Layered Generalized Adaptively Biased Optical OFDM for IM/DDOWC Systems

To improve the spectral efficiency of the widely used asymmetrical clipped optical orthogonal frequency division multiplexing (ACO-OFDM), layered ACO-OFDM (LACO-OFDM) has been proposed by using more subcarriers. However, LACO-OFDM suffers relatively high complexity and poor peak-to-average power ratio (PAPR). In this paper, based on generalized adaptively biased optical OFDM (GABO-OFDM), we propose layered GABO-OFDM (LGABO-OFDM) to preserve the spectral efficiency as LACO-OFDM with fewer layers and lower complexity. Each layer of LGABO-OFDM employs GABO-OFDM which adds an adaptive bias orthogonal to the reserved subcarriers to generate nonnegative signals. Numerical results suggest that LGABO-OFDM has lower PAPR and a bit error rate (BER) performance close to LACO-OFDM.