# An Intersection Signal Control Mechanism Assisted by Vehicular Ad Hoc Networks
## 1 Introduction
[23] presented a comprehensive survey of Quality of Service (QoS)-aware routing protocols and examined the protocols based on their ability to support ITS infotainment services; their multi-constraint path problem (MCP); and the protocol's functionality and weaknesses, objectives, and design challenges. VANETs have been widely applied in the field of intersection signal control as well. [PERSON] et al. [24] realized a form of traffic navigation communication through the aid of V2V, which reduced the risk of intersection collisions and significantly improved the throughput of intersections. [PERSON] et al. [25] improved the inter-vehicle communication capability by using the Ad hoc On-demand Distance Vector routing protocol AODV in a VANET at the intersection, based on which, the signal control system can effectively alleviate the congestion of an intersection. In [PERSON] et al. [26], a traffic flow zoning control idea and a mathematical model of the system optimization at intersections is proposed based on the analysis of the environmental technical characteristics of the IoV. [PERSON] et al. [27] proposed a novel coordination method for intersection management in a connected vehicle environment in which the road network is divided into three logical sections, i.e., a buffer area, core area, and free driving area. [PERSON] et al. [28] proposed a traffic signal control algorithm that assigns intersection vehicles to the group of each lane and calculates the traffic volume and congestion degree using the traffic information of each group through inter-vehicle communication in a VANET. [PERSON] et al. [29] proposed an adaptive and intelligent traffic control system based on a VANET in which a traffic signal controller is placed at each intersection. The system uses it to communicate with the vehicles in the area, and calculate the priority of each signal phase according to the waiting time. In this study, aiming at the issue of optimal decision-making for intersection signal control [11; 30; 31; 32], we designed a real-time information collection scheme for the far vehicles using a VANET, and took them into consideration, as well as the information of the intersection vehicles, to determine the intersection traffic condition at a certain time in the future. According to the calculated waiting time of each traffic flow, the signal decision could be made more precisely. In addition, two implementation schemes based on the signal control mechanism were proposed, i.e., fixed phase and period timing improvement scheme, and a dynamic phase and period control scheme. Simulation results showed that these schemes effectively reduced the average waiting time of vehicles and the ratio of long-waiting vehicles, and outperformed the traditional signal control method significantly. The rest of this paper is organized as follows. In Section 2, we describe how to collect the information of far vehicles using a VANET. In Section 3, we present the calculation method for the waiting time of traffic flows and propose the two concrete decision-making schemes. The simulation results and performance analysis are presented in Section 4. The last section concludes this paper. In order to enhance the readability of this paper, the summary of presented symbols is shown in Table 1.