An RSU Deployment Strategy Based on Traffic Demand in Vehicular Ad Hoc Networks (VANETs)

The rapid development of connected automatic vehicle (CAV) technology makes vehicular ad hoc networks (VANETs) an urgently needed research field. It includes vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) message flows. A roadside unit (RSU) is an important infrastructure for V2I communication and provides roadside information services for CAVs. However, an unoptimal RSU deployment may result in RSUs failing to improve the efficiency of VANETs and compromising the capability of service to most vehicles. Motivated by this observation, this study focuses on balancing the two objectives of efficiency and coverage and establishing an RSU deployment strategy based on traffic demand. In detail, this model optimizes both the average data delivery delay in VANETs and the number of vehicles covered by RSUs. The effectiveness of the method is verified by simulation in a 4 km ${\times }4$ km virtual road network. We also found that: 1) if 25% of the road segments in the road network are covered by RSUs, most vehicles can be served, and the delay of VANETs can be reduced; 2) compared with the road network with low traffic demand, more RSUs need to be deployed in the road network with high traffic demand to achieve the same effect; and 3) early RSU investment is more cost effective. Our method can provide a reference for the areas where RSU investments should be made and the priority of the areas.

I. Introduction

Vehicular ad hoc networks (VANETs) are a type of self-organizing network for information dissemination between vehicles through wireless communication, which is a typical mobile ad hoc network. In ad hoc networks, data are usually transmitted in multiple hops. Based on this communication feature, a vehicle with a communication function can obtain further information, not just its surroundings. Therefore, VANETs can provide a variety of application scenarios, including driving safety, driving information services, commercial applications, etc. [1], [2]. For example, when a vehicle operates outside the context of the Internet, if the vehicle wants to obtain parking lot information or sales information of a store several kilometers away, the data can be transmitted in multiple hops through VANETs [3]. In the traffic safety scenario, when a car has an accident, the information can be broadcast to the road network through VANETs to ensure that other vehicles traveling a longer distance can plan the route in advance [4]. VANETs have great potential both in driving services and in improving traffic safety.