In this work, we present an innovative approach for effective cross-network information dissemination, with applications to vehicular ad hoc networks (VANETs). The proposed approach, denoted as "Cross-Network Effective Traffic Alert Dissemination" (X-NETAD), leverages on the spontaneous formation of local WiFi (IEEE 802.11b) VANETs, with direct connections between neighboring vehicles, in order to disseminate, very quickly and inexpensively, traffic alerts received from the cellular network. The proposed communication architecture has been implemented on Android smartphones. The obtained experimental results show that an effective cross-network information dissemination service can entirely rely on smartphone-based communications. This paves the way to future Internet architectures, where vehicles will play a key role as information destinations and sources.
In recent years, Vehicular Ad-hoc NETworks (VANETs) have experienced an intense development phase, driven by academia, industry, and public authorities. On the basis of the obtained results, it is reasonable to expect that VANETs will finally hit the market in the near future. In order to reach commercial success, VANETs must effectively operate during the first years of deployment, when the market penetration rate will be unavoidably low, and, consequently, only a small number of suitably equipped vehicles (VANET-enabled) will be present on the roads. Among the possible strategies to face the initial sparse VANET scenarios, the deployment of an auxiliary network constituted by fixed Road Side Units (RSUs), either Dissemination Points (DPs) or relays, is certainly one of the most promising. In order to maximize the benefits offered by this support infrastructure, the placement of RSUs needs to be carefully studied. In this chapter, the authors analyze, by means of numerical simulations, the performance of an application that leverages on a finite number of DPs for disseminating information to the transiting vehicles. The positions of the DPs are determined through a recently proposed family of optimal placement algorithms, on the basis of proper vehicular mobility traces. The analysis is carried out considering two realistic urban scenarios. In both cases, the performance improvement brought by the use of multi-hop broadcast protocols, with respect to classical single-hop communications with DPs, is investigated.
Abstract.In this paper, we analyze the performance of vertical handover (VHO) algorithms for seamless mobility between WiFi and UMTS networks. We focus on a no-coupling scenario, characterized by the lack of any form of cooperation between the involved players (users and network operators). In this context, we first propose a low-complexity Received Signal Strength Indicator (RSSI)-based algorithm, and then an improved hybrid RSSI/goodput version. We present experimental results based on the implementation of a real testbed with commercial WiFi (Guglielmo) and UMTS (Telecom Italia) deployed networks. Despite the relatively long handover times experienced in our testbed, the proposed RSSI-based VHO algorithm guarantees an effective goodput increase at the MTs. Moreover, this algorithm mitigates the ping-pong phenomenon.
In recent years, Vehicular Ad-hoc NETworks (VANETs) have experienced an intense development, driven by academia, industry, and public authorities. On the basis of this, it is reasonable to expect that VANETs will finally hit the market in the near future. In order to reach commercial success, VANETs must effectively operate also during the first years of deployment, when the market penetration rate will be unavoidably low and, consequently, only a small number of suitably equipped vehicles (VANET-enabled) will be present in the roads. Among the possible strategies to face the initial sparse VANET scenarios, the deployment of an auxiliary network constituted by fixed Road Side Units (RSUs), either Dissemination Points (DPs) or relays, is certainly a promising one. In order to maximize the benefits offered by this support infrastructure, the placement of RSUs needs to be carefully studied. In this work, we analyze, by means of numerical simulations, the performance of an application that leverages on a finite number of DPs for disseminating information to the transiting vehicles. The positions of the DPs are determined through a recently proposed family of optimal placement algorithms, on the basis of properly generated (through simulations) vehicular mobility traces. The analysis is carried out considering two realistic urban scenarios. In both cases, the performance improvement brought by the use of multi-hop broadcast protocols, with respect to classical singlehop communications with DPs, is investigated.
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