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Distributed Mobility Management using IEEE 802.21
No full textIMDEA Networks researchers have been contributing actively and extensively to this body of work over the last years. This contribution was produced in the following context:
Vice-chairing IEEE 802.21 TGb
Antonio de la Oliva was elected as IEEE 802.21 TGb Vice-chair in July 2011. The main responsibility of the position resides in shepherding the IEEE 802.21b specification until it is finally approved by the IEEE 802 Executive Committee. The specification, which contains significant contributions from on-going (MEDIEVAL) and past (CARMEN) European projects, passed the Sponsor Ballot in November 2011 and is currently awaiting approval-which will hopefully be ratified on the March 2012 plenary meeting.
Leading of the IEEE 802.21 Future Project Planning Ad-hoc group
The IEEE 802.21a and IEEE 802.21b amendments are already completed and waiting for ratification from IEEE 802 EC. This opens the door to new projects within the IEEE 802.21. IMDEA Networks, through one of its collaborators, is currently leading the Ad- Hoc group in charge of defining the new working items. Even more, some of the ideas developed within MEDIEVAL have been proposed and accepted as working items. A new Project Authorization Request (on MIHF_ID Group Management) was prepared through the last months of 2011, and submitted for approval on January 2012. The new project, to be named IEEE 802.21 TGd, will hopefully be approved on the March 2012 meeting.
Contributions to IEEE 802.21a/b/c and IEEE 802.11
Apart from the above activities, several technical contributions to IEEE 802.21a/b/c and IEEE 802.11 were performed during the 2011 period. In IEEE 802.21a several contributions and comments to address the different letters and sponsor ballots were performed. The main technical contributions from MEDIEVAL and CARMEN were introduced in IEEE 802.21b during 2010 and beginning of 2011 (2011 being devoted to defending such contributions during the different ballots). IEEE 802.21c standardizes the mechanisms to enable optimized single radio handover. Some of the technical details of this approach are very similar to the issues analyzed for DMM, hence the solutions designed within MEDIEVAL have been contributed to the task group. Finally, part of the work performed in FLAVIA was presented at the Next Wireless Generation Steering Committee (NWG SC), and was received positively.Mechanism to support DMM through IEEE 802.21IEEEpu
A Case for Packet Deflection in Structured Wireless Topologies
No full textISBN: 978-1-4673-0010-0We promote the idea of deflecting packets in a structured wireless mesh deployment. In any wireless network, upon arrival of new packets when the sources and destinations are selected uniformly the majority of traffic goes through the center of the network, while the edges are underutilized. This situation becomes more apparent in a structured mesh deployment. We demonstrate that the throughput could be improved by deflecting packets away from the congested part of the network and towards the underutilized parts. We develop a simple routing protocol that allows network nodes to deflect packets. We demonstrate that the performance of deflection routing improves as the network size increases. Our extensive simulations show that despite of its simplicity deflection routing not only outperforms conventional shortest path routing but newly developed and complex opportunistic routing mechanisms as well. Our simulations show that for a moderate size network, deflection routing gives 51% higher throughput than the conventional routing mechanism, when a newly arrived packet selects its source and destination uniformly.TRUEpu
Deterministic Recurrent Communication and Synchronization in Restricted Sensor Networks
Get PDFMonitoring physical phenomena in Sensor Networks requires guaranteeing permanent communication between nodes.
Moreover, in an effective implementation of such infrastructure, the delay between any two consecutive communications should be minimized. The problem is challenging because, in a restricted Sensor Network, the communication is carried out through a single and shared radio channel without collision detection. Dealing with collisions is crucial to ensure effective communication between nodes. Additionally, minimizing them yields energy consumption minimization, given that sensing and computational costs in terms of energy are negligible with respect to radio communication. In this work, we present a deterministic recurrent-communication protocol for Sensor Networks. After an initial negotiation phase of the access pattern to the channel, each node running this protocol reaches a steady state, which is asymptotically optimal in terms of time efficiency, and optimal (0) or constant (for a worst-case adversary) in terms of transmissions overhead, which we use as energy efficiency metric. As a by-product, a protocol for the synchronization of a Sensor Network is also proposed. Furthermore, the protocols are resilient to an arbitrary node power-up schedule and a general node failure model.TRUEpu
Empirical characterization of Internet Exchange Points
Get PDFToday's public Internet eXchange Points (IXP) are an important factor in the Internet ecosystem, nevertheless, despite their importance, the community still lacks empirical data on the nature of the traffic exchanged through IXPs. We strive in obtaining a deeper understanding of exchange points by closely examining the history of a typical regional European IXP: the Slovakian-IX.
By crawling the web archive we obtained several snapshots of the Slovak-IXP website from the last 14 years. This historical data allows us to study the dynamics of the IXP in terms of: the (low-tier) AS-level topology, the traffic dynamics, the port capacity and the traffic matrix. Our datasets show that, different from Customer-Provider links, peering links are very stable as we observe that once they are created they are very unlikely to disappear. After the proliferation of content service providers in 2006, the traffic profiles of the ISPs peering at the IXP experienced significant changes reflected in the extreme growth of the content ISPs traffic and heavily imbalanced traffic ratios. An analysis on the distribution of traffic of the IXP hints that since the beginning of SIX a small fraction of heaviest peering pairs carry the majority of the SIX traffic while most of the peering pairs exchange very low amount of traffic and hence enjoy close-to-zero monetary gain.
