Beijing Key Laboratory of Space-Ground Interconnection and Convergence, School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing, China
Electronics and Computer Science, University of Southampton, Southampton, U.K.
Jinlong Wei
Huawei DRusseldorf GmbH, European Research Center, München, Germany
Qixiang Cheng
Department of Electrical Engineering, Columbia University, New York, NY, USA
Tiantian Zhang
Beijing Key Laboratory of Space-Ground Interconnection and Convergence, School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing, China
Zhanyu Yang
Department of Electrical and Computer Engineering, University of Virginia, Charlottesville, VA, USA
Aiying Yang
School of Optoelectronics, Beijing Institute of Technology, Beijing, China
Yueming Lu
Key Laboratory of Trustworthy Distributed Computing and Service, Ministry of Education, Beijing University of Posts and Telecommunications, Beijing, China
Yaojun Qiao
Beijing Key Laboratory of Space-Ground Interconnection and Convergence, School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing, China
In this paper, we propose a faster-than-Nyquist non-orthogonal frequency-division multiplexing (NOFDM) scheme for visible light communications (VLCs) where the multiplexing/demultiplexing employs the inverse fractional cosine transform (IFrCT)/FrCT. Different to the common fractional Fourier transform-based NOFDM (FrFT-NOFDM) signal, FrCT-based NOFDM (FrCT-NOFDM) signal is real-valued, which can be directly applied to the VLC systems without the expensive up-conversion and thus it is more suitable for the cost-sensitive VLC systems. Under the same transmission rate, FrCT-NOFDM signal occupies smaller bandwidth compared to OFDM signal. When the bandwidth compression factor α is set to 0.8, 20% bandwidth saving can be obtained. Therefore, FrCT-NOFDM has higher spectral efficiency and suffers less high-frequency distortion compared to OFDM, which benefits the bandwidth-limited VLC systems. As the simulation results show, bit error rate performance of FrCT-NOFDM with α of 0.9 or 0.8 is better than that of OFDM. Meanwhile, FrCT-NOFDM has a superior security performance. In conclusion, FrCT-NOFDM shows the potential for application in the future VLC systems.
