477 research outputs found
Traditional IP Measurements: What Changes in a Today Multimedia IP Network
No full textIn this paper we present measurement results collected from real traces on the network of FastWeb, an Italian ISP which is the main broadband telecommunication company in Italy. The network relies on a fully IP architecture and delivers to the user data, VoIP and IPTV services over a single broadband connection. The aims of this work are the evaluation of traditional measurement indexes in a novel network environment with a mixture of traffic generated by various services and the identification of possible changes of the traffic properties due to this traffic mixture. Our measurement campaign, based on passive techniques, provides traffic characterization at both the packet and the connection/flow levels and focuses on time evolution, distributions, long range dependence and periodicity properties. We discover that the main characteristics of data traffic are kept unmodified, showing LRD properties both at the packet and flow levels. VoIP and IPTV traffic instead presents periodicities of the packet arrival process, due to periodicity of the sources. Considering the VoIP flow arrival process, the traditional Markovian assumption still holds tru
Impact of Correlated Mobility on Delay-Throughput Performance in Mobile Ad-Hoc Networks
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Peer-assisted VoD Systems: An Efficient Modeling Framework
Full text linkWe analyze a peer-assisted Video-on-Demand (VoD) system in which users contribute their upload bandwidth to the redistribution of a video that they are downloading or that they have cached locally. Our target is to characterize the additional bandwidth that servers must supply to immediately satisfy all requests to watch a given video. We develop an approximate fluid model to compute the required server bandwidth in the sequential delivery case, as well as in controlled nonsequential swarms. Our approach is able to capture several stochastic effects related to peer churn, upload bandwidth heterogeneity, and nonstationary traffic conditions, which have not been documented or analyzed before. Finally, we provide important hints for the design of efficient peer-assisted VoD systems under server capacity constraints
Multiple daily base station switch-offs in cellular networks
Full text linkIn this paper we study base station sleep modes, which are today considered a viable approach to improve the energy efficiency of cellular access networks, by reducing power consumption in periods of low traffic. When some base stations are switched off, radio coverage and service provisioning are taken care of by the base stations that remain active, so as to guarantee that service is available over the whole area at all times. This is a realistic assumption in the case of the dense base station layouts of urban areas, which consume most of the network energy. We develop simple analytical models that allow optimal base station switch-off times to be identified as a function of the daily traffic pattern, in the cases in which either just one switch- off per day is possible (bringing the network from a high- power, fully-operational configuration, to a low-power reduced configuration), or several switch-offs per day are permitted (progressively reducing the number of active base stations and the network power). We first assume that any fraction of base stations can be switched off, then we consider a realistic case. We quantify the percentage of energy which can be saved with base station sleep modes, proving that it can be close to 50% of the total network energy consumptio
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