Sandra Céspedes

IP mobility management for vehicular communication networks: challenges and solutions

Vehicular communication networks have emerged as a promising platform for the deployment of safety and infotainment applications. The stack of protocols for vehicular networks will potentially include Network Mobility Basic Support (NEMO BS) to enable IP mobility for infotainment and Internet-based applications. However, the protocol has performance limitations in highly dynamic scenarios, and several route optimization mechanisms have been proposed to overcome these limitations. This article addresses the problem of IP mobility and its specific requirements in vehicular scenarios. A qualitative comparison among the existent IP mobility solutions that optimize NEMO BS in vehicular networks is provided. Their improvements with respect to the current standard, their weaknesses, and their fulfillment of the specific requirements are also identified. In addition, the article describes some of the open research challenges related to IP mobility in vehicular scenarios.

VIP-WAVE: On the Feasibility of IP Communications in 802.11p Vehicular Networks

Vehicular communication networks, such as the 802.11p and Wireless Access in Vehicular Environments (WAVE) technologies, are becoming a fundamental platform for providing real-time access to safety and entertainment information. In particular, infotainment applications and, consequently, IP-based communications, are key to leverage market penetration and deployment costs of the 802.11p/WAVE network. However, the operation and performance of IP in 802.11p/WAVE are still unclear as the WAVE standard guidelines for being IP compliant are rather minimal. This paper studies the 802.11p/WAVE standard and its limitations for the support of infrastructure-based IP applications, and proposes the Vehicular IP in WAVE (VIP-WAVE) framework. VIP-WAVE defines the IP configuration for extended and non-extended IP services, and a mobility management scheme supported by Proxy Mobile IPv6 over WAVE. It also exploits multi-hop communications to improve the network performance along roads with different levels of infrastructure presence. Furthermore, an analytical model considering mobility, handoff delays, collisions, and channel conditions is developed for evaluating the performance of IP communications in WAVE. Extensive simulations are performed to demonstrate the accuracy of our analytical model and the effectiveness of VIP-WAVE in making feasible the deployment of IP applications in the vehicular network.

iCAR: Intersection-based connectivity aware routing in vehicular ad hoc networks

In this paper, we propose an intersection-based connectivity-aware routing protocol (iCAR) for vehicular ad hoc networks (VANETs) to enable infotainment and interactive applications, as well as multi-hop Internet access in urban environments. iCAR is a novel protocol that takes into consideration real-time vehicular traffic information and the experienced packet delivery delay per road, in order to improve the routing performance by dynamically selecting roads with a guaranteed connectivity and a reduced delivery delay. This is achieved by deploying a microscopic view of vehicles location to proactively estimate roads connectivity and the minimum link lifetime per road. Detailed analysis and simulation-based evaluations show that iCAR significantly improves the network performance in terms of packet delivery ratio and end-to-end delay with a negligible cost of communication overhead.

A Seamless Quality-Driven Multi-Hop Data Delivery Scheme for Video Streaming in Urban VANET Scenarios

The inherent characteristics of vehicular networks, such as dynamic topology and high mobility, pose significant challenges for the deployment of delay-sensitive applications, e.g., video streaming, in urban Vehicular Ad-hoc Networks (VANET). In this paper, we propose an integrated network-layer scheme for seamless delivery of video packets in VANET. First, we propose a new quality-driven routing scheme for delivering video streams from a fixed network to a destination vehicle via multihop communications. The routing scheme aims to optimize the visual quality of the transmitted video frames by minimizing the distortion, the start-up delay, and the frequency of the streaming freezes. We further propose an efficient network mobility management scheme, which introduces a novel adaptation of Proxy Mobile IPv6 (PMIPv6) for multi-hop VANET scenarios, and incorporates a handover prediction mechanism. Numerical results are given to demonstrate that our integrated scheme can achieve a better performance for the video quality metrics, the handover delay and the signalling cost.

Comparison of data forwarding mechanisms for AMI networks

Advance Metering Infrastructure (AMI) networks are often deployed under challenging and unreliable conditions. One of the issues for the transmission of data packet in these unreliable networks is the routing of packets, because routing paths may behave differently from the time when the route is discovered to the time when a data packet is forwarded. In addition, control packets may get lost and give routers an inconsistent view of the network. While previous research has focused on designing the control-plane of routing protocols to deal with the AMI network conditions, there is comparatively a smaller amount of research on the advantages of new data forwarding mechanisms designed for unreliable networks. This paper introduces a set of data forwarding mechanisms inspired by distributed depth-first search algorithms, and designed for the challenging conditions of large-scale unreliable networks envisioned by smart-grid deployments. These forwarding mechanisms use data packets to detect loops, update routing tables, and perform rerouting of data packets through alternate paths, recovering thus, packets that would have been normally dropped due to failures at the link layer. We perform simulations based on a real field AMI deployment to evaluate the performance of the proposed mechanisms. We also provide the evaluation results for the data forwarding mechanisms that have been implemented in a real AMI network.

