hollywoodnanax.blogg.se - february 2022

Optical ofdm with quadrature modulator optisystem

In addition, spectral-efficient multiple access techniques such as non-orthogonal multiple access (NOMA) can also be adopted to enhance the achievable data rate for a given modulation bandwidth. Specifically, orthogonal frequency division multiplexing (OFDM) with high-order quadrature amplitude modulation (QAM) constellations has been widely considered in high-speed VLC systems. Moreover, for a given modulation bandwidth, the available data rate of VLC systems can also be improved by applying spectral-efficient modulation techniques. On the one hand, in order to break the bandwidth limitation of COTS LEDs, their available modulation bandwidth can be efficiently extended by applying various analog or digital equalization techniques. So far, many techniques have been introduced to address the two challenges faced by practical VLC systems. However, practical VLC systems built upon COTS LEDs face two critical challenges: one is the limited available modulation bandwidth and the other is the severe nonlinearity. By leveraging commercial off-the-shelf (COTS) light emitting diodes (LEDs) for simultaneous illumination and communication, VLC enjoys many inherent advantages such as abundant and license-free spectrum resources, low-cost front-ends, no electromagnetic interference (EMI) radiation and enhanced physical-layer security. In recent years, visible light communication (VLC) has been envisioned as one of the key enabling technologies for 6G and Internet of Things (IoT) systems. © 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement 1. The superiority of the proposed DFT-S-OFDM-QIM scheme over other benchmark schemes has been successfully verified by both simulation and experimental results. Moreover, the peak-to-average power ratio (PAPR) of OFDM-QIM can be substantially reduced by applying DFT spreading, and hence DFT-S-OFDM-QIM exhibits high tolerance against light-emitting diode (LED) nonlinearity. By performing subcarrier index modulation on both the in-phase and quadrature components of each subcarrier, OFDM-QIM achieves a higher spectral efficiency than conventional OFDM with index modulation (OFDM-IM). In this paper, we for the first time propose and investigate a novel discrete Fourier transform-spread-orthogonal frequency division multiplexing with quadrature index modulation (DFT-S-OFDM-QIM) scheme for practical visible light communication (VLC) systems.

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