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Quality of service (QoS) is a key problem in wireless environments where bandwidth is scarce and channel conditions are time varying and sometimes implies highly packet losses. IEEE 802.11b/g/a wireless LAN (WLAN) are the most widely used WLAN standards today, and the IEEE 802.11e QoS enhancement standard exists and introduces QoS support for multimedia applications. This paper presents a class based...
Series of queues are suitable performance models for a variety of communication network components and access technologies, but the usual assumption of independent service times at different nodes is critical. We consider delays in a series of queues with identical service times at each network node where for each customer the service time at the first node is a random variable and the successive...
Using simulations, we analyze the performance of new TCP variants currently used in the Internet and that gradually replacing TCP NewReno, as they are already activated by default in operating systems or network equipment. We compare these new variants using some metrics that have been recently standardized in order to evaluate new congestion control mechanisms. We observe a trade-off between more...
Owing to packet forwarding throughout different paths and asynchronous behavior of TCP/IP networks, voice packets of a voice flow may arrive at their destination with varying delay. This impairment, known as jitter, is smoothed at the receiver side by applying dejitter buffer algorithms, which store some packets for an amount of time before playout. This paper presents a manager algorithm of dejitter...
Several industrial applications require mobile robots to exchange data between them or with a static sink. In this paper, we consider a fleet of mobiles moving in an environment, carrying sensors and actuators. As they move close to a manager, the mobiles exchange data with this static entity. This communication is performed on a meeting channel, different from the channel used for the intra-mobile...
With the development of vehicular networks, it is possible to implement accident warning systems that directly (i.e., without any external supporting infrastructure) alert approaching vehicles. In this scenario, each vehicle is provided with a sensor that, under abnormal conditions, triggers an alarm message. A vehicle that receives this information: (a) warns the driver; and (b) relays such information...
The flexibility and self-organization properties of Wireless Mesh Networks (WMNs), and the benefits arising from the split of a physical network in several context-aware Virtual Networks (VNs), are a two-fold force to deal with the huge heterogeneity of user requirements and network resources in a future Internet architecture. In this scope, we provide a novel context-aware architecture for WMNs,...
In this paper we present a QoS-aware solution to manage heterogeneous wireless and Broadband PLC communications infrastructures for Smart Electricity Networks (SENs). The proposal is related to the framework of the ITU Next Generation Network of the ITU and it is based on a QoS Broker architecture. This paper explains how QoS capabilities of different transport technologies are leveraged to attain...
Network lifetime is often a crucial measure of the cost-effectiveness of underwater wireless sensor networks and a guiding factor of their deployment. In this paper, we propose a placement strategy for surface gateway nodes in order to maximize network lifetime under a given set of functional requirements. We formulate the problem as an optimization problem and solve it for sample networks. Results...
TCP is the most widely used congestion protocol in the Internet. However, TCP has some limitations, even in the wired world, such as not providing high utilizations in high bandwidth-delay product networks, and introducing high load and overhead in the network. Due to these limitations, several congestion protocols have been proposed. Some of the most known and recent protocols developed to provide...
Performance evaluation via simulation requires to create models that are often difficult and are not able to faithfully reflect the operating conditions. This paper discusses an approach based on the integration of trace files into an OMNeT + + model. This approach allows to represent and evaluate complex systems by simple models. Moreover, in the case a simulation model of the communication system...
With the wide emergence of real time applications in mobile ad hoc networks, delay guarantees become increasingly required. Many routing protocols are proposed, in the few last years, for improving the overall delay in mobile ad hoc networks. In this paper, we propose an extension of our earlier QoS routing protocol called “AMDR” (Adaptive Mean Delay Routing) which is based on an adaptive approach...
We propose a dual TCAM architecture - DUOS, for routing tables. Four memory management schemes for TCAMs also are proposed and evaluated. DUOS and our memory management schemes support control-plane incremental updates without delaying data-plane lookups. Compared to other TCAM architectures such as CAO OPT [19] that support incremental updates without delaying lookups, DUOS offers reduction in power...
We present in this work the performance evaluation of MPEG-4 video transmission with our proposed single rate multicast protocol named Adaptive Smooth Multicast Protocol (ASMP). ASMP key attributes are: a) adaptive scalability to large sets of receivers, b) TCP-friendly behavior, c) high bandwidth utilization, and finally d) smooth transmission rates which are suitable for multimedia applications...
Advances in sensor technology, wireless mesh networking and embedded processors are pushing development of new technologies in Wireless Sensor Networks (WSN). The wide variety of potential applications and platforms makes hard to port and develop new applications to different platforms keeping smart and efficient behavior of the nodes of WSN. For this reason nowadays middlewares are emerging as a...
The wide range of applications that are supported on the Internet requires it to deliver a diverse set of classes of service. For example, network providers need to support both delay-sensitive multimedia services and less time-sensitive applications such as web browsing and peer-to-peer transfers. Differentiated routing is one approach to delivering these different classes of service. In this paper...
Quality of Service (QoS) provisioning is one of the main requirements in the 3GPP IP Multimedia Subsystem (IMS) and it has been addressed in different works since the beginning of the IMS standardization process. As a result of the fixed and mobile networks evolution, parameters standardized in IMS have changed constantly until the specification of the Policy and Charging Control (PCC) architecture...
Personalization and group communications have always been conflicting approaches. From one side, the user wants to get the services with their specific characteristics. From the other side, group communications imply the support of the same service, with the same characteristics, by a group of users. To simultaneously enable personalization and profit from the resources improvements provided by group-based...
A device with embedded cognitive radio (CR) seeks to join a novel low-cost multi-radio wireless network, one which adopts the whole spectrum for transmission. However, the amount of spectrum bands that a CR device is able to sense within a given time is limited, and in addition, CR node transmissions may co-interfere. Thus, we propose a link-based pre-allocated spectrum section sensing for unicast...
The IEEE 802.16e standard is proposed for mobile nodes to access high data rate and long transmission radius in WiMAX. For supporting contention-free-based initial ranging and early performing the initial ranging during handoff, IEEE 802.16e specifies the association handoff mechanism in the MAC layer. However, an MS is difficult to determine the scan duration in the association handoff mechanism...
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