Efficient Interference Cancellation Techniques for Advanced DS-CDMA Receivers
The focus of this dissertation is the study of advanced processing techniques for multiuser interference cancellation in direct sequence code division multiple access communications. Emphasis is placed on the development of efficient techniques that are practical to implement.
The work begins with a study of several sub-optimal multiuser detection techniques under a variety of conditions. Multistage parallel interference cancellation is identified as a practical and robust approach for mitigating multiple access interference. In order to reduce the effect of biased decision statistics inherent to parallel cancellation, a low-complexity modification to parallel interference cancellation that significantly improves performance is derived. Based on this approach, two real-time DSP implementations are devised, one fully coherent and one non-coherent. Multi-symbol differential detection is then explored as an alternative for improving the performance of the non-coherent approach. Additionally, dual-antenna diversity techniques are also investigated as a means for improving performance in multipath environments.