Comprehensive study on UAV-based FSO links for high-speed train backhauling.

In this paper, we introduce the idea of using unmanned aerial vehicle (UAV)-based free-space optical communication systems to backhaul high-speed trains. We introduce a composite channel model that includes effects of both atmospheric turbulence and pointing errors due to position/orientation deviation. Based on the derived fading model, we present an approximation expression for the outage probability.

Efficiency analysis of cellular/LiFi traffic offloading.

Data offloading is a promising low-cost and power-efficient solution for the expected high demands for high-speed connectivity in the near future. We investigate offloading efficiency in a cellular/light fidelity (LiFi) network. This offloading efficiency is a measure of the ratio of traffic carried by the LiFi network to the total traffic carried by both LiFi and cellular networks.

On the performance of adaptive hybrid MQAM-MPPM scheme over Nakagami and log-normal dynamic visible light communication channels.

In this paper, we introduce the idea of using adaptive hybrid modulation techniques to overcome channel fading effects on visible light communication (VLC) systems. A hybrid $ M $M-ary quadrature-amplitude modulation ($ M{\rm QAM} $MQAM) and multipulse pulse-position modulation (MPPM) technique is considered due to its ability to make gradual changes in spectral efficiency to cope with channel effects. First, the Zemax optics studio simulator is used to simulate dynamic VLC channels.

Hybrid two-level MPPM-MDPSK modulation for high-speed optical communication networks.

A hybrid optical modulation approach is described, which layers a continuous wave $M$M-ary differential phase-shift keying ($M{\rm DPSK}$MDPSK) and a two-level ($2L$2L) multipulse pulse-position modulation (MPPM) intensity-modulated signal for improved spectral efficiency. These $2L$2L techniques are a generalization of earlier hybrid MPPM-$M{\rm DPSK}$MDPSK techniques and have the added advantage of reducing transmitter and detector complexities over previous hybrid modulation approaches. The spectral and power efficiencies for the proposed $2L$2L-MPPM-$M{\rm DPSK}$MDPSK modulation techniques are formulated and shown to have the highest spectral efficiency in comparison to other hybrid techniques with lower implementation complexity.