Andrea Ghittino

CSP - Innovazione nelle ICT, Torino, Piedmont, Italy

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Publications (14)4.14 Total impact

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    ABSTRACT: Evaluating the available bandwidth in a wireless LAN is a challenging task because the throughput depends on several factors such as RSSI (Received Signal Strength Indication), interferers and packet size. Moreover, in a real scenario it is not sufficient to evaluate periodically the throughput of the network, but a continuous monitoring is required in order to detect as soon as possible network problems and saturation phenomena. When wireless LAN is used to transmit high priority traffic (e.g. voice and video flows), an admission control procedure based on residual bandwidth evaluation is necessary to verify that required resources are available. We propose a mechanism based on active traffic probing with low priority packets: this approach enables us to simulate a real data flow and, on the other hand, does not interfere with existing flows. Our method relies on IEEE 802.11e (WMM — Wireless MultiMedia) support and does not require any customization of network devices. Through this approach the residual bandwidth can be continuously monitored. This measurement accounts for both the characteristics of active flows (different packet sizes and rates) and external interferences, offering accurate bandwidth estimation.
    9th Annual Conference on Wireless On-demand Network Systems and Services, WONS 2012, Courmayeur, Italy, January 9-11, 2012; 01/2012
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    ABSTRACT: Vehicular networks are expected to support both safety and non-safety applications, through Dedicated Short Range Communications (DSRC) in 5-GHz bands. These channels, however, are of limited capacity and recent studies have high-lighted their scarcity, in comparison to the broad range of services that are envisioned in vehicular networks. We therefore explore the benefit of using UHF bands for the transmission of control messages, so as to acquire more capacity. Specifically, we focus on content downloading, and design a protocol that leverages the UHF band for control messages and the high-throughput, 5-GHz bands for data delivery. We develop a testbed to quantify the performance of our approach, and show a 3x throughput gain in content delivery with respect to the case where only 5-GHz bands are used.
    01/2012;
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    ABSTRACT: The provision of UDP-based multimedia streams to vehicular users through a roadside wireless mesh network requires a fast-switching, robust protocol architecture. We consider vehicles (e.g., cars, buses or streetcars) that connect to different roadside mesh nodes as they move in an urban environment, and study the joint problem of traffic delivery and connectivity management in such scenario. We identify BATMAN as a candidate layer-2 implementation of a routing protocol for vehicular networks, and we use simulation to compare its performance with other routing protocols for wireless ad hoc and mesh networks. Since BATMAN shows some inconsistencies in its behavior, we propose an improved version of the protocol, named smart-window BATMAN (sw-BATMAN). Then, we design two testbeds that include both roadside and vehicular mesh nodes. There, we implement the selected routing solution along with a handover mechanism that, by leveraging a channel selection scheme, allows vehicles to connect to the different roadside mesh nodes in a seamless manner. The performance assessment on our testbeds shows the efficiency of the proposed solution and highlights that our traffic routing and connectivity management are suitable for sustaining the handover of UDP streams in a vehicular environment, in a seamless manner.
    IEEE Journal on Selected Areas in Communications 04/2011; · 4.14 Impact Factor
  • IEEE Journal on Selected Areas in Communications. 01/2011; 29:501-514.
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    ABSTRACT: The cognitive paradigm allows exploiting spectral resources, generally allocated for licensed systems, as 'secondary' users. When this paradigm is applied to television broadcasting, the unused frequencies are called 'white spaces'. In this work we reports some experimental results of a 802.11- based system that uses a 'white space' for providing a bi- directional service in order to overcome the digital divide problem in an alpine valley.
    01/2011;
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    ABSTRACT: A time-domain recognition of different wireless technologies may be obtained using energy detection. In this work, an energy detector was implemented using the Universal Software Radio Peripheral SDR platform. The energy detector output allows the formation of a packet presence/absence diagram. Experimental results indicate that the observation of Bluetooth packet exchange patterns reveals technology-specific MAC layer procedures, leading to the conclusion that technology recognition can be obtained on the basis of time domain technology-specific features.
