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. Cooperative 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 transmissions [5]-[9], and cooperative transmissions (see [10]-[12] and references therein). As far as V2V and V2I communications are concerned, several works investigated the effect of interference in highway scenarios [13]-[15]. In [16], the authors derive the expressions for the intensity of concurrent transmitters and packet success probability in multi-lane highways with CSMA MAC protocols. The performance of IEEE 802.11p using tools form queuing theory and stochastic geometry is analyzed in [17]. The outage probability is obtained in [18] for Nakagamim fading and Rayleigh fading channels and the results are verified with real-world dataset containing the locations of Beijing taxis. The authors in [19] derivate the outage probability and rate coverage probability of vehicles, when the line of sight path to the base station is obstructed by large vehicles sharing other highway lanes. In [20] , the performance of automotive radar is evaluated in terms of expected signal-to-noise ratio, when the locations of vehicles follow a Poisson point process and a Bernoulli lattice process.
In REF , The authors study the interference dynamic of cooperative transmission at road junctions.
Performance Analysis of Cooperative Communications at Road Intersections Using Stochastic Geometry Tools
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