Marivi Higuero

Railway signaling systems and new trends in wireless data communication

With the increment of passenger railway traffic especially in high speed lines, improvements in railway transportation safety become even more crucial. This paper presents technological and commercial trends in this area, enumerates innovative on-going related projects and proposes the application of new wireless communication standards such as, DSRC - WAVE (Dedicated Short Range Communications and Wireless Access in Vehicular Environment) or 802.11p; 802.16 or WiMAX; and MBWA (Mobile Broadband Wireless Access) or 802.20, in train control communications networks. In order to validate this proposal, we have designed a model for a wireless communication system deployed in a fully redundant configuration. The application of these new open-standard technologies will allow an affordable deployment, ubiquitous, always-on and interoperable muti-vendor mobile broadband train control communication system that supports new safety services and applications. Railway, signaling, wireless, 802.11b/g, MBWA

A survey on the contributions of Software-Defined Networking to Traffic Engineering

Since the appearance of OpenFlow back in 2008, software-defined networking (SDN) has gained momentum. Although there are some discrepancies between the standards developing organizations working with SDN about what SDN is and how it is defined, they all outline traffic engineering (TE) as a key application. One of the most common objectives of TE is the congestion minimization, where techniques such as traffic splitting among multiple paths or advanced reservation systems are used. In such a scenario, this manuscript surveys the role of a comprehensive list of SDN protocols in TE solutions, in order to assess how these protocols can benefit TE. The SDN protocols have been categorized using the SDN architecture proposed by the open networking foundation, which differentiates among data-controller plane interfaces, application-controller plane interfaces, and management interfaces, in order to state how the interface type in which they operate influences TE. In addition, the impact of the SDN protocols on TE has been evaluated by comparing them with the path computation element (PCE)-based architecture. The PCE-based architecture has been selected to measure the impact of SDN on TE because it is the most novel TE architecture until the date, and because it already defines a set of metrics to measure the performance of TE solutions. We conclude that using the three types of interfaces simultaneously will result in more powerful and enhanced TE solutions, since they benefit TE in complementary ways.

Ladon 1 : end-to-end authorisation support for resource-deprived environments

The authors present Ladon, an enhanced version of Kerberos which extends the original protocol with authorisation capacity and relaxes the necessity of clock synchronisation by adding to the protocol special limited-lifetime nonces. This way, although all entities need timers, only the clocks of the two servers that constitute the key distribution centre must be synchronised with each other. The design of this protocol is motivated by the emergence of a new trend of applications in which sensors and low-capacity devices become tiny information or application servers directly addressable by any Internet-connected entity. Despite the huge potential of these environments, security is probably the greatest barrier to their long-term success. To address this issue, Ladon allows for end-to-end pair-wise key establishment in an authenticated and authorised manner, while keeping the introduced storage, computational and communication overhead very low. The security analysis with the AVISPA formal validation tool shows that the protocol meets the stated security goals, whereas the performance analysis shows that the overhead of the protocol is bounded and comparable to that of other security protocols which provide even less functionalities.

Analytical Evaluation of a HIP Registration Enhancement for NEMO Scenarios

Covering NEtwork MObility (NEMO) scenarios based on end-to-end mobility management protocols such as the Host Identity Protocol (HIP) is not straightforward. However, it has been demonstrated that HIP based NEMO solutions outperform NEMO Basic Support (NEMO BS), hence, HIP is being considered also for addressing NEMO scenario necessities. In this work we focus on the Registration Extension process of HIP, which is mandatory for providing reachability of HIP enabled mobile nodes. More specifically, we describe our proposal, the Bulk Registration process, which has been analytically modeled to show that it outperforms other registration approaches in more than 90% in terms of delay and signaling overhead. Obtained results are highly valuable for a common NEMO scenario where several nodes are present in a vehicle to control its operation.

Design and formal security evaluation of NeMHIP

NEtwork MObility Basic Support (NEMO BS) is a standardized protocol for managing the mobility of a set of nodes that move together as a whole while having continuous connectivity to the Internet through one or more Mobile Routers (MRs). Because it is based on Mobile IPv6 (MIPv6), it inherits the properties of MIPv6, such as the use of IPsec. However, NEMO BS does not address all the features required by the demanding Intelligent Transportation Systems (ITS) scenario to provide an integrated and global secure mobility management framework. In addition, unlike MIPv6, the routing in NEMO BS is suboptimal, which makes difficult the provision of an adequate service performance. These characteristics make the application of the NEMO BS protocol not optimum in this scenario. An interesting strategy to provide security and good service performance is to consider a protocol that establishes and maintains Security Associations (SAs), such as the Host Identity Protocol (HIP). Different HIP-based approaches have been defined. However, these HIP-based network mobility solutions still present unsolved issues. In this article, we present a secure and efficient network mobility protocol named NeMHIP. NeMHIP provides secure and optimum mobility management and efficient end-to-end confidentiality and integrity protection apart from the basic security properties inherited from HIP. To evaluate the security provisions of NeMHIP, we have conducted a belief-based formal evaluation. The results demonstrate that the defined security goals are achieved by the protocol. Furthermore, we have performed an automated formal evaluation to validate additional security aspects of NeMHIP. Thus, we have modeled NeMHIP using the AVISPA tool and assessed its security when an intruder is present. The results confirm that NeMHIP is a secure protocol that ensures end-to-end confidentiality and integrity without introducing security leaks to the basic HIP. Thus, we have addressed the need found in the literature for providing security and efficiency in the network mobility scenario.

Scanning on handover enhancement issues in video application deployments on WiMAX mobile networks

WiMAX evolution is expected to go through Wireless broadband last mile access, backhaul solutions ending with handset integration. This paper outlines the challenging scenario WiMAX networks face when deploying mobile Internet applications, including the most demanding in terms of latency and data rate: the video applications. The proposed strategy to enhance global network performance has been to apply new handover policies. Several validation methodologies have been approached: testbeds, simulation scenario and a mixed real-to- simulation scenario.

