A Two-Stage Power Allocation-Based NOMA Architecture for Optical Camera Communication

Abstract

Visible light communication (VLC) is an emerging technology that provides ubiquitous connectivity by complementing radio frequency communication for the fifth-generation (5G) wireless communication and beyond. However, inadequacies in modulation bandwidth of light-emitting diode (LED) reduce the achievable data rate for image sensor-based VLC, also known as optical camera communication (OCC). Hence, for densely deployed OCC networks, multiple channel access is a major challenge faced when supporting large numbers of users. This article proposes an optical nonorthogonal multiple access based OCC (NOMA-OCC) system, where each LED can transmit two separate signals of two different power levels by superimposing them into one signal. An image sensor based receiver system is designed to separate these two signals supporting two users by implying an intensity threshold. The distinct channel capacities for both the users as well as the sum rate of the LED access point were analyzed. In order to validate the proposed NOMA-OCC scheme, the bit error rate performance of the system is also investigated through simulation for both channels and then compared with the conventional frequency shift ON-OFF keying scheme. Index Terms-Image sensor (IS), light-emitting diode (LED), nonorthogonal multiple access (NOMA), optical camera communication (OCC), visible light communication (VLC). I. INTRODUCTIONO PTICAL wireless communication is considered a robust candidate for the fifth-generation (5G) and beyond 5G (B5G) communications, as it paves the way for the utilization of wide optical terahertz bands for future communication [1]-[3]. Moreover, B5G communication requires massive user connectivity and heterogeneous backhaul network support.

Hybrid Precoding-Based Millimeter Wave Massive MIMO-NOMA Systems

“…022, 14, x FOR PEER REVIEW users increases, the diversity of user channels makes it difficult t cluster heads. interval is [4,8]. Clearly, as the number of RF chains increases, the increases at the same time-frequency domain, therefore the spec decreasing trend.…”

“…The proposed algorithm not only selects the initial cluster head, but also obtains the optimal user grouping result by iteratively performing user grouping; therefore, the proposed algorithm can achieve better spectral efficiency. The interval of the number of users [6,20] The interval of the number of RF chains [4,8] The interval of the number of RF chains [4,8]…”

“…When the n eight, the proposed algorithm outperforms the CHS algorithm, th and the FPA algorithm by 0.9%, 5.3% and 8.0%, respectively. W chains is equal to the number of users, the system is actually a MIM the hardware overhead increases dramatically due to the increas Figure 6 shows the spectral efficiency of the proposed algorithm with the number of RF chains, where SNR = 10, the number of the user k = 10, and the number of RF chains interval is [4,8]. Clearly, as the number of RF chains increases, the number of beams also increases at the same time-frequency domain, therefore the spectral efficiency shows a decreasing trend.…”

“…These problems make the spectrum efficiency largely reduced; therefore, how to improve the spectral efficiency is a significant research issue for 6G communication [1,2]. The MIMO-NOMA technology based on NOMA can serve multiple users in the same time-frequency domain, which can vastly improve spectral efficiency [3,4]. However, there are two serious technical obstacles in the mMIMO-NOMA communication system, The first problem is that the number of users is much larger than the number of radio frequency (RF) chains, which can lead to severe inter-beam and intra-beam interference, i.e., inter-user interference problem [5,6].…”