LACO-OFDM With Index Modulation for Optical Wireless Systems

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.