A survey

VehicularAd Hoc Networks a Survey

Advances and Current Issues

Priscila Copeland Palmeira, Marcos Pereira dos Santos

Computer Science Department

Tiradentes University

Sergipe, Brazil

Email: priscilacopeland,[e-mail]

Abstract— Vehicular networks are increasingly as a kind of technology that requires advances and discoveries on the subject. In this article, we chose to give an overview of the ITS (Intelligent Transportation System), citing current problems in the VANETs (Vehicular Ad Hoc Networks) and proposed solutions existing in literature, with emphasis on the following topics: geo-localization, QoS (Quality of Service), and traffic safety.

Keywords-VANET; issues; geo-localization; QoS; traffic safety.

1.  Introduction

With the population increase and industrial development in the world, the traffic is getting heavier every day, this way increases the likelihood of accidents, which increases the interest of the automobile industries to equip their vehicles with ITS, to make it more secure and comfortable vehicle traffic.

To support ITS, the IEEE 802.11 group produced the IEEE 802.11p protocol, which developed applications that include the exchange of data between vehicles in all road infrastructure, thus bringing the internet to the car framework. Using dedicated wireless DSRC (Device Short-Range Communication), cars are able to communicate with each other through VANETs, i.e., vehicles are equipped with intelligent sensors able to detect the road conditions [1].

VANETs correspond to a field of vehicular networks, which are widely recognized as an essential element for ITS. These, have potential to allow a wide range of applications and services [2]. So far, the focus has been mainly on security applications, such as road awareness, accident warning, traffic surveillance, which have a huge impact on avoiding traffic accidents and increase the safety of road transport [3][4].

One of the definitions of VANETs defined as a type of wireless network where each node is a moving vehicle on the road. This type of node acts as a router transmitting a message to another node. This network has two types of communication, V2V (vehicle-to-vehicle), and V2I (vehicle-to-infrastructure). Its main function is to provide secure applications in real time to users. Handing thus the data at the right time, reducing accidents and delays [18].

However, there are security-related issues, and problems with the management of the media. This is for the complexity to achieve the desired communication requirements due to a large number of adverse effects on the characteristics of VANETs, for example, multi-path disappearance and shading the wireless channel, fluctuating density nodes in different scenarios, and network topologies rapid changes.

Other problem is the creation of flexible services, where they are able to adapt easily to the environment in which they are, so that you can connect to any device, while ensuring the safety and performance of communication.

VANETs allow a simple exchange of information to an integration of highly complex infrastructure. The general application framework takes into account the following: dissemination of warning messages for those vehicles that could meet accidents or dangerous situations, to get useful information for drivers, as in restaurants, hotels and service stations, as well as entertainment: Internet, download multimedia, or chat between vehicles [5].

This paper is organized as follows. In Section II presents the related work; Section III describes the current problems and the proposed solutions; and Section IV shows the conclusion and future works.

1. RELATED WORK

So many researches were interested in advances and issues on VANETs. Part of the researches do an overview about de general information and others do about a specific topic. For this article, we based on both of those, taking a better look into specifics problems e advances for VANETs.

One of the general ones is paper [19]. The authors provide focus on the various aspects of VANET like architecture, characteristic, challenges, glimpse of routing protocols, and simulation models used for VANET. They presented basics about the subject and displays some of the challenges that still need to be addressed in VANETs as security, reliability, enchantment in routing strategies, and others services like internet and entertainment.

Paper [20], also provides an overview on current research state, challenges, potentials of VANETs as well as the ways forward to achieving the long awaited ITS. The authors present: a comparison of high-speed wireless communication technologies for vehicular networks, spectrum allocation issues in VANETs, message broadcasting, routing protocols, congestion control techniques in inter-vehicle communication, security, privacy, anonymity and liability, reliability and cross-layer approach between transport layer and network layer.

In [21], it has presented a clear guideline of the benefits and drawbacks associated with different schemes. The authors do a review of the most relevant broadcast dissemination available in a fair comparative scheme analysis by evaluating them under the same environmental conditions, focusing on the same metrics, and using the same simulation platform, specially designed for VANETs, highlighting their features, and studying their performance under the same simulation conditions.

Others researches, in these cases with specifics subjects, such as [5], designed a collaborative virtual environment that covers the needs of integration of knowledge from different vehicles to endow the final user with the necessary information. The authors developed a model-driven approach that generates a groupware application for improving collaborative work and access to services. The implemented tool facilitates the development and implementation of collaborative frameworks in VANETs.

In [7], the authors have developed an interference-aware high-throughput channel allocation mechanism, called HT-CAM that addresses the unique challenges of CRVANETs. They create conflict graphs of link-band pairs to extract non-interfering OBU pairs that can communicate simultaneously on a given channel, increasing the spatial reuse of the available channels. In addition, this work formulates a high-throughput channel allocation problem as a MILP (Mixed-integer Linear Programming) problem, showing that the proposed HT-CAM provides with better network performances compared to state-of-the-art protocols.