The New Jersey Institute of Technology's
Electronic Theses & Dissertations Project

Title:	Adaptive receivers for direct-spread and multi-carrier code division multiple access systems
Author:	Liu, Xiangqun
View Online:	njit-etd1994-103 (x, 64 pages ~ 2.0 MB pdf)
Department:	Department of Electrical and Computer Engineering
Degree:	Master of Science
Program:	Electrical Engineering
Document Type:	Thesis
Advisory Committee:	Bar-Ness, Yeheskel (Committee chair) Ansari, Nirwan (Committee member) Siveski, Zoran (Committee member)
Date:	1994-10
Keywords:	Data transmission systems. Mobile communication systems. Code division multiple access.
Availability:	Unrestricted
Abstract:	In this thesis, the detection of Direct Sequence Code Division Multiple Access (DS-CDMA) signals in an AWGN channel and Multi-Carrier (MC) CDMA signals in a time-dispersion channel is discussed. The DS-CDMA receiver employs an adaptive multiuser interference canceler that utilizes deadzone limiters in the tentative decision stage. With weights adjusted adaptively, the prior knowledge of signal powers is unnecessary. The steady state error performance of this receiver is obtained and found to be superior to the performance of the same receiver using hard limiters for tentative decisions. The channel is considered non-fading in. this receiver. Modeling the frequency selective channel lading as narrowband fiat-flat fading centered at each subcarrier, the MC-CDMA technique reduces the effect of channel dispersion. A decorrelating multiuser interference canceler is introduced in the MC-CDMA receiver to reduce the multi-access interference, especially when the orthogonality of signature codes is degraded by the fading channel.