一個適用於表格式球型解碼之快速搜尋法則

Abstract

在這篇論文中，我們基於正交振幅調變之星座點位於同心圓上之特性及表格式列舉法，提出三種適用於球型解碼的列舉法。首先是一個低複雜度的列舉法，我們將星座點分散在幾個同心圓上並由內圈而外圈進行列舉。針對同一圈上的星座點，我們提出法則以決定列舉順序。接下來是一個表格式列舉法的延伸，我們以候選點集合的方式建立列舉表以增大選擇範圍。基於實現上的考量，我們進一步將表格簡化並省下50%以上的記憶體。最後，我們將第一種列舉法的選擇法結合提出的列舉表作為適用於球型解碼的快速搜尋法，其表現近似於最大相似度偵測，並能依我們提出的低複雜度架構實現。

In this thesis, we propose 3 enumeration methods based on the concentric property of QAM modulation and the tabular enumeration. The first is a complexity-reduced enumeration which separates constellation points into several concentric circles. The candidate nodes are enumerated from inner to outer circles following the decision rules. The second method is an extension of tabular enumeration which we expand the enumeration tables by adopting the candidate sets to enlarge the selection range. For the implementation, we further simplify the proposed tables and save more than 50% of the memory units comparing with direct storing. Finally, we combine the selection approach in the first method with the expanded tables as fast search method for the depth-first sphere decoder. The performance is comparable to that of the ML detector and it can be carried out by the proposed low-complexity architecture.