LIAITHON: A location-aware multipath video streaming scheme for urban vehicular networks* Renfei Wang 1 , Cristiano Rezende 1 , Heitor S. Ramos 1,2,3 Richard W. Pazzi 1 , Azzedine Boukerche 1 , Antonio A.F. Loureiro 2 1 PARADISE Research Laboratory, University of Ottawa, Ottawa, ON, Canada 2 Depart. of Comp. Science, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil 3 Institute of Computing, Federal University of Alagoas, Maceio, AL, Brazil {rwang086, creze019, hramos, rwerner, boukerch}@site.uottawa.ca, loureiro@dcc.ufmg.br Abstract—Transmitting video content over Vehicular Ad Hoc Networks (VANETs) faces a great number of challenges caused by strict QoS (Quality of Service) requirements and highly dynamic network topology. In order to tackle these challenges, multipath forwarding schemes can be regarded as potential solutions. However, route coupling will severely impair the performance of multipath schemes. In this work, we present a LocatIon-Aware multIpaTH videO streamiNg (LIAITHON) scheme to address video streaming over urban VANETs. LIAITHON uses location information to discover two relatively short paths with minimum route coupling effect. The performance results have shown it outperforms the underlying single path solution as well as the node-disjoint multipath solution. Keywords-multipath, route coupling, location-aware, VANETs I. I NTRODUCTION As an emerging research area, Vehicular Ad Hoc Networks (VANETs) have received a lot of attention in the recent years. In support of the rapid development of VANETs, standards such as IEEE P1609 (WAVE), DSRC and IEEE 802.11phave been developed to accommodate for VANETs’ requirements. In addition, a great number of applications have been proposed to enable the idea of Intelligent Transportation System (ITS). Typically, VANETs applications can fall into three categories: safety, transport efficiency and infotainment [3]. Enabling video streaming can either provide an underpinning solution or achieve a higher Quality of Experience (QoE) for these applications. Fortunately, it is feasible to stream video over vehicles. Abundant electricity supplied by vehicle engines can provide ample energy for video transmission and playback. Also, enough room is available inside vehicles to accommodate large on-board computational devices and storage for video encoding and decoding. As for network connectivity, afore- mentioned standards provide VANETs sufficient bandwidth and communication range. However, by using vehicles as nodes to transmit video content, a lot of tricky challenges arise from the highly dynamic network topology. For instance, video source, destination and forwarder may become transient *This research is partially sponsored by grants from NSERC DIVA Research Network, the Canada Research Chair Program, the Ontario Dis- tinguished Researcher Award, the Ontario Research Funds (ORF), and the Ontario Centres of Excellence (OCE). which causes link disconnection. Moreover, these challenges are exacerbated as they face the stringent QoS requirements for video streaming. Among the approaches to improve performance in video transmission over ad hoc networks, multipath schemes are considered as potential solutions. By using multiple paths to deliver video content simultaneously, performance can be increased from several aspects. Congestion, especially under high data rate, can be controlled and reduced by balancing traffic load between several paths. Path diversity will provide fault tolerance while one path is disconnected. Although the benefits of multipath scheme are quite impressive, delivering video content along multiple paths introduces a wide variety of difficulties as well. The main problem is route coupling effect, which can be explained as nodes from neighboring paths contending for the shared channel access while they are in each other’s communication range. To put it simply, lots of collisions happen between transmissions on different paths. Additionally, compared to the single path protocol, multipath solutions usually suffer from a set of longer paths. Thus, there is a tradeoff between keeping all paths as separate from each other as possible and keeping them as close to the shortest path as possible. In this paper, we are interested in discovering a multipath solution for video transmission over urban vehicular net- works. The proposed scheme, namely LIAITHON, discovers relatively short paths with minimum route coupling effect based on location information. We focus on urban scenarios, because it is hard to find diverse decoupled paths for highway scenarios. We also set the number of path as 2 in order to simplify and clarify the problem we are addressing. But the scheme can be easily extended to have more than 2 paths. Video Reactive Tracking-based UnicaSt (VIRTUS) [13] is chosen as the underlying single path solution. VIRTUS is a unicast video protocol which uses receiver based forwarding scheme and location prediction to relay video content over VANETs. According to performance evaluation, LIAITHON outperforms VIRTUS and the node-disjoint solution in terms of frame loss, delay and overhead when data rate increases. The remainder of the paper is structured as follows: Section II presents related works including approaches for video streaming over VANETs and for multipath transmission. Sec- 978-1-4673-2713-8/12/$31.00 ©2012 IEEE 000436