Blind adaptive interference suppression for direct-sequence CDMA

Publisher Website
Google Scholar
Abstract
Direct sequence (DS) code division multiple access (CDMA) is a promising technology for wireless environments with multiple simultaneous transmissions because of several features: asyn- chronous multiple access, robustness to frequency selective fading, and multipath combining. The capacity of DS-CDMA systems is interference-limited and can therefore be increased by tech- niques that suppress interference. In this paper, we present recent developments in interference suppression using blind adaptive receivers that do not require knowledge of the signal waveforms and propagation channels of the interference, and that require a minimal amount of information about the desired signal. The framework considered generalizes naturally to include additional capabilities such as receive antenna diversity. The most powerful application of the methods described here is for linearly modulated CDMA systems with short spreading waveforms (i.e., spreading waveforms with period equal to the symbol interval), for which they provide substantial performance gains over conventional recep- tion. Implications for future system design due to the restriction of short spreading waveforms and directions for further investigation are discussed. In this introductory section, we motivate the problem con- sidered, provide a perspective on the state of the art in this area, and discuss the new thinking in terms of system design that would be needed to exploit the relatively new tech- niques discussed in this paper. We end with an outline of the remainder of the paper. Our objective in this paper is not to survey the rapidly changing state of the art in this field, but to convey a basic understanding of some key concepts.

This publication has 64 references indexed in Scilit: