Blind PARAFAC receivers for DS-CDMA systems

This paper links the direct-sequence code-division multiple access (DS-CDMA ) multiuser separation-equalization-detection problem to the parallel facto r (PARAFAC) model, which is an analysis tool rooted in psychometrics and ch emo metrics. Exploiting this link, it derives a deterministic blind PARAFAC DS-CDMA receiver with performance close to nonblind minimum mean-squared e rror (MMSE). The proposed PARAFAC receiver capitalizes on code, spatial, an d temporal diversity-combining, thereby supporting small sample sizes, more users than sensors, and/or less spreading than users. Interestingly, PARAF AC does not require knowledge of spreading codes, the specifics of multipat h (interchip interference), DOA-calibration information, finite alphabet/co nstant modulus, or statistical independence/whiteness to recover the inform ation-bearing signals. Instead, PARAFAC relies on a fundamental result rega rding the uniqueness of low-rank three-wag array decomposition due to Krusk al (and generalized herein to the complex-valued case) that guarantees iden tifiability of all relevant signals and propagation parameters. These and o ther issues ar-e also demonstrated in pertinent simulation experiments.