Iterative multiuser detection techniques for CDMA systems

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item.Includes bibliographical references (leaves 52-54).Issued also on microfiche from Lange Micrographics.The presence of the multiple-access interference (MAI) and intersymbol interference (ISI) constitutes a major impediment to reliable communications in multipath code-division multiple-access (CDMA) channels. Recently iterative processing techniques, which are known as excellent techniques for reducing MAI and ISI, have received considerable attention. In this thesis, existing iterative multiuser detection techniques, including the low-complexity approximate soft-input soft-output (SISO) multiuser detector, iterative improved parallel interference cancellation, gradient descent algorithm and slowest-descent algorithm, are studied. Two new iterative multiuser detection methods, namely the simplified low-complexity approximate SISO multiuser detector, and the slowest-descent-based nonlinear detector, are developed and compared with the above existing techniques. It is seen that the two new iterative multiuser detectors significantly outperform the above existing methods in coded CDMA systems except the low-complexity approximate SISO detector for CDMA systems