Orthogonal frequency-division multiplexing (OFDM)是一個相當適合運用於寬頻通訊上的調變技術，但其缺點為高速移動之時變通道下的強烈普勒擴散。此時，子載波間的正交性被破壞並互相干擾(inter-carrier interference)使系統性能大大降低。此篇論文假設通道響應已知的情況下，比較各種不同之演算法在CD2(coded-decision directed)與D2(decision directed)系統下之性能差異，並提出一種基於AML(approximate maximum-likelihood)的共同搜索技巧，以提高系統效能。最後，以線性近似化簡消去法之高複雜度。 Orthogonal frequency-division multiplexing (OFDM) is a technique well suited for wireless broad-band communications.A drawback of OFDM is its sensitivity to time-varying channel effect in a mobile receiving environment with significant Doppler spread. In this scenario, the orthogonality between subcarriers is destroyed and the inter-carrier interference (ICI) is thus arised.In this thesis, we propose a modified iterative ICI mitigation method, which incorporates code-decision direct and an approximate maximum-likelihood detection, to improve the performance of a OFDM receiver in high-mobility environemt .
