| With the demand for higher data rates and wireless services rising as fast as the Internet permeated our lives, the need to cope with the idiosyncrasies of the shared wireless medium increases along with the challenges: multiuser interference (MUI), frequency selective multipath-induced fading, time-selective mobility-induced impairments, and high-performance transceivers that are also bandwidth- and power-efficient. Today's Code-Division Multiple Access (CDMA) systems rely on long aperiodic pseudo-noise codes and strict power control to suppress MUI statistically.; This thesis offers a novel approach to designing low-complexity bandwidth-efficient quasi-synchronous CDMA transceivers capable of eliminating MUI deterministically in the presence of unknown and even rapidly varying multipath. Relying on chip-interleaving and block spreading (CIBS), mutual orthogonality among user codes is preserved even after time- and/or frequency-selective multipath propagation, which allows for deterministic multiuser separation through a low-complexity receiver front-end. Converting multiuser detection into a set of equivalent single user equalization problems, the proposed CIBS-CDMA enables applications of any single user scheme in a multiple access framework.; Our research on multiple access over time- and frequency-selective channels offers the potential for enhanced performance, capacity, and high-speed delivery of information in broadband wireless communication systems. The ultimate goal is to have wireless services such as mobile computing, high-speed internet access, and other personal communication services delivered with improved quality of service, and be accessible to more people. |
