Dario Di Sorte

Autonomic control and personalization of a wireless access network

As ICT services are becoming more ubiquitous and mobile and access technologies grow to be more heterogeneous and complex, we are witnessing the increasing importance of two related needs: (i) users need to be able to configure and personalize their services with minimal effort; (ii) operators desire to engineer and manage their networks easily and efficiently, limiting human agency as far as possible. We propose a possible solution to reach these goals. Our vision, developed in the so-called Simplicity project, is based on a personalization device, which, together with a brokerage framework, offers transparent service configuration and runtime adaptation, according to user preferences and computing/networking context conditions. The capabilities of this framework can be exploited: (i) on the user side, to personalize services, to improve the portability of services over heterogeneous terminals and devices, to adapt services to available networking and terminal technologies; (ii) on the network side, to give operators more powerful tools to define new solutions for distributed, technology-independent, self-organizing, autonomic networking systems. Such systems could be designed so as to be able to react autonomously to changing contexts and environments. In this paper, we first describe the main aspects of the Simplicity solution. We then want to show that our approach is indeed viable. To prove this point, we present an application which exploits the capabilities of the Simplicity system: a mechanism to drive mobile users towards the most appropriate point of access to the network, taking into account both user preferences and network context. We use simulation to evaluate the performance of this procedure in a specific case study, where the aim is to balance the load in an 802.11b access network scenario. The numerical results show the effectiveness of the proposed procedure when compared to a legacy scenario and to another solution from literature. To give ample proof of the feasibility of our solution, we also designed and implemented a real prototype. The prototype enables not only the load to be balanced among different 802.11 access points, but also network and application services to be differentiated as a function of user profiles and network load. The main aspects of this prototype are presented in this paper.

On the Performance of Service Publishing in IEEE 802.11 Multi-Access Environment

In a multi-access/service IEEE 802.11 environment, the problem of providing users with service-related information to support a correct and fast network selection is expected to become a very important issue. We present a quantitative comparison between the legacy scenario, where each user must enter a network point of access to check its service offer, and the enhanced scenario where some service-related information is broadcasted through beacons. Results confirm the effectiveness of the beacon-based approach, in terms of discovery time, server load, and bandwidth consumption

Minimum price inter-domain routing algorithm

We show a minimum price (MP) inter-domain routing algorithm that selects the cheapest paths among a number of independent domains, used for supplying end users with application services. The price of the network service is determined by the so-called service parameters and network parameters. The former represents the negotiable quality of service (QoS) parameters, summarized by the so-called virtual end-to-end delay, and the latter characterizes the intrinsic quality of the network.

A QoS index for IP services to effectively support usage-based charging

The goal of this letter is to present a model to compute a quality-of-service (QoS) index to characterize IP services. Then, we show how such a score may be used in a clear and flexible way for defining advanced usage-based tariff criteria to charge QoS guaranteed network services to address the dynamics of the expected future telecommunications scenario.

Usage-based pricing law to charge IP network services with performance guarantees

In the present day Internet, the provision of different levels of performance guarantees, appropriate for the type of supported applications and the willingness of users to pay, is a pressing need. Since flat-rate fees are probably inadequate to charge differentiated services, the need to provide usage-based tariff models to charge IP guaranteed services, and therefore to develop business interactions, is expected. We define the network service commodity, traded in a future Internet scenario, as the transfer of information units between two points of the network, and we present an approach to measure it as a function of so called virtual delay. In our approach, the virtual delay summarizes the parameters characterizing the performance guarantees of the transfer service. Under these assumptions, we propose a pricing law to charge improved IP services depending on the duration of the connection and on the traffic volume exchanged during the communication. The tariff is a function of the actually used and/or reserved network resources, so as to satisfy the requirements of users and network management, respectively.

Toward an autonomic control of wireless access networks

In this paper, we present a solution to control automatically a wireless access network and we focus on load balancing target. The reference scenario is that of a single administrative domain that offers a heterogeneous wireless access. We propose a monitoring procedure able to track the access network context, i.e., the current state of resources, the amount of service demand, and the wireless access points available to mobile terminals. To this end, we exploit a cooperative brokerage framework, distributed between terminals and network. The access network context is the input of a selection process that aims to distribute suitably mobile users among available access points. The objective is to balance the users demand, thus improving the quality of the service. The numerical analysis shows the effectiveness of the proposed system in an 802.11b access network.

