湍流信道中零填充三模光正交频分复用索引调制的性能分析

Performance analysis of zero-padded tri-mode optical orthogonal frequencydivision multiplexing with index modulation in turbulent channels

针对无线光通信中湍流信道下正交频分复用索引调制(orthogonal frequency division multiplexing index modulation, OFDM-IM)传输速率不高、误码率性能不佳等问题,通过在不同激活子载波上加载2种不同模式的星座符号的方式,并结合离散小波变换提出了一种零填充三模光正交频分复用索引调制(zero-padded tri-mode optical OFDM-IM,ZTM-OOFDM-IM)。详细介绍了信号的映射过程,利用矩量母函数推导出其理论误码率,并在弱湍流信道下与已有的光OFDM-IM与双模光OFDM-IM (dual-mode optical OFDM-IM,DM-OOFDM-IM)进行了对比。结果表明,在保证传输速率的条件下,ZTM-OOFDM-IM有效改善了系统的误码性能。相较于光OFDM-IM和DM-OOFDM-IM,当误码率为10-3时,所提系统的信噪比分别改善了约2.8和3.2 dB。

To address the problems of low transmission rate and poor BER performance of orthogonal frequency division multiplexing index modulation(OFDM-IM)under turbulent channel in optical wireless communication,this paper proposes a zero-padded tri-mode optical orthogonal frequency division multiplexing index modulation(ZTM-OOFDM-IM).This approach involves loading two different modes of constellation symbols on different active subcarriers and combining them with discrete wavelet transform.The paper thoroughly elaborates on the signal mapping process and derives the theoretical BER using the momenta generating function.A comparative analysis is conducted against existing optical OFDM-IM and DM-OOFDM-IM in the context of weak turbulent channels.The results show that ZTM-OOFDM-IM is effective in improving the BER performance of the system under the condition of guaranteed transmission rate.Compared with optical OFDM-IM and DM-OOFDM-IM,the signal-to-noise ratio of the proposed system is improved by about 2.8 and 3.2 dB,respectively,at the BER of 10-3.