Voice Service Support in Mobile Ad Hoc Networks

Mobile ad hoc networks are expected to support voice traffic. The requirement for small delay and jitter of voice traffic poses a significant challenge for medium access control (MAC) in such networks. User mobility makes it more complex due to the associated dynamic path attenuation. In this paper, a MAC scheme for mobile ad hoc networks supporting voice traffic is proposed. With the aid of a low-power probe prior to DATA transmissions, resource reservation is achieved in a distributed manner, thus leading to small delay and jitter. The proposed scheme can automatically adapt to dynamic path attenuation in a mobile environment. Simulation results demonstrate the effectiveness of the proposed scheme.Comment: To appear in the Proceedings of the IEEE Global Communications Conference (GLOBECOM), Washington, DC, November 26 - 30, 200

EVEREST IST - 2002 - 00185 : D23 : final report

Deliverable públic del projecte europeu EVERESTThis deliverable constitutes the final report of the project IST-2002-001858 EVEREST. After its successful completion, the project presents this document that firstly summarizes the context, goal and the approach objective of the project. Then it presents a concise summary of the major goals and results, as well as highlights the most valuable lessons derived form the project work. A list of deliverables and publications is included in the annex.Postprint (published version

Transport of video over partial order connections

A Partial Order and partial reliable Connection (POC) is an end-to-end transport connection authorized to deliver objects in an order that can differ from the transmitted one. Such a connection is also authorized to lose some objects. The POC concept is motivated by the fact that heterogeneous best-effort networks such as Internet are plagued by unordered delivery of packets and losses, which tax the performances of current applications and protocols. It has been shown, in several research works, that out of order delivery is able to alleviate (with respect to CO service) the use of end systems’ communication resources. In this paper, the efficiency of out-of-sequence delivery on MPEG video streams processing is studied. Firstly, the transport constraints (in terms of order and reliability) that can be relaxed by MPEG video decoders, for improving video transport, are detailed. Then, we analyze the performance gain induced by this approach in terms of blocking times and recovered errors. We demonstrate that POC connections fill not only the conceptual gap between TCP and UDP but also provide real performance improvements for the transport of multimedia streams such MPEG video

Enabling Scalable Inter-AS Signaling: a Load Reduction Approach

In order to achieve better scalability, inter-domain signaling protocols rely on aggregation to reduce the amount of state information that routers are required to maintain. Nonetheless, they do not address another scalability key factor, the signaling load associated with establishing and maintaining reservations. Such load can be reduced if bandwidth is over-reserved. Over-reservation allows accommodating reservations without exchanging signaling messages, but may result in additional blocking. In this paper, we carry out a systematic investigation of the impact of over-reservation in different aggregation approaches, evaluating such impact in terms of the achieved signaling reduction, and blocking

Information Switching Processor (ISP) contention analysis and control

Future satellite communications, as a viable means of communications and an alternative to terrestrial networks, demand flexibility and low end-user cost. On-board switching/processing satellites potentially provide these features, allowing flexible interconnection among multiple spot beams, direct to the user communications services using very small aperture terminals (VSAT's), independent uplink and downlink access/transmission system designs optimized to user's traffic requirements, efficient TDM downlink transmission, and better link performance. A flexible switching system on the satellite in conjunction with low-cost user terminals will likely benefit future satellite network users

GMPLS energy efficiency scheme for green photonic networks

Since its emergence the internet has been a significant part of today's modern living. Defined by its interconnections and routing policies, it has fuelled increased demands for provisioning of new more advanced services that are able to dynamically react to changes within the network. These services however, lead to enormous energy consumption in contrast to a global drive for a greener environment. Hence the existence of an optical infrastructure that complies with the principles of zero-carbon emission is imperative. Subsequently, in this paper, we present an energy model of Generalized Multi-Protocol Label Switching (GMPLS) network for more power efficient Green Photonic Networks. We are proposing a greener network design based on a novel routing algorithm to deliver power reduction through implementation of so called "Hibernation" approach. The scheme includes network topology such as group the nodes configuration, segmentation of the link/ports, and wavelength provisioning via partitioning. The performance evaluations of these energy saving schemes are investigated by including various challenging issue on "greening the internet" and reduces carbon footprint. In addition, to study the impact of wavelength request, blocking probability and power consumption in relation to network load is taken into account. A trade-off is observed between energy per bit, wavelengths offered (Erlang) and blocking probability as a result of the idling nodes

Final report on the evaluation of RRM/CRRM algorithms

Deliverable public del projecte EVERESTThis deliverable provides a definition and a complete evaluation of the RRM/CRRM algorithms selected in D11 and D15, and evolved and refined on an iterative process. The evaluation will be carried out by means of simulations using the simulators provided at D07, and D14.Preprin

On-board B-ISDN fast packet switching architectures. Phase 2: Development. Proof-of-concept architecture definition report

For the next-generation packet switched communications satellite system with onboard processing and spot-beam operation, a reliable onboard fast packet switch is essential to route packets from different uplink beams to different downlink beams. The rapid emergence of point-to-point services such as video distribution, and the large demand for video conference, distributed data processing, and network management makes the multicast function essential to a fast packet switch (FPS). The satellite's inherent broadcast features gives the satellite network an advantage over the terrestrial network in providing multicast services. This report evaluates alternate multicast FPS architectures for onboard baseband switching applications and selects a candidate for subsequent breadboard development. Architecture evaluation and selection will be based on the study performed in phase 1, 'Onboard B-ISDN Fast Packet Switching Architectures', and other switch architectures which have become commercially available as large scale integration (LSI) devices