Figure 1 - uploaded by Lionel M. Ni
Content may be subject to copyright.
Source publication
Test and performance evaluation of protocols and algorithms in mobile wireless networks is known to be challenging. Due to the highly varying characteristics of mobile wireless networks, one cannot merely rely on either network simulation or a testbed. Network emulation provides a controllable and reproducible environment, yet it generally lacks th...
Contexts in source publication
Context 1
... link in the target network is mapped to a Virtual Link in the emulation configuration. As shown in Figure 1, a router with four physical ports is mapped to a virtual router with four virtual ports in an emulator node. A virtual port is a combination of a physical Ethernet port to connect with other virtual routers, and a software module of virtual device to control the outgoing packets from this virtual port. ...
Context 2
... virtual port is a combination of a physical Ethernet port to connect with other virtual routers, and a software module of virtual device to control the outgoing packets from this virtual port. In Figure 1, the emulator node has a total number of seven virtual ports; four of them are used in this example. An emulation configuration physically consists of a number of emulator nodes and fast Ethernet switches to establish a virtual topology. ...
Similar publications
Tele-immersive 3D multi camera environments are beginning to emerge and they bring with them lots of applications as well as challenging research problems. They enable coop-erative interaction between geographically distributed sites. One of the important questions that arises in the design and implementation of such systems is that how to trans-mi...
In this paper, we present an adaptive architecture for the transport of VoIP traffic over heterogeneous wired/wireless Internet en-vironments. This architecture uses a VoIP gateway associated with an 802.11e QoS enhanced access point (QAP) to transcode voice flows be-fore their transmissions over the wireless channel. The instantaneous bit rate is...
Mobile ad hoc networks (MANETs) consist of a collection of wireless mobile nodes which dynamically exchange data among themselves without the reliance on a fixed base station or a wired backbone network. Due to the limited transmission range of wireless network nodes, multiple hops are usually needed for a node to exchange information with any othe...
Recently, various sophisticated strategies adapted to current network conditions have been proposed for channel allocation based on intelligent techniques such as evolutionary and genetic algorithms. These approaches constitute heuristic solutions to resource management problems in modern cellular systems. On the other hand, the ant colony optimiza...
Citations
... c). Trace based wireless emulation, which collect the traces from the target network and then construct a wireless network model with collected traces, and then reproduces the traced network effect in a wired network and provide a reproducible environment [3]. Clearly these emulators provide a controllable and reproducible environment, but it generally lacks the support for network topology, mobility and an interactive interface for users. ...
... Using a wired connection of RF elements we overcome these drawbacks. EMWIN [3] is an IP based mobile wireless network emulation system; provide a unique feature of emulating multiple mobile hosts in one single emulator node, also to emulate the mobility using a wired network of computers. To the best of our knowledge, we have not seen a system which uses wired connection of RF elements like attenuators, splitters, switches etc., to imitate the RF environment and manipulate the path characteristics. ...
Institute of Reliable Embedded Systems and Communication Electronics, Offenburg University of Applied Sciences, Germany has developed an automated testing environment, Automated Physical TestBeds (APTB), for analyzing the performance of wireless systems and its supporting protocols. Wireless physical networking nodes can connect to this APTB and the antenna output of this attaches with the RF waveguides. To model the RF environment this RF waveguides then establish wired connection among RF elements like splitters, attenuators and switches. In such kind of set up it's well possible to vary the path characteristics by altering the attenuators and switches. The major advantage of using APTB is the possibility of isolated, well controlled, repeatable test environment in various conditions to run statistical analysis and even to execute regression tests. This paper provides an overview of the design and implementation of APTB, demonstrates its ability to automate test cases, and its efficiency.
... [5] ...
