| The wireless telecommunications industry is currently experiencing significant change in the types of wireless systems deployed. For cellular, this has meant a movement from existing second generation to third generation networks. In addition, there has been accelerating interest in high speed wireless local area networks. Contributing technologies to these advances in speed and breadth of services have centered around advanced modulation and detection as well as the use of multiple antenna elements for both the transmitter and receiver. One such technology, which has been actively researched, is multiuser detection for code-division multiple-access. These receiver designs have included both linear techniques, such as the decorrelator or minimum-mean squared-error (MMSE) detector, as well as nonlinear processing in the form of interference cancellation. Due to its low complexity and ability to operate well in near-far environments, the successive interference canceller (SIC) has become a popular multiuser detection receiver design. In this dissertation, we discuss the application of the SIC receiver to a particular communication system: the IS-95 downlink.; By addressing a particular signaling format, we are able to enhance the performance of the SIC receiver. We begin by providing models of cancellation and BER performance when a variety of enhancements, some unique to the IS-95 downlink, are employed during detection and reconstruction. In the proceeding chapters, analysis is provided to determine under what signaling conditions these enhancements offer performance gains over an SIC receiver which does not take the unique properties of the IS-95 downlink into account. These enhancements include taking several symbol level specifics into account during reconstruction: repeated bits, power control symbols, and variable amplitude levels. Additional gains are achieved through interference mitigation approaches: pilot cancellation, beamforming, and joint detection. Next, a completely blind SIC receiver is discussed for a more generic DS/CDMA system than the IS-95 downlink. Building on the work of linear detectors, a hybrid approach to interference cancellation is proposed. This detector uses a weight combination of other interference cancellation schemes to provide improved average performance in dynamic signaling scenarios. |
