Catálogo de publicaciones - libros

We present an architecture for a class of systems that perform distributed, collaborative, adaptive sensing (DCAS) of the atmosphere. Since the goal of these DCAS systems is to sense the atmosphere when and where the user needs are greatest, end-users naturally play the central role in determining how system resources (sensor targeting, computation, communication) are deployed. We describe the meteorological command and control components that lie at the heart of our testbed DCAS system, and provide timing measurements of component execution times. We then present a utility-based framework that determines how multiple end-user preferences are combined with policy considerations into utility functions that are used to allocate system resources in a manner that dynamically optimizes overall system performance. We also discuss open challenges in the networking and control of such end-user-driven systems.

In this paper, we describe our evaluation work of a DHT-DNS hybrid naming system together with our prototype design and implementation of the DHT-DNS mounter. For the evaluation we conducted a series of experiments in a large-scale emulation testbed. We found a bottleneck limiting scalability of the proposed hybrid naming system at the mounter.

AOMP (Ad-hoc Overlay Multicast Protocol) is a novel approach for application-layer multicast in ad-hoc networks. We introduce in this paper a new algorithm that exploits a few properties of IP-routing to extract underlying topology information. The basic idea is to match nodes’ path to the source in order to detect near neighbors in the physical topology. Then, in a dynamic and decentralized way, we construct a minimum cost mobility-aware delivery tree, connecting nodes that are close to each other. We design a tree improvement algorithm in order to enhance the global performance of AOMP during data distribution. Our simulations results show that, compared to previously proposed application-layer multicast structures, AOMP yields trees with lower cost and traffic redundancy. In addition, it performs well in terms of packet losses, especially in case of node mobility.

The objective of this research work is to provide the IP Multimedia Subsystem of UMTS with a SIP-based mechanism for managing the interaction, composition and reuse of a limited number of standardized Service Capabilities in order to develop the Next Generation Network (NGN) services. The service invocation mechanism that we propose in this paper is extensible to deal with the interaction and composition management of a wide range of NGN services.

The Live E! project is an open research consortium among industry and academia to explore the platform to share the digital information related with the earth and our living environment. We have getting a lot of low cost sensor nodes with Internet connectivity. The deployment of broadband and ubiquitous networks will enable autonomous and global digital information sharing over the globe. In this paper, we describe the technical and operational overview of Live E! project, while discussing the objective, such as education, disaster protection/reduction/recovery or business cases, and goal of this project activity.

Although multicast communication has been widely deployed and extensively studied for several years, it is still difficult to quantitatively compare the performance of multicast and unicast transmission schemes, especially in limited bandwidth environments. This paper presents a simple stochastic Markov model for multicast communication over infrastructure wireless LANs. The model addresses configurations where a variable number of mobile hosts request access to one or more concurrent communication streams. The steady state transition probabilities are derived and used to obtain numerical results for average bandwidth used for streaming transmissions under typical wireless LAN conditions, under both unicast and multicast transmission. Parameters in the model include number of avialable streams, maximum permitted number of sessions, and arrival rates of mobile hosts. The stochastic model and quantitive results can have application to evaluation of proposed designs for multicast service models and protocols.

This work investigates Network Address Translation – Protocol Translation (NAT-PT) as an IPv4/IPv6 transition technique. NAT-PT is adequate for unicast communication, however, there is no provision for multicast address mapping. This paper presents a solution to improve NAT-PT by adding support for multicast. As a result, NAT-PT can provide multicast address translation, and applications using multicast can interoperate between IPv4 and IPv6. An application level gateway (ALG) for the Session Advertisement Protocol (SAP) is added to perform and announce group address mapping.

Speed-up of networks is faster than that of processors. For high-speed networks, general-purpose computers can no longer play the management role of network streams such as Intrusion Detection System, and hardware approaches are required. This paper introduces two approaches of network processing hardware; a approach and a approach.

IEEE 802.15.3 High-Rate WPAN(Wireless Personal Area Network) which is operated in ISM unlicensed frequency band is easily affected by channel errors. In this paper, we propose a scheduling algorithm which takes channel errors into consideration in scheduling asynchronous data traffic. The proposed scheduling algorithm can allocate CTA(Channel Time Allocation) proportionally in accordance with the requested channel time of each device. It also prevents the waste of channel time by allocating CTA of the devices that are in channel error status to other devices and preserves the fairness among the devices by compensating the channel time to the devices recovering from channel error. Simulation results show that proposed scheduling algorithm is superior to existing SRPT(Shortest Remain Processing Time) and RR(Round Robin) in throughput and fairness aspects.

Using ad hoc networks as alternative means of communication in disaster situations is a salutary solution. However, analysing application performance is mandatory for evaluating such a possibility. In this paper we present the two aspects of our approach to application performance assessment on wireless ad hoc networks. The first aspect refers to real-world tests in which we quantify objectively the relationship between network conditions and application performance. The second aspect is represented by the wireless network (WLAN) emulator that we design to run on StarBED, the large-scale network experiment environment of the Hokuriku Research Centre in Ishikawa, Japan. By combining these two aspects we perform experiments with real applications, while having full control of the network conditions in which the application is tested (when using emulation).