IMDEA Networks Institute Digital Repository
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1915 research outputs found
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Second minimum approximation for Min-Sum decoders suitable for high-rate LDPC codes
Get PDFIn this paper a method to approximate the second-minimum required in the computation of the check node update of an LDPC decoder based on Min-sum algorithm is presented. The proposed approximation compensates the performance degradation caused by the utilization of a first-minimum and pseudo second-minimum finder instead of a true two-minimum finder in the Min-sum algorithm and improves the BER performance of high-rate LDPC codes in the error floor region. This approach applied to a complete decoder reduces the critical path and the area with independence of the selected architecture. Therefore, this method increases the maximum throughput achieved by the decoder and its area-throughput efficiency. The increase of efficiency is proportional to the degree of the check node, so the higher the code rate is, the higher the improvement in area and speed is.pu
DeepFloat: Resource-Efficient Dynamic Management of Vehicular Floating Content
Get PDFOpportunistic communications are expected to play a crucial role in vehicular services that are based on location and require extremely low latency. A widely investigated opportunistic communication paradigm for the local dissemination of contextualized information is Floating Content (FC), which tries to make content float over a geographical area by replicating it whenever two users meet. The key Quality of Service (QoS)indicator for FC is content availability, defined as the fraction of users that received the information that is supposed to float.
Optimizing the use of FC resources while meeting the availability target QoS is a highly complex issue. Fully distributed, distance-based approaches proved to be highly inefficient, and may not meet the target QoS. Centralized, model-based approaches do not perform well in realistic inhomogeneous settings.
In this work, we present a data-driven centralized approach to resource-efficient, QoS-aware dynamic management of FC. We propose a Deep Learning strategy for FC operation, which employs a Convolutional Neural Network (CNN) to capture the relations between the patterns of users mobility, the patterns of content diffusion and replication, and the performance of FC in terms of resource efficiency and availability within a given Zone of Interest (ZOI).
Numerical evaluations show the effectiveness of our approach, as well as the capability of our approach to adapt to mobility pattern changes over time.TRUEpu
The Impact of Human Mobility on Edge Data Center Deployment in Urban Environments
Get PDFMulti-access Edge Computing (MEC) brings storage and computational capabilities at the edge of the network
into so-called Edge Data Centers (EDCs) to better low-latency applications. To this end, effective placement of EDCs in urban environments is key for proper load balance and to minimize outages. In this paper, we specifically tackle this problem. To fully understand how the computational demand of EDCs varies, it is fundamental to analyze the complex dynamics of cities. Our work takes into account the mobility of citizens and their spatial patterns to estimate the optimal placement of MEC EDCs in urban environments in order to minimize outages. To this end, we propose and compare two heuristics. In particular, we present the mobility-aware deployment algorithm (MDA) that outperforms approaches that do not consider citizens mobility. Simulations are conducted in Luxembourg City by extending the CrowdSenSim simulator and show that efficient EDCs placement significantly reduces outages.TRUEpu
Atomic Appends: Selling Cars and Coordinating Armies with Multiple Distributed Ledgers
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Measuring the Global Recursive DNS Infrastructure: A View From the Edge
No full textThe Domain Name System (DNS) is one of the most critical Internet subsystems. While the majority of ISPs deploy and operate their own DNS infrastructure, many end users resort to third-party DNS providers with hopes of enhancing their privacy, security, and web performance. However, bad user choices and the uneven geographical deployment of DNS providers could render insecure and inefficient DNS configurations for millions of users. In this paper, we propose a novel and flexible measurement method to (1) study the infrastructure of recursive DNS resolvers, including both ISP's and third-party DNS providers' deployment strategies; and (2) study end-user DNS choices, both in a timely manner and at a global scale. For that, we leverage the outreach capacity of online advertising networks to distribute lightweight JavaScript-based DNS measurement scripts. To showcase the potential of our technique, we launch two separate ad campaigns that triggered more than 3M DNS lookups, which allow us to identify and study more than 76k recursive DNS resolvers giving support to more than 25k eyeball ASes in 178 countries. The analysis of the data offers new insights into the DNS infrastructure, such as user preferences towards third-party DNS providers (namely, Google, OpenDNS, Level3, and Cloudflare recursive DNS resolvers account for ~13% of the total DNS requests triggered by our campaigns), and into deployment decisions of many ISPs providing both mobile and fixed access networks to separate the DNS infrastructure serving each type of access technology.pu
A Survey on Mobile Crowdsensing Systems: Challenges, Solutions, and Opportunities
Get PDFMobile crowdsensing (MCS) has gained significant attention in recent years and has become an appealing paradigm for urban sensing. For data collection, MCS systems rely on contribution from mobile devices of a large number of participants or a crowd. Smartphones, tablets, and wearable devices are deployed widely and already equipped with a rich set of sensors, making them an excellent source of information. Mobility and intelligence of humans guarantee higher coverage and better context awareness if compared to traditional sensor networks. At the same time, individuals may be reluctant to share data for privacy concerns. For this reason, MCS frameworks are specifically designed to include incentive mechanisms and address privacy concerns. Despite the growing interest in the research community, MCS solutions need a deeper investigation and categorization on many aspects that span from sensing and communication to system management and data storage. In this paper, we take the research on MCS a step further by presenting a survey on existing works in the domain and propose a detailed taxonomy to shed light on the current landscape and classify
applications, methodologies and architectures. Our objective is not only to analyze and consolidate past research but also to outline potential future research directions and synergies with other research areas.pu
How does Google know my gender if I didn't say it? Measuring how Google infers the gender of the users
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Li-Tect: 3D Monitoring and Shape Detection using Visible Light Sensors
Get PDFIn this paper, we propose Li-Tect, an algorithm to detect the shape of an object located in an indoor environment using low cost optical elements through sensing the environment's light. The algorithm analyzes, relying on the predictability of optical propagation paths, how much light is expected to propagate in the absence of obstructions caused by the presence of an object. Then, based on the received light when the object is in the room, the algorithm infers the shape of the object. In addition, the algorithm considers the reflected paths from surfaces in order to determine the object's estimated shape. We study five different scenarios characterized by different levels of complexity, room sizes and a range of reflection nodes. The algorithm is also tested in a real prototype where several experiments are carried out in two scenarios to demonstrate the capabilities of Li-Tect in two and three dimensional monitoring and shape detection cases. Finally, the results show that the shape and the detection of objects in the scenarios can be easily acquired with high accuracy, even if the number of transceivers is reduced.pu