M. Isabel Sanchez

On providing mobility management in WOBANs: integration with PMIPv6 and MIH

The Wireless-Optical Broadband Access Network (WOBAN) is a promising access architecture that combines the high performance of optical networks with the ubiquity and convenience of wireless technologies. This article proposes a network-based mobility framework that is specially tailored for WOBANs. The proposed architecture is based on Proxy Mobile IPv6 and IEEE 802.21 mobility management protocols, but it also defines a number of optimizations that enable the seamless handover of mobile nodes. In particular, the hierarchical architecture together with the broadcast-and-select nature of the optical part of the WOBAN are leveraged to: optimize the mobility of users with respect to the overall network resources, both at the wireless access and optical distribution parts, remove the overhead of IP-in-IP tunneling between the PMIPv6 entities, and perform an efficient bicasting during the handover process to minimize packet loss.

Experimental evaluation of an SDN-based distributed mobility management solution

The current wireless network architecture needs to be re-thought to support mobility in very dense and heterogeneous network deployments. We propose and experimentally evaluate a novel SDN-based architecture which makes use of DMM concepts to deploy fast, flexible, reliable, and scalable mobility management mechanisms at both local and regional scopes. Our solution is compatible with existing protocols deployed in wireless access and backhaul networks, and is therefore technology transparent to the user. Although our architecture is generic and can be used with heterogeneous wireless networks, we prove the validity of our approach in a lab prototype, by implementing our distributed mobility management mechanism on a set of OpenFlow-controlled IEEE 802.11 networks.

The costs and benefits of combining different IP mobility standards

Several IP mobility support protocols have been standardized. Each solution provides a specific functionality and/or requires operations of particular nodes. The current trend is towards the co-existence of these solutions, though the impact of doing so has not been yet fully understood. This article reviews key standards for providing IP mobility support, the functionality achieved by combining them, and the performance cost of each combination in terms of protocol overhead and handover latency. We show that combining different mobility mechanisms has a non-negligible cost. Finally we identify a strategy for combining mobility protocols and properties that facilitate this combination.

On IEEE 802.11K/R/V amendments: Do they have a real impact?

The IEEE 802.11 standard has contributed to increasing ubiquitous connectivity. Its success is motivated, among other factors, by its inexpensive costs and the easiness of its deployment, turning WiFi into the most widespread wireless access technology. However, most users are not aware of the constant evolution in the IEEE 802.11 family. In this article we focus on some of the IEEE 802.11 amendments included in the latest version of the standard, which address interesting challenges in the context of WLANs, such as minimization of the interruption when changing the point of attachment to the network. However, these amendments have not had much commercial impact, and have gone somehow unnoticed by the majority of users and even part of the research community. We analyze their motivation, the functionality they provide, and their existing practical applications, if any. We also evaluate the possible factors that influence their adoption. If most of the commercial hardware does not implement these amendments, their impact on real WLAN deployment and experimental research will be limited.

Mobility management: Deployment and adaptability aspects through mobile data traffic analysis

Abstract The expected boost in mobile data traffic and the evolution towards the next generation of networks are making cellular operators reconsider whether current approaches for handling mobility could be improved, according to the characteristics of the mobile traffic that actually flows through real networks. In this work, we make use of extensive analysis of real network traces to infer the main characteristics of mobile data traffic for a particular operator. Our analysis focuses on the features related to mobility, i.e., location information, number of handovers, or duration of the data traffic exchange. New techniques to gather the mobility characteristics of the user based on data and control packets correlation are designed and applied to compare the gains of deploying different mobility management approaches. We show that adapting the mobility management mechanism to the degree of mobility and the network characteristics brings some benefits to the network operator over the current approach, especially in scenarios of low mobility, where a dstributed mobility management solution proves to be more efficient.

Tackling the Increased Density of 5G Networks: The CROWD Approach

The significant growth in mobile data traffic and the ever- increasing users demand for high-speed, always connected networks continue challenging network providers and lead research towards solutions to enable faster, scalable and more flexible networks. In this paper we present the CROWD approach, a networking framework providing mechanisms to tackle the high densification and heterogeneity of wireless networks. The goal of CROWD is to design protocols and algorithms for very dense and heterogeneous wireless networks, which we call DenseNets. The mechanisms we propose include energy efficiency, MAC enhancements, connectivity management and backhaul configuration to contribute to the next generation of networks considering density as a resource instead of as an obstacle.

