Cross-Layer Solutions for Enhancing Multimedia Communication QoS over Vehicular Ad hoc Networks Ali Hassoune Mustafa, Mekkakia Zoulikha and Bendella Fatima Department of Computer Engineering, University of Sciences and Technology of Oran Oran, Algeria {mustafa.alihassoune; zoulikha.mekkakia; fatima.bendella}@univ-usto.dz Abstract—Vehicular Ad hoc NETworks (VANET) are a new emergent technology based on wireless ad hoc networks. They are characterized by their high speed nodes, which affect on network topology. This can affect network services, especially those having big packet size and need high bandwidth, such as Multimedia services. Many solutions have been proposed in the literature in order to serve a better multimedia communication over VANET. In this paper, we will focus on cross-layer solutions because of their high performance in term of Quality of Service (QoS). We present a survey of existing cross-layer solutions, which try to enhance multimedia services over VANETs. Works will be classified depending on the nature of information exchanged and their belonging to OSI Layers. Keywords- Cross-Layer; QoS; Multimedia; VANET. I. INTRODUCTION Vehicular Ad hoc NETworks (VANET) are the main interesting instantiation of mobile Ad hoc networks, which could have an important role in future services. They are characterized by their high mobility due to high speed nodes, which affect on network topology. They are composed of vehicles equipped with On-Board Units (OBUs), and Gateways installed in the streets, which are called Road Side Units (RSUs). VANETs can be deployed in different kind of roads, such as “Highways” where nodes move with high speed (80-120 km/h) and have generally low density. Also, VANETs can be deployed in “Urban roads” where nodes move with less speed (20-60 km/h), which affects network density. The urban roads are also characterized by the existence of buildings, which act as obstacles for VANET communications. VANETs use a special MAC protocol called 802.11p, which is an enhancement of 802.11, using two types of channels: Control Channel (CCH) and Service Channels (SCH). The CCH is used for the periodical dissemination of control information and for the dissemination of traffic safety messages. The SCH is used to disseminate non- critical information for infotainment applications, such as the Video Streaming. In addition, VANET applications can be classified into Safety and Non-Safety applications (like downloading files or accessing the internet). Safety applications can help to prevent accidents and road congestions, while the non Safety applications may be used for user’s convenience like video streaming or Video on Demand (VoD) applications, such as TV Broadcasting. Sending these kinds of data in such networks is very challenging because of large data size, link breaks, and sensibility to losses. These features are rare in such networks where nodes move with high speed and where topology changes rapidly. Therefore, robust multimedia applications encounter many challenges that oblige applications to be able to tolerate link failures and packet losses in order to have a high quality video at the receiver side. Hence, many solutions have been proposed in the literature in order to enhance Multimedia QoS to serve better video services in VANET. We shall focus in this paper on cross-layer solutions where information is exchanged between different layers in order to have a better multimedia service. These techniques will be classified depending on data exchanging nature. This paper is organized into three sections. In Section I, we survey existing cross-layer solutions and techniques, which enhance multimedia Qos. Section II is reserved for discussing the solutions and presenting open issues. In Section III, we conclude our work and present future works. II. CROSS-LAYER SOLUTIONS FOR ENHANCING MULTIMEDIA QOS OVER VANET Cross-layer approach is an ‘escape’ from the Open Systems Interconnection (OSI) model, which applies virtually strict boundaries between the layers, data are kept within a given layer. Protocol architectures follow strict layering principles, which ensure interoperability, fast deployment, and efficient implementations. However, lack of coordination between layers limits the performance of such architectures due to the specific challenges posed by wireless nature of the transmission links. Cross-layer solutions remove such strict boundaries to allow communication between layers. Its core idea is to maintain the functionalities associated to the original layers but to allow coordination, interaction and joint optimization of protocols crossing different layers. In this paper, it is notable that all studied mechanisms are cross-layer solutions, which serve a high quality video on the receiver’s end. We can distinguish between the aforementioned techniques based on exchange nature, as shown in Table 1. TABLE 1. STUDIED CROSS-LAYER TECHNIQUES Works APP NET MAC PHY [1;2;3;4;6;7;8] √ √ [9;10;11;12] √ √ [13;14;15;16;17;18;19; 20;21] √ √ [22;23;24;25;26;27;28] √ √ [29;30;31] √ √ [32;33;34] √ √ √ 60 Copyright (c) IARIA, 2014. ISBN: 978-1-61208-377-3 AFIN 2014 : The Sixth International Conference on Advances in Future Internet