Blind asynchronous multiuser CDMA receivers for ISI channels using code-aided CMA

A code-aided constant modulus algorithm (CMA) based approach is presented for blind detection of asynchronous short-code DS-CDMA (direct sequence code division multiple access) signals in intersymbol interference (ISI)/multipath channels. Only the spreading code of the desired user is assumed to be known; its transmission delay may be unknown. A linear equalizer is designed by minimizing the Godard/CMA cost function of the equalizer output with respect to the equalizer coefficients subject to the fact that the equalizer lies in a subspace associated with the desired user's code sequence. Constrained CMA leads to the extraction of the desired user's signal whereas unconstrained minimization leads to the extraction of any one of the active users. The results are further improved by using unconstrained CMA initialized by the results of the code-aided CMA. Identifiability properties of the approach are analyzed. Illustrative simulation examples are provided.

[1]  Petre Stoica,et al.  Blind multiuser MMSE detector for CDMA signals in ISI channels , 1999, IEEE Communications Letters.

[2]  H. Vincent Poor,et al.  Blind equalization and multiuser detection in dispersive CDMA channels , 1998, IEEE Trans. Commun..

[3]  Upamanyu Madhow,et al.  Blind adaptive multiuser detection , 1995, IEEE Trans. Inf. Theory.

[4]  Vijay K. Bhargava,et al.  Recent advances in cellular wireless communications , 1999, IEEE Commun. Mag..

[5]  Murat Torlak,et al.  Blind multiuser channel estimation in asynchronous CDMA systems , 1997, IEEE Trans. Signal Process..

[6]  Jitendra K. Tugnait,et al.  Identification and deconvolution of multichannel linear non-Gaussian processes using higher order statistics and inverse filter criteria , 1997, IEEE Trans. Signal Process..

[7]  Philip Schniter,et al.  On the robustness of blind linear receivers for short-code CDMA , 1999, 1999 2nd IEEE Workshop on Signal Processing Advances in Wireless Communications (Cat. No.99EX304).

[8]  Stuart C. Schwartz,et al.  Adaptive feedforward/feedback architectures for multiuser detection in high data rate wireless CDMA networks , 2000, IEEE Trans. Commun..

[9]  S. Moshavi,et al.  Multi-user detection for DS-CDMA communications , 1996, IEEE Commun. Mag..

[10]  Jitendra K. Tugnait,et al.  Blind spatio-temporal equalization and impulse response estimation for MIMO channels using a Godard cost function , 1997, IEEE Trans. Signal Process..

[11]  Behnaam Aazhang,et al.  Subspace-based channel estimation for code division multiple access communication systems , 1996, IEEE Trans. Commun..

[12]  Joaquín Míguez,et al.  A linearly constrained constant modulus approach to blind adaptive multiuser interference suppression , 1998, IEEE Communications Letters.

[13]  Jitendra K. Tugnait,et al.  Spatiotemporal signal processing for blind separation of multichannel signals , 1996, Defense, Security, and Sensing.

[14]  Michail K. Tsatsanis.  Inverse filtering criteria for CDMA systems , 1997, IEEE Trans. Signal Process..

[15]  B. A. D. H. Brandwood.  A complex gradient operator and its applica-tion in adaptive array theory , 1983 .

[16]  Gene H. Golub,et al.  Matrix computations (3rd ed.) , 1996 .

[17]  Yu Song,et al.  Subspace blind detection of asynchronous CDMA signals in multipath channels , 1999, 1999 2nd IEEE Workshop on Signal Processing Advances in Wireless Communications (Cat. No.99EX304).

[18]  Don H. Johnson,et al.  Array Signal Processing: Concepts and Techniques , 1993 .

[19]  D. Luenberger.  Optimization by Vector Space Methods , 1968 .

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

[21]  M.K. Tsatsanis,et al.  Performance analysis of minimum variance CDMA receivers , 1998, IEEE Trans. Signal Process..

[22]  Upamanyu Madhow.  Blind adaptive interference suppression for direct-sequence CDMA , 1998 .

[23]  E. Polak.  Introduction to linear and nonlinear programming , 1973 .

[24]  T. Moon,et al.  Mathematical Methods and Algorithms for Signal Processing , 1999 .