二維耙式接收機於 MC-DS-CDMA 系統之研究設計

Designing a Two-Dimensional (2-D) Rake Receiver Scheme for an MC-DS-CDMA System

本文源於假設在多載波直序式分碼多重近接系統（MC-DS-CDMA system）之中，基於分支相關（BC）的背景考量，利用二維耙式（2-D Rake）接收機之設計進而改良MC-DS-CDMA系統的效能。隨之提出的系統改良方法，並經由效能之評估以確認系統工作於選頻性通道（frequency selective channel）中所呈現的設計之有效性。進而，透過一些系統參數加以証明，例如，多路徑解析數，耙型接收分支數，衰落參數，功率衰減因素，與多路徑強度面等等。本文係原創提出對於MC-DS-CDMA 系統分支相關之改善方法。値得說明的結論是；經過本研究的設計發現，不只相關衰落分支的不同模式支配著MC-DS-CDMA 系統的效能，而且接收天線的數目也確實影響著系統效能，然而它們可以經由本文提出之方法加以改善。 On the basis of a scenario that assumes the existence of a BC (branch correlation) in the environments of an MC-DS-CDMA (multi-carrier direct-sequence coded-division multiple-access) system, a two-dimensional Rake (2-D Rake) receiver for such a system is proposed and designed in this research. The performance of the proposed system is validated by an evaluation that considers the state of the working space in frequency-selective fading environments. Furthermore, some of the system parameters, e.g., the resolvable multipath number, the finger number of a Rake receiver, the fading parameters, the power decay factor, the MIP (multipath intensity profile), and the correlation characteristics between the antennas, are adopted for analysis, thus constituting the original proposal for a scenario with this kind of receiver in this system. To validate the accuracy of the derivation, some of the numerical results are presented in this report. It is worthwhile to assert that the fading parameter of the correlated-fading model dominates the performance of the MC-DS-CDMA system and that the number of antennas also definitely affects the system performance.