To overcome the limitations of visible light communications (VLC) systems while still benefiting from the high data rates and inherently secure transmissions, hybrid systems combining radio frequency (RF) and VLC have gained appeal towards the next generation of wireless networks. In this paper, the potential of hybrid systems from the security perspective is investigated by proposing a joint precoding and user association (JPUA) scheme to maximize the sum secrecy rate of a multiuser hybrid RF/VLC system. Specifically, it is assumed that the RF access point is equipped with multiple antennas while the VLC access point is equipped with multiple light emitting diodes. The optimization problem is divided into two sub-problems, the user association strategy and the precoding design for each of the access points. For the former, an algorithm based on coalitional game theory is proposed. The latter leads to a non-convex fractional programming problem, which is reformulated using the constrained convex-concave procedure, thus efficiently converging to an optimal solution. Numerical results show that the proposed hybrid RF/VLC scheme provides significant gains in terms of sum secrecy rate, compared to different baseline schemes, such as the VLC or RF standalone schemes, in addition to allowing the connection of a higher number of users.
To overcome the limitations of visible light communications (VLC) systems while still benefiting from the high data rates and inherently secure transmissions, hybrid systems combining radio frequency (RF) and VLC have gained appeal towards the next generation of wireless networks. In this paper, the potential of hybrid systems from the security perspective is investigated by proposing a joint precoding and user association (JPUA) scheme to maximize the sum secrecy rate of a multiuser hybrid RF/VLC system. Specifically, it is assumed that the RF access point is equipped with multiple antennas while the VLC access point is equipped with multiple light emitting diodes. The optimization problem is divided into two sub-problems, the user association strategy and the precoding design for each of the access points. For the former, an algorithm based on coalitional game theory is proposed. The latter leads to a non-convex fractional programming problem, which is reformulated using the constrained convex-concave procedure, thus efficiently converging to an optimal solution. Numerical results show that the proposed hybrid RF/VLC scheme provides significant gains in terms of sum secrecy rate, compared to different baseline schemes, such as the VLC or RF standalone schemes, in addition to allowing the connection of a higher number of users.
To overcome the limitations of visible light communications (VLC) systems while still benefiting from the high data rates and inherently secure transmissions, hybrid systems combining radio frequency (RF) and VLC have gained appeal towards the next generation of wireless networks. In this paper, the potential of hybrid systems from the security perspective is investigated by proposing a joint precoding and user association (JPUA) scheme to maximize the sum secrecy rate of a multiuser hybrid RF/VLC system. Specifically, it is assumed that the RF access point is equipped with multiple antennas while the VLC access point is equipped with multiple light emitting diodes. The optimization problem is divided into two sub-problems, the user association strategy and the precoding design for each of the access points. For the former, an algorithm based on coalitional game theory is proposed. The latter leads to a non-convex fractional programming problem, which is reformulated using the constrained convex-concave procedure, thus efficiently converging to an optimal solution. Numerical results show that the proposed hybrid RF/VLC scheme provides significant gains in terms of sum secrecy rate, compared to different baseline schemes, such as the VLC or RF standalone schemes, in addition to allowing the connection of a higher number of users.
To overcome the limitations of visible light communications (VLC) systems while still benefiting from the high data rates and inherently secure transmissions, hybrid systems combining radio-frequency (RF) and VLC have gained appealing towards future generation of wireless networks. In this paper, the potential of hybrid systems from the security perspective is investigated by proposing a joint precoding and user association (JPUA) scheme to maximize the sum secrecy rate of a multiuser hybrid RF/VLC system. Specifically, it is assumed that the RF access point is equipped with multiple antennas while the VLC access point is equipped with multiple light emitting diodes. The optimization problem is divided into two sub-problems, the precoding design and the user association strategy. The former leads to a non-convex fractional programming problem, which is reformulated using the constrained convex-concave procedure, thus efficiently converging to an optimal solution. For solving the latter, an algorithm based on coalitional game theory is proposed. Numerical results show that the JPUA scheme provides significant gains in terms of the sum secrecy rate in comparison to different baseline schemes.
