Vehicular safety communications (VSC) are known to provide relevant contributions to avoid congestions and prevent road accidents, and more particularly at road intersections since these areas are more prone to accidents. In this context, one of the main impairments that affect the performance of VSC are interference. In this paper, we develop a tractable framework to model cooperative transmissions in presence of interference for VSC at intersections. We use tools from stochastic geometry, and model interferer vehicles locations as a Poisson point process. First, we calculate the outage probability (OP) for a direct transmission when the received node can be anywhere on the plan. Then, we analyze the OP performance of a cooperative transmission scheme. The analysis takes into account two dimensions:the decoding strategy at the receiver, and the vehicles mobility. We derive the optimal relay position, from analytical and simulation results, for different traffic densities and for different vehicles mobility models. We also show that the OP does not improve after the number of infrastructure relays reached a threshold value. Finally, we show that the OP performance of VSC is higher at intersections than on highways. We validated our analytical results by Monte-Carlo simulations.
Index TermsCooperative communications, interference, outage probability, decode-and-forward, stochastic geometry, Poisson point process, vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), intersection. July 24, 2018 DRAFT arXiv:1807.08532v1 [cs.IT] 23 Jul 2018 2 I. INTRODUCTION A-Motivation: Road traffic safety is a major issue, especially at road intersections. Studies showed that 50% of all crashes are in junction roads (intersections) including fatal crashes, injury crashes and property damage crashes [1]. This makes intersections critical areas not only for vehicles, but also for cyclists and pedestrians. Vehicular communications offer a wide range of applications to avoid potential accidents, or to warn vehicles of an accident happening in their vicinity. Vehicular communications consist of vehicle-to-vehicle (V2V) communications, and vehicleto-infrastructure (V2I) communications, in which vehicles interact with infrastructures, e.g. road-side units (RSUs). However, the main limiting factors that can jeopardize V2V and V2I communications, and degrade the performance in terms of outage probability are the interference originated from other transmitting vehicles [2]. Hence, understanding interference dependence is crucial when designing safety and low latency applications and protocols [3]. In order to deal with interference, cooperative communications have been shown to reduce the outage probability, and increase the throughput in the presence of interference [4]. B-Related works: Several works focus on the effect of interference using tools from stochastic geometry, and point process theory. However, few researches focus on interference dependence between interferer nodes and how it affects the performance considering direct t...