Multimedia Transmissions over a MANET Testbed: Problems and Issues Elis Kulla ∗ , Makoto Ikeda † , Tetsuya Oda ∗ , Leonard Barolli † , Fatos Xhafa ‡ and Makoto Takizawa § ∗ Graduate School of Engineering Fukuoka Institute of Technology (FIT) 3-30-1 Wajiro-Higashi, Higashi-Ku, Fukuoka 811–0295, Japan Email: bd10002@bene.fit.ac.jp, oda.tetsuya.fit@gmail.com † Department of Information and Communication Engineering Fukuoka Institute of Technology (FIT) 3-30-1 Wajiro-Higashi, Higashi-Ku, Fukuoka 811–0295, Japan Email: makoto.ikd@gmail.com, barolli@fit.ac.jp ‡ Technical University of Catalonia Department of Languages and Informatics Systems C/Jordi Girona 1-3, 08034 Barcelona, Spain E-mail: fatos@lsi.upc.edu § Department of Computer and Information Science, Seikei University 3-3-1 Kichijoji-kitamachi, Musashino, Tokyo, Japan Email: makoto.takizawa@computer.org Abstract—A set of wireless mobile terminals, which coop- erate by routing packets to each other create a Mobile Ad hoc Network (MANET). MANETs are attracting attention for their potential use in several fields such as collaborative computing and disaster recovery environments. Considering mobility of the terminals, the routes change dynamically and routing becomes a key process for operation of MANETs. Until now we considered only the Constant Bit Rate (CBR) transmission over UDP transport protocol in our testbed. In this paper, we analyse the performance of our MANET testbed in an indoor environment considering multimedia transmissions with variable packet rate. Using linear and mesh topologies for connecting the nodes, and BATMAN routing protocol, we measure throughput, delay and packet loss metrics. Keywords-Multimedia Transmissions; MANET Testbed; Problems and Issues; BATMAN; Audio; Video I. I NTRODUCTION A collection of wireless mobile hosts that can dy- namically establish a temporary network without any aid from fixed infrastructure is known as a Mobile Ad-hoc Network (MANET). The mobile hosts act as routers for each other and they are connected via wireless links. Recently, MANETs are continuing to attract the attention for their applications in several fields, where the communi- cation infrastructure is expensive and/or time consuming. Mobility and the absence of any fixed infrastructure make MANET very attractive for rescue operations and time- critical applications. Research for MANETs has been done usually in sim- ulation, because in general, a simulator can give a quick and inexpensive evaluation of protocols and algorithms. However, experimentations in the real world [1] are very important to verify the simulation results and to revise the models implemented in the simulator. A typical example of this approach has revealed many aspects of IEEE 802.11, like the gray-zones effect [2], which usually are not taken into account in standard simulators, as the well- known ns-2 simulator. We conducted many experiments with our MANET testbed, which are shown in our previous works [3], [4]. We proved that while some of the Optimized Link State Routing (OLSR) problems can be solved (for in- stance the routing loop), but this protocol still has the self-interference problem. There is an intricate inter- dependence between MAC layer and routing layer, which can lead the experimenter to misunderstand the results of the experiments. For example, the horizon is not caused only by IEEE 802.11 Distributed Coordination Function (DCF), but also by the routing protocol. We carried out the experiments with different routing protocols such as OLSR and Better Approach to Mobile Ad-hoc Networks (BATMAN) and found that throughput of TCP was improved by reducing Link Quality Window Size (LQWS), but there were packet loss because of ex- perimental environment and traffic interference. For TCP data flow, we got better results when the LQWS value was 10. Moreover, we found that the node join and leave operations affect more the TCP throughput and Round Trip Time (RTT) than UDP [5]. In [6], we showed that BATMAN buffering feature showed a better performance than Ad-hoc On-demand Distance Vector (AODV), by handling the communication better when routes changed 2012 Sixth International Conference on Complex, Intelligent, and Software Intensive Systems 978-0-7695-4687-2/12 $26.00 © 2012 IEEE DOI 10.1109/CISIS.2012.82 141