To overcome the limitations of visible light communications (VLC) systems while still benefiting from the high data rates and inherently secure transmissions, hybrid systems combining radio-frequency (RF) and VLC have gained appealing towards future generation of wireless networks. In this paper, the potential of hybrid systems from the security perspective is investigated by proposing a joint precoding and user association (JPUA) design to maximize the sum secrecy rate of a multiuser hybrid RF/VLC system. Specifically, it is assumed that the RF access point is equipped with multiple antennas while the VLC one is equipped with multiple light emitting diodes. The optimization problem is divided into two sub-problems, the precoding design and the user association. The former leads to a non-convex fractional programming problem, which is reformulated using the constrained convex-concave procedure, thus efficiently converging to an optimal solution. For solving the latter, an algorithm based on coalitional game theory is proposed. Numerical results show that the JPUA method provide significant gains in terms of the sum secrecy rate in comparison to different baseline schemes.
To overcome the limitations of visible light communication (VLC) systems while benefiting from high data rates and inherently secure transmissions, hybrid systems combining radio frequency (RF) and VLC have gained appeal for the next generation of wireless networks and their use cases, including the Internet of Things (IoT) and sensor networks. In this article, a theoretical study is carried out to investigate the potential of hybrid systems from the security perspective by proposing a joint precoding and user association (JPUA) scheme to maximize the sum secrecy rate of a multiuser indoor downlink hybrid RF/VLC system. Specifically, it is assumed that the RF access point (AP) is equipped with multiple antennas while the VLC AP is equipped with multiple light-emitting diodes (LEDs). The optimization problem is divided into two subproblems, the user association strategy and the precoding design for each of the APs. For the former, an algorithm based on coalitional game theory is proposed to associate each user (or sensor node) with one of the APs. The latter leads to a nonconvex fractional programming problem, which is reformulated using the constrained convex-concave procedure, thus efficiently converging to an optimal solution. Numerical results based on simulations show that the proposed hybrid RF/VLC scheme provides significant gains in terms of sum secrecy rate, compared with different baseline schemes, such as standalone VLC or RF schemes, in addition to allowing the connection of a greater number of users.
Integrating visible light communication (VLC) and radio-frequency (RF) networks can improve the performance of communication systems in terms of coverage and data rates. However, adding RF links to VLC networks weakens the secrecy performance due to the broadcast and ubiquitous nature of RF links. This paper studies the physical layer security (PLS) in cooperative non-orthogonal multiple access (CoNOMA) hybrid VLC/RF systems. Consider a VLC system, where two entrusted users close to a VLC access point (AP) help an out-of-coverage legitimate user using RF signals in the presence of an eavesdropper. The AP transmits data to both entrusted users and the legitimate user using the principle of NOMA, where the entrusted users harvest energy from the received light intensity, decode the legitimate user's message, forward it using a RF link, and then decode their messages. It is required to maximize the secrecy rate at the legitimate user under quality-of-service (QoS) constraints using beamforming and DC-bias and power allocation. Different solutions are proposed for both active and passive eavesdropper cases, using semidefinite relaxation, zero-forcing, beamforming, and jamming. Numerical results compare between the different proposed approaches and show how the proposed approaches contribute in improving the secrecy performance of the proposed model.
Recently, the hybrid radio frequency (RF)/ visible light communication (VLC) network has been widely studied due to the advantages of high data transmission and no interference between the two networks. Taking the physical layer security (PLS) into account, most work on hybrid RF/VLC network focused on single user. However, many practical scenarios require hybrid network to serve multiple users (MU). Thus, in this paper, we make a study on the PLS of MU hybrid RF/VLC network where the messages to each of the users must be kept confidential from the other and also from the external eavesdropper. To enhance the secrecy performance of the hybrid network, we propose a zero forcing (ZF) beamforming strategy to ensure that the information of each legitimate user can not be received by other users and the eavesdropper. A sum secrecy rate (SSR) optimization problem is formulated under the ZF constraint and the constraint of the power transmitted from the VLC and the RF access point. To reduce the complexity of the original problem, we decouple it into two successive sub-problems and solve them via convex optimization theory and matrix theory. Simulation results show that a positive SSR can always be achieved, and the SSR of the MU hybrid RF/VLC network is superior to that of the standalone RF and VLC networks.