Physical Layer Security in Visible Light Communication Systems With Randomly Located Colluding Eavesdroppers

Abstract

Abstract-This paper considers secrecy enhancement mechanisms in visible light communication (VLC) systems with spatially distributed passive eavesdroppers (EDs) under the assumption that there are multiple LED transmitters and one legitimate user equipment (UE). Based on certain amplitude constraints, we propose a beamforming scheme to improve secrecy performance. Contrary to the case where null-steering is made possible by using knowledge of the ED locations, the proposed beamforming when only statistical information about ED locations is available directs the transmission along a particular eigenmode related to the intensity of the ED process and the intended channel. Then, a LED selection scheme that is less complicated than beamforming is provided to reduce the secrecy outage probability (SOP). An approximate closed-form for the SOP is derived by using secrecy rate bounds. All the analysis is numerically verified by MonteCarlo simulations. The analysis shows that the beamformer yields superior performance to LED selection. However, LED selection is still a highly efficient alternative scheme due to the complexity associated with the use of multiple transmitters in the full beamforming approach. These performance trends and exact relations between system parameters can be used to develop a secure VLC system in the presence of randomly distributed EDs.Index Terms-Physical layer security, visible light communication, beamforming, stochastic geometry, secrecy outage probability.

Physical Layer Security for Visible Light Communication Systems: A Survey

“…When the EDs' CSI is not available at the transmitter, it becomes more challenging to characterize the secrecy capacity and quantify the achievable secrecy rate. To overcome this obstacle, researchers have proposed invoking stochastic geometry approaches [109]- [111]. In this context, the locations of the EDs are treated as random variables, and therefore, one may quantify the achievable secrecy rates by averaging over all possible locations.…”

“…In this context, the locations of the EDs are treated as random variables, and therefore, one may quantify the achievable secrecy rates by averaging over all possible locations. In [109], only one randomly located ED is considered, whereas in [110], [111], multiple randomly located EDs were considered. All receivers, including that of the AU, were assumed to be uniformly distributed within the coverage area and their orientation was assumed to be fixed and facing the transmitter.…”

“…In [110], [111], the PPP process was used to model the number of EDs. The main differences between [110], [111] are as follows. The EDs were assumed to be non-colluding in [110] and colluding in [111].…”

On the Secrecy Performance of Random VLC Networks With Imperfect CSI and Protected Zone

“…3 shows five cases of the integral region in (18). According to the five cases, the ACS in (18) can be written as (19), the theoretical expression of the ASC is derived as the following theorem.…”

“…With spatially random terminals in VLC, the closed-form expressions for the SOP and the average secrecy capacity (ASC) are derived in [18]. In [19] and [20], the SOP and beamforming are analyzed respectively for VLC with randomly located eavesdroppers. However, the dimming requirement for indoor VLC is not considered in [17]- [20].…”