We strongly believe that in contrast with confidential datasets typically used in studying the Internet traffic characteristics, IXP's data provide rich and publicly available resources crucial for understanding various aspects of the Internet.Telematics EngineeringUniversidad Carlos III de Madrid, Spainpu
Obscure Giants: Detecting the Provider-Free ASes
Get PDFWe study the detection of the provider-free AS set (PFS),
i.e., the set of those Autonomous Systems (ASes) that
reach the entire Internet without paying anyone for the
traffic delivery. Using trustworthy but non-verifiable sources for sanity checks, we derive the PFS from public datasets of inter-AS economic relationships. Whereas a straightforward method for extracting the PFS performs
poorly because the datasets are noisy, we develop a more
sophisticated Temporal Cone (TC) algorithm that relies
on topological statistics and exploits the temporal diver-
sity of the datasets. The evaluation shows that our TC
algorithm detects the PFS with a high accuracyTelematics EngineeringUniversidad Carlos III de Madrid, Spainpu
Qoe-based transport optimization for video delivery over next generation cellular networks
Get PDFVideo streaming is considered one of the most important
and challenging application for next generation cellular
networks. Current infrastructures are not prepared to deal with the increasing amount of video traffic. The current Internet, and in particular the mobile Internet, was not designed with video requirements in mind and, as a consequence, its architecture is very inefficient for handling video traffic. Enhancements are needed to cater for improved Quality of Experience (QoE) and improved reliability in a mobile network. In this paper we design
a novel dynamic transport architecture for next generation mobile networks adapted to video service requirements. Transport optimization of video delivery is achieved through a Quality of Experience (QoE) oriented redesign of networking mechanisms as well as the integration of Content Delivery Networks (CDN) techniques.TRUEpu
Energy-efficient fair channel access for IEEE 802.11 WLANs
Get PDFGreening the communication protocols is nowadays recognized as a primary design goal of future global network infrastructures. The objective function for optimization is the amount of information transmitted per unit of energy, replacing the amount of information transmitted per unit of time (i.e., throughput). In this paper we investigate the case of IEEE 802.11-based WLANs and first show that, given the existing diversity of power consumption figures among mobile devices, performing a fair allocation of resources among devices is challenging. We then propose a criterion to objectively balance between the most energy-efficient configuration (where all resources are given to the single most energy efficient device) and the throughput-optimal allocation (where all devices evenly share the resources regardless of their power consumption). By means of analytical modeling, we derive a closed-form expression for the optimal configuration of the WLANs with respect to the energy-efficiency criterion. We validate our analysis through simulations, and show that our approach betters the prevalent allocation schemes discussed in literature in terms of energy efficiency, while maintaining the notion of fairness among competing devices.TRUEpu
Practical adaptive user association policies for wireless systems with dynamic interference
Get PDFWe study the impact of user association policies on flow-level performance in interference-limited wireless networks. Most research in this area has used static interference models(neighboring base stations are always active) and resorted to intuitive objectives such as load balancing. In this paper, we show that this can be counterproductive in the presence of dynamic interference which couples the transmission rates to users at various base stations. We propose a methodology to optimize the performance of a class of coupled systems, and apply it to
study the user association problem. We show that by properly
inducing load asymmetries, substantial performance gains can
be achieved relative to a load balancing policy (e.g., 15 times reduction in mean delay). We present a practical, measurement-based, interference-aware association policy that infers the degree of interference-induced coupling and adapts to it. Systematic simulations establish that both our optimized static and adaptive association policies substantially outperform various dynamic policies which can, in extreme cases even be susceptible to Braess’s paradox like phenomena, i.e., an increase in the number
of base stations can lead to worse performance under greedy
association policies. Further, these results are robust to changes in file size distributions, large-scale propagation parameters, and spatial load distributions.TRUEpu
Algorithmic Mechanisms for Internet Supercomputing under Unreliable Communication
Get PDFThis work, using a game-theoretic approach, considers
Internet-based computations, where a master processor
assigns, over the Internet, a computational task to a set of
untrusted worker processors, and collects their responses. The master must obtain the correct task result, while maximizing its benefit. Building on prior work, we consider a framework where altruistic, malicious, and rational workers co-exist. In addition, we consider the possibility that the communication between the master and the workers is not reliable, and that workers could be unavailable; assumptions that are very realistic for Internet-based master-worker computations. Within this framework, we design and analyze two algorithmic mechanisms that provide, when necessary, appropriate incentives to rational workers to act correctly, despite the malicious’ workers actions
and the unreliability of the network. These mechanisms are
then applied to two realistic Internet-based master-worker
settings, a SETI-like one and a contractor-based one, such as Amazon’s mechanical turk.TRUEpu