Recently, MANET (Mobile Ad Hoc Network) researchers have shown increased interest in using mobile robot technology for their testbed platforms. Despite the existence of review papers that discuss the usage of mobile robot technology pertaining to a MANET testbed from the perspective of a MANET researcher, said ndings are rather lacklustre as it is not the sole purpose of said reviews. Hence, this review aims to comprehensively discuss and analyse MANET testbeds that were facilitated with mobile robot technology for previous undertaken research. To enable readers to keep abreast with mobile robot technology used in previous research, whilst presenting the advantages and disadvantages of said methods, this review will rst supercially discuss prior robot based MANET testbed facilities, before presenting technical analysis overview and critical analysis. Additionally, suggestions to heighten mobility mechanisms by using mobile robots to be more practical, easy and inexpensive are also included in this paper. The technical and critical content of this review is expected to be a source of reference for other MANET researchers interested in the most suitable mobile robots to ensure real mobility in their MANET testbeds.

Introduction

Most research that involves mobile ad-hoc network (MANET) evaluation utilise simulation methods. Recently, it has become increasingly clear that the current practice of utilizing network simulators could only provide summarized assumptions in modeling the characteristics of the real systems. As the researcher needs to observe the eect and inuence of the MAC and the physical network layer due to mobility and topology changes against the links and communication quality of the MANET, a MANET testbed with real mobility is therefore vital. In terms of accuracy, the results obtained from this approach are not available using methods such as network simulation and emulation. As of now, only a few experiments have been conducted in the MANET testbeds as compared to simulation based MANET experiments [1۲۱]. There are various methods of mobility implementation that are used in MANET testbeds, which can be divided into two main types, namely real mobility and emulated mobility (sometimes called virtual mobility). Both methods have their own advantages and disadvantages. The distinctive feature of emulated mobility is its non-physical node mobility. In other words, although the real implementation of the MANET testbed is performed on the data-link layer and the application layer above, the node mobility is not conducted physically. Physical node movement and topology changes are carried out through the use of emulation [22]. There are several dierent methods of emulated mobility such as instance migration [23], on connections [22], RF matrix switches [7, 24۲۷] and the use of virtual machine technology and virtual networks [28]. Among the wireless testbed platforms that have used emulated mobility methods Open-Access Research Testbed for Next-Generation Wireless Networks (ORBIT)3 [23], Ad-hoc Protocol Evaluation (APE) testbed with emulated mobility4 [29۳۱], the Carnegie Mellon University Wireless Emulator (CMUWE)5 [32۴۰], Castadiva6 [41۴۳], Mobi-emu7 [44], Emulab8 [45, 46], MOBNET [47, 48], MobiNet [49], the Resilience Evaluation Framework for Ad Hoc Networks (REFRAHN) [50, 51], MeshTest9 [7, 24۲۷] and WISEBED10 [52]. Emulated mobility methods have the advantage of being repeatable and reproducible that are almost the same as the network simulators. Mobility mechanisms that are conducted are therefore more manageable and predictable. However, emulated mobility methods are unable to represent the actual MAC layer and physical layer and hence the result obtained using emulated mobility are less accurate than the use of real mobility [22, 44]. Real mobility in MANET testbed experiments is vital in order to obtain accurate and realistic result. However, implementing real mobility in the testbeds is a dicult task. If this is done correctly, real mobility is able to provide very accurate experimental result on the impact of mobility on MANETs [1, 10, 53]. Previous research on MANETs have reported the use of various approaches to provide real mobility mechanisms in their MANET testbeds. Some of the methods included the use of cars [54۵۹], taxis [60], trains [61], [52, 62۶۶], bicycles [67, 68], humans [1, 8۱۲, ۶۹۸۱], remote control cars [82], and multiple mobile robots (to be discussed in the next section).