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Blind Reduced-Rank MMSE Detector for DS-CDMA Systems

Abstract

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.

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Correspondence to Xiaodong Cai.

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Cai, X., Ge, H. & Akansu, A.N. Blind Reduced-Rank MMSE Detector for DS-CDMA Systems. EURASIP J. Adv. Signal Process. 2002, 356983 (2003). https://doi.org/10.1155/S1110865702209087

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Keywords

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