Las líneas principales de investigación sobre los sistemas de seguridad para vehículos se encaminan actualmente hacia el diseño de sistemas de transporte inteligentes. Dentro de este marco evolutivo, los sistemas de comunicaciones móviles entre vehículos están adquiriendo un importante peso. El objetivo prioritario de estos sistemas y la formación de redes de comunicaciones entre vehículos es el intercambio de información relativa a la seguridad vial. Con ello, se pretenden proporcionar a cada conductor datos referentes a los vehículos que se encuentren en su zona de influencia, especialmente de los que no estén en su campo visual. Para el correcto diseño de estos sistemas hay que tener en cuenta que en un entorno como el vehicular, la velocidad de desplazamiento es elevada, la formación de las redes es muy dinámica y el entorno de propagación altamente variable. Esto, unido a que las transmisiones deben ser fiables para poder dar robustez a las aplicaciones de seguridad, hace que el proceso de definición de un protocolo de comunicaciones adecuado sea complejo y se requiera un dimensionado previo. La finalidad de este trabajo es el dimensionado de dichos sistemas de comunicaciones móviles entre vehículos en escenarios realistas, considerando parámetros clave como la velocidad de los vehículos, la potencia de transmisión o la densidad del tráfico, e incluyendo factores como el tiempo de reacción del conductor. Dicho dimensionado proporciona los indicadores necesarios para iniciar el proceso de diseño de mecanismos de gestión de recursos radio que posibiliten un intercambio de información de seguridad vial entre vehículos, robusto, fiable y eficiente. Los resultados obtenidos mediante simulación ponen de manifiesto la necesidad de implementar mecanismos de control de potencia y control de la tasa de transmisión de mensajes de seguridad en función de la velocidad de desplazamiento, la posición de los vehículos e incluso la congestión del canal. Abstract-Inter-vehicle wireless communication systems are currently being developed as a promising technology to improve traffic safety. Considering their decentralized nature, its deployment faces important challenges to guarantee an efficient and reliable transmission of broadcast safety messages. This paper investigates the dimensioning of such systems by analysing the impact of key operating conditions on its performance (traffic density, vehicular speed, radio propagation effects and transmission power). Based on the observed results, the paper proposes the development and implementation of efficient radio resource management techniques for inter-vehicle wireless systems, such as adaptive power control and opportunistic-driven transmission rate. These techniques are aimed at efficiently and reliably guarantee safety based inter-vehicle wireless systems.
... There is no bandwidth adaptation in MobiEmu, while NE offers a limited mechanism for bandwidth limitation in which properties of contention-based media access for wireless channel are not considered. EMWIN/EMPOWER [18], [19] and MASSIVE [20] do not implement any bandwidth limitation mechanism but just determine basic on/off connectivity based on a predefined event list. DINEMO [21] is a distributed version of NEMAN emulator in which nodes are emulated as virtual nodes inside a single physical machine. ...
... 3) Clients cannot affect any changes in nodes topology because of possible events during emulation are decided at batch time in TCL scripts. EMWIN [6] is an IP-based MANET emulation system. It is used to test and evaluate mobile wireless network protocols, such as multi-hop mobile ad hoc routing protocols, directly. ...
... Algunos emuladores y testbed son híbridos, combinando las ventajas de la simulación, la emulación y las pruebas con equipos reales. Entre las plataformas híbridas existentes en la literatura podemos destacar en primer lugar EMWin[ZN02], que emula la capa MAC, mientras que la pila de protocolos y las aplicaciones son reales. NCTUns[Wan06] emula nodos que generan tráfico, que luego es capturado por el simulador para introducir el comportamiento de un escenario inalámbrico. ...
This Doctoral Thesis presents a set of studies about optimization techniques for real-time services, which can be used in the case of a number of flows sharing the same path.
In these scenarios, the efficiency can be improved by header compression, as many header fields are the same for every packet, or increase by one with respect to the previous packet. In addition, many packets can be multiplexed in a bigger one, which is sent to the destination via a tunnel. Some multiplexing methods have been standardized by IETF, as it happens with the ones based on RTP. The methods could be adapted to other services with similar characteristics.
Some measurements have been carried out so as to quantify the improvement which can be achieved by the use of these methods for real-time services. Different test environments have been used: real hardware, virtual emulation and simulation. Some objective quality parameters, like delay and packet loss, have been obtained, and they have been properly combined in order to calculate some subjective quality estimators, in terms of MOS (Mean Opinion Score).
First, VoIP service has been tested using an IP telephony system which has been designed using the scheme of commercial solutions. It includes a multiplexing system, which merges the calls that share the same origin and destination offices. The system has also been implemented in a testbed using free software tools. Some measurements of the obtained improvements in terms of quality parameters have been carried out. Finally, a simulation environment has allowed us to study the improvements of admission probability obtained by multiplexing.
The optimization method has also been tested for another real-time service, i.e. First Person Shooter (FPS) games. The multiplexing standard has been adapted to this service, as these games do not use RTP but only UDP. The savings in terms of bandwidth and packets per second have been calculated analytically, and corroborated by simulations. Finally, some tests have been carried out in order to show the improvements in terms of quality parameters.
... Most existing solutions are based on a distributed architecture where a virtual MAC layer is embedded on each terminal. For instance, EMWin [6] is fully distributed across the end nodes and emulates the medium access CSMA/CA on an Ethernet experimentation testbed. Each terminal has a neighbor table evolving over time, and the virtual MAC layer uses it to determine whether frames to the next hop are lost or not. ...
