Performance Improvement Techniques for Cellular OFDMA Systems
| Autor: | I-Kang Fu, 傅宜康 |
|---|---|
| Rok vydání: | 2007 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 96 OFDMA (Orthogonal Frequency Division Multiple Access) is one of the key multiple access techniques to enable broadband wireless transmission for next generation mobile cellular systems. In order to improve and investigate the performance of cellular OFDMA systems, this dissertation proposes several advanced techniques and part of the designs have been adopt by the international standard organization. The downlink capacity of cellular OFDMA systems is first investigated through the proposed mathematical analysis. The proposed analysis is general and incorporates the effects of propagation environment, cell size, frequency reuse factors, reuse partitioning (fractional frequency reuse), antenna setups and etc. The numerical results show that the downlink capacity of cellular OFDMA system can be significantly improved by reuse partitioning and intra-cell frequency reuse. Then, an improved FBSS (Fast Base Station Switching) handover technique is proposed to improve the packet loss rate for the handover users. Simulation results show that the proposed technique can significantly reduce the packet loss rate for the users during FBSS at a slight expense on system capacity. In addition, a recent advance in multi-hop relay technology is introduced and investigated, and the benefit on user throughput enhancement and coverage extension by relay deployment are justified by simulation results. But it also shows that the capacity may not be improved by deploying relay stations with respect to the cellular OFDMA system with no relay. In order to improve the capacity of multi-hop cellular OFDMA systems, advanced frequency planning (reuse) techniques and path selection techniques are investigated and proposed. Compare to existing techniques, the proposed frequency planning (reuse) technique can lead to 60.87% ~ 137.75% capacity improvements under the guaranteed coverage. In addition, simulation results also show that further 16.87% ~ 26.31% capacity improvement can be achieved by advanced path selection based on proposed SINR prediction technique. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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