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Publications (27)
We 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 a...
We compare the performance of three base station management schemes on three different network topologies. In addition, we explore the effect of offloading traffic to heterogeneous femtocell layer upon energy savings taking into account the increase of base station switch-off time intervals. Fairness between mobile operator and femtocell owners is...
In this paper we study base station sleep modes that, by reducing power consumption in periods of low traffic, improve the energy efficiency of cellular access networks. We assume that when some base stations enter sleep mode, radio coverage and service provisioning are provided by the base stations that remain active, so as to guarantee that servi...
We consider a communication system in which a given digital content has to be delivered sequentially at constant rate to a set of users who asynchronously request it according to a Poisson process. Users can retrieve data: 1) from one or more sources that statically store the entire content; and 2) from users who have previously requested the conte...
Nowadays two main approaches are being pursued to reduce energy consumption of networks: the use of sleep modes in which devices enter a low-power state during inactivity periods, and the adoption of energy proportional mechanisms where the device architecture is designed to make energy consumption proportional to the actual load. Common to all the...
We propose an analytical framework to tightly characterize the scaling laws for the additional bandwidth that servers must supply to guarantee perfect service in peer-assisted Video-on-Demand systems, taking into account essential aspects such as peer churn, bandwidth heterogeneity, and Zipf-like video popularity. Our results reveal that the catalo...
In 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 acti...
We analyze a peer-assisted Video-on-Demand 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 appr...
We consider a peer-assisted Video-on-demand system, in which video distribution is supported both by peers caching the whole video and by peers concurrently downloading it. We propose a stochastic fluid framework that allows to characterize the additional bandwidth requested from the servers to satisfy all users watching a given video. We obtain an...
We study base stations energy-efficient management algorithms in a cellular access network taking into account different planning strategies. To provide energy savings, sleep modes are adopted at the Base Stations (BSs). We propose two switch-off strategies that are based either on the cell load or the BS coverage overlap. Our results show that ene...
We extend the analysis of the scaling laws of wireless ad hoc networks to the case of correlated nodes movements, which are commonly found in real mobility processes. We consider a simple version of the Reference Point Group Mobility model, in which nodes belonging to the same group are constrained to lie in a disc area, whose center moves uniforml...
In this article, we consider the adoption of sleep modes for the base stations of a cellular access network, focusing on the design of base station sleep and wake-up transients.. We discuss the main issues arising with this approach, and we focus on the design of base station sleep and wake-up transients, also known as cell wilting and blossoming....
The introduction of sleep modes in the operations of base stations is today considered one of the most promising approaches to reduce the energy consumption of cellular access networks. Several papers have considered this option, assuming that the switch-on and switch-off transients are of negligible duration. In this paper we study the switch-off...
Nowadays two main approaches are being pursued to reduce energy consumption of network devices: the use of sleep modes in which devices can be put in low-power state, and the adoption of energy proportional approaches where the device architecture is designed to make energy consumption proportional to the actual load. In this paper, we formulate a...
Energy optimization is a significant component of Wireless Sensor Network (WSN) design. In this paper we consider transmission energy optimization in WSNs where messages are collected by a mobile receiver (collector). The collector is responsible for gathering data messages by choosing the optimal path that minimizes the total transmit energy at th...
We extend the analysis of the scaling laws of wireless ad hoc networks to the case of correlated nodes movements, which are commonly found in real mobility processes. We consider a simple version of the Reference Point Group Mobility model, in which nodes belonging to the same group are constrained to lie in a disc area, whose center moves uniforml...
Early P2P-TV systems have already attracted millions of users, and many new commercial solutions are entering this market. Little information is however available about how these systems work, due to their closed and proprietary design. In this paper, we present large scale experiments to compare three of the most successful P2P-TV systems, namely...
The power consumption of the Internet is becoming more and more a key issue, and several projects are studying how to reduce its energy consumption. In this paper, we provide a first evaluation of the amount of redundant resources (nodes and links) that can be powered off from a network topology to reduce power consumption. We first formulate a the...
Energy efficient networks are becoming a hot research topic, and the networking community is increasingly devoting its attention to the identification of approaches to save energy in the networks of today. However, the networks of tomorrow will require built-in energy efficiency capabilities, so that new design techniques based on network models th...
Motivated by the amount of short-lived TCP traffic due to interactive applications like Web browsing, we propose two schemes to reduce the download time of TCP flows. Both schemes explicitly try to overcome the long delay suffered when TCP has to recover from the loss of the last data segment in a flow, loss for which fast retransmit cannot be trig...
The increasing concern about the energy consumption of telecommunication networks is driving operators to manage their equipments so as to optimize energy utilization without sacrificing the user experience. In this paper, we focus on UMTS access networks, since access devices are the main energy consumers in UMTS networks. We propose a novel appro...
In 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 provisi...
Early P2P-TV systems have already attracted millions of users, and many new commercial solutions are entering this market. Little information is however available about how these systems work. In this paper we present large scale sets of experiments to compare three of the most successful P2P-TV systems, namely PPLive, SopCast and TVAnts. Our goal...
The sensitiveness toward energy consumption problems is driv- ing Telecommunications operators to optimize network equipment utilization. Since cellular systems are often dimensioned for peak hour traffic, during low traffic periods, such as night, many devices are underutilized but still, by being active, consume power. In this paper, we show that...
In 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 evalua...
In this paper, we consider two popular peer-to-peer TV (P2P-TV) systems: PPLive, one of the today most widely used P2P-TV systems, and Joost, a promising new generation application of which no previous measurement study has been considered. Besides the traditional measurements like the amount of generated traffic for signaling and data transmission...
Early P2P-TV systems have already attracted a millions of users, and many new commercial solutions are entering this market. Little information is however available about how these systems work. Therefore, experi-mental studies are required to characterize the traffic generated by P2P-TV applications, as well as to infer some properties of the adop...