IMDEA Networks Institute Digital Repository
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1915 research outputs found
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Robust WiFi Time-of-Flight Positioning System
Get PDFReusing commercial off-the-shelf (COTS) WiFi access
points (AP) for location-based services is an attractive and cost-effective approach to provide the much-needed positioning information in those scenarios where GPS fails. Classical solutions for WiFi-based positioning are based on signalstrength measurements [1]. Relying on signal-strength measurements has well-known limitations, such as the high dependency of the signal propagation with respect to the material of the obstacles between radio devices like walls, doors, etc.TRUEpu
5G radio access above 6 GHz
Get PDFDesigning and developing a millimetre-wave (mmWave)-based mobile radio access technology (RAT) in the 6–100 GHz frequency range is a fundamental component in the standardisation of the new 5G radio interface, recently kicked off by 3rd Generation Partnership Project. Such component herein called the new mmWave RAT will not only enable extreme mobile broadband services but also support ultra-high definition/three-dimensional streaming, offer immersive applications and ultra-responsive cloud services to provide an outstanding quality of experience to the mobile users. The main objective of this paper is to develop the network architectural elements and functions that will enable tight integration of mmWave technology into the overall 5G radio access network. A broad range of topics addressing mobile architecture and network functionalities will be covered–starting with the architectural facets of network slicing, multi-connectivity and cells clustering, to more functional elements of initial access, mobility, radio resource management and self-backhauling. The intention of the concepts presented here is to lay foundation for future studies towards the first commercial implementation of the mmWave RAT above 6 GHz.pu
Adaptive Scheduling over a Wireless Channel under Constrained Jamming
Get PDFWe consider a wireless channel between a single pair of stations (sender and receiver) that is being “watched” and disrupted by a malicious, adversarial jammer. The sender’s objective is to transmit as much useful data as possible, over the channel, despite the jams that are caused by the adversary. The data is transmitted as the payload of packets, and becomes useless if the packet is jammed. In this work, we develop deterministic scheduling algorithms that decide the lengths of the packets to be sent, in order to maximize the total payload successfully transmitted over period T in the presence of up to f packet jams, useful payload.
We first consider the case where all packets must be of the same length and compute the optimal packet length that leads to the best possible useful payload. Then, we consider adaptive algorithms; ones that change the packet length based on the feedback on jammed packets received. We propose an optimal scheduling algorithm that is essentially a recursive algorithm that calculates the length of the next packet to transmit based on the packet errors that have occurred up to that point. We make a thorough non trivial analysis for the algorithm and discuss how our solutions could be used to solve a more general problem than the one we consider.TRUEpu
Per-Frame Energy Consumption in 802.11 Devices and Its Implication on Modeling and Design
Get PDFThis paper provides an in-depth understanding of the per-frame energy consumption behavior in 802.11 wireless LAN devices. Extensive measurements are performed for seven devices of different types (wireless routers, smartphones, tablets, and embedded devices) and for both UDP and TCP traffic. Experimental results unveil that a substantial fraction of energy consumption, hereafter descriptively named cross-factor, may be ascribed to each individual frame while it crosses the protocol stack (OS, driver, NIC) and is independent of the frame size. Our findings, summarized in a convenient energy consumption model, contrast traditional models that (implicitly) amortize such energy cost component in a fixed baseline cost or in a toll proportional to the frame size and raise the alert that, in some cases, conclusions drawn using traditional energy models may be fallacious.pu
Node Sampling using Random Centrifugal Walks
Get PDFA distributed algorithm is proposed for sampling networks, so that nodes are selected by a special node (source), with a given probability distribution. We define a new class of random walks, that we call Random Centrifugal Walks (RCW). A RCW starts at the source and always moves away from it.
The algorithm assumes that each node has a weight, so the nodes are selected with a probability proportional to its weight. It requires a preprocessing phase before the sampling of nodes. This preprocessing is done only once, regardless of the number of sources and the number of samples taken from the network. The length of RCW walks are bounded by the network diameter.
The RCW algorithms that do not require preprocessing are proposed for grids and networks with regular concentric connectivity, for the case when the probability of selecting a node is a function of its distance to the source.pu
A Coupled Processors Model for 802.11 Ad Hoc Networks Under Non Saturation
No full textIn this paper we present an analytic approach to performance analysis of ad hoc networks under non saturation conditions, which does not rely on any assumption on traffic statistics. Our approach assumes traffic to be constrained by leaky bucket arrival curves, and it relies on a coupled processors model to capture the dependencies between user achievable rates due to sharing of the wireless transmission medium. We derive sufficient conditions for stability of transmission queues in an ad hoc network, and we describe a method for the determination of a proportionally fair allocation of resources, which allows trading the fairness of the solution for computational complexity. We validate our results through simulations, showing how our approach allows deriving operating points which both increase the fairness of the allocation, and the overall average utilization of network resources, with respect to saturated models.TRUEinpres
Tools for a Multi-Controller SDN Architecture
Get PDFSoftware Define Network (SDN) is a recent paradigm based on the separation between the data plane and the control plane, allowing to handle the traffic network by means of software. The SDN ecosystem is fragmented due to the multitude of different controller platforms. This creates a danger of a controller lock-in for SDN application developers and for SDN network operator. In order to tackle this problem an innovative SDN architecture is presented whose aim is to execute SDN applications written for different controller in an unique network. This architecture presents an important problem to debug and analyze the SDN network. Therefore, a set of tool is design and developed with the purpose of solving this limitation and guarantee the proper operation of the network. Three of these tools are detailed in depth, a logger which displays the messages that cross the architecture, a profiler that shows information of the applications and parameters of the network and a model checker whose main task is to validate important properties of the network such as assure that there are no black holes.Telematics EngineeringUniversidad Carlos III de Madrid, Spainpu
Deseeding Energy Consumption of Network Stacks
Get PDFAbstract—Regular works on energy efficiency strategies for
wireless communications are based on classical energy models
that account for the wireless card only. Nevertheless, there is a non-negligible energy toll called cross-factor that encompasses the energy drained while a frame crosses the network stack of an OS.
This paper addresses the challenge of deepen into the roots of the cross-factor, deseed its components and analyse its causes. Energy issues are critical for IoT devices. Thus, this paper conceives and validates a new comprehensive framework that enables us to measure a wide range of wireless devices, as well as multiple devices ynchronously. We also present a rigorous methodology to perform whole-device energy measurements in laptops, a more generic and suitable device to perform energy debugging. Finally, and using this framework, we provide a collection of measurements and insights that deepens our understanding
of the cross-factor.TRUEpu
Hiding Mobile Traffic Fingerprints with GLOVE
Get PDFPreservation of user privacy is paramount in the publication of datasets that contain fine-grained information about individuals. The problem is especially critical in the case of mobile traffic datasets collected by cellular operators, as they feature high subscriber trajectory uniqueness and they are resistant to anonymization through spatiotemporal generalization. In this work, we first unveil the reasons behind such undesirable features of mobile traffic datasets, by leveraging an original measure of the anonymizability of users’ mobile fingerprints. Building on such findings, we propose GLOVE, an algorithm that grants k-anonymity of trajectories through specialized generalization. We evaluate our methodology on two nationwide mobile traffic
datasets, and show that it achieves k-anonymity while
preserving a substantial level of accuracy in the data.TRUEpu