應用於高速動正交分頻多工系統分組子載波干擾消除及資料偵測之研究

Abstract

由移動所造成的頻道變化會使得一個正交分頻多工系統的符元有頻率選擇性的衰減，這樣的現象使傳統一級等化器的方法不能被利用，且此現象更進一步的會破壞子載波之間的正交性使得正交分頻多工系統的符元遭受到內部子載波互相干擾的現象，若是在高速移動的情況下會造成系統效能嚴重的被降低，為了減輕此現象帶來的問題，這篇文章提出一個運用球形解碼或列表式球形解碼反覆式的分組子載波干擾消除方法，在接收端子載波會被分成許多組，並使用球形解碼或列表式球形解碼去產生資訊再將這些資訊傳送到其它組做子載波干擾消除，分組的方法是用來減輕使用球形解碼或列表式球形解碼的計算複雜度，而子載波干擾消除的方法是用來使系統效能更好。

The channel variation due to vehicle mobility produces frequency selective fading among OFDM symbols which makes the traditional one-tap equalizer can not be utilized. Moreover, the orthogonal property of OFDM subcarriers is destroyed and OFDM symbol experiences inter-carrier interference (ICI) that severely degrades the performance in high vehicle mobility environment. To reduce the problem, an iterative group based ICI cancellation method which applies sphere decoding and list sphere decoding (LSD) is proposed. At the receiver, subcarriers are partitioned into several groups, each group uses SD or LSD to generate the message information and pass it to other groups for ICI cancellation. The grouping procedure is used to reduce the computation complexity of the SD and LSD, and ICI cancellation procedure is used to make BER performance better.