A Location-Aware Cross-Layer MAC Protocol for Vehicular Visible Light Communications

Vehicular Visible Light Communications (V-VLC) has emerged as a technology complementing RF-based Vehicle-toVehicle (V2V) communication. Indeed, such RF-based protocols have certain disadvantages due to the limited radio resources and the, in general, omnidirectional interference characteristics. Making use of LED head- and taillights, V-VLC can readily be used in vehicular scenarios. One of the challenging problems in this field is medium access; most approaches fall back to ALOHA or CSMA-based concepts. Thanks to modern matrix lights, VVLC can now also make use of Space Division Multiple Access (SDMA) features. In this paper, we present a novel approach for medium access in V-VLC systems. We follow a location-aware cross-layer concept, in which dedicated light sectors of matrix lights are used to avoid interference and thus collisions. We assess the performance of our protocol in an extensive simulation study using both a simple static scenario as well as a realistic urban downtown configuration. Our results clearly indicate the advantages of our location-aware protocol that exploits the space-division features of the matrix lights.