The use of light-emitting diodes (LED) for ambient illumination leads to visible light communications (VLC) as a promising technology for providing both constant lighting and high-speed wireless services in indoor environments. Since multiple LED sources can transmit to several users, this scenario naturally forms a multiple user multiple-input single-output (MU-MISO) system. In this sense, transmit precoding (TPC) schemes based on channel state information at the transmitter (CSIT) originally devised for radio-frequency (RF) systems have been proposed for their implementation in VLC. However, beyond providing CSIT or the need for cooperation among transmitters, which also result challenging in RF systems, there are several constraints such as the non-negativity of the transmitted signal or providing constant illumination that hamper the performance of TPC schemes in VLC. Taking into consideration these constraints, this paper explores the use of Blind Interference Alignment (BIA) for achieving multiplexing gain without CSIT or cooperation among LED lights. To do that, we devise the concept of reconfigurable photodetector that allows to switch among distinct and linearly independent channel responses. Simulation results show that the use of vBIA schemes based on the proposed reconfigurable photodetector results suitable for VLC systems.

Physical layer security is a promising approach that can benefit traditional encryption methods. The idea of physical layer security is to take advantage of the propagation medium's features and impairments to ensure secure communication in the physical layer. This work introduces a comprehensive review of the main information-theoretic metrics used to measure the secrecy performance in physical layer security. Furthermore, a theoretical framework related to the most commonly used physical layer security techniques to improve secrecy performance is provided. Finally, our work surveys physical layer security research over several enabling 5G technologies, such as massive multiple-input multiple-output, millimeter-wave communications, heterogeneous networks, non-orthogonal

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Network Simulators (NS) is typically used to study services and applications in complex scenarios due to the infeasibility of deploying real testbeds. This is the case of Mobile Ad hoc Networks (MANETs) which can be extensively used in emergency situations or to gather information without infraestructure. An important factor to get realiable results in the MANETs’ simulations is the wireless channel module of NSs. In this report, we explain how thw wireless channel is implemented in NS-3 and it can be configured.

Physical-layer security is emerging approach that can benefit conventional encryption methods. The main idea of physical layer security is to take advantage of the features of the wireless channel and its impairments in order to ensure secure communication in the physical layer. This paper provides a comprehensive review of information-theoretic measures of the secrecy performance in physical layer security. In addition, our work survey research about physical layer security over several enabling 5G technologies, such as massive multiple-input multiple-output, millimeter wave communications, heterogeneous networks, and full-duplex, including the key concepts of each of the aforementioned technologies. Finally, future research directions and technical challenges of physical layer security are identified.