在這篇論文當中，為了消除主要由於使用者在移動環境中所產生的都卜勒頻率飄移所造成的載波間的相互干擾，我們提出了一個新的架構用來降低載波間的相互干擾效應對系統的影響。我們的系統架構是一個多根輸入天線多根輸出天線且正交分頻多工的系統，它使用了空時格狀編碼當作編碼器，使用維特比解碼器來解出所傳送的資料。系統是使用M-相移鍵控來做調變，且是一個擁有四根傳輸天線和四根接收天線的架構，並且使用八個狀態的格狀解碼器來做解碼。我們分析了載波間的相互干擾，並且知道主要的訊號所受干擾大部分是來自鄰近的載波所造成，所以利用了維特比解碼器先解出初始初估的資料，之後針對每一個載波來消除彼此載波間的相互干擾，之後再跑一次維特比解碼器得出最後所需的資料。由模擬結果可以看出當新架構搭配了消除載波間的相互干擾的機制，當在時變有衰減的通道環境下，它可以藉由移除載波間的相互干擾效應來提升位元錯誤率的效能。並且在我們的系統架構中，我們可以藉由調整所考慮消除的載波間的相互干擾數目來降低運算的複雜度，而不需考慮消除所有的載波間的相互干擾數目，就能達到和消除所有的載波間的相互干擾數目接近的效能，進而達到降低運算複雜度且又接近最好效能的結果。

In this thesis, to mitigate intercarrier interference (ICI), a new scheme used to reduce the effect of the ICI is proposed. Our system structure is a multi-input multi-output (MIMO) orthogonal frequency division multiplexing (OFDM) system which uses space-time trellis codes (STTC) and Viterbi as the encoder and the decoder, respectively. The system applies M-ary PSK modulation with 8-state trellis decoding in four transmit antennas and four receive antennas. We analyze the ICI effect that the desired signals are influenced by the other subcarriers especially from neighbor subcarriers and use Viterbi decoder to do the ICI cancellation step by step. The simulation results show that the new ICI cancellation scheme improves the bit error rate (BER) performance by removing the effect of the ICI in the time-varying fading channel.

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