María Calderón

Design and Experimental Evaluation of a Route Optimization Solution for NEMO

An important requirement for Internet protocol (IP) networks to achieve the aim of ubiquitous connectivity is network mobility (NEMO). With NEMO support we can provide Internet access from mobile platforms, such as public transportation vehicles, to normal nodes that do not need to implement any special mobility protocol. The NEMO basic support protocol has been proposed in the IETF as a first solution to this problem, but this solution has severe performance limitations. This paper presents MIRON: Mobile IPv6 route optimization for NEMO, an approach to the problem of NEMO support that overcomes the limitations of the basic solution by combining two different modes of operation: a Proxy-MR and an address delegation with built-in routing mechanisms. This paper describes the design and rationale of the solution, with an experimental validation and performance evaluation based on an implementation

IP flow mobility: smart traffic offload for future wireless networks

The recent proliferation of smartphone-based mobile Internet services has created an extraordinary growth in data traffic over cellular networks. This growth has fostered interest in exploring alternatives to alleviate data congestion while delivering a positive user experience. It is known that a very small number of users and applications cause a big percentage of the traffic load. Hence, adopting smarter traffic management mechanisms is one of the considered alternatives. These mechanisms allow telecom operators to move selected IP data traffic, for instance, between the cellular infrastructure and the WLAN infrastructure, which is considered a key feature in the latest 3GPP and IETF specifications. This article presents and compares two possible approaches to IP flow mobility offloading that are currently being considered by the IETF. The first one is based on extending existing client-based IP mobility solutions to allow flow mobility where the user terminal is fully involved in the mobility process, and the second one is based on extending current network- based IP mobility solutions where the user terminal is not aware of the mobility.

Nemo-enabled localized mobility support for internet access in automotive scenarios

This article surveys the major existing approaches and proposes a novel architecture to support mobile networks in network-based, localized mobility domains. Our architecture enables conventional terminals without mobility support to obtain connectivity either from fixed locations or mobile platforms (e.g., vehicles) and move between them, while keeping their ongoing sessions. This functionality offers broadband Internet access in automotive scenarios such as public transportation systems, where users spend time both in vehicles and at stations. The key advantage of our proposal, as compared with current alternatives, is that the described mobile functionality is provided to conventional IP devices that lack mobility functionality. We also performed an experimental evaluation of our proposal that shows that our architecture improves the quality perceived by the end users.

Active network support for multicast applications

This article analyzes the necessity and feasibility of designing a protocol for active networks that supports multicasting applications with different characteristics in terms of data loss tolerance. The article begins with a presentation of the service elements required by multicast applications, and from this study a network service description is given. The advantages of providing this service over active networks are studied. The service description is then used as the set of requirements for the design of RMANP (reliable multicast active network protocol), which is capable of providing the service over active network technology. Then a prototype implementation of RMANP over the active node transport system (ANTS) is presented, and some data for the evaluation of its performance is provided. Finally, the main conclusions are that active networks provide flexible support for the development of new network services, but further improvements in runtime efficiency are required.

MIRON: MIPv6 route optimization for NEMO

Network Mobility (NEMO) Basic Support Protocol enables mobile networks to change their point of attaehment to the Internet, while preserving estahlished sessions of the nodes within the mobile network. NEMO basie solution is an extension of Mobile 1Pv6 and it is based on tunnelling, whieh leads to sUboptimal routing, packet overhead and latency, especially when nesting (i.e. a mobile network that contains other mobile networks within) is involved. In this article we present a route optimisation solution for mobile networks based on Mobile 1Pv6. The goal is to use the route optimisation support for Mohile 1Pv6 available in the Correspondent Nodes to provide route optimisation for mobile networks. The solution also supports nested mobile networks without requiring additional tunnelling, thus reducing packet overhead and lateney with regard to Network Mobility basil:: solution.

Vehicular networks on two Madrid highways

There is a growing need for vehicular mobility datasets that can be employed in the simulative evaluation of protocols and architectures designed for upcoming vehicular networks. Such datasets should be realistic, publicly available, and heterogeneous, i.e., they should capture varied traffic conditions. In this paper, we contribute to the ongoing effort to define such mobility scenarios by introducing a novel set of traces for vehicular network simulation. Our traces are derived from high-resolution real-world traffic counts, and describe the road traffic on two highways around Madrid, Spain, at several hours of different working days. We provide a thorough discussion of the real-world data underlying our study, and of the synthetic trace generation process. Finally, we assess the potential impact of our dataset on networking studies, by characterizing the connectivity of vehicular networks built on the different traces. Our results underscore the dramatic impact that relatively small communication range variations have on the network. Also, they unveil previously unknown temporal dynamics of the topology of highway vehicular networks, and identify their causes.

