In this letter, we propose layered asymmetrically clipped optical-orthogonal frequency-division multiplexing (LACO-OFDM) with index modulation (IM), i.e., LACO-OFDM-IM for optical wireless systems. In classical LACO-OFDM, the spectral leakage because of out-of-band clipping harmonics increases the baseband bandwidth (BB) resulting in lower spectral efficiencies. For LACO-OFDM-IM, we use IM and optimize the BB by filtering the out-of-band clipping harmonics. This amalgamation of IM and BB optimization leads to better spectral efficiency (SE). Simulation results shall affirm that LACO-OFDM-IM achieves higher SE, affords a comprehensive granularity for SE/energy efficiency trade-off, and outperforms classical alternatives in terms of bit-error-rate in both line-of-sight and time-dispersive channels.

中文翻译：

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用于光无线系统的具有索引调制功能的LACO-OFDM

在这封信中，我们提出了具有索引调制（IM）的分层非对称限幅光正交频分复用（LACO-OFDM），即用于光学无线系统的LACO-OFDM-IM。在经典的LACO-OFDM中，由于带外削波谐波引起的频谱泄漏会增加基带带宽（BB），从而导致频谱效率降低。对于LACO-OFDM-IM，我们使用IM并通过过滤带外削波谐波来优化BB。IM和BB优化的这种融合可带来更好的频谱效率（SE）。仿真结果应确认LACO-OFDM-IM具有更高的SE，为SE /能效折衷提供了全面的粒度，并且在视距和时间分散方面的误码率均优于传统的替代方案渠道。