Asymptotic multiuser efficiencies for decision-directed multiuser detectors

TitleAsymptotic multiuser efficiencies for decision-directed multiuser detectors
Publication TypeJournal Article
Year of Publication1998
AuthorsX Zhang, and D Brady
JournalIeee Transactions on Information Theory
Start Page502
Pagination502 - 515
Date Published12/1998

The asymptotic multiuser efficiencies (AME's) are derived for various classes of decision-directed multiuser detectors, including multistage detectors, and decision-feedback detectors. Novel classes of soft-decision multistage detectors are proposed and analyzed in this paper. Each class is specified in part by a soft-decision nonlinearity, such as a symmetric quantizer or a linear clipper. Closed-form expressions for two-user AME's are derived for soft-decision two-stage detectors and can be used as a design criterion to optimize the soft-decision nonlinearities. For a special case of two synchronous users, the soft-decision two-stage detector using an optimized linear clipper with either conventional or decorrelated tentative decisions is shown to achieve optimum AME. Upper and lower bounds on the AME are obtained for decision-feedback detectors using either conventional or decorrelated tentative decisions. It is demonstrated that decision-directed multiuser detectors with conventional tentative decisions have low near-far resistance compared to those with decorrelated tentative decisions. © 1998 IEEE.

Short TitleIeee Transactions on Information Theory