Effectiveness of LED index modulation and non DC biased OFDM for optical wireless communication

Optical wireless communication (OWC) can be classified into visible light communication (VLC) and pixelated communication. The multicarrier modulation schemes for VLC and pixelated OWC are orthogonal frequency division multiplexing (OFDM) and spatial OFDM, respectively. In the literature, two power-efficient forms of OFDM termed as light emitting diode (LED) index optical OFDM (LIM-OFDM) and non DC biased optical OFDM (NDC-OFDM) are developed only for VLC. This paper, for the first time, considers the spatial domain forms of LIM-OFDM and NDC-OFDM in the context of pixelated OWC. For pixelated communication, four and two consecutive image frames are used to realize spatial LIM-OFDM and spatial NDC-OFDM, respectively. Simulation results show that for both VLC and pixelated OWC, LIM-OFDM and NDC-OFDM show equal electrical power efficiency in the presence of stand-alone channel noise. Moreover, for the above-mentioned conditions, LIM-OFDM shows 1.3 dB better optical power efficiency than NDC-OFDM at a target uncoded bit error rate (BER) of 10
⁻⁴
. However, for a pixelated OWC affected by spatial impairments of defocus, linear fractional misalignment, vignetting and channel noise, NDC-OFDM is 3 dB electrically and 4 dB optically power efficient than LIM at a BER of 10
⁻⁴
.