Franco Davoli

The potential impact of green technologies in next-generation wireline networks: Is there room for energy saving optimization?

Recently, network operators around the world reported statistics of network energy requirements and the related carbon footprint, showing an alarming and growing trend. Such high energy consumption can be mainly ascribed to networking equipment designed to work at maximum capacity with high and almost constant dissipation, independent of the traffic load. However, recent developments of green network technologies suggest the chance to build future devices capable of adapting their performance and energy absorption to meet actual workload and operational requirements. In such a scenario, this contribution aims at evaluating the potential impact on next-generation wireline networks of green technologies in economic and environmental terms. We based our impact analysis on the real network energy-efficiency targets of an ongoing European project, and applied them to the expected deployment of Telecom Italia infrastructure by 2015-2020.

Cutting the energy bills of Internet Service Providers and telecoms through power management

The energy consumption of the Information and Communication Technology (ICT) sector has been increasing recently; this sector is estimated to account for 2% of the total energy consumption. An even more aggressively increasing trend is the volume of Internet traffic and the number of connected devices. Thus, reducing the energy needs of the Internet is recognised as one of the main challenges that the ICT sector will have to face in the near future to reduce its overall energy footprint. Introducing energy-efficient techniques, both at the device level and the network level, is required.The main goal of this work is to quantitatively evaluate the potential energy savings from applying energy-efficient techniques, while examining the trade-off between network performance and the achieved energy savings.We introduce a categorisation of the energy-aware design space, focusing on the existing techniques in the device data plane, and contribute an analytical framework to represent the impact of energy-aware technologies and solutions for network devices. Our energy profile model represents the diverse energy-aware states of the network devices and is applied over two reference scenarios, one of a large-scale Telco (Telecom Italia) and one of a medium size Internet Service Provider (GRNET), to evaluate the impact of each energy-aware technology and the energy savings potential at the Home, Access, Metro/Transport and Core parts of each network.The results show the estimates of energy savings exceed 60% in many cases, while maintaining the same quality of service as in the energy-agnostic case.

Static and dynamic resource allocation in a multiservice satellite network with fading

A control architecture for resource allocation in satellite networks is proposed, along with the specification of performance indexes and control strategies. The latter, besides being based on information on traffic statistics and network status, rely upon some knowledge of the fading conditions over the satellite network channels. The resource allocation problem consists of the assignment, by a master station, of a total available bandwidth among traffic earth stations in the presence of different traffic types. Traffic stations are assumed to measure continuously their signal fade level, but this information may either be used only locally or also communicated to the master station. According to the information made available on-line to the master station on the level of the fading attenuation of the traffic stations, the assignment can be made static, based on the a priori knowledge of long-term fading statistics, or dynamic, based on the updated measurements. In any case, the decisions can be adapted to slowly time-varying traffic characteristics. At each earth station, two basic traffic types are assumed to be present, namely guaranteed bandwidth, real time, synchronous data (stream traffic) and best-effort traffic (datagram traffic). Numerical results are provided for a specific architecture in the dynamic case, in a real environment, based on the Italsat satellite national coverage payload characteristics. Copyright

A survey of architectures and scenarios in satellite‐based wireless sensor networks: system design aspects

This paper is not a survey related to generic wireless sensor networks (WSNs), which have been largely treated in a number of survey papers addressing more focused issues; rather, it specifically addresses architectural aspects related to WSNs in some way connected with a satellite link, a topic that presents challenging interworking aspects. The main objective is to provide an overview of the potential role of a satellite segment in future WSNs. In this perspective, requirements of the most meaningful WSN applications have been drawn and matched to characteristics of various satellite/space systems in order to identify suitable integrated configurations. Copyright

Decentralized optimal control of Markov chains with a common past information set

Decentralized dynamic (closed-loop) optimal control strategies are sought for a class of finite state Markov decision processes, characterized by the sharing of a common past after k steps of delay. The control is considered over a finite time horizon, and it is shown that a nonclassical dynamic programming procedure can be applied, based on the existence of a sufficient statistic of constant dimension. Finally, the infinite horizon case is briefly discussed, in view of an extention of existing results on the minimization of average expected cost for the centralized and decentralized control of Markov chains.