Routing in Neighborhood Area Networks: A survey in the context of AMI communications

Smart Grid is the modern infrastructure of the electric grid, which has the objective to improve efficiency, reliability, and security. This is achieved through the control automation of the transmission and distribution lines, the enhancement of metering technologies, the implementation of renewable energy sources, and new energy management techniques. The growing demand of energy, changes in global weather, problems in the storing and distribution, and the need to implement more efficient metering systems are some of the factors that influence the transit toward a more complex and robust electric grid. A fundamental component of the Smart Grid is an Advanced Metering Infrastructure (AMI), which provides a two-way communication flow between utilities and meters at the customer side. In this survey, we outline the main features of this new infrastructure, including a classification of communication technologies and routing protocols employed in the Neighborhood Area Network domain. We introduce a set of metrics for the AMI network (such as scalability, interoperability, latency, security, and quality of service), and present a full analysis and comparison of AMI-related routing protocols and technologies. Open issues related to wireless and wired technologies, as well as routing for the neighborhood area network domain are also provided.

A Multihop-Authenticated Proxy Mobile IP Scheme for Asymmetric VANETs

Vehicular communications networks are envisioned for the access to drive-thru Internet and IP-based infotainment applications. These services are supported by roadside access routers (ARs) that connect vehicular ad hoc networks (VANETs) to external IP networks. However, VANETs suffer from asymmetric links due to variable transmission ranges caused by mobility, obstacles, and dissimilar transmission power, which make it difficult to maintain the bidirectional connections and to provide the IP mobility required by most IP applications. Moreover, vehicular mobility results in short-lived connections to the AR, affecting the availability of IP services in VANETs. In this paper, we study the secure and timely handover of IP services in an asymmetric VANET and propose a multihop-authenticated Proxy Mobile IP (MA-PMIP) scheme. MA-PMIP provides an enhanced IP mobility scheme over infrastructure-to-vehicle-to-vehicle (I2V2V) communications that uses location and road traffic information. The MA-PMIP also reacts, depending on the bidirectionality of links, to improve availability of IP services. Moreover, our scheme ensures that the handover signaling is authenticated when V2V paths are employed to reach the infrastructure so that possible attacks are mitigated without affecting the performance of the ongoing sessions. Both analysis and extensive simulations in OMNeT++ are conducted, and the results demonstrate that the MA-PMIP improves service availability and provides secure seamless access to IP applications in asymmetric VANETs.

On Achieving Seamless IP Communications in Heterogeneous Vehicular Networks

The supporting infrastructure and communications technologies for vehicular networking contexts are heterogeneous by nature. Large coverage access networks, such as 3G/4G, coexist with wireless local area networks and dedicated short-range communications. In such a scenario, we investigate the seamless provision of mobile Internet access and general IP services over the heterogeneous network, in particular for loosely coupling architectures. We propose a hybrid global mobility scheme that allows for the ongoing IP sessions to be transferred across dissimilar radio access networks that may belong to different administrative domains. In order to achieve the global mobility, our scheme combines host- and network-based mobility. The solution focuses on urban vehicular scenarios and enables seamless communications for in-vehicle networks, passengers with mobile devices, and users of public transportation commuting along the system. By means of analytical evaluations and simulations of realistic urban vehicular scenarios, we show that our hybrid scheme can achieve seamless IP communications for mobile Internet access over the heterogeneous vehicular network.

Genetic diversity and virulence determinants of Escherichia coli strains isolated from patients with Crohn's disease in Spain and Chile

Adherent-invasive Escherichia coli (AIEC) strains are genetically variable and virulence factors for AIEC are non-specific. FimH is the most studied pathogenicity-related protein, and there have been few studies on other proteins, such as Serine Protease Autotransporters of Enterobacteriacea (SPATEs). The goal of this study is to characterize E. coli strains isolated from patients with Crohns disease (CD) in Chile and Spain, and identify genetic differences between strains associated with virulence markers and clonality. We characterized virulence factors and genetic variability by pulse field electrophoresis (PFGE) in 50 E. coli strains isolated from Chilean and Spanish patients with CD, and also determined which of these strains presented an AIEC phenotype. Twenty-six E. coli strains from control patients were also included. PFGE patterns were heterogeneous and we also observed a highly diverse profile of virulence genes among all E. coli strains obtained from patients with CD, including those strains defined as AIEC. Two iron transporter genes chuA, and irp2, were detected in various combinations in 68–84% of CD strains. We found that the most significant individual E. coli genetic marker associated with CD E. coli strains was chuA. In addition, patho-adaptative fimH mutations were absent in some of the highly adherent and invasive strains. The fimH adhesin, the iron transporter irp2, and Class-2 SPATEs did not show a significant association with CD strains. The V27A fimH mutation was detected in the most CD strains. This study highlights the genetic variability of E. coli CD strains from two distinct geographic origins, most of them affiliated with the B2 or D E. coli phylogroups and also reveals that nearly 40% of Chilean and Spanish CD patients are colonized with E.coli with a characteristic AIEC phenotype.

Poster: Smart networked bicycles with platoon cooperation

Urban roads are venues of social interaction where many actors try to accomplish their transportation-related individual goals. It has been demonstrated that when individuals act with scarce contextual information they offer resistance to one anothers programs of action hindering coordination. In this work we address the problem of smart networked bicycles assisting cyclist coordination. Coordination is based on vehicular communications together with a cooperative adaptive cruise control. We propose to combine effective dissemination mechanisms in mesh-networks, a platoon cooperation logic, and a novel cyclist-bicycle interface to adapt the behaviour of cyclists while driving. Initial simulations and experimental results demonstrate that our cooperation mechanism helps cyclists achieve individual and collective goals, such as moving fluidly at the best possible speed while maintaining a safe distance to other cyclists.