IMDEA Networks Institute Digital Repository
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1915 research outputs found
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Location-aware Wireless Resource Allocation in Industrial-like Environment
Get PDFThe advent of the fourth Industrial Revolution (Industry 4.0) requires wireless networked solutions to connect machines. However, the industrial environment is notorious for being averse to wireless communication, with traditional wireless resource mechanisms prone to errors because of metallic objects. In this work, we propose to exploit the knowledge of location to derive context
information and dynamically allocate wireless resources in time and space to target devices. We exploit the spatial geometry of the Access Points (APs) and we introduce a statistical model that maps the user position’s spatial distribution to an angle error distribution and derive a hypothesis test to declare if the link is under metallic blockage or not. In order to avoid changes to the client side and operate with a single interface radio, we use the same wireless network both for positioning and scheduling. We experimentally show that our system can localize four mobile robots deployed in a very harsh environment with metal obstacles and reflections. Context information applied to wireless resources protocol help increasing up to 40% of the network throughput in the above industrial-like scenario.pu
IoTLS: Understanding TLS Usage in Consumer IoT Devices
Get PDFConsumer IoT devices are becoming increasingly popular, with
most leveraging TLS to provide connection security. In this work,
we study a large number of TLS-enabled consumer IoT devices to
shed light on how effectively they use TLS, in terms of establishing
secure connections and correctly validating certificates, and how
observed behavior changes over time. To this end, we gather more
than two years of TLS network traffic from IoT devices, conduct
active probing to test for vulnerabilities, and develop a novel black-
box technique for exploring the trusted root stores in IoT devices
by exploiting a side-channel through TLS Alert Messages. We find a
wide range of behaviors across devices, with some adopting best
security practices but most being vulnerable in one or more of
the following ways: use of old/insecure protocol versions and/or
ciphersuites, lack of certificate validation, and poor maintenance
of root stores. Specifically, we find that at least 8 IoT devices still
include distrusted certificates in their root stores, 11/32 devices are
vulnerable to TLS interception attacks, and that many devices fail
to adopt modern protocol features over time. Our findings motivate
the need for IoT manufacturers to audit, upgrade, and maintain
their devices’ TLS implementations in a consistent and uniform
way that safeguards all of their network traffic.USA NSFEU H2020Spanish Ministry of ScienceConsumer ReportsTRUEinpres
Robust Distributed Monitoring of Traffic Flows
Get PDFUnrelenting traffic growth, device heterogeneity, and load unevenness create scalability challenges for traffic monitoring. In this paper, we propose Robust Distributed Computation (RoDiC), a new approach that addresses these challenges by shifting a portion of the monitoring-task execution from an overloaded network element to another element that has spare resources. Moving the entire execution of the task away from the overloaded element might be infeasible because execution on multiple elements is inherent in the task or requires at least partial participation by the designated overloaded element. Furthermore, distributed execution of a stateful task has to be resilient to network noise in the form of packet reordering and loss. The RoDiC approach relies on two main principles of packet grouping and state overlap to support exact robust distributed monitoring of traffic flows under network noise. RoDiC uses an open-loop paradigm that does not add any control packets, communicates flow state in-band by appending few control bits to packets of monitored flows, and keeps measurement latency low. We apply RoDiC to the problem of flow-size computation and discuss how to instantiate our general technique for real-time packet-loss telemetry. The paper develops robust algorithms, proves their correctness and performance properties, and reports an evaluation driven by realistic traffic traces. The RoDiC algorithms successfully distribute the monitoring-task load while keeping the memory and computation overhead low.pu
802.11ad in Smartphones: Energy Efficiency,vSpatial Reuse, and Impact on Applications
Get PDFWe present an extensive experimental evaluation of the performance and power consumption of the 60 GHz
IEEE 802.11ad technology on commercial smartphones. We also compare 802.11ad against its main competitors in the 5 GHz band – 802.11ac and, for first time, 802.11ax, on mobile devices. Our performance comparison focuses on two aspects that have not been extensively studied before: (i) dense multi-client and multi-AP topologies and (ii) popular mobile applications under realistic mobility patterns. Our power consumption study covers both non-communicating and communicating modes. We also present the first study of the power saving mode in 802.11ad-enabled smartphones and its impact on performance. Our results show that 802.11ad is better able to address the needs of emerging bandwidth-intensive applications in smartphones than its 5 GHz counterparts. At the same time, we identify several key research directions towards realizing its full potential.TRUEpu
Fragmented Objects: Boosting Concurrency of Shared Large Objects
Get PDFThis work examines strategies to handle large shared data objects in distributed storage systems (DSS), while boosting the number of concurrent accesses, maintaining strong consistency guarantees, and ensuring good operation performance. To this respect, we define the notion of fragmented objects: concurrent objects composed of a list of fragments (or blocks) that allow operations to manipulate each of their fragments individually. As the fragments belong to the same object, it is not enough that each fragment is linearizable to have useful consistency guarantees in the composed object. Hence, we capture the consistency semantic of the whole object with the notion of fragmented linearizability. Then, considering that a variance of linearizability, coverability, is more suited for versioned objects like files, we provide an implementation of a distributed file system, called CoBFS, that utilizes coverable fragmented objects (i.e., files). In CoBFS, each file is a linked-list of coverable block objects. Preliminary emulation of CoBFS demonstrates the potential of our approach in boosting the concurrency of strongly consistent large objects.TRUEpu
Detecting and classifying outliers in big functional data
Get PDFWe propose two new outlier detection methods, for identifying and classifying different
types of outliers in (big) functional data sets. The proposed methods are based on an
existing method called Massive Unsupervised Outlier Detection (MUOD). MUOD
detects and classifies outliers by computing for each curve, three indices, all based
on the concept of linear regression and correlation, which measure outlyingness in
terms of shape, magnitude and amplitude, relative to the other curves in the data.