    01/2010;
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    ABSTRACT: We address the joint problem of traffic routing and mobility support in wireless mesh networks that are built by many fixed nodes and few mobile nodes. We focus on a vehicular setting, where buses or streetcars connect to different fixed mesh nodes as they move in a urban environment. First, through simulation we identify the best candidate for routing traffic in such a scenario and we find that our improved version of the BATMAN protocol, named smart window BATMAN, outperforms other reactive and proactive approaches. Then, we develop a testbed which includes both roadside mesh nodes and vehicular mesh nodes. There, we implement the selected routing solution, along with a handover scheme that allows vehicles to connect to the different mesh nodes in a seamless manner. Our testbed and performance assessment show that mobility can be efficiently supported in mesh networks, and that our modified version of the BATMAN protocol is a good candidate for sustaining the handover of UDP streams in a seamless manner.
    01/2009;
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    ABSTRACT: This paper presents a route management protocol for multi-homed infrastructured WMNs aiming to preserve active sessions of mobile nodes. Every mesh access point (MAP) has at least one MAP interface configured as a traditional AP and another one dedicated to the WMN backhaul. The clients are mesh-unaware to avoid installing special software on them. We propose a mechanism based on dynamic IP-within-IP tunnels to pin routes and guarantee (in time) the communication between clients and Internet gateways. MAPs select the best gateway for each new connection and maintain tunnels for the connection duration to allow the seamless communication during the whole flow life. When a client changes MAP, the old and the new one exchange tunnel information so that the new MAP reestablishes tunnels with the correct gateway ensuring smooth packet delivery. The protocol is an extension to OLSRD, and has been implemented in Linux-based MAPs. Evaluation is carried out both emulating complex scenarios with user mode Linux (UML) and in a real WMN testbed.
    Wireless on Demand Network Systems and Services, 2008. WONS 2008. Fifth Annual Conference on; 02/2008
  • S. Annese, A. Ghittino
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    ABSTRACT: Mobile ad hoc networking allows the development of several infrastructure free applications. One of the arguments we focused on is the possibility of deploying a set of services in areas lacking of low-cost and wide band connectivity to Internet, as rural or mountain communities. The main idea is that it is possible to transfer data by mobile vehicles such as bus, letter carriers and other similar means, by equipping them with an ad hoc kit able to discover clients capable to receive news, e-mail or, generally, to act as a server for other kind of services. In this context we used AODV protocol to interconnect the hosts involved in the test-bed and SLP to develop some applications to offer e-mail and news pushing services over discontinuous connectivity.
    Testbeds and Research Infrastructures for the Development of Networks and Communities, 2005. Tridentcom 2005. First International Conference on; 03/2005
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    ABSTRACT: In this paper, we address the problem of Quality of Service (QoS) support in the current generation of IEEE 802.11 WLANs. We propose and investigate a novel approach, called Host Qs, aiming at LLC-layer differentiation of traffic depending on its QoS requirements. The approach is based on creating one LLC queue for each traffic category and on scheduling queue service according to the concept of "virtual contention" among different priorities, within the wireless station. The frame at the head of the LLC queue winning the contention is delivered to the MAC layer and handled according to the access functions of the MAC layer. We have implemented the proposed mechanism on an Open-Source Access Point using a Prism2 chipset on a Linux box. Several experiments have been performed to show the effectiveness of the approach in presence of multimedia and data traffic.
    System Sciences, 2005. HICSS '05. Proceedings of the 38th Annual Hawaii International Conference on; 02/2005
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    ABSTRACT: In this paper we described UbiquiTO, an agent-based system that acts as an expert tourist guide for mobile users, providing different information according to the device, the user and the context. The system uses feedbacks coming from localization to acquire the knowledge required to provide location-based services and to update the user model.
    Proceedings of the 7th Conference on Human-Computer Interaction with Mobile Devices and Services, Mobile HCI 2005, 2005, Salzburg, Austria, September 19-22, 2005; 01/2005
  • ANDREA TOMATIS, DOVIS F, ANDREA GHITTINO
    ATTI DELL'ISTITUTO ITALIANO DI NAVIGAZIONE.
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    Conference Paper: Wireless Campus Project