Fernando Bernal

A Framework for Supporting Network Continuity in Vehicular IPv6 Communications

The appearance of recent standards about cooperative ITS architectures towards a reference communication stack has been an inflection point in the research about vehicular networks. The ISO Communication Access for Land Mobiles (CALM) and the ETSI European ITS communication architecture have paved the way towards real and interoperable vehicular cooperative systems. Within these convergent proposals, IPv6 communications are recognized as a key component to enable traffic efficiency and infotainment applications. The proper operation of these applications and the achievement of value-added ITS services require an uninterrupted network connectivity. This paper addresses this problem by proposing a novel communication stack to support the provision of continuous and secure IPv6 vehicular communications. The solution follows the ISO/ETSI guidelines for the development of cooperative ITS systems and is based on standardized technologies such as Network Mobility (NEMO) protocol to provide an integral management of IPv6mobility. The solution integrates IEEE 802.21 media independent handover services for optimizing the handover process. While the support to the handover optimization offered by the proposed ITS communication stack is demonstrated through a mobility use case, a real testbed supporting most of the communications features is developed to validate and assess the real performance of the stack design.

Increased transcutaneous oxygen pressure is an indicator of revascularization after peripheral transluminal angioplasty

Background: In recent years, the use of peripheral transluminal angioplasty (PTA) procedures for revascularization of an ischemic limb has increased. Evaluation of reperfusion has been carried out by Doppler scan; however, a successful PTA does not necessarily result in improved oxygen delivery to the distal parts of the limb. Purpose: To evaluate the efficacy of the revascularization in diabetic patients with critical limb ischemia after treatment with PTA by comparing transcutaneous oxygen tension (TcpO2) with the ankle-brachial index (ABI) post PTA. Material and Methods: This prospective study included 151 consecutive diabetic patients. We evaluated the posterior tibial and dorsalis pedis Doppler, ABI, TcpO2, and duplex scan results. If two of these four examinations were abnormal, arteriography was carried out and PTA was performed concomitantly. At least 64 patients were considered suitable candidates for PTA. Results: The ABI increased from 0.67±0.25 to 0.84±0.25 following PTA (P<0.001). TcpO2 increased from 27.20±11.10 mm Hg to 40±12.10 mm Hg after PTA (P<0.001). While the TcpO2 could be measured in all patients, the ABI was not measurable in 25.37% pretreatment and in 17.91% post treatment. Statistical analysis revealed a scant correlation between the techniques used: TcpO2 and ABI (P=0.20). Conclusion: Our study confirms that the increase in TcpO2 in diabetic patients following PTA points to the physiologic significance of microvascular revascularization achieved in the treated limb and serves to assess functional improvement in tissue oxygenation obtained by PTA. The use of TcpO2 may represent an alternative to traditional assessment of peripheral transluminal angioplasty results.

Secure three-party key distribution protocol for fast network access in EAP-based wireless networks

In this paper, we present a solution that reduces the time spent on providing network access in multi-domain mobile networks where the authentication process is based on the Extensible Authentication Protocol (EAP). The goal is to achieve fast and smooth handoffs by reducing the latency added by the authentication process. This process is typically required when a mobile user moves from one authenticator to another regardless of whether the new authenticator is in the same domain (intra-domain) or different domain (inter-domain). To achieve an efficient solution to this problem, it has been generally recognized that a fast and secure key distribution process is required. We propose a new fast re-authentication architecture that employs a secure three-party key distribution protocol which reduces the number of message exchanges during the network access control process. Our approach is proved to preserve security and verified by means of a formal tool. The resulting performance benefits are shown through our extensive simulations. 2010 Elsevier B.V. All rights reserved.

