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Thanks to the fact that Belgium is a densely populated country, and also lags behind in the roll-out of Long Term Evolution (LTE) / 4G, it is still possible to visit areas enjoying different Radio Access Technology (RAT) coverages within a limited territory. This paper reports an analysis of the dataset of web requests collected through a field survey mostly performed in south-western Belgium and northern France. This analysis highlights the impact of Radio Access Network (RAN) conditions (signal strength, mobility) and settings (timers) on the canvas Page Load Time (cPLT).

Thanks to the fact that Belgium is a densely populated country, and also lags behind in the roll-out of Long Term Evolution (LTE) / 4G, it is still possible to visit areas enjoying different Radio Access Technology (RAT) coverages within a limited territory. This paper reports an analysis of the dataset of web requests collected through a field survey mostly performed in south-western Belgium and northern France. This analysis focuses on the impact of the spreading of web sites across CDNs.

Average consensus algorithms have attracted increasing interest in the last decade because of their potential for use in high-density wireless sensor networks. This paper analyzes an algorithm that is based on a model of asymmetric broadcasting on a random geometric graph, in which nodes broadcast and listen only intermittently. We show that each node can easily estimate its update weight from the degree of silence in its neighborhood, and, after the weights have been assigned in this way, that the consensus algorithm converges to the true average. Both a synchronous and an asynchronous update model are analyzed.

In this paper we present a stochastic network model for packet-switching networks with no buffering capabilities at the nodes. This model can be directly used in the study of all-optical packet-switching (OPS) and optical burst switching (OBS) networks without fiber delay lines (FDLs). Our model provides for the first time a complete description of the dependencies arising among packets from different sources in the network. Such dependencies originate when packets from different sources share a finite number of channels for their transmission through a network link. We relate our model to well-known loss network models for circuit-switching networks and derive expressions for the packet loss probability. We briefly show how our work can be extended to model parallel hybrid optical networks, and propose some promising future lines of work. Our numerical results suggest that the well-known Erlang fixed-point approximation (EFPA) overestimates the blocking probability when compared to our model predictions. They also show that our model is scalable up to network scenarios with at least 30 links with 160 wavelength channels per link. This makes the proposed model an interesting tool for studying the dependencies arising among packets in a realistically-sized OPS/OBS network without FDLs.

The design of OBS networks that guarantee QoS provisioning for different classes of traffic is a major topic under current research. In this work we formulate a unified framework for studying QoS in OBS networks with a GMPLS-based control plane. We use this framework in order to investigate two problems. First, the configuration of the parameters of an aggregation strategy so that a given Forwarding Equivalency Class observes its corresponding QoS requirements. Second, we address the problem of planning a whole OBS network given a series of QoS constraints for each one of the Forwarding Equivalency Classes in the network. The presented QoS framework constitutes a valuable tool for studying QoS-related issues in OBS networks.

Recently, new services have emerged which utilize the Internet as a delivery mechanism for multimedia content. With the advent of broadband accesses, more users are willing to download large volume content from servers, such as video files of TV shows. While some popular video services (e.g. YouTube.com) or some broadcasting companies (e.g. ABC.com) use streaming data with Flash technology, some media distributors (e.g. iTunes) offer entire TV shows for download. In this study, we investigate the performance of the German site OnlineTVRecorder.com (OTR), which acts as an online video cassette recorder (VCR) where users can program their favorite shows over a web interface and download the recorded files from a server or its mirrors. These files are offered in different file formats and can consist of several hundred megabytes up to 1 GB or more depending on the length of the TV show as well as the encoding format. OTR can, thus, be seen as an example for a server-based content distribution system with large data files.

Wireless sensor networks (WSNs) are useful for gathering information from the environment, either periodically for monitoring purposes or when certain events need to be detected. Since the wireless communication range of each sensor node is limited, data is propagated in a multi-hop manner until it reaches one or more specific sink nodes. However, sensor nodes usually employ a sleep scheduling mechanism for power saving to prolong the operational lifetime of the network and are therefore not always available for forwarding messages received from neighboring nodes. In this paper, we analytically investigate the diffusion behavior of information in a WSN modeled as a two-dimensional spatial branching process. Our analysis permits the derivation of the extinction probability of information being diffused from a source node. Our model permits observing how the activity pattern of each node influences the probability of maintaining time-dependent information in the network.

In this paper we analytically derive the sojourn time of a user accessing an online IPTV recording service. Basically, the system consists of a server (or server farm) and the bandwidth at which a user can download recorded files depends on the number of other concurrently downloading users. In particular, we consider both cases, one in which the user's download speed is limited by his own access bandwidth, whereas in the other case the server is the bottleneck and all downloading users share the server's upload capacity. Our model includes user impatience which depends on the actual download speed. A user may abort his download attempt if a threshold duration is exceeded. The file size distribution is obtained by measurements of offered files at an existing server.

Recent measurement studies [8] have shown that peer-to-peer (P2P) file sharing applications are the major traffic source in the Internet. P2P applications, such as eDonkey, Kazaa, or BitTorrent, form overlay networks on the application layer and offer its peers to download and share their files with other peers in a highly distributed way. As a consequence, peers act simultaneously as both clients and servers. For a comprehensive survey of P2P technology, we refer to [7].