Abstract
This paper proposes a new hybrid orthogonal frequency division multiplexing (OFDM) form termed as DC-biased pulse amplitude modulated optical OFDM (DPO-OFDM) by combining the ideas of the existing DC-biased optical OFDM (DCO-OFDM) and pulse amplitude modulated discrete multitone (PAM-DMT). The analysis indicates that the required DC-bias for DPO-OFDM-based light fidelity (LiFi) depends on the dimming level and the components of the DPO-OFDM. The bit error rate (BER) performance and dimming flexibility of the DPO-OFDM and existing OFDM schemes are evaluated using MATLAB tools. The results show that the proposed DPO-OFDM is power efficient and has a wide dimming range. Furthermore, a switching algorithm is introduced for LiFi, where the individual components of the hybrid OFDM are switched according to a target dimming level. Next, machine learning algorithms are used for the first time to find the appropriate proportions of the hybrid OFDM components. It is shown that polynomial regression of degree 4 can reliably predict the constellation size of the DCO-OFDM component of DPO-OFDM for a given constellation size of PAM-DMT. With the component switching and the machine learning algorithms, DPO-OFDM-based LiFi is power efficient at a wide dimming range.
Highlights
The demand for high bandwidth is increasing rapidly, resulting in a spectrum crunch
There are some hybrid forms of orthogonal frequency division multiplexing (OFDM) such as asymmetrically clipped DC-biased optical OFDM (ADO-OFDM) [12,16], hybrid asymmetrically clipped optical OFDM (HNCOFDM) [16], hybrid asymmetrically clipped optical OFDM (HACO-OFDM) [19], hybrid diversity combined OFDM (HDC-OFDM) [16,20], asymmetrical hybrid optical OFDM (AHO) [21], hybrid DC biased asymmetrically clipped pulse amplitude modulated discrete multitone modulation optical OFDM (HDAP-OFDM) [22], and pulse amplitude-modulated hybrid optical OFDM (PHO-OFDM) [23]
This paper proposes a new hybrid modulation approach termed DC-biased pulse amplitude modulated optical (DPO-OFDM), where DCO will be kept in the odd subcarriers, and pulse amplitude modulated discrete multitone (PAM-DMT) will be kept in the imaginary portion of the even subcarriers
Summary
Itisha Nowrin 1, M. Rubaiyat Hossain Mondal 1 , Rashed Islam 1 and Joarder Kamruzzaman 2,* Citation: Nowrin, I.; Mondal, M.R.H.; Islam, R.; Kamruzzaman, J. A Novel OFDM Format and a Machine Learning Based Dimming Control for LiFi. Electronics 2021, 10, 2103. https://doi.org/10.3390/ electronics10172103
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