978-1-6654-4171-1/21/$31.00 ©2021 IEEE Link Quality Estimation for Reliable Data Dissemination in Vehicular Ad hoc Networks Samia MOULAI HACENE LAMOS Research Unit, Faculty of Exast Sciences University of Bejaia Bejaia, Algeria samia.moulaihacene@univ-bejaia.dz jhSamira YESSAD LAMOS Research Unit, Faculty of Exast Sciences University of Bejaia Bejaia, Algeria samira.yesssad@ univ-bejaia.dz Louiza BOUALLOUCHE- MEDJKOUNE LAMOS Research Unit, Faculty of Exast Sciences University of Bejaia Bejaia, Algeria louiza.medjkoune@ univ-bejaia.dz Abstract— The special characteristics of Vehicular Ad hoc Networks such as dynamic topology, high mobility and frequent disconnection causes major problems during data dissemination. Since, the latter requires reliable communication in low delay, effective link quality estimation is a vital issue. Motivated by these facts, several link quality based dissemination approaches have been proposed. These approaches need to be surveyed to give a complete literature review and a comprehensive comparison. Therefore, we study and survey in this paper most of proposed link quality estimation based dissemination approaches. We, also, propose a classification of link quality estimation methods and according to this, we present a comparative study and analyze the presented works. Based on our study, we propose a new dissemination approach which aims to take advantages of the analyzed approaches. Keywords—Link Quality, Reliability, Dissemination, Vehicular Ad hoc Networks. I. INTRODUCTION Vehicular Ad hoc NETworks (VANETs) are considered a particular class of Mobile Ad hoc NETworks (MANETs) that have the constraint of high mobility and dynamic topology. In VANETs, vehicles that represent the nodes of network can communicate directly with each other giving rise to the Vehicle-to-Vehicle communications (V2V), as they can communicate with existing communication infrastructure giving rise to the Vehicle-to-Infrastructure communications (V2I). VANETs can implement several applications which are classified into three classes: Safety Applications, Information and Entertainment Applications and Traffic Management Applications. The sharp increase in the number of vehicles in recent years has made driving more difficult and dangerous. In fact, 60% of road collisions can be reduced if drivers can receive warning information half a second earlier before collisions occur [1], [2]. Therefore, safety applications require efficient data dissemination approaches for reliable and rapid broadcast of emergency messages. The easiest way to manage the dissemination of information is flooding. Unfortunately, pure flooding is inefficient especially in dense networks. In fact, simultaneous transmissions commonly known as broadcast storm problem, causes many redundant rebroadcasts, message collisions, wasted bandwidth, packet loss, and delayed messages. To avoid this serious problem, several works proposed dissemination approaches which were classified based on the selection method of the next forwarder to rebroadcast the message, on receiver-based broadcast and sender-based broadcast. In sender-based broadcast, before the broadcast process, the sender selects the candidate based on the neighbor information and inserts the decision in the broadcast packet. After receiving the broadcast packet, neighbor vehicles are aware of the determined forwarding relay according to the pre-assigned decision. While, in receiver-based broadcast, each vehicle that receives emergency message estimates the transfer of the message by setting a waiting timer according to a distributed algorithm considering different metrics. When a vehicle broadcasts the message after its timer expires, other vehicles overhearing the same message abort their forwarding process canceling the waiting timer [3]. Generally, the protocols which use the sender-based or receiver-based methods choose a relay node only according to the distance, and assign higher priorities to the more distant relays to reduce the number of broadcast hops [4], [5]. However, more the distance increases, the attenuation of the signal worsens, causing therefore, the loss of the message [2]. To remedy this problem, some works proposed to use the estimation of link quality to choose the next relay. Link quality determines the quality of communication between any two nodes; it indicates the probability of the successful reception of the message. The parameters which influence the quality of link are interferences, collisions, distance and velocity. There are several works which propose solutions for the dissemination in VANETs, and there are several surveys which summarize these works [6]-[10]. Most of these surveys presented the most of proposed dissemination approaches with different classifications, others focused on clustering-based solutions such as [11], [12]. But, none of these surveys summarized the solutions based on link quality. In this perspective, we propose in this paper to summarize these approaches given the importance of this parameter which allows to ensure a reliable dissemination. We also propose a new classification of link quality estimation methods used in the summarized dissemination approaches. Finally, we have taken advantage of this study which was useful to have at least a preliminary idea for a reliable link quality estimation. II. LINK QUALITY ESTIMATION BASED DISSEMINATION APPROACHES Reliability is the most important factor that