Multistage linear detectors for DS-CDMA communications.
Item
-
Title
-
Multistage linear detectors for DS-CDMA communications.
-
Identifier
-
AAI9618086
-
identifier
-
9618086
-
Creator
-
Moshavi, Shimon.
-
Contributor
-
Adviser: Donald L. Schilling
-
Date
-
1996
-
Language
-
English
-
Publisher
-
City University of New York.
-
Subject
-
Engineering, Electronics and Electrical
-
Abstract
-
A new family of multiuser multistage low-complexity linear detectors for direct sequence code division multiple access (DS-CDMA) communications is introduced. The result of the proposed design is to mitigate the effect of multiple access interference (MAI), the most significant limiting factor of user capacity in the conventional DS-CDMA channel.;This study begins by examining the parallel linear subtractive interference cancellation (PL-SIC) detector (also known as a parallel soft-decision successive interference cancellation receiver). It consists of multiple stages; the idea is to use the soft data estimates at the output of one stage to regenerate and cancel out, in parallel, the MAI of each user in the next stage. While this receiver affords moderate capacity gains, a careful analysis of the one stage PL-SIC detector leads to a modification that yields significant performance improvement. This modification entails simply combining the outputs of consecutive PL-SIC stages.;After introduction of a matrix-vector system model, it is found that the modified PL-SIC detector is effectively implementing a crude, but powerful, approximation of the decorrelating detector. This observation leads to the development of a new family of multiuser multistage linear detectors. Each stage of the underlying receiver design recreates the overall modulation, channel (without noise), and demodulation process; this in turn implements the code correlation matrix, R. The proposed receiver structure is completed by linearly combining the outputs of the stages. This has the effect of applying a polynomial in R to the output of the conventional DS-CDMA matched filter detector. The performance of the proposed detector is determined by the choice of combining weights; one can choose the weights to exactly or approximately implement the decorrelating detector, the minimum mean square error (MMSE) detector, or a different detector based on some other performance criterion. In this study, combining weights are chosen that minimize the mean square error according to the number of available detector stages. The resulting detectors are referred to as constrained MMSE, or C-MMSE, detectors. Extensive simulation results illustrate that substantial performance gains can be achieved through C-MMSE detection.
-
Type
-
dissertation
-
Source
-
PQT Legacy CUNY.xlsx
-
degree
-
Ph.D.
