Radio Engineering of OFDMA Access Networks.
Ingénierie radio des réseaux d'accès OFDMA.
Résumé
Multi-carrier Orthogonal Frequency Division Multiple Access (OFDMA) systems promise enhanced performance as compared to preceding single carrier ones. It is imperative to analyze the performance evaluation of these systems prior to network deployment which is approaching quite fast. Therefore, in this thesis we look into dimensioning issues related to OFDMA based system. The study of network engineering for OFDMA networks into two major components: Radio Coverage and Capacity and Traffic Analysis. While analyzing the former, we consider a static system such that users have full buffers and always have something to transmit. Traffic Analysis, on the other hand, takes into account a dynamic system in which users receive an elastic traffic during active phase and go to sleep for some duration after download is over. In the study of Radio Coverage and Capacity, we evaluated the system performance under various frequency reuse schemes keeping in view both cell capacity and outage probability. This study is based on Monte Carlo simulations and an original analytical model. We have investigated the possibility of achieving reuse 1 and shown under which conditions it is possible while using beamforming technique. A time efficient method to acquire the spatial effective SINR distribution is also proposed. As far as study of dynamic system is concerned, the validation and robustness study of analytical models, developed for WiMAX systems, is carried out in this thesis. The analytical models take into account different scheduling policies and different classes of traffic. The performance parameters furnished by these models could be used in the dimensioning process. We have shown that models results obtained through model have little variation with respect to those of simulations. It has also been concluded that the model provides acceptable results for different radio channels, traffic distributions and load conditions. This thesis offers a frame work for dimensioning process of an OFDMA system. The proposed tools are based on analytical, semi-analytical and Monte Carlo simulation based approaches. In addition to its utility, the work carried out in this thesis will pave the way for future research.
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