本篇論文在研究現今的4G無線通訊的架構，並且使用更近一步的遞迴式偵測(Detection)與解碼(Decoder)架構，在行動上網與無線通訊的普及率越來越高之下，使用無線通訊的人日益增加，對於有限的無線頻譜來說除了進行有效的頻譜分配，要再更近一步的最大化頻譜利用率，於是使用multi-input multi output(MIMO)技術，使能夠在空間中產生多個獨立且並行的無線通道同時傳輸資料，在頻寬不增加的情況之下進而提高了頻譜利用率，並且再結合orthogonal frequency-division multiplexing(OFDM)調變技術，組成現在4G行動通訊實體層所使用的MIMO-OFDM系統，並且使用IRA code在MIMO-OFDM系統上，再使用EXIT charts進一步分析偵測與解碼的特性且利用curve fitting技術使其達大最大通道容量(channel capacity)，並且分析EXIT charts在次佳偵測搭配通道編碼時因為額外資訊的PDF無法近似高斯分佈以及其PDF的平均值與變異數的比例並不如預期，造成EXIT charts特性曲線的不精準以及trajectory時的不準確，我們提出了方法使得偵測器輸出額外資訊的PDF近似高斯與偵測器跟解碼器特性曲線必須做一些修正之後，在EXIT charts上才能夠更準確的分析與預測其偵測器跟解碼器的搭配是否能夠匹配，使得額外資訊的交換能夠收歛到終點。

In this thesis, we worked on the architecture of 4G wireless communication systems. Our research was focused on iterative detection and decoding algorithms in MIMO-OFDM systems. Since the popularity of wireless online and wireless communications is increasing, the number of users has also increased. For the finite wireless spectrum, we have to divide wireless spectrum effectively and maximize spectrum efficiency. Then we can generate multiple independent parallel channels and transmit data simultaneously by using the multi-input multi-output (MIMO). Therefore using MIMO improves spectrum efficiency without increasing bandwidth. We can obtain the physical layer for 4G wireless communications by combining MIMO with orthogonal frequency-division multiplexing (OFDM). Then we used IRA code on the MIMO-OFDM system, and analyzed the detector and decoder characteristics by using EXIT charts. Furthermore, we employed curve fitting techniques to approach channel capacity. In addition to we observed that the PDF of its extrinsic information does not approach a Gaussian distribution, and the mean-to-variance ratio of the PDF is not what we expected. The two events described above caused inaccuracies in the trajectory and characteristic curves. So, we propose a method to solve the problem and also modify the curve fitting technique to analyze the behavior of the detector and decoder accurately. Then we can know if the detector matches the decoder and make their trajectory curves to convergence.

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