IEEE 802.15.7-Compliant Ultra-Low Latency Relaying VLC System for Safety-Critical ITS

Abstract

The integration of Visible-Light Communications technology (VLC) in Intelligent Transportation Systems (ITS) is a very promising platform for a cost-effective implementation of revolutionary ITS and cooperative ITS protocols. In this paper, we propose an infrastructure-to-vehicle-to-vehicle (I2V2V) VLC system for ITS, implementing it through a regular LED traffic light serving as a transmitter and a digital Active Decodeand-Relay (ADR) stage for decoding and relaying the received information towards further incoming units. The proposed VLC system targets the challenging and important case of ultra-low latency ADR transmission of short packets, as this is needed for emerging applications of automatic braking, car platooning and other critical automatic and/or assisted driving applications. The experimental validation of the ADR VLC chain, as well as a thorough statistical analysis of errors distribution in the transmission, has been performed for short to medium distances, up to 50 meters. The performances of the designed system are evaluated by measuring the packet error rate (PER) and latency in the whole ADR transmission chain. Our analysis shows that our system attains ultra-low, sub-ms latencies at 99.9% confidence level for PER as high as 5 × 10 −3 , yet granting a latency below 10 ms even for distances of 50 m. The demonstrated system prototype is compatible with IEEE 802.15.7 standard.

Characterization of Field of View in Visible Light Communication Systems for Intelligent Transportation Systems

“…After the commercial spread of high-power LED sources, VLC has proven to grant for either high data rates for indoor wireless applications (Li-Fi) [4], or pervasive broadcast of short information packets with very low latency. The latter feature is especially important in outdoor ITS safety-critical applications [5], where smart vehicles must be equipped with ultra-reliable and low-latency communication systems to share information with infrastructures and nearby vehicles for triggering autonomous or assisted actions aimed at avoiding critical events.…”

“…One of the key features of the VLC technology in ITS applications relies on the intrinsic directionality of the optical channel. In a VLC system, optical elements such as lenses or compound parabolic concentrators [6], [7] can be used both at transmitter side to provide for light-beam shaping capabilities, and at receiver side, as image-forming stages in camera-based implementations [8]- [12], or as optical antennas in photodiode-based schemes [5], [13]- [19]. These optical stages could increase the optical gain of the optical detector, hence improving communication distances and link quality at the expense of reducing the angle of field of view (AFOV) of receiver.…”

Noise Resilient Outdoor Traffic Light Visible Light Communications System Based on Logarithmic Transimpedance Circuit: Experimental Demonstration of a 50 m Reliable Link in Direct Sun Exposure

“…On the other hand, the vehicular VLC systems presented in [47][48][49][50][51][52] are developed while considering the communication range as the main priority. Again, one can see that even if the communication distance is significantly increased, in most cases the experimental testing procedure is totally different compared to the real life use case.…”

“…Although the 10 Mb/s data rate is quite high considering the 66 m range, the indoor testing involved only low level artificial light interferences that can be approximated to only 200-800 lux. A high performance automotive VLC system, compatible to the IEEE 802.15.7 standard [5] is presented in [51]. This prototype is able to provide up to 200 kb/s data rates and reliable communication distances of 50 m at 99.9% confidence level, while having latencies lower than 10 ms.…”

Analysis of Low Cost Communication Technologies for V2I Applications

“…In [12], they worked with Li-Fi (Light Fidelity) (standard IEEE802.15.7) for short range V2I communication, although it could be used for V2V. In [13], they demonstrated that VLC could offer a good performance for V2I up to 50 m, achieving lower latencies (below 10 ms) and higher reliability (packet error rate below 10 −5 ). In addition, their VLC system was integrable with 5G systems.…”