仿真研究了整數倍和分數倍定時誤差對于預均衡OFDM系統的性能影響，結果表明：定時誤差將造成解調數據的相位旋轉, 并導致預均衡系統性能的快速下降，其程度由系統的子載波數和誤差精度等因素決定；仿真顯示，在QPSK，1/3Turbo編碼，90 ms交織，子載波數4 096，信道模型為ITU RM.1225 車載30 km/h的條件下，每當誤差增加1/16的歸一化定時誤差，性能下降約1 dB。
關 鍵 詞 預均衡OFDM; 預均衡因子; 定時誤差; 相位旋轉因子

Abstract This paper investigated the impact of the timing error on the receiver BER performance in the pre-equalization OFDM systems through simulations. The results showed that the timing error would bring on the phase rotation of demodulation data, and degrade the system performance critically. So it must be revised by assistant methods. The timing error and the number of sub-carriers together decide the degradation. Simulations showed that the performance would fall down 1 dB every 1/16 normalized timing error.
Key words pre-equalization OFDM; pre-equalization factor; timing error; phase rotation coefficient