Multiuser detections for optical CDMA networks based on expectation-maximization algorithm

• Published in: IEEE transactions on communications Vol. 52; no. 4; pp. 652 - 660
• Main Authors: Motahari, A.S., Nasiri-Kenari, M.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.04.2004; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Expectation-maximization algorithms; Interference constraints; Iterative algorithms; Maximum likelihood detection; Maximum likelihood estimation; Multiaccess communication; Multiuser detection; Optical detectors; Optical fiber networks; Robustness
• ISSN: 0090-6778; 1558-0857
• DOI: 10.1109/TCOMM.2003.811410

In this paper, we introduce new unblind and blind multiuser detectors for an optical code-division multiple-access system. The detectors have two soft and hard stages. In the soft stage, a soft estimation of the interference is obtained by solving an unconstrained maximum-likelihood problem via the iterative expectation-maximization (EM) algorithm. Then, the hard stage detects the user information bit by solving a one-dimensional Boolean constrained problem conditioned on knowing the interference. Our results reveal that the proposed detectors have very low complexity, and are robust against changes in parameters. Moreover, the numerical results illustrate that despite of their simplicities, our detectors substantially outperform other well-known suboptimum detectors, such as multistage and decorrelating detectors.