Comparacion

ns-2 vs. OPNET: a comparative study of the IEEE 802.11e technology on MANET environments
P. Pablo Garrido, Manuel P. Malumbres
Miguel Hernandez University Avda. Universidad, s/n - 03202 Elche, Spain Technical University of Valencia Camino de Vera, s/n - 46022 Valencia, Spain

Carlos T. Calafate

{pgarrido,mels}@umh.es

calafate@disca.upv.es

ABSTRACT
In this work we present the resultsof a comparative study between two well-known network simulators: ns-2 and OPNET Modeler. In particular, we focus on a performance evaluation of the IEEE 802.11e technology on Mobile Ad-hoc Networks (MANETs) in both stationary and mobile scenarios. The paper describes the tested scenarios in detail, and discusses simulation results obtained with OPNET Modeler, comparing them with those obtainedwith ns-2. The performance of IEEE 802.11e in the presence of legacy IEEE 802.11 stations is also analyzed. Due to the significant differences between both simulators, we enumerate those changes required so as to make results obtained via both simulators comparable. The results that have been reached support the conclusion that the behavior of both simulators is quite similar in general.Categories and Subject Descriptors
C.2.1 [Network Architecture and Design]: Wireless communication

General Terms
Algorithms, Measurement, Performance

Keywords
MANET, 802.11e, Network simulators, performance comparative

1.

INTRODUCTION

A Mobile Ad-hoc Network (MANET) is composed by a group of stations that communicate wirelessly with each other to form a network without the need for anyinfrastructure or centralized control. Two of the most important factors that characterize MANETs are the routing protocol and the wireless technology employed by the stations within the network. When referring to wireless technology we mean

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the combination of the physical (PHY) and Medium AccessControl (MAC) layers of the protocol stack. The IEEE 802.11 standard [1] was created to provide wireless local area networks (WLANs) to different environments, such as public access networks, enterprise networks, or home networks. It operates in free bands such as the industrial, scientific and medical (ISM) band at 2.4 GHz or in the unlicensed 5 GHz band. The IEEE 802.11e [2] task group has finished someextensions to the IEEE 802.11 standard to provide Quality of Service (QoS) at the MAC level. The availability of a wireless technology that offers QoS support is one of the most important requirements to deploy a QoS framework in MANET environments. By enabling traffic differentiation at the MAC level it is possible to design a strategy, built on top of the IEEE 802.11e technology, that cansuccessfully support traffic with QoS constraints. Examples of QoS traffic include VoIP, videoconference, and that generated by any other real-time application. Supporting real-time video and voice traffic in MANETs is an upcoming need that results from the fusion of two technological areas that have been receiving much interest in the past few years. On the one hand, the proliferation of devices with embeddedaudio/video capturing and processing capabilities has made audiovisual communications the new human communication paradigm. On the other hand, recent improvements in network technologies aim at supporting mobile wireless communications through self-configuring and fully flexible networks. Therefore, one of the greatest technological challenges to be met, according to the current state-of-the-art,...