Its characteristics are as follows: the field of view (FOV) angle, the gain (being a product of filter and concentrator gains), the photodetector area and the conversion efficiency (measured in A/W).įor our numerical simulations, we will use a standard “office environment” arrangement, akin to the ones typically used in similar work. The receiver is a simple non-imaging photodetector with an optical filter, optical concentrator and a single photodiode element. A single transmitting LED is characterized by a half-power semi-angle and center luminous intensity (measured in cd). We assume the multiple input single output (MISO) model with multiple luminaires, each consisting of multiple transmitting LEDs (both legitimate and rogue) and one photodiode detector. We use ray optics to calculate signal and noise levels and to derive adequate metrics. The received signal depends on the physical characteristics of the transmitting LED, the receiver, and channel characteristics which, in turn, are determined by a room’s physical properties (dimensions, wall reflectivity). The system components are an LED transmitter, consisting of multiple light sources, and a photodiode receiver. In a related work, this approach was also in part verified in a real environment. A similar approach was proposed in using the multiple input single output (MISO) technique, together with null-steering and artificial noise-an achievable secrecy rate was calculated numerically.
This was attained without significant influence on the lighting characteristics and was therefore unobservable to the users. In this way, a potential eavesdropper physically located some distance from the legitimate receiver was unable to properly decode the data. The bit error rate (BER) was minimized at the receiver’s location, while it remained unacceptably high in the rest of the area. In, the authors proposed to use the MIMO technique and beam-forming (similar to BF/MIMO implemented in Wi-Fi networks) to establish a secure channel between the transmitter and the receiver located in a particular physical location. Up till now, the confidentiality of VLC communication has mainly been tackled on the information-theory level, referring to the discrete memoryless wiretap channel and the metric of the channel’s secrecy capacity, as originally introduced by Wyner.
#Relux suite 2014 windows#
The authors evaluated different room configurations and were able to decode high-order modulated 64-QAM VLC signals outside of the room, via door gaps, key holes and windows protected by special “privacy” coatings. The equipment used, based on a standard low-cost SDR design, was able to achieve acceptable BER rates in a range of different scenarios.
In, it was shown experimentally that eavesdropping on VLC transmission is indeed possible. Snooping on VLC transmission is, of course, limited by high obstacle impermeability and is more difficult than Wi-Fi snooping, but there is no obvious reason why it should not be possible. Both in the case of the NLOS channel and LOS, an unauthorized receiver may be easily introduced into the environment without being recognized. However, this is not always true let us consider a case of communication with an “infrastructure” transmitter.
In order to ensure the dependability of VLC networks, we must better understand the physical layer mechanisms of executing a hostile-transmitter type attack.Ī common assumption in VLC, as stated for example in the IEEE 802.15.7 standard, is that: “Because of directionality and visibility, if an unauthorized receiver is in the path of the communication signal, it can be recognized”. By analyzing basic physical characteristics of the VLC communication channel, it was shown that particularly in the case of infrastructure downlink communication, security with respect to data snooping, jamming and modification must be carefully provided for. A risk assessment of VLC communication with respect to the communicating parties of three basic classes: mobile (smartphones, tablets, wearables, etc.), fixed (PCs, peripherals, and appliances) and infrastructure (fixed in-room transmitters) was conducted in. Attacks on the physical level that disregard MAC-level protocols can effectively block the network and are not remedied by traditional security mechanisms. Attackers may not only easily monitor communication but also launch jamming (denial of service) attacks. The shared nature of the medium allows wireless networks to be easily monitored and broadcast on.
0 kommentar(er)
