate on the blind reduced-rank MMSE detector which is obtained from an estimated covariance matrix. Our analysis and simulation results show that when the desired user′s signal is in a low-dimensional subspace, there exists an optimal subspace so that the blind reduced-rank MMSE detector lying in this subspace has the best performance. By properly choosing a subsspace, we guarantee that the optimal blind reduced-rank MMSE detector is obtained. An adaptive blind reduced-rank MMSE detector, based on a subspace tracking algorithm, is developed. The adaptive blind reduced-rank MMSE detector exhibits superior steady-state performance and fast convergence speed.


  • CDMA
  • blind multiuser detection
  • reduced-rank
  • MMSE
  • subspace tracking

Authors’ Affiliations

Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455, USA
Department of Electrical and Computer Engineering, New Jersey Institute of Technology, Newark, NJ 07102, USA


© Cai et al. 2002