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结合离散正弦变换(DST)和离散余弦变换(DCT),提出一种新的DST/DCT直流偏置-离散多音频(DCDMT)调制方案。在不增加系统复杂度的情况下,该方案可拓展独立子载波的个数,有望提高可见光系统的传输速率。通过推导该调制方案下的误码率表达式及该调制信号峰均功率比(PAPR)的互补累积分布,分析了限幅噪声对离散多音频(DMT)、直流偏置光正交频分复用(DCO-OFDM)及非对称限幅光正交频分复用(ACO-OFDM)可见光系统误码率的影响。研究结果表明,理论分析的误码率与仿真结果一致,在相同的传输速率下所提方案误码率更低;PAPR的互补累积分布与调制阶数无关,但随子载波数N增加而增大,在N较大时理论分析与仿真结果吻合。误码率仿真结果表明,相同传输速率下DST/DCT DC-DMT与DCO-OFDM在低信噪比时误码率性能相当,均优于脉冲幅度调制-离散多音频(PAM-DMT)、DC-DMT及ACO-OFDM;在高信噪比时,限幅噪声会使系统误码率增大。
Combining Discrete Sine Transform (DST) and Discrete Cosine Transform (DCT), a new DST / DCT DC bias-discrete multi-tone (DCDMT) modulation scheme is proposed. Without increasing system complexity, this scheme can expand the number of independent subcarriers and is expected to increase the transmission rate of the visible light system. By deriving the expression of the bit error rate (BER) under the modulation scheme and the complementary cumulative distribution of the peak-to-average power ratio (PAPR) of the modulated signal, the effects of clipping noise on discrete multi-tone (DMT) Effect of DCO-OFDM and ACO-OFDM on bit error rate of visible light system. The results show that the bit error rate of the theoretical analysis is consistent with the simulation results, and the bit error rate of the proposed scheme is lower under the same transmission rate. The complementary cumulative distribution of PAPR has nothing to do with the modulation order, but increases with the number of subcarriers N Large, the theoretical analysis agrees well with the simulation when N is large. The BER simulation results show that the BER performance of DST / DCT DC-DMT and DCO-OFDM at the same transmission rate is better than that of PAM-DMT at low signal-to-noise ratio -DMT and ACO-OFDM; at high signal-to-noise ratio, clipping noise will increase the system bit error rate.