Comparative Characterization of Indoor VLC and MMW Communications via Ray Tracing Simulations

Abstract

The demand for ultra-high-speed indoor wireless connectivity is ever-increasing, which poses unique challenges for the next generation wireless communication system design. This has prompted the exploration of higher frequency bands including millimeter wave (MMW) and visible light bands in addition to the conventional sub-6 GHz band. This paper provides a comprehensive comparison of the propagation channels of these frequency bands under the same indoor environment and scenarios. We adopt ray tracing techniques for site-specific channel modeling, which enables the consideration of the three-dimensional models of the indoor environment and objects inside. It allows us to take into account different frequencies, i.e., 2.4 GHz, 6 GHz, 28 GHz, 60 GHz, 100 GHz, and visible light band as well as different transmitter types, i.e., omnidirectional/directional antennas for radio frequency systems and indoor luminaries for visible light communications (VLC). For different frequencies under consideration, we obtain channel impulse responses (CIRs) and present the channel path losses for various user trajectories in indoor environments. Furthermore, we propose closed-form expressions for the cumulative distribution functions (CDFs) of received power levels for all frequency bands under consideration. Our results demonstrate that VLC channels exhibit lower path loss than that in MMW bands but higher than that of 2.4 GHz band. In addition, it is observed that VLC systems exhibit more sensitivity to shadowing and blockage effects. Our findings further indicate that the characteristics of the propagation channel are greatly influenced by the antenna type. For instance, using omnidirectional and rectangular patch antennas results in lower path loss compared to horn antennas, and this difference becomes more significant as the transmission distance decreases.INDEX TERMS Radio frequency (RF), visible light communication (VLC), hybrid RF/VLC, wireless fidelity (Wi-Fi), hybrid networks, hybrid RF/VLC environments.

A Survey of Vehicular VLC Methodologies

“…The most popular method for modulating information on the transmitter side and demodulating it on the reception side is known as Intensity Modulation and Direct Detection (IM/DD). A simplified block diagram of the VLC system is shown in Figure 2 [ 12 , 18 , 29 ].…”

“…Moreover, image sensors are also used in mobile devices (smartphones). However, the throughput rate realized is limited (kilobits per second) [ 12 ]. In the meantime, photodiode (non-imaging) devices have a higher data rate when receiving the signal (up to hundreds of megabits per second), so the PDs used in VLCs vary widely.…”

“…Thus, there is a need to create alternative energies with maximum throughput and spectrum reduction. The visible light spectrum, “Equivalent to the 380 to 780-nanometer frequency band “is 10,000, which is much more significant than the range of radio signals [ 11 , 12 ]. Moreover, VLC is not subject to spectrum control or license compared to radio frequency communication.…”

“…The most prominent features are brighter lighting levels and a high-rapidity switching function, which ensure longer lifetimes and minimize heat dissipation [ 16 ]. Over the last decade, research into VLC systems for indoor applications has received significant attention [ 12 , 14 ]. Nevertheless, their uses in outdoor contexts, like vehicle communications, are still relatively new and require further research [ 15 ].…”

“…In addition, it offers free and massive bandwidth, and it is used for both communication and lighting purposes simultaneously. Another key advantage is that it is energy efficient because VLC uses LEDs (presenting small size as well as energy and cost savings) [11,12]. VLC can be used for indoor or outdoor applications, depending on the application environment.…”