在多重輸入輸出-正交分頻多工的系統下有效率地內插方向性向量

Abstract

在多重輸入輸出-正交分頻的系統下，為了使用所有通道容量，藉著奇異值分解出的方向性向量，可用在傳送端及接收端身上。 最佳化的方向性向量需要精準的通道狀態資訊給每一個正交分頻的頻率。在這篇論文裡，提出一個有限的回傳及有限的通道分解架構基於使用了適合的內插方式，使其降低來自方向性向量的計算量。在所提出的系統裡，接收端只需回傳在導向頻率上所估測出的通道資訊，以及傳送端使用這些通道資訊，藉著正交內插的方式來得到所有頻率上分解的結果。這是個個圓形內插的方法，且必須陪伴著重要的假設是奇異值在相鄰頻率間的改變差不多是線性的狀態。數值的模擬會展現出在適當的環境，如適當的快速傅立葉轉換的大小、內插的間距等等，所提出的架構，在犧牲一點點的效能下可以大幅降低計算量。

To fully exploit the channel capacity in multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems, beamforming vectors derived from SVD can be used at the transmitter and the receiver. The optimal beamforming requires accurate the channel state information for each OFDM subcarrier. This paper proposes a limited feedback and limited channel decomposition architecture by deploying a novel suitable interpolation method to reduce the computation cost of beamforming. In the proposed system, the receiver feedbacks only the estimated channel information on the pilot subcarrier and the transmitter use these channel information to get decomposition results on all subcarrier by an orthogonal interpolation method. This method is a circular interpolator with the important assumption that the singular modes on adjacent subcarriers approximately change in a linear way. Numerical simulations show that under certain circumstances, e.g., proper FFT size, interpolation gap etc., the proposed scheme can reduce computation efficiently while only sacrifice little performance.