‘Semifast-MUOD’, the first method, uses a sample of the observations in computing
the indices, while ‘Fast-MUOD’, the second method, uses the point-wise or L1 median
in computing the indices. The classical boxplot is used to separate the indices of
the outliers from those of the typical observations. Performance evaluation of the
proposed methods using simulated data show significant improvements compared to
MUOD, both in outlier detection and computational time. We show that Fast-MUOD
is especially well suited to handling big and dense functional datasets with very small
computational time compared to other methods. Further comparisons with some recent
outlier detection methods for functional data also show superior or comparable outlier
detection accuracy of the proposed methods. We apply the proposed methods on
weather, population growth, and video data.Department of Education and Research of the Regional Government of MadridTRUEpu
Experimental assessment of IEEE 802.11-based V2I communications
Get PDFConnected and automated vehicles are becoming a reality, and the necessity of assessing the performance of their technical enablers plays a pivotal role in the automotive field. Several technologies
have been proposed by different standardization bodies, with the aim of enabling the connectivity between vehicles, and between vehicles and the infrastructure. Before the deployment of any technology, it is fundamental to perform a testing and validation phase, which is often performed in simulation environments. However, in order to assess the actual performance of a V2X (Vehicle-toEverything) communication technology, field tests are of utmost importance. In this paper, we present the results of an extensive field test campaign of non-mmWave and mmWave IEEE 802.11 technologies for V2I (Vehicle-to-Infrastructure) communications, namely, IEEE 802.11p, IEEE 802.11ac, and IEEE 802.11ad. We assess
the performance of each of them, in terms of connection stability, received signal level, Round Trip Time and UDP throughput, in both Line-Of-Sight and Non-Line-Of-Sight conditions. Our results show
that, although not specifically designed for vehicular communications, IEEE 802.11ac and IEEE 802.11ad emerge as very promising technologiesTRUEpu
An experimental publish-subscribe monitoring assessment to Beyond 5G networks
Get PDFThe fifth generation (5G) of mobile networks is designed to accommodate different types of use cases, each of them with different and stringent requirements and key performance indicators (KPIs). To support the optimization of the network performance and validation of the KPIs, there exist the necessity of a flexible and efficient monitoring system and capable of realizing multi-site and multi-stakeholder scenarios. Nevertheless, for the evolution from 5G to 6G, the network is envisioned as a user-driven, distributed Cloud computing system where the resource pool is foreseen to integrate the participating users. In this paper, we present a distributed monitoring architecture for Beyond 5G multi-site platforms, where different stakeholders share the resource pool in a distributed environment. Taking advantage of the usage of publish-subscribe mechanisms adapted to the Edge, the developed lightweight monitoring solution can manage large amounts of real-time traffic generated by the applications located in the resource pool. We assess the performance of the implemented paradigm, revealing some interesting insights about the platform, such as the effect caused by the throughput of monitoring data in performance parameters such as the latency and packet loss, or the presence of a saturation effect due to software limitations that impacts in the performance of the system under specific conditions. In the end, the performance evaluation process has confirmed that the monitoring platform suits the requirements of the proposed scenarios, being capable of handling similar workloads in real 5G and Beyond 5G scenarios, then discussing how the architecture could be mapped to these real scenarios.pu
Principles of Blockchain Systems
No full textThis book is the first to present the state of the art and provide technical focus on the latest advances in the foundations of blockchain systems. It is a collaborative work between specialists in cryptography, distributed systems, formal languages, and economics, and addresses hot topics in blockchains from a theoretical perspective: cryptographic primitives, consensus, formalization of blockchain properties, game theory applied to blockchains, and economical issues.
This book reflects the expertise of the various authors, and is intended to benefit researchers, students, and engineers who seek an understanding of the theoretical foundations of blockchains.TRUEpu