GeoSAC - Scalable address autoconfiguration for VANET using geographic networking concepts

In this paper, we propose a novel mechanism for application of an IPv6 automatic address configuration technique to vehicular ad-hoc networks. The solution consists of combining standardized IPv6 schemes with geographic routing functionalities, which enables the matching of geographically-scoped network partitions to single IPv6 multicast-capable links. Unlike existing solutions described in this paper and mostly derived from MANET approaches, our proposal explicitly targets automotive requirements, which we identify and analyze based on a real system architecture and its target applications. Furthermore, we examine the solutionpsilas timely aspects both analytically and experimentally with laboratory tests and compare the results. Finally, we outline intended future work on extending the proposed scheme.

New insights from the analysis of free flow vehicular traffic in highways

Building vehicular networks in roads and highways is a challenging research topic with a large number of applications ranging from traffic jams and car collisions prevention to efficient route planning. The analysis of the distance between vehicles in roads is a key factor in, e.g., designing vehicular networks protocols or planning a supporting infrastructure to improve vehicular connectivity. This work proposes a Gaussian-exponential mixture model to characterize the time distance between vehicles in a highway lane, based on measurements collected at different locations in several highways of the city of Madrid, in Spain. The model arises from the observed behavior that some vehicles travel very close together, like in a burst mode, showing Gaussian inter-arrival times, while other vehicles are somehow isolated, showing exponentially distributed inter-arrival times. The experiments show that such a Gaussian-exponential mixture model accurately characterizes inter-vehicle times observed from real traces.

IP Flow Mobility in PMIPv6 Based Networks: Solution Design and Experimental Evaluation

The ability of offloading selected IP data traffic from 3G to WLAN access networks is considered a key feature in the upcoming 3GPP specifications, being the main goal to alleviate data congestion in cellular networks while delivering a positive user experience. Lately, the 3GPP has adopted solutions that enable mobility of IP-based wireless devices relocating mobility functions from the terminal to the network. To this end, the IETF has standardized Proxy Mobile IPv6 (PMIPv6), a protocol capable to hide often complex mobility procedures from the mobile devices. This paper, in line with the mentioned offload requirement, further extends PMIPv6 to support dynamic IP flow mobility management across access wireless networks according to operator policies. Considering energy consumption as a critical aspect for hand-held devices and smart-phones, we assess the feasibility of the proposed solution and provide an experimental analysis showing the cost (in terms of energy consumption) of simultaneous packet transmission/reception using multiple network interfaces. The end-to-end system design has been implemented and validated by means of an experimental network setup.

Seamless internet 3G and opportunistic WLAN vehicular connectivity

Most of the cellular network operators are nowadays striving to solve the problem caused by the increasing demand of mobile data users. In the near future, vehicles will be equipped not only with cellular connectivity, but also with dedicated short-range wireless devices, used to connect via single or multiple hops to fixed road side units attached to the infrastructure network to gain Internet access. Taking this hybrid-connectivity scenario, we propose S eamless I nternet 3G and Opportunistic WL AN V ehicular I nternet Co nnectivity (SILVIO), a solution for providing Internet connectivity in multi-hop vehicular ad hoc networks. Vehicles use the cellular network to assure always-on connectivity, while they opportunistically select to offload some non-critical flows to the multi-hop wireless local area network (WLAN). The advantages of this approach are twofold: the users can benefit from a higher bandwidth, while the operators can alleviate their overloaded cellular networks. SILVIO makes use of existing standard mobility mechanisms integrated, enhanced and extended to provide a seamless connectivity experience without introducing much complexity nor signalling overhead. One of the main contributions of this article is the proposal and analysis of different handover strategies between 3G and multi-hop WLAN networks for the vehicular scenario. A trace-driven simulator was developed to evaluate the performance improvements provided by SILVIO. Real traffic traces from the city of Madrid were used to feed the simulator which considers large vehicles as obstacles, as well. The obtained results show that using SILVIO the cellular network can be offloaded by a factor up to 80%.