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• The transmission of OFDM signal in integration system of FSO and W-band mm-wave. • The ISFA and the DFT-Spread are used to optimize system performance. • 1Gbaud OFDM signal is transmitted for 100 m SMF, 100 m FSO link and 4 m wireless. In this paper, we propose and experimentally demonstrate a novel multi-access orthogonal frequency division multiplexing (OFDM) signal transmission system for free space optical communication and photon-assisted W-band millimeter-wave (mm-wave) communication. This new structure can combine the advantages of the free space optical communication and the W-band mm-wave wireless communication. Besides, the OFDM signal with high spectral efficiency and anti-interference capability can improve the data transmission rate and flexibility. Furthermore, it can adapt to the requirements of different communication scenarios. Utilizing the intra-symbol frequency-domain averaging (ISFA) technique and the discrete Fourier transform-spread (DFT-Spread) technique, 1Gbaud 16-ary quadrature amplitude modulation (16QAM) OFDM signal is transmitted successfully with the distance of 100 m for single-mode fiber (SMF), 100 m for FSO link and 4 m for wireless. The BER is under the soft-decision Forward Error Correction (SD-FEC) threshold of 2 × 10−2. To our knowledge, this is the first time to realize the transmission of OFDM signal in the integration system of free space optical communication and photon-assisted W-band mm-wave communication. [ABSTRACT FROM AUTHOR]

Power domain sparse code multiple access (PD-SCMA) scheme-based visible light communications (VLC) can support higher spectrum efficiency and increased number of users in wireless access networks. In PD-SCMA-VLC, successive interference cancellation (SIC) and message passing algorithm (MPA)-based receivers are used to recover the transmitted signals in the power and code domains, respectively, which are complex requiring higher signal to noise ratio levels to deliver the quality of services. We propose a deep neural networks (DNN) based scheme to recover the PD-SCMA signal effected by the mixed noise, multipath distortions, and the nonlinearity due to the light emitting diode, channel and photodiode. We show by experiment that, the proposed DNN significantly outperforms the conventional SIC-MPA in terms of the achievable data rate and bit error rate performance. For DNN-based PD-SCMA-VLC, the achievable data rates are more than 100 and 120 Mbps for the user groups 2 and 1, respectively. • PD-SCMA can support higher spectrum efficiency and increased number of users for visible light communications (VLC). • There were a few issues such as a highly complex SIC-MPA, transmission impairments and the need for higher SNR. • We propose a DNN to significantly improve the transmission performance thus reducing the required SNR. [ABSTRACT FROM AUTHOR]

Non-line-of-sight (NLOS) optical camera communications (OCC) is a potential wireless communication technology, which offers robustness to blocking and blooming effect, higher data throughput over longer transmission distances compared with line-of-sight OCC. In this work, we propose a wavelength division multiplexing (WDM)-multiple inputs multiple outputs (MIMO) NLOS OCC system with multi-level pulse width modulation (MPWM) and difference-based pulse width recognition (DBPWR) schemes. Signals on different color channels are separated through the RGB filter of the CMOS camera, while MPWM signals on the same color channel are separated using the DBPWR algorithm. Compared with the conventional threshold-based demodulation scheme, the proposed DBPWR scheme has lower complexity, higher reliability, and improved sampling frequency offset tolerance. A total data rate of 10.8 kb/s is experimentally demonstrated over more than 2 m NLOS link using the proposed WDM-MIMO OCC system, which is sufficient in many Internet of things applications. • In this work, we first time employ the wavelength division multiplexing (WDM) and multiple inputs multiple outputs (MIMO) for NLOS OCC. • A total data rate of 10.8 kb/s is experimentally demonstrated over more than 2 m NLOS link, which is the highest reported so far to the best of our knowledge. • Signals on different color channels are separated through the RGB filter of the CMOS camera, while MPWM signals on the same color channel are separated using the DBPWR algorithm. • Through the proposed MPWM and DBPWR algorithm, we have addressed the implementation challenge of WDM-MIMO in a NLOS OCC link. [ABSTRACT FROM AUTHOR]