Adaptive Quality-of-Service-Based Routing for Vehicular Ad Hoc Networks With Ant Colony Optimization

Developing highly efficient routing protocols for vehicular ad hoc networks (VANETs) is a challenging task, mainly due to the special characters of such networks: large-scale sizes, frequent link disconnections, and rapid topology changes. In this paper, we propose an adaptive quality-of-service (QoS)-based routing for VANETs called AQRV. This new routing protocol adaptively chooses the intersections through which data packets pass to reach the destination, and the selected route should satisfy the QoS constraints and fulfil the best QoS in terms of three metrics, namely connectivity probability, packet delivery ratio (PDR), and delay. To achieve the given objectives, we mathematically formulate the routing selection issue as a constrained optimization problem and propose an ant colony optimization (ACO)-based algorithm to solve this problem. In addition, a terminal intersection (TI) concept is presented to decrease routing exploration time and alleviate network congestion. Moreover, to decrease network overhead, we propose local QoS models (LQMs) to estimate real time and complete QoS of urban road segments. Simulation results validate our derived LQM models and show the effectiveness of AQRV.

I. Introduction

As an important component of smart cities and intelligent transportation systems (ITSs), vehicular ad hoc networks (VANETs) have been attracting increasing attention from both the research and industrial communities, and they are considered to be a special type of mobile ad hoc network (MANET) [1]. In the environments of VANETs, all vehicles can act as routers to communicate with each other without relying on fixed infrastructure supports. There are two types of wireless communication, i.e., vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) [2] for various applications, which are classified into safety and infotainment applications [3], such as collision warning, driver assistance, Internet access, and so on. Compared with other MANETs, VANETs have special characteristics [4] involving the high mobility, self-organization, road pattern restrictions, no energy constraints, large-scale network sizes, and so on. Although we have achieved remarkable developments in VANETs, there are still many challenges in the fields of designs and implementations, such as security, privacy, routing, scalability, and quality of service (QoS). In this paper, we mainly focus on the network routing problems with QoS constraints.