In opportunistic networks the availability of an end-to-end path is no longer required. Instead opportunistic networks may take advantage of temporary connectivity opportunities. Opportunistic networks present a demanding environment for network emulation as the traditional emulation setup, where application/transport endpoints only send and receive packets from the network following a black box approach, is no longer applicable. Opportunistic networking protocols and applications additionally need to react to the dynamics of the underlying network beyond what is conveyed through the exchange of packets. In order to support IP-level emulation evaluations of applications and protocols that react to lower layer events, we have proposed the use of emulation triggers. Emulation triggers can emulate arbitrary cross-layer feedback and can be synchronized with other emulation effects. After introducing the design and implementation of triggers in the KauNet emulator, we describe the integration of triggers with the DTN2 reference implementation and illustrate how the functionality can be used to emulate a classical DTN data-mule scenario.
... Most of the available platforms are based on wired emulation of wireless networks [20]. Wired wireless emulators such as EMPOWER [21], and EMWIN [22] use a centralized emulation layer and rely on switching equipment to disseminate messages to " mobile " nodes. Non-centralized wireless testbed emulators such as SEAWIND [23] or SWOON [24] rely on a wired configurable testbed similar to Emulab [25]. ...
In this paper, we present a middleware architecture for dependable mobile systems and an experimentation platform for its evaluation. The proposed architecture includes three building blocks tailored for mobile cooperative applications: a Proximity Map, a Trust and Cooperation Oracle, and a Cooperative Data Backup service. To illustrate our platform, we developed a Distributed Black-box application, whose aim is to record critical data while tolerating the failure of a node, and implemented a hardware evaluation platform of mobile systems for experimenting with the application. We provide here some insights on the development of the platform, focusing on wireless communication emulation via signal attenuation.
... There is no bandwidth adaptation in MobiEmu, while NE offers a limited mechanism for bandwidth limitation in which properties of contention-based media access for wireless channel are not considered. EMWIN/EMPOWER [18], [19] and MASSIVE [20] do not implement any bandwidth limitation mechanism but just determine basic on/off connectivity based on a predefined event list. DINEMO [21] is a distributed version of NEMAN emulator in which nodes are emulated as virtual nodes inside a single physical machine. ...
In this paper, we present AEROMAN (Architecture to Evaluate Routing Protocols for Multi-hop Ad-hoc Networks) which is designed and implemented for evaluation of routing protocols for multi-hop wireless networks. AEROMAN uses QOMET, a wireless link emulation tool, to compute parameters of wireless links, such as bandwidth, delay, packet loss rate, in contention-free conditions. In order to take into account the properties of contention-based media access for wireless channel, AEROMAN uses an Adaptive Traffic (AT) model to emulate the sharing feature of CSMA/CA mechanism in IEEE 802.11. The evaluations show that the AEROMAN with AT model effectively captures the characteristics of wireless communications. Several experiments using OLSR as routing protocol with different routing metrics are performed in order to illustrate the main features and usability of AEROMAN.
... This virtual layer needs to provide the same services as a regular data link layer so that the routing protocol under test does not need any modifications. EMWin [7] is a fully distributed wireless emulator focusing on the impact of mobility. For this purpose, an emulated MAC layer has been developed to mimic the medium access CSMA/CA on an ethernet experimentation testbed. ...
... Two solutions can be considered. First, the simulation process can be done partially in real time as in the EMWin [7] solution. Every node in the experiment can embed a small part of the simulator that will react in real time according to the traffic. ...
More and more applications and protocols are now running on wireless networks. Testing the implementation of such applications and protocols is a real challenge as the position of the mobile terminals and environmental effects strongly affect the overall performance. Network emulation is often perceived as a good trade-off between experiments on operational wireless networks and discrete-event simulations on Opnet or ns-2. However, ensuring repeatability and realism in network emulation while taking into account mobility in a wireless environment is very difficult. This paper proposes a network emulation platform, called W-NINE, based on off-line computations preceding online pattern-based traffic shaping. The underlying concepts of repeatability, dynamicity, accuracy and realism are defined in the emulation context. Two different simple case studies illustrate the validity of our approach with respect to these concepts.
... Wired wireless emulators such as EMPOWER [9], and EMWIN [8] use a centralized emulation layer. Even though these centralized approaches can avoid time synchronization issues because everything happens on a centralized controller, these approaches rely on switching equipment to disseminate messages to enduser nodes. ...
A wired testbed's usefulness for wireless research hinges on its ability to faithfully reproduce the wireless medium. One of the key properties of a wireless medium is its broadcast nature. Wireless broadcast behavior is used in applications such as cell phone and satellite networks to disseminate the same data to multiple users as well as perform time synchronization. In this paper, we investigate two methods that can be used to ascertain if a given wireless emulator is modeling the broadcast property correctly. Our results indicate that the better of the two proposed methods offers micro-second precision.
