Open AccessNon‐linear companding transform for DCO‐OFDM‐based VLC systems
Author(s) -
Xin Duqiang,
Xu Qiang,
Qiao Shuang,
Zhang Tian
Publication year - 2019
Publication title -
iet communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.355
H-Index - 62
eISSN - 1751-8636
pISSN - 1751-8628
DOI - 10.1049/iet-com.2018.5864
Subject(s) - companding , visible light communication , orthogonal frequency division multiplexing , transmitter , light emitting diode , transmission (telecommunications) , reduction (mathematics) , computer science , linearity , power (physics) , electronic engineering , mathematics , telecommunications , electrical engineering , physics , engineering , channel (broadcasting) , geometry , quantum mechanics
In this study, a novel non‐linear companding transform (NCT) is proposed for the DC‐biased optical orthogonal frequency division multiplexing (DCO‐OFDM) based visible light communications (VLC). The authors lower the peak‐to‐average power ratio (PAPR) of the original DCO‐OFDM signals to mitigate the transmission performance degradation induced by the non‐linearity of the light‐emitting diodes (LEDs) transmitter. Firstly, the positive and negative amplitudes of the original DCO‐OFDM signals are separated into two groups. Then, the group with the maximum peak is first processed with a given compress coefficient u 1 and power compensation coefficient c . After that, another coefficient u 2 is calculated by the emission power conservation criteria to further compress the rest group. Finally, these two groups of amplitude samples are combined together before adding a suitable DC bias for driving LEDs. As the mean power is not changed, a PAPR reduction can be obviously realised by the proposed NCT scheme.