AdPS: Adaptive Priority Scheduling for Data Services in Heterogeneous Vehicular Networks

Abstract

Data service scheduling is paramount in realization of Intelligent Transportation System (ITS). ITS services recon upon real-time information sharing among vehicular network components. To provide real time information services in vehicular networks, numerous challenges are imposed due to unique characteristics of such networks. For efficient information dissemination, there is a prime requirement of an adaptive scheduling algorithm for approximate vehicular dynamics information. In this work, a Dedicated Short Range Communication (DSRC) based vehicular communication model has been used for efficient data services in heterogeneous traffic environment. A novel Adaptive Priority data Service scheduling (AdPS) algorithm has been proposed to provide real-time data services, which is based on fuzzy logic request deadline estimation and request prioritization. The prioritized requests has been stored in multilevel queues according to the urgency of requests to provide simultaneous access. The proposed algorithm has been simulated for different traffic scenarios for a real city environment and its performance has been analyzed at different traffic instances. The proposed protocol ensures the real time service scheduling which provides fairness among the users.

Introduction

With rapid growth in urbanization and infrastructure sector, the traffic density in existing transportation system is growing rapidly. This magnification in traffic on roads has increased the demand for road safety applications. In regard to this, it has become mandatory to enhance the capabilities of existing transportation system. The emergence of electronic and auto-mobile industries have opened up new horizons for Intelligent Transportation System (ITS) [1]. ITS provides road safety, traffic efficiency and infotainment applications to users. The realization of ITS is possible by incorporating the communication capabilities to vehicles and road-side infrastructure. Vehicular Ad-hoc Network (VANETs) provides the foundation for ITS.

VANETs are a special case of mobile ad-hoc networks (MANETs) in which vehicles are equipped with On-Board units (OBUs) to share information amongst vehicles and Road Side Units (RSUs) [2], [3], [4]. VANETs have two communication modes as V2V (Vehicle to Vehicle) and V2I (Vehicle to Infrastructure) [5], [6], [7]. The communication between vehicles and RSUs rely on Dedicated Short Range Communication (DSRC) radio. For DSRC, Federal Communication Commission (FCC) has allocated 75 MHz spectrum at 5.850–5.925 GHz [8], [9]. The Wireless Access in Vehicular Communication Environment (WAVE) enables communication between vehicles and RSUs [10], [11], [12], [13].

ITS services have two categories as safety and non-safety services [14]. Safety services provide the information related to road safety and warning alters. Non-safety services include traffic efficiency and infotainment applications [15]. To provide efficient data services, there are numerous challenges in vehicular network because of its dynamic topology, intermittent connection time, and strict delay constraints [16], [17], [18]. Firstly, ITS services demand application specific Quality of Service (QoS) requirements. Secondly, vehicular dynamics information shared among network components is approximate, imprecise and incomplete due to dynamical vehicular network topology. Due to these diverse challenges, vehicular communication has become very promising area of research for research fraternity across the globe.

There are lot of studies available in literature which are focused on data services in VANETs. However, these studies lack in providing the adaptive real-time service scheduling for imprecise vehicular network dynamics information. Although, emerging ITS services rely on reliable information sharing and demand a lot of information sharing amongst vehicles and RSUs. Thus, for efficient ITS services, there is a need to provide adaptive data scheduling for vehicular network.

In the present research work, a fuzzy logic based adaptive data service scheduling algorithm has been proposed to provide real-time ITS service scheduling. The algorithm relies on priority scheduling for reliable data service scheduling for safety and non-safety services. The major contributions of the present study are:

• A fuzzy Request Deadline Estimator (F-RDE) module has been presented to estimate request deadline based on real-time vehicular information.

• A fuzzy priority index (F-PrI) module has been designed to compute priority based on real-time vehicle and service type information.

• An Adaptive Data Services Scheduling (AdPS) algorithm has been proposed for efficient real time data service scheduling.

The rest of the research work in the present study has been organized as follows: Section 2 discusses related work and flaws in existing system. Section 3 discusses the assumptions and system model. Section 4 discusses preliminary definitions and message formats. Section 5 discusses fuzzy logic decision architecture. Section 6 presents the protocol description. Section 7 presents the queue selection procedure. Section 8 discusses the adaptive priority scheduling algorithm. In Section 9, the simulation model and performance evaluation has been presented. Finally, Section 10 concludes the entire work.