A solution to ankle-brachial index limitations in peripheral transluminal angioplasty

PurposeWe evaluated the limitations of the ankle-brachial index (ABI) in the revascularisation of diabetic patients with critical limb ischaemia (CLI) who were undergoing peripheral transluminal angioplasty (PTA) compared with the degree of arterial stenosis and with transcutaneous oxygen tension (TcpO2).Materials and methodsThis prospective study assessed 250 consecutive diabetic patients in whom we evaluated results of posterior tibial and dorsalis pedis Doppler, ABI, TcpO2, and duplex scans. In total, 104 patients were considered suitable candidates for PTA.ResultsIn 42% of the patients studied, ABI could either not be used (9.34% due to no signal; 14.02% because the artery could not be compressed) or was incorrect (18.7% before PTA; 15.9% after PTA). In contrast, TcpO2 was determined in all cases. After PTA, vessel stenosis decreased from 58.33±20.07% to 21.87±13.57% (p<0.001), whereas ABI increased from 0.79±0.57 to 0.95±0.47 (p<0.001) and TcpO2 from 27.37±10.40 mmHg to 38.23±10.25 mmHg (p<0.001). A statistical analysis revealed scant correlation between techniques (TcpO2 and ABI) (r=0.14).ConclusionsABI shows significant limitations for the diagnosing and treating CLI patients compared with TcpO2.RiassuntoObiettivoScopo del presente lavoro è stato valutare i limiti dell’indice caviglia-braccio (ABI) nella rivascolarizzazione del paziente diabetico con ischemia critica dell’arto inferiore (CLI) sottoposto ad angioplastica translumninale periferica (PTA) in rapporto al grado di stenosi arteriosa e della tensione transcutanea di ossigeno (TcpO2).Materiali e metodiIn questo studio prospettico sono stati inclusi consecutivamente 250 pazienti diabetici. Sono stati valutati i risultati dell’indagine Doppler dell’arteria tibiale posteriore e dell’arteria dorsale del piede, dell’ABI, della TcpO2 e del duplex. In totale, 104 pazienti sono stati considerati idonei alla ricanalizzazione mediante PTA.RisultatiNel 42% dei pazienti reclutati non si è potuta utilizzare l’ABI (nel 9,34% non era rilevabile un polso arterioso e nel 14,02% l’arteria non era comprimibile) oppure si è rivelato inesatto (nel 18,7% prima e nel 15,9% dopo la realizzazione della PTA). Al contrario, in tutti i casi si è potuta determinare la TcpO2. Dopo PTA, la stenosi dell’arteria si è ridotta dal 58,33%±20,07% al 21,87%±13,57% (p<0,001), mentre l’ABI è aumentata dal 0,79±0,57 al 0,95±0,47 (p<0,001) e la TcpO2 dal 27,37±10,40 mmHg al 38,23±10,25 mmHg (p<0,001). L’analisi statistica ha evidenziato una scarsa correlazione tra le tecniche utilizzate (TcpO2 e ABI) (r=0,14).ConclusioniL’ABI mostra limiti significativi nella diagnosi e nel trattamento dei pazienti con CLI rispetto alla TcpO2.

Securing Vehicular IPv6 Communications

A common practice is applying security after a network has been designed or developed. We have the opportunity of not committing this error in vehicular networks. Apart from particular works in the literature, ETSI TC ITS has defined general security services for (vehicular) cooperative systems. However, existent efforts do not pay the needed attention to the integration of IPv6 yet. The potential of IPv6 in the field is being described within ISO TC 204, above all, but further work is needed for a proper integration of security. This work follows this direction, and a reference vehicular communication architecture considering ETSI/ISO regulations, uses Internet Protocol security (IPsec) and Internet Key Exchange version 2 (IKEv2) to secure IPv6 Network Mobility (NEMO). A key advance is also the implementation and experimental evaluation of the proposal in a challenging vertical handover scenario between 3G and 802.11p. The performance of the secured NEMO channel is widely analyzed in terms of the movement speed, bandwidth, traffic type or signal quality, and it is concluded that the addition of IPv6 security only implies a slight reduction in the overall performance, with the great advantage of providing confidentiality, integrity and authenticity to the communication path.

