Generalized adaptively biased optical OFDM for optical wireless communications

Abstract

Orthogonal frequency division multiplexing (OFDM) has been applied to optical wireless communication to achieve high data rates and wide bandwidth and solve the issues of inter-symbol interference (ISI). Due to the non-negative and real-valued characteristics of intensity modulation/direct detection (IM/DD) signaling for optical wireless communication systems, some optical OFDM schemes have been proposed to reach the requirements. Among these optical OFDM schemes, adaptively biased OFDM (ABO-OFDM) reserves 1/4 of the subcarriers and utilizes Hermitian symmetry to generate non-negative and real values after invert fast Fourier transformation (IFFT) and adding bias in time domain. In this paper, we extend the original ABO-OFDM scheme and proposed a generalized ABO-OFDM scheme in which 1/m subcarriers are reserved for any positive integer m. It is demonstrated that the bias added in time domain can be counteracted exactly in frequency domain, which means it has lower implementation complexity at the receiver than most of the other optical OFDM schemes. This generalized ABO-OFDM scheme has higher frequency efficiency and lower peak-to-average power ratio (PAPR) than asymmetrically clipped optical OFDM (ACO-OFDM) and higher power efficiency than direct current biased optical OFDM (DCO-OFDM). We also evaluate the impact of parameter m on system performance in terms of PAPR and bit error rate (BER). Consider the comparison with other optical OFDM schemes and the tradeoff above-mentioned, the generalized ABO-OFDM is a potential scheme to facilitate optical wireless communications with a flexible parameter m.