Critical load of oversaturated systems with multistage successive interference cancellation

The allowable load in oversaturated CDMA systems is investigated, so that the uncoded performance with multistage successive interference cancellation (m-SIC) remains close to the single user bound. As oversaturated systems, we consider pseudo-noise CDMA (PN), pseudo noise/ orthogonal CDMA (PN/O) and orthogonal/orthogonal CDMA (O/O). For O/O, we make a distinction between scrambled O/O (s-O/O) and overall-permuted O/O (o-O/O). Because of the special structure of the O/O signature set, the intrinsic delay of m-SIC is drastically reduced in O/O as compared to PN and PN/O. For all systems, it is found that the achievable acceptable overload increases with the spreading factor. The o-O/O system outperforms s-O/O, while PN/O is inferior to o-O/O. Both O/O systems and the PN/O system clearly outperform PN.

[1]  Ramjee Prasad,et al.  Overview of multicarrier CDMA , 1997, IEEE Commun. Mag..

[2]  Shlomo Shamai,et al.  Spectral Efficiency of CDMA with Random Spreading , 1999, IEEE Trans. Inf. Theory.

[3]  Upamanyu Madhow,et al.  MMSE interference suppression for direct-sequence spread-spectrum CDMA , 1994, IEEE Trans. Commun..

[4]  Marc Moeneclaey,et al.  Increasing CDMA capacity using multiple orthogonal spreading sequence sets and successive interference cancellation , 2002, 2002 IEEE International Conference on Communications. Conference Proceedings. ICC 2002 (Cat. No.02CH37333).

[5]  Marc Moeneclaey,et al.  Extending the capacity of multiple access channels , 2000 .

[6]  P. Vijay Kumar,et al.  Quasi-orthogonal sequences for code-division multiple-access systems , 2000, IEEE Trans. Inf. Theory.

[7]  Marc Moeneclaey,et al.  Multiple access using two sets of orthogonal signal waveforms , 2000, IEEE Communications Letters.

[8]  Marc Moeneclaey,et al.  DS/CDMA with two sets of orthogonal spreading sequences and iterative detection , 2000, IEEE Communications Letters.

[9]  Bijan Jabbari,et al.  Spreading codes for direct sequence CDMA and wideband CDMA cellular networks , 1998, IEEE Commun. Mag..

[10]  E. H. Dinan.  Spreading Code for Direct Sequence CDMA and Wideband CDMA Cellular Networks , 1998 .

[11]  Lars K. Rasmussen,et al.  A matrix-algebraic approach to successive interference cancellation in CDMA , 2000, IEEE Trans. Commun..

[12]  Sergio Verdú,et al.  Linear multiuser detectors for synchronous code-division multiple-access channels , 1989, IEEE Trans. Inf. Theory.

[13]  Marc Moeneclaey,et al.  Optimal performance of an oversaturated OCDMA/OCDMA system based on scrambled orthogonal bases , 2002, The 13th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications.