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This study investigates the optimization of energy efficiency in robust visible light communication (VLC)—intelligent reflecting surface (IRS) systems through a novel resource allocation strategy based on coalitional game theory. By employing coalitional game theory, the proposed strategy optimizes LED power and IRS energy consumption within practical constraints. IRS elements form coalitions centered around a central unit or units, enhancing the system performance through coordinated element management. Simulation results demonstrate significant improvements in energy efficiency and signal quality compared to conventional methods, validating the effectiveness of the proposed strategy. [ABSTRACT FROM AUTHOR]

The advancement of smart cities and intelligent industries has accentuated the necessity for reliable indoor communication and precise indoor positioning. In response, this paper presents an innovative integrated system for indoor visible light communication and positioning, designed to facilitate robust communication and pinpoint accuracy in positioning for indoor applications. We incorporate multiband carrierless amplitude and phase (m $m$CAP) modulation to mitigate interference between communication and positioning subcarriers. Unlike the conventional orthogonal frequency division multiplexing‐based subcarrier modulation (OFDM‐SCM), m $m$CAP demonstrates reduced out‐of‐band interference and a diminished peak‐to‐average power ratio (PAPR). Moreover, we introduce the frequency domain optical zero correlation zone (FD‐OZCZ) code, integrated within the m $m$CAP signal to optimize the distribution of positioning subcarriers. Simulation outcomes substantiate that our proposed m $m$CAP, augmented with FD‐OZCZ, outperforms OFDM‐SCM systems in delivering reliable communication and exceptional positioning accuracy. [ABSTRACT FROM AUTHOR]

In this work, a novel resource allocation scheme is proposed for the self-powered visible light communication and positioning (SPVLCP) system based on orthogonal frequency division multiplexing (OFDM). This scheme can balance the performance of communication, positioning, and energy harvesting by optimizing the power splitting (PS) at the receiver and power allocating on each subcarrier using the multi-verse optimization (MVO) algorithm. The performance of the SPVLCP system using the proposed resource allocation scheme is investigated through simulation and experiment for different constraint conditions and transmission rates. The results indicate that the SPVLCP system using the proposed resource allocation scheme has better performance compared with that using the uniform power allocation scheme. • Communication, positioning, and energy harvesting can be performed simultaneously. • Resource competition exists in the integrated system. • The scheme of resource allocation has better performance than uniform power allocation. [ABSTRACT FROM AUTHOR]

An equalization scheme consisting of two square-root-raised-cosine filters and a finite impulse response (FIR) filter is proposed to compensate the channel fading at high frequency induced by light-emitting diodes (LEDs) in visible light communication (VLC). Using the digital equalizer based on this scheme, the performance of the VLC system with different multilevel baseband signals is analyzed experimentally. It is demonstrated that, when the proposed digital equalizer is introduced in the VLC system, the transmission rate is shown to double under forward error correction threshold. As a result, a transmission rate of 120 Mb/s is realized when the LED's 3-dB bandwidth is only 13 MHz. The number of the FIR tap coefficients was also optimized by considering the transmission performances and computational complexity, which is set to 32 in the adopted digital equalizer. The relation between the system performance improvement and signal Euclidean distance with the same bit per symbol is further investigated. The results reveal that the longer Euclidean distance is beneficial to the improvement of transmission performance for the VLC system with the proposed equalizer. [ABSTRACT FROM AUTHOR]

In this work, a hybrid multiple access scheme for multi-user underwater wireless optical communication (UWOC) systems is proposed and presented. The scheme combines the respective advantages of orthogonal frequency-division multiple access (OFDMA) and non-orthogonal multiple access (NOMA) scheme to reduce the unfairness among users caused by the unique high-frequency fading characteristics of the underwater optical channel. Multi-verse optimizer (MVO) algorithm is further introduced for solving the nonlinear problem of user power allocation. Experimental results in different water quality environments demonstrate that the hybrid OFDMA/NOMA scheme with MVO effectively improves the communication performance of the established 4-user UWOC system compared to the pure NOMA scheme and the pure OFDMA scheme, and a system sum rate of 3.94 Gbit/s is achieved. • A hybrid OFDMA/NOMA scheme is proposed for UWOC system. • MVO algorithm is introduced for user power allocation. • A sum rate of 3.94 Gbit/s is experimentally achieved in a 4-user UWOC system. [ABSTRACT FROM AUTHOR]

In this paper, power domain non-orthogonal multiple access (NOMA) is introduced in underwater visible light communication (UVLC) to improve the spectrum efficiency and the sum transmission rate. A NOMA-UVLC system employing two LEDs with different colors is designed to improve the propagation efficiency, by bearing different information on different carriers. We experimentally investigate the BER performance of the system in air and water environment, respectively. The results demonstrate that the proposed NOMA system works better in underwater environment than in air environment. The total transmission rate in underwater environment achieves 117.4 Mb/s when employing red/blue LEDs in the proposed system, and 93.9 Mb/s when employing red/green LEDs in the proposed system, with a transmission distance of 1 m. • Power domain NOMA is introduced in underwater VLC system. • The NOMA-UVLC system using different color LEDs has more excellent BER performance. • The rates of 117.4 Mb/s can be experimentally realized by red and blue LEDs. [ABSTRACT FROM AUTHOR]

In this paper, the performance of a one-channel PDM-VLC system with different signal power ratios, sample rates and transmission distances are investigated, and for three users' transmission, 150 Mbit/s rate and 1.2 m distance can be realized. Furthermore, a two-channel PDM-VLC system with distance of 1 m is established and analyzed for the multi-user application. The total transmission rate can reach 150 Mbit/s for three users and 250 Mbit/s for two users under the influence of the channel interference. • One-channel and two-channel PDM-VLC systems are presented for three users to simultaneously transmit their own signal. • A 150 Mbit/s transmission for three users at a distance of 1.2 m can be realized in one-channel PDM-VLC system. • Two-user 250 Mbit/s and three-user 150 Mbit/s transmissions at 1 m are realized in two-channel PDM-VLC system. • The impact of signal power ratio, sample rate, and transmission distance on PDM-VLC system performance is demonstrated. • It is revealed that PDM can be successful used for multiple user transmission in VLC system with high spectrum efficiency. [ABSTRACT FROM AUTHOR]