Intelligent antennas for DS-CDMA systems

Abstract: This paper considers the performance of a DS-CDMA system which employs adaptive antenna technology at the basestation site. By utilising the capability of ray-tracing to provide the complex channel impulse response, a new ray-based simulation methodology for an adaptive antenna in a DS-CDMA system is presented. Results for a typical microcellular environment highlight the behaviour of the adaptive antenna. Finally, with the help of a DS-CDMA capacity analysis, the potential spectrum efficiency enhancement is evaluated and the improvement of some of the statistics of the system is discussed. I. INTRODUCTION The need for mobile radio systems with increased spectrum efficiency is paramount in the drive towards third generation systems [ 1-21. Currently favoured solutions in today's systems, which are generally applicable to any modulation scheme or access technique, include the deployment of smaller cells as well as fixed sector, or multi-beam antennas at the basestation site. In terms of modulation schemes and access techniques the application of spread spectrum modulation techniques with Code Division multiple access (CDMA) and especially Direct Sequence (DS) CDMA is one

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