有一種新的相差編碼器被提出，它是藉由查表法所得到，且相差編碼若使用查表法可降低複雜度和有較好的錯誤效能，再者使其N符號差分編碼表檢測最佳化。本篇論文以此一主題，針對各種N來調整16QAM、16APSK及32APSK的星座圖，當我們調整星座圖的參數時，相對應會建立差分編碼表，而其中選擇的參數結果是具有最佳的最小非同調距離，調整後的星座圖最小非同調距離會大於原本星座圖，而其錯誤效能也在模擬結 果證實有較好表現。;A new differential encoder by a look-up table was proposed. Using a table for differential encoding has the advantages of both low complexity and good error performance. The table for N symbol differential detection was optimize as well. In this thesis, we modify the signal constellation of 16QAM , 16APSK and 32APSK for various values of N . The parameters of signal constellation are changed, and the corresponding differential encoding table is constructed. The parameters which result in the best minimum noncoherent distance are selected. The minimum noncoherent distance of modified constellation is larger than that of the original constellation. The error performance of the modified constellations are verified by computer simulations.
