前瞻性行動無線都會網路之設計與性能評估

Abstract

本計畫將設計一套改良式行動無線都會網路系統架構，我們將運用現行先進技術， 如正交分頻多重進接/分碼多重進接系統技術(OFDM/CDMA)，多路徑干擾消除技術 (MPIC)，低密度同位檢查碼(LDPC code)，渦輪等化(turbo equalizer)等技術來改善行動無 線都會網路系統的效能。更進一步，我們將估計所設計系統在蜂巢式細胞空間內的系統 容量，並且用來比較其與傳統行動無線都會網路系統的容量，來知曉所設計系統在總用 戶使用容量的改善程度。因為行動無線都會網路現在在世界上正蓬勃發展，因此對系統 的效能要求也越來越高。行動無線都會網路系統可提供無線高速行動應用，但也因此將 面對嚴重的多路徑干擾效應而減低系統的效能。因此處理多路徑干擾效應的解決方案目 前正被行動無線都會網路研究論壇所注意。我們所提供的以正交分頻多重進接/分碼多重 進接系統技術為基礎的行動無線都會網路系統，將在傳收端應用展頻技術並在接收端應 用多路徑干擾消除技術，不但可以減低多路徑干擾的效應，而且可以提供更好的系統效 能。換言之，系統效能的改善，意味著平均細胞內的服務容量將可以提升。我們也將研 究系統的低密度同位檢查碼，來發展對於整體系統效能有更適合的編碼方式。

this project, we will design a modified mobile WiMAX system architecture. We will use several advanced techniques, such as OFDM/CDMA system technique, multipath interference cancellation (MPIC) technique, low density parity check code (LDPC code), turbo equalization to improve the mobile WiMAX system performance. Furthermore, we will estimate the capacity of the proposed system in the cellular environment to compare it with the capacity of the traditional mobile WiMAX system and to achieve the improvement of the total subscribers. Because the mobile WiMAX is under developed in the world, there are still a lot of demands for system performance. In the mobile WiMAX, the system can provide high speed mobile application, but it may suffer from serious multipath effects which will degrade the system performance. Therefore, the solutions for the multipath effect need to be noticed by the WiMAX research forum. We provide the OFDM/CDMA based mobile WiMAX system that uses the spreading technique and the MPIC technique in the tranceiver that can not only reduce the multipath effect but also provide the better system performance. In other words, basing on the improvement of the system performance, the total capacity in an average cell can be increased. We will also focus on the research of LDPC code for the system to develop suitable coding methods for the WiMAX system.