A Hybrid NOMA/OFDM Model for Next Generation Communication Systems

Abstract

Abstract Visible light communication (VLC) is an innovative optical wireless communication (OWC) technology that can provide both lighting and high-speed wireless data transmission. Another advantages of VLC system that allow for a wide range of applications are its fast data rate, reliable communication channels, and interference protection against electromagnetic (EM) waves. Light Emitting Diodes (LEDs) are used as transmitters while Photodetectors are utilized at the receiver side. The LED has to be supplied with a positive real valued signal. Orthogonal frequency division multiplexing (OFDM) uses multiple subcarriers with orthogonal frequencies to enhance the spectral efficiency of the system. There are two types of unipolar OFDM used to obtain real-valued and positive signal, they are DC-biased optical OFDM (DCO-OFDM) and asymmetrically clipped optical OFDM (ACO-OFDM). A hybrid design NOMA/OFDM is introduced in this paper to be able to study the performance of the VLC system. Three users are positioned in different spots throughout an interior environment. User1 is considered as the farthest user with lower channel gain while user3 is the near user that has high channel gain. The bit error rate (BER) is estimated for the three users vs. the SNR with different power allocation coefficients. The results show that NOMA/ACO-OFDM performs better than NOMA/DCO-OFDM. Also, the BER of the three users converges to each other with the increasing of the SNR for the two models.