Deployment Optimization of Roadside Unit With Failure Probability Based on Stochastic Mixed Traffic Equilibrium

The reasonable deployment of roadside units (RSUs) in a vehicular ad hoc network (VANET) is important for the efficient and safe operation of automated vehicles (AVs) that are mixed with human-driven vehicles (HVs) in a near future modern city. Because an RSU faces failure under the circumstances of such as electricity depletion and line fault, we consider RSU failure probability in studying the problem of RSU deployment optimization. First, we establish the formulas of connectivity considering failure probability and communication radius of RSUs. Second, assuming that the road traffic is mixed with AVs and HVs, we propose a connectivity-based stochastic user equilibrium model to describe the route choice of mixed traffic. Third, we propose a bi-level programming for optimizing RSUs deployment with the objective function as total connectivity and coverage (TCC) of the network. The lower level is the stochastic user equilibrium of mixed traffic. Fourth, we design an improved binary particle swarm optimization algorithm embedded with the method of successive average to solve the bi-level model to obtain the optimal deployment scheme of RSUs. Numerical results show that: 1) the optimal RSUs deployment scheme suggests deploying the optimal number of RSUs with appropriate communication radius at selected sites. Especially, to ensure at least 90% TCC, the optimal scheme reduces the number of deployed RSUs; and 2) failure probability significantly affects the TCC in scenarios with low modal share of AV (0.05-0.1). RSU communication range, compared with the failure probability, has greater influence on deployed RSU number to ensure at least 90% TCC.