Modeling and Analysis of Opportunistic Routing in Multi-hop Wireless Networks

Opportunistic Routing (OR) takes advantage of the broadcast nature of the wireless medium to increase reliability in communications. Instead of selecting one node as the next-hop forwarder, OR selects a set of candidates to forward the packet. In this way, if one of them does not receive the packet from the source, another candidate will be able to do it, this avoids the need for a re-transmission from the source. To increase the successful delivery ratio, we can increase the size of the candidate set or the number of re-transmissions, but, we must take into account the impact on the use of the network resources. In this paper, we propose a Markov chain as a general model for OR that can be applied to any kind of network topology and any candidate selection algorithm without any constraint. The only input parameters needed are: i) the candidate list of each node, ii) the link delivery probability between nodes, and, iii) the maximum number of re-transmissions in each node. Taking this data into account, our model allows for the evaluation of the performance of different candidate selection algorithms according to different metrics, such as the expected number of transmissions (ExNT), which is one of the most relevant metrics in OR. Our model also enables an evaluation of the influence of the number of candidates, its relation to the number of re-transmissions and how these two parameters together contribute to the successful delivery of data packets.

On the implementation, deployment and evaluation of a networking protocol for VANETs: The VARON case ☆

Abstract Research on vehicular communications has been quite extensive over the past few decades. Most of the initial studies were theoretical and research has just recently moved to more experimental works. Conducting real field operational tests is extremely challenging due to the number of vehicles required, the lack of control over the environment and the cost of the necessary equipment and personnel. However, simulation tools may not reflect properly the highly dynamic and complex characteristics of the vehicular scenario. This article explores why practical research in the field of vehicular communications is so demanding, by reporting on our experience in prototyping and experimentally evaluating VARON. Published in 2008, VARON is a multi-hop wireless vehicular communication protocol which was already validated via extensive simulations. In this work, we have fully implemented it, first on a lab-based environment, and then in a real-life testbed. This long and exhausting process has shown that some common assumptions do not necessarily hold when evaluated under real situations, as well as taught us valuable lessons on how to design and conduct experiments with real vehicles. We believe that the experience and lessons learned during this process do not only apply to VARON, but also to other multi-hop wireless vehicular communication solutions, and that therefore these lessons are helpful for other researchers willing to validate their protocols in a real scenario.

Energy Consumption Savings with 3G Offload

Current trends on mobile traffic show an exponential grow of the traffic consumed by users from smartphones and other portable devices. The explosion of traffic in cellular networks has forced operators to start deploying solutions to alleviate the congestion on their capacity-limited and expensive radio access networks. One of the solutions being discussed is the so called 3G offload that enables the terminals to use other technologies such as WiFi to offload some of the traffic. IP flow mobility is one mechanism providing 3G offload, by enabling selected flows to be moved among network interfaces. Although this is a very promising technology, it is not clear yet how it will affect the protocols currently in use to provide IP mobility in cellular networks, e.g., Proxy Mobile IPv6. The use of 3G offloading does not only benefits the operators, but also the final user, as it might extend the battery lifetime of its terminal. In this paper we first describe some network-based IP flow mobility extensions, highlighting important design choices. Secondly, we focus on providing experimental measurements showing how the use of this technology can result in an extended battery life for the case of 3G and WiFi enabled terminals.

Experimental analysis of connectivity management in mobile operating systems

We are immerse in a world that becomes more and more mobile every day, with ubiquitous connectivity and increasing demand for mobile services. Current mobile terminals support several access technologies, enabling users to gain connectivity in a plethora of scenarios and favoring their mobility. However, the management of network connectivity using multiple interfaces is still starting to be deployed. The lack of smart connectivity management in multi-interface devices forces applications to be explicitly aware of the variations in the connectivity state (changes in active interface, simultaneous access from several interfaces, etc.). In this paper, we analyze the present state of the connection management and handover capabilities in the three major mobile operating systems (OSes): Android, iOS and Windows. To this aim, we conduct a thorough experimental study on the connectivity management of each operating system, including several versions of the OS on different mobile terminals, analyzing the differences and similarities between them. Moreover, in order to assess how mobility is handled and how this can affect the final user, we perform an exhaustive experimental analysis on application behavior in intra- and inter-technology handover. Based on this experience, we identify open issues in the smartphone connectivity management policies and implementations, highlighting easy to deploy yet unimplemented improvements, as well as potential integration of mobility protocols.