QoS-enabled multicast for delivering live events in a Digital Cinema scenario

Digital Cinema (DC) consists of integration of new advanced digital technologies in the context of the cinema system. As regards the transport of DC content towards theatres, Distributors may select the method that is both economically and technically sound. In this work, which is carried out within the framework of the IST Integrated Project Enhanced Digital CINEma (EDCINE), we deal with the network distribution service provided by a Network Service Provider, which becomes a new actor in the DC business. One of the main criticalities of the system is the very large size of the contents to be transferred towards theatres. From the operators perspective, this criticality translates into the objective of optimising the usage of network resources while complying with quality of service (QoS) constraints. The goal of this paper is to present the system which is able to support the network delivery of DC contents, with a special focus on live event delivery. This service can consume a large amount of network bandwidth, not only because of the volume of transmitted data, but also due to the number of receivers, and thus multicast transmission proves to be very useful. Consequently, a key issue of the overall distribution system is the request-routing algorithm, the goal of which is to optimise the QoS-guaranteed delivery of a number of live streams in the backbone, each one of which is sent towards a set of theatres (QoS multicast routing). We consider the MultiProtocol Label Switching mechanism, which has emerged as an elegant solution to meet traffic engineering and resource reservation requirements in backbone networks, and focus especially on the overall request-routing procedure, the mathematical modelling of the problem, and relevant solving algorithms. Finally, we present the comparative performance evaluation of these algorithms by means of an extensive simulation campaign performed with the OMNeT++ simulation platform.

Network delivery of live events in a Digital Cinema scenario

The goal of this paper is to present a system able to support the network delivery of live events in an expected, future Digital Cinema scenario. This service can consume a large amount of network bandwidth, due to the large volume of transmitted data and to the number of receivers, thus multicast transmission proves to be very useful. Consequently, a key issue of the system is the request routing algorithm, the goal of which is to optimise the QoS-guaranteed delivery of live streams in the backbone, each one towards a set of theatres. We consider the Multi Protocol Label Switching, which has emerged as an elegant solution to meet traffic engineering and resource reservation requirements, and focus on the overall request routing procedure, the mathematical modelling of the problem, and relevant solving algorithms. We present the comparative performance evaluation of these algorithms by means of an extensive simulation campaign performed with the OMNET++ simulation platform.

Performance evaluation of the push-mode-multicast based candidate access router discovery (PMM CARD)

In order to provide nomadic users with QoS-enabled services, advanced mobility management will prove to be of fundamental importance in the future Internet. It has been widely recognized that the basic Mobile IPv4/v6 protocols could perform poorly, especially with QoS-demanding applications. One of the main steps to achieve seamless handover is the quick discovery of the surrounding wireless coverage at each access router (AR), i.e., the discovery of IP addresses and service capabilities (SCs) of candidate access routers (CARs) to hand over to. The rapid knowledge of IP addresses allows mobile nodes (MNs) to speed-up the handover process, whereas information about SCs are important for the selection of the most appropriate wireless access (target access router, TAR) among the set of CARs, according to a given criterion (e.g., load balancing).In this paper, we first describe the candidate access router discovery (CARD) solutions proposed within the framework of the IETF SEAMOBY WG, which has inspired research in this field. Then, we propose the distributed push-mode-multicast based CARD (PMM CARD) approach and compare it with the IETF proposals. The novelty of our solution is the use of push-mode multicast transmissions, which enables an efficient distribution of CARD information within the network, together with a significant reduction in latency due to explicit queries to a remote entity.Then, we develop a theoretical model to compute the signaling burden associated with different CARD solutions. Our analysis shows that, even though the amount of signaling required to implement all CARD approaches is generally low, our approach gives a certain improvement over the IETF proposals in terms of the average signaling load. In addition, the results obtained by a simulation campaign show the effectiveness of the PMM CARD solution in terms of the time needed by ARs to discover the surrounding wireless coverage.

Target access router selection in advanced mobility scenarios

To provide nomadic users with QoS-enabled services, advanced mobility management will prove to be of fundamental importance in the future Internet. Mobile IP is the reference protocol supporting mobility at IP level. However, it has been widely recognised that it could perform poorly, especially with QoS demanding applications. In order to improve Mobile IP performance, the discovery and selection of the target access router to hand over to will play a crucial role. In this paper, we present a novel approach for Candidate Access Router Discovery and Target Access Router selection. The process is fully distributed, multicast-based, and allows timely intra and inter-access router handover, which can be either intra or inter-technology. The effectiveness of the solution to drive mobile terminal handovers has been tested by simulations.