第四代無線行動通訊是目前許多國家和團體研究的主要目標，其中正交分頻
多工的使用為該世代的重要基礎是無庸至疑的，在此我們將更進一步地，把正交
分頻多工與MIMO系統相結合，以期達到更快速的傳輸；在追求高速傳輸的同時，
確保資料的正確傳輸亦是我們研究的最主要目標。在兼顧高傳輸速度及低錯誤率
的標準下，接收端的運算成本也同時的被大大提高，因此透過各種不同的近似演
算法，將運算成本及運算複雜度降低便是我們最主要的研究方向。

　　一般傳統的接收端大都為MMSE標準下所發展的演算法，但以MMSE為基礎的複雜度至少是N(天線維度)的三次方，若使用MIMO系統其複雜度更高達N的四次方，若再加上錯誤更正碼的計算，其接收端之計算成本將會是一個驚人的數字。所以，在此我們提出了新的演算法，透過高斯近似及接收端資料分佈為獨立之設來達到降低複雜度的目的，經由上述的兩種假設，我們可以將原本為N四次方的演算法取代成N三次方。在錯誤率的模擬結果顯示，使用新式演算法一樣可以達到低錯誤率的標準，再加上錯誤更正碼之後，與傳統MMSE-SIC之效能可以說是相差無幾，甚至與複雜度最高的MAP(最大事後機率)演算法比較，也沒有太大的落差。

In 4th generation mobile communication, OFDM and MIMO are very important technology. We can provide speedy transmission by combine OFDM with MIMO. Accuracy of transmission is another important purpose over the speedy transmission. In order to reach above purpose, which require high complexity. Therefore complexity reduce to acceptable range, which is our purpose.

Conventional MMSE-SIC algorithm commonly is used to linear iterative MUD. In MIMO-OFDM systems, complexity of MMSE-SIC is . If MIMO-OFDM combine with ECC(Error Control Code) than complexity is increased to very high in iterative MUD systems. Therefore, we provide a novel low complexity detection algorithm. This novel algorithm reduce complexity by Gaussian approximation and assorted integral. Complexity of novel detection algorithm is . We not only reduce complexity but also keep BER performance. Novel algorithm have the same performance with MMSE-SIC and very close to optimal detection algorithm.

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