| Summary: | 碩士 === 國立交通大學 === 電信工程系 === 90 === CDMA is one of the most potential techniques in the third generation mobile communication system because of its resistance of interference and high frequency efficiency. Because the CDMA system can serve many users with various services requirements at the same time, radio resource management (RRM) becomes a very important issue. The goal of this thesis is to study cell site selection technique for hierarchical CDMA networks with multi class traffic.
Data services, such as WWW, E-mail and video, etc, will become primary services in the next generation mobile wireless communication system. Theses services require higher bandwidth and diverse QoS requirements. Thus, it is difficult to find a common traffic model that can approximate all kinds of data traffic. This thesis will compare two data traffic models, i.e. a modified on-off data traffic model and Pareto based data traffic model, and evaluate their impacts on the system performance of cellular network.
Secondly, hotspot micro cells often occur in a small area requesting high traffic load. Employing hotspot micro cells can increase system capacity and improve system performance. Because a micro cell and a macro cell use the same frequency band, the system may suffer interference with each other. In this thesis, we investigate different cell site selection algorithms for hierarchical cellular systems to ensure that the system can effectively improve system capacity without suffering severe interference with each other. For this purpose, we propose a new relative pilot based cell site selection algorithm. Through assigning a protection threshold, the relative pilot based cell site algorithm not only can ensure a micro cell to effectively relieve hotspot data traffic load, but avoid the micro cell from serving too much traffic beyond its capability. We will demonstrate that the proposed relative pilot based cell site selection algorithm outperforms most current site selection algorithms in hierarchical CDMA cellular system with multiple traffic classes.
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