Analysis of timer-based message dissemination protocols for inter-vehicle communications

Message dissemination protocols are a key component of the communication infrastructure of the Intelligent Transportation System. They have been targeted by several research and standardization efforts. An especially interesting class of dissemination protocols are so called timer (or delay) based ones. The recently standardized GeoBroadcast service of the GeoNetworking protocol of ETSI falls into this category. This work lays out an analytical model of message coverage distance and delivery delay with timer-based dissemination protocols in a highway environment. The model is based on the assumption of (possibly non homogeneous) Poisson vehicle spatial distribution. The model results are compared with computer simulations and measured data driven experiments, including scenarios with traffic discontinuities (signalized intersections). The limits of applicability of the proposed model are assessed, showing that it provides accurate predictions with a wide range of system parameters for highway scenarios. It is also shown that one of the most popular timer-based dissemination protocols achieves the same connectivity and coverage performance of the ideal message flooding.