對於合作式網路通訊的最大概度序列估測等化器與多個同步錯誤

Abstract

在位元交錯調變碼正交分頻多工-合作式網路系統下，由於每個中繼站的本地震盪器精準度不同以及在無線的環境中受到都普勒效應的影響，使得多個載波頻率受到位移，因此造成彼此間載波互相影響干擾導致每個載波並未正交，而然效能大大的降低。在此因為系統為線性關係，所以我們可以推導出等效的通道環境，以格子碼的架構為基礎以及考慮附近影響載波能量較大的載波，我們利用且結合MLSE等效器及turbo等效器對此做載波干擾補償，經由模擬後我們得到全部的多樣性，並且消除載波及都普勒效應的干擾。

In cooperative communication systems, multiple carrier frequency offsets (MCFOs) due to the varying accuracies of each node’s oscillators and different Doppler spreads may result in severe Inter-Carrier Interference (ICI), which drastically degrades the performance of BICM-OFDM systems. With proper approximation of the transmission environment, it is straightforward to obtain an equivalent channel matrix taking ICI into account. Based on the trellis structure and the fact that ICI energy is concentrated in adjacent subcarriers, we incorporate an MLSE equalizer into a turbo decoder to eliminate ICI caused by MCFOs and the Doppler effect; henceforth the full diversity is achieved, as shown in computer simulations.