空間上的多樣性通常需要有多根天線。然而, 許多無線通訊的設備由於尺寸或硬體複雜度的限制, 只能裝備一根天線。合作式的多樣性能使多用戶環境中裝備一根天線的移動節點分享他們的天線來構成一個多天線的傳送器並達成空間上的多樣性。
在這篇論文裡, 我們發展了一些以正交分頻多工存取技術為基礎的合作式多樣性的架構。我們採用解碼-重傳的中繼轉傳方式。我們比較兩個以Alamouti 的架構為基礎的合作式空時/頻方塊編碼系統。
我們接著討論合作式的網格編碼系統。我們主要著眼於解碼的演算法。我們提出了一種專為合作式網格解碼設計的低複雜度的結合法。我們也討論了在有多個中繼的情況下, 合作式網格編碼的效能分析。最後, 我們提出了一種能節省中繼點使用頻寬的合作式網格編碼。

Spatial diversity generally requires more than one antenna. However, many wireless devices are limited by size or hardware complexity to one antenna. Cooperative diversity enables single antenna mobiles in a multi-user environment to share their antennas and generate a virtual multiple-antenna transmitter that allows them to achieve spatial diversity.
In this thesis, we develop some cooperative diversity schemes based on OFDMA systems. We adopt decode-and-forward as our relaying method. We first compare two cooperative space-time/frequency block code systems based on Alamouti's scheme.
We then consider the cooperative network coding system. We focus on the decoding algorithm. We propose a new low complexity combining method for the cooperative network decoding. We also consider the performance of the cooperative network coding in the multi-relay condition. At last, we propose a relay bandwidth saved scheme.

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