最近在2010年提出的一種使用查表法的差分編碼，確實可以降低編碼的複雜度以及改善錯誤效能。本篇論文即是以此做為延伸，試著去調整16QAM、16APSK星座圖的架構，使得差分編碼表有最大的最小非同調距離。除此之外，查表法的差分編碼也可以等效成籬柵式的差分編碼，因此，我們在差分檢測器使用維特比演算法來改進錯誤效能，並且也提出一定理來降低籬柵解碼時的狀態數量，以降低複雜度。最後也嘗試了把查表法應用在2000年所提出的差分時空調變，我們除了提出幾個資料速率較大的例子，而且也避免了星座圖擴展的問題。 Recently, a new differential encoder was proposed, by a look-up table instead of a rule. In this thesis, we present further research results on this subject. We propose some constellations maximizing minimum noncoherent distance. Then we show that differential encoding by a table is equivalent to differential encoding by a trellis, so we use the Viterbi algorithm at the differential detector to improve the error performance. A theorem about the sufficient number of states for various modulations is proposed. Finally, we extend the new differential encoding and detection to differential space time modulation(DSTM). We use a new definition of DSTM, by which the transmitted block is determined according to the previously transmitted block and current data bits. The encoding table that determines the transmitted block can be optimized. We also propose a theorem to reduce the number of states of the decoding trellis.