Bandwidth allocation and admission control in ATM networks with service separation

The statistical multiplexing operation within an ATM network node is considered, with respect to different methods for the allocation of the bandwidth of an outgoing link. Service separation is assumed by dividing the overall traffic flows into classes, homogeneous in terms of performance requirements and statistical characteristics. Which share the bandwidth of a link according to some specified policy. This context allows one to clearly define, by means of several existing approaches, a region in the space of connections of the different classes (call space) where quality of service (QoS) requirements at the cell level are satisfied. Within this region, some criteria for allocating the bandwidth of the link to the service classes are proposed, and the resulting allocation and call admission control (CAC) strategies are defined and analyzed. The goal of these operations is to achieve some desired QoS at the call level. Several numerical simulation results are presented, in order to highlight the different performance characteristics of the various methods.

Energy-aware performance optimization for next-generation green network equipment

Besides a more widespread sensitivity to ecological issues, the interest in energy-efficient network technologies springs from heavy and critical economical needs, since both energy cost and network electrical requirements show a continuous growth, with an alarming trend over the past years. In this contribution, we explore and try to evaluate the feasibility and the impact of power management policies, able to well suit a heterogeneous set of highly modular architectures, generally used for developing todays network equipment. The proposed policies aim at optimizing the power consumption of each device component with respect to its expected network performance. Finally, in order to provide an experimental evaluation of the proposed ideas, we applied such power management policies to a new generation SW router platform, and we evaluated it with real traffic traces.

An integrated dynamic resource allocation scheme for ATM networks

Dynamic bandwidth allocation among traffic classes with different performance requirements sharing an asynchronous transfer mode (ATM) link is considered as an integrated control problem with a multilevel structure. At the lower level, call admission control rules are applied that maintain a certain grade of service, in terms of cell loss probability and cell delay, given the buffer space and bandwidth assigned to each class; unlike those used in previous works, these rules are derived on the basis of homogeneous (based on similar quantities) measures of the performance requirements. At the higher level, bandwidth shares are periodically recomputed online by an allocation controller, whose goals reflect overall cell loss and refused traffic, as well as overall average delay. These goals are expressed by an optimization problem that is solved by numerical techniques. The whole control system should provide a dynamic feedback controller, capable of reacting in real time to changes in the traffic patterns. Simulation results are presented and are discussed in regard to the efficiency of the admission controllers, the performance of the overall scheme, and the capability of reacting to sudden changes in the load of some traffic class.<<ETX>>

Road traffic estimation from location tracking data in the mobile cellular network

Mobile communications are widespread in a large part of industrialized countries and cellular networks, by which mobile radio-communications are supported, can give directly or potentially a huge amount of frequently updated information on the position of their users. This information can be used to estimate on-line the traffic conditions of important roads and highways, by exploiting the presence of mobile phones on-board a good deal of vehicles. This paper analyzed this possibility and proposes a mechanism, which gives the capability to estimate traffic parameters in the cells along a road with a partial presence of active cellular phones in the vehicles. The proposal has been tested by using an integrated vehicle and communication traffic simulator and different situations have been verified. The results are presented in the paper and they show a good level of accuracy and a satisfactory behavior of the proposed technique.

Green Networking With Packet Processing Engines: Modeling and Optimization

With the aim of controlling power consumption in metro/transport and core networks, we consider energy-aware devices able to reduce their energy requirements by adapting their performance. In particular, we focus on state-of-the-art packet processing engines, which generally represent the most energy-consuming components of network devices, and which are often composed of a number of parallel pipelines to “divide and conquer” the incoming traffic load. Our goal is to control both the power configuration of pipelines and the way to distribute traffic flows among them. We propose an analytical model to accurately represent the impact of green network technologies (i.e., low power idle and adaptive rate) on network- and energy-aware performance indexes. The model has been validated with experimental results, performed by using energy-aware software routers loaded by real-world traffic traces. The achieved results demonstrate how the proposed model can effectively represent energy- and network-aware performance indexes. On this basis, we propose a constrained optimization policy, which seeks the best tradeoff between power consumption and packet latency times. The procedure aims at dynamically adapting the energy-aware device configuration to minimize energy consumption while coping with incoming traffic volumes and meeting network performance constraints. In order to deeply understand the impact of such policy, a number of tests have been performed by using experimental data from software router architectures and real-world traffic traces.