IPv6 Communication Stack for Deploying Cooperative Vehicular Services

New-age cooperative services for vehicles involve communication nodes in nomadic devices, vehicles, roads and central stations. However, as the number of vehicular services hosted in both the vehicle and infrastructure side increase, it is more and more necessary to use a proper framework to deploy them effectively using a common interconnection network. Following the ISO/ETSI recommendations, which provide a reference ITS communication architecture, the current work provides an implementation, deployment and experimental assessment of a vehicular communications stack for providing infrastructure-to-vehicle services. The architecture presented in this paper considers open issues such as communications security, the support of geo-referenced facilities, the need of a service deployment framework in vehicles and central stations, and the management of host software.

A vehicular network mobility framework: Architecture, deployment and evaluation

Research on vehicular networks has increased for more than a decade, however, the maturity of involved technologies has been recently reached and standards/specifications in the area are being released these days. Although there are a number of protocols and network architecture proposals in the literature, above all in the Vehicular Ad-hoc Network (VANET) domain, most of them lack from realistic designs or present solutions far from being interoperable with the Future Internet. Following the ISO/ETSI guidelines in field of (vehicular) cooperative systems, this work addresses this problem by presenting a vehicular network architecture that integrates well-known Internet Engineering Task Force (IETF) technologies successfully employed in Internet. More precisely, this work describes how Internet Protocol version 6 (IPv6) technologies such as Network Mobility (NEMO), Multiple Care-of Address Registration (MCoA), IP Security (IPsec) or Internet Key Exchange (IKE), can be used to provide network access to in-vehicle devices. A noticeable contribution of this work is that it not only offers an architecture/design perspective, but also details a deployment viewpoint of the system and validates its operation under a real performance evaluation carried out in a Spanish highway. The results demonstrate the feasibility of the solution, while the developed testbed can serve as a reference in future vehicular network scenarios.

A transport-based architecture for fast re-authentication in wireless networks

In this paper we propose an architecture aimed for reducing the latency of network access authentication based on the Extensible Authentication Protocol (EAP). The architecture is based on the design of a new EAP method for which a standalone authenticator is used, and does not require any change to the EAP specification or the specifications of EAP lower-layers such as IEEE 802.11 and IEEE 802.16e. We also show

Trusted Network Access Control in the Eduroam Federation

In order to ensure end user devices are healthy enough to gain access to the network, providers are making use of advanced network access control solutions, which propose an evaluation of configuration information (posture) about the device itself before providing access to the network. However, current solutions are focused on intra-domain scenarios, where end users and network belong to the same organization. This work proposes an architecture to provide this trusted network access control in other emerging scenarios: network roaming federations, like eduroam, where the accessed network provider is not where the end user belongs to. The paper describes how authentication and authorization mechanisms for these scenarios can be integrated to provide trusted network access control.

The Use of IPv6 in Cooperative ITS: Standardization Viewpoint

Internet Protocol version 6 (IPv6) is envisaged to be the cornerstone for the future development of ITS services. Both research communities and standardization forums are considering the use of IPv6 as a media-agnostic carrier for non-time critical safety applications as well as for traffic management. This interest is based on the numerous benefits brought by IPv6: large addressing space able to cope with ambitious deployment scenarios such as the vehicular one, easier support of management operations related to node auto-configuration and native support of security mechanisms. This chapter surveys the current European standard specifications in the field of IPv6-based communications applied to cooperative ITS systems. The convenience of using IPv6 technology is demonstrated by identifying a wide set of relevant ITS specifications where the application of IPv6 networking protocols outperforms other protocol solutions. Furthermore, this study is complemented with a performance assessment of IPv6 communications over a cooperative ITS scenario using a real IPv6-enabled communications stack compliant with the standardized ITS station reference architecture specified by International Standards Organization (ISO) and European Telecommunications Standards Institute (ETSI).