WiMAX Role on CBTC Systems

The recent progresses in mobile telecommunications technologies have allowed railway telecommunications technology to go a step forward, and, in the same way, the railway control systems. In this sense, while the mobile telecommunications technology evolved from the first generation of analogue mobile communication systems to what is known today as B3G (Beyond 3G), the same occurred with the telecommunication systems used in railways, from those based on analogue telecommunications, to the most recent ones based on 2G such as GSM-R or TETRA. Till recently, there was a technological gap regarding high mobility environments, high transmission rate and high interactivity (low latency). However, new emerging telecommunications technologies have shortened this gap significantly. This way, the train control systems will be affected by the availability of telecommunications technologies capable of offering earth-train broadband communications in real time. This article presents a telecommunications network architecture based on WiMAX (Worldwide Interoperability for Microwave Access) mobile technology (IEEE 802.16e) that fulfils the telecommunications needs in the railway environment. The WiMAX mobile technology most relevant features are: transmission rates up to 30Mbps at 15 km distance; mobility support up to 200km/h; QoS, security, low latency, fast, scalable and cost effective deployment, mainly compared to GSM-R deployment. In the mobile node design of this network telecommunications architecture, the multipath fading effect, and the Doppler effect, present in high speed mobility scenarios, have been taken into account. An improvement in the handoff between BSs, through a neighbouring and predictive mobility algorithm, is included. The architecture proposed supports the functional and system requirements identified in the UIC Project EIRENE (European Integrated Railway Radio Enhanced Network), and demanded to GSM-R technology. Measures on a real testbed and a model developed with the discrete event simulation tool, Opnet, have been employed in this work.Copyright

A high performance link layer mobility management strategy for professional private broadband networks

Abstract In this paper, we present an innovative approach to solving the mobility management problem in the context of professional private broadband networks in the vehicular scenario. These heterogeneous communication networks are commonly deployed and managed by mission-critical organisations with the aim of supporting their specific and highly demanding services. Taking advantage of the specific characteristics of these networks, we propose to solve the mobility problem at Layer 2. This way, the mobility management overhead is reduced compared to solutions that operate at Layer 3 or above and therefore, shorter handover delays and better end-to-end application performances are achieved. The core element of our proposal is an intelligent mobile switch that makes use of the services provided by the IEEE 802.21 protocol to enhance vertical or heterogeneous handover performance. To validate our approach, we have developed a prototype implementation of the designed mobile switch with IEEE 802.11 and IEEE 802.16 support. Using this mobile switch implementation, we have carried out a set of experiments over a real testbed and measured some key indicators to assess the mobility management process. The obtained results show that our handover strategy comfortably meets the requirements of the ITU-T Y.1541 recommendation for highly demanding applications and ITU-R report M.2134 for high-speed handover. To the best of our knowledge, our contribution is the first proposal that solves the mobility management problem at Layer 2 while addressing the multi-access technology context in the vehicular professional private network scenario.

A novel architecture for secure, always-best connected ship-shore communications

Together with the IMOs future navigation system implementation strategy, the e-navigation, wireless access technologies are proliferating on the maritime scenario, covering last mile communications. In the near future, we foresee that communication technologies will coexist and will be available in overlapping areas through the maritime last mile. Therefore, in order to enhace ship-shore communications, always-best-connected procedures and an efficient mobility management protocol is required to satisfy maritime context peculiarities such as safety and security. In this article we analyze the most suitable mobility management protocol in terms of security and handover efficiency and propose a novel architecture that integrates the HIP protocol and always-best-connected procedures to best achieve maritime context specifications.

Performance evaluation of user applications in the ITS scenario: An analytical assessment of the NeMHIP

Internet connectivity in the ITS context is a flourishing demand that has to be covered by efficient information and communication technologies. Thanks to the provision of this connectivity, not only end users will profit from communication services, but also services for controlling the operation of the vehicle will benefit from the Internet connectivity. Services related to the operation and control of the vehicles exchange sensitive data, so strong security properties have to be ensured for this type of services. In addition, because of the privacy concerns related to the end users, it is desired to provide this kind of services with an adequate security level. From the communication point of view, a vehicle can be regarded as a mobile network where nodes onboard obtain continuous and optimal Internet connectivity, so, its mobility has to be managed. In the same way, network mobility management protocols should not only avoid security leaks, but also they have to ensure an adequate security level. It is needless to say that the introduction of security properties cannot render not fulfilling service performance requirements. In fact, the trade-off between security and application performance is a must. ITS standardisation bodies have adopted the NEtwork MObility Basic Support (NEMO BS) protocol to manage the mobility of networks. However, it still presents shortcomings like lack of security support and routing problems, which leads to a bad performance. One of the most promising design approaches is to consider a base mobility management protocol that provides out of the box security and route optimisation support like the Host Identity Protocol (HIP). Different solutions based on HIP can be found to solve network mobility in the literature, but none of these solutions aim at solving securely and efficiently network mobility management. That is, the provision of security properties to the network mobility management itself and to the end-to-end data communications while not increasing the signalling overhead and the manageability level remains unsolved. In this paper, we present the NeMHIP. NeMHIP is a secure and efficient network mobility management protocol which is based on HIP. In order to demonstrate its feasibility, we have carried out a study by means of analytical modelling to assess the performance of user applications with stringent QoS requirements like VoIP. Results demonstrate that the introduction of the NeMHIP in the ITS context is feasible because security properties are ensured while application performance requirements are satisfied. Therefore, we successfully achieve the trade-off between security and performance.