IMDEA Networks Institute Digital Repository
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VoIP over WLAN Performance
No full textThe number of worldwide VoIP customers is well over 38 million. Thanks to the popularity of inexpensive, high-quality services, it's projected to increase to nearly 250 million within the next three years.
The VoIP Handbook: Applications, Technologies, Reliability, and Security captures the state of the art in VoIP technology and serves as the comprehensive reference on this soon-to-be ubiquitous technology. It provides:
-A step-by-step methodology to evaluate VoIP performance prior to network implementation
- An invaluable overview of implementation challenges and several VoIP multipoint conference systems
- Unparalleled coverage of design and engineering issues such VoIP traffic, QoS requirements, and VoIP flow
As this promising technology’s popularity increases, new demands for improved quality, reduced cost, and seamless operation will continue to increase. Edited by preeminent wireless communications experts Ahson and Illyas, the VoIP Handbook guides you to successful deployment.TRUEpu
Compensating Device Inertia for 6-DOF Haptic Rendering
Get PDFIn this paper, the importance of the user’s primary
holding pivot point on the end effector of a haptic interface is discussed. Both theoretical analysis and experimental results demonstrate that this holding pivot point is critical for the correct perception of the haptic properties assigned to the virtual objects. We also study the physical inertia effects of the end effector on the non-uniform stiffness perception of simulated virtual objects. To the best of our knowledge, no such combined
consideration of holding pivot point and device structure related inertia has so far been made for works in 6-DOF haptic rendering.
We have instrumented the end effector of a haptic interface
with a membrane potentiometer to measure the user’s primary
holding pivot point in real-time. Accordingly, a preliminary
adaptive feedback method is developed to render the appropriate forces/torques to compensate for the effects of the end effector’s inertia on the haptic stiffness perception.TRUEpu
Loop-freeness in multipath BGP through propagating the longest path
Get PDFThe concurrent use of multiple paths through a communications network has the potential to provide many benefits, including better utilisation of the network and increased robustness. A key part of a multipath network architecture is the ability for routing protocols to install multiple routes over multiple paths in the routing table. In this paper we propose changes to local BGP processing that allow a BGP router to use multiple paths concurrently without compromising loop-freeness.TRUEpu
A survey of inter-vehicle communication protocols and their applications
No full textInter-vehicle communication (IVC) protocols have the potential to increase the safety, efficiency, and convenience of transportation systems involving planes, trains, automobiles, and robots. The applications targeted include peer-to-peer networks for web surfing, coordinated braking, runway incursion prevention, adaptive traffic control, vehicle formations, and many others. The diversity of the applications and their potential communication protocols has challenged a systematic literature survey. We apply a classification technique to IVC applications to provide a taxonomy for detailed study of their communication requirements. The applications are divided into type classes which share common communication organization and performance requirements. IVC protocols are surveyed separately and their fundamental characteristics are revealed. The protocol characteristics are then used to determine the relevance of specific protocols to specific types of IVC applications.TRUEpu
Feature Selection and Classification in Genetic Programming: Application to Haptic-based Biometric data
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A MAC Layer Abstraction for Heterogeneous Carrier Grade Mesh Networks
Get PDFProviding carrier grade services to a large number of mobile users is becoming an important challenge for wireless network operators. One promising solution
for offering cost-efficient alternatives compared to classical cellular approaches is the use of wireless mesh networks along with the use of heterogeneous radio technologies. In this paper we propose a MAC abstraction layer to lessen the management burden of heterogeneous radio technologies. This abstraction layer is intended to hide the complexity and specifics of different wireless interfaces, this way supporting the use of a single set of routing and capacity handling mechanisms.TRUEpu
User Association to Optimize Flow Level Performance in Wireless Systems with Dynamic Interference
Get PDFWe study the impact of user association policies on flow-level performance in interference limited
wireless networks. Most research in this area has used static interference models (neighboring base stations are
always active) and resorted to intuitive objectives such as load balancing. In this paper, we show that this can
be counterproductive in the presence of dynamic interference which couples the transmission rates to users at various base stations.We propose a methodology to optimize the performance of a class of coupled systems, and
apply it to study the user association problem.We show that by properly inducing load asymmetries, substantial
performance gains can be achieved relative to a load balancing policy (e.g., 15 times reduction in mean delay).
Systematic simulations establish that our optimized static policy substantially outperforms various dynamic
policies and that these results are robust to changes in file size distributions, channel parameters, and spatial
load distributions.TRUEpu
Extending the address space of the Internet
Get PDFIn the nearest future Internet in its current shape will have to face the problem of shortage of IPv4 addresses. IPv4 architecture reserves 32 bits for addressing purposes, which occurs not to be enough in the face of a rapid growth of the Internet. To overcome this problem, the successor of IPv4, IPv6, was designed with 128 bits of addressing space. However, deployment of IPv6 goes very slowly mainly because of the cost of transition, even if many transition mechanisms were already proposed. Therefore, it could be advantageous to explore solutions which can occur better than IPv6 in terms of deployment ease or will allow for IPv4 and IPv6 coexistance with minimal cost. This thesis presents new approach for solving a problem with lack of addresses. xIP architecture creates new address space by extending IPv4 address scheme. xIP can be incorporated as a completely new protocol or can be used as a mechanism which can improve IPv6 and IPv4 coexistance (xIP6). The common characteristics of both of the architectures are integrated routing and addressing and reusing extensive part of IPv4 world. This solution seriously decreases management cost during coexistence period and makes deployment less expensive and easier to accept by users.Telematics EngineeringUniversidad Carlos III de Madrid, Spainpu
Optimal Energy Savings in Cellular Access Networks
Get PDFIn this paper we study with simple analytical models
the energy-aware management of cellular access networks, trying to characterize the amount of energy that can be saved by reducing the number of active cells during the periods when they are not necessary because traffic is low. When some cells are switched off, radio coverage and service provisioning are taken care of by the cells that remain active, so as to guarantee that service is available over the whole area. We show how to optimize the energy saving, first assuming that any fraction of cells can be turned off, and then accounting for the constraints resulting from the cell layout.TRUEpu
Evaluation of Tree-Based Routing Ethernet
Get PDFTree-based Routing (TRE) revisits Tree-based Routing
Architecture for Irregular Networks (TRAIN)—a forwarding
scheme based on a spanning tree that was extended to use some shortcut links.We propose its adaptation to Ethernet, using a new type of hierarchical Ethernet addresses and a procedure to assign them to bridges. We show that compared to RSTP, TRE offers improved throughput. The impact of transient loops in TRE is lower compared to the application of the classical shortest path routing protocols to Ethernet. Finally, TRE is self-configuring and its forwarding process is simpler and more efficient than in standard Ethernet and shortest path routing proposals.TRUEpu