IMDEA Networks Institute Digital Repository
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1915 research outputs found
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α-OMC: Cost-Aware Deep Learning for Mobile Network Resource Orchestration
Get PDFOrchestrating resources in 5G and beyond-5G systems will be substantially more complex than it used to be in previous generations of mobile networks. In order to take full advantage of the unprecedented possibilities for dynamic reconfiguration offered by network softwarization and virtualization technologies, operators have to embed intelligence in network resource orchestrators. We advocate that the automated, data-driven decisions taken by orchestrators must be guided by considerations on the cost that such decisions involve for the operator. We show that such a strategy can be implemented via a deep learning architecture that forecasts capacity rather than plain traffic, thanks to a novel loss function named α-OMC. We investigate the convergence properties of α-OMC, and provide preliminary results on the performance of the learning process in case studies with real-world mobile network traffic.TRUEpu
Robust Distributed Monitoring of Traffic Flows
No full textScalable monitoring of traffic flows faces challenges
posed by unrelenting traffic growth, device heterogeneity, and load unevenness. We explore an approach that tackles 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 to a lightly loaded element might be infeasible because execution on multiple elements is inherent in the task or requires at least
partial participation by the particular overloaded element (e.g., flow-size computation at the ingress element for billing purposes). Distributed execution of a stateful traffic-monitoring task has to be robust against packet reordering or loss, i.e., network noise. This paper designs robust traffic monitoring where the goal is to
determine a flow metric for each flow exactly in spite of network noise. We follow the open-loop paradigm that does not add any control packets, communicates flow state in-band by appending few (on the order of 2 or 4) control bits to packets of the monitored flows, and keeps latency low. We consider the task of flow-size computation, analytically derive conditions assuring correct operation of the designed algorithms, and evaluate the algorithms on realistic traffic traces. The algorithms successfully
distribute the monitoring-task load without imposing significant computation or storage overhead.TRUEpu
How to deal with range-based packet classifiers
Get PDFEfficient representations of multi-field packet classifiers with fields represented by ranges is a core mechanism to express services on data plane. To implement classifiers in ternary addressable memory (TCAM), each range should be encoded into multiple ternary bit strings whose number is at most linear to the width (in bits) of a represented field independently from range encoding method. In this paper we introduce a notion of a subrange allowing to represent a field range on any chosen subset of bit indices that significantly improve efficiency of classifier representations. Our analytic results are confirmed with a comprehensive evaluation study showing applicability of our approach to implement desired levels
of expressiveness and scalability in packet classifiers.TRUEpu
Q-Tag: A transparent solution to measure ads viewability rate in online advertising campaigns
No full textThe viewability standard defines the visibility conditions that an ad impression has to meet (e.g., 1 second and 50% of the pixels for display ads) to achieve the sufficient marketing effect to be considered viewed. Viewability is one of the most important metrics used by advertisers and ad-tech stakeholders to measure the performance quality of ad campaigns.
The ad-tech industry offers opaque measures of viewability whose performance is questionable. To address this issue, we propose a novel methodology for measuring viewability in ad campaigns. The disclosure of the functional details of this technique and the availability of the code makes it reproducible and auditable. Our solution has been deployed in production by a Demand Side Platform (DSP) to measure
the viewability rate of its ad campaigns. Leveraging the infrastructure of this DSP, we have compared the performance of our methodology with a popular commercial solution. Both techniques report a similar overall viewability rate of 50%.
However, our solution can measure the viewability in 93% of the served ads by the DSP, in contrast to 74% measured ads by the commercial solution. A ballpark estimation indicates that this significant increase of the measured ads rate may translate into a revenue increase of $3.5 million per year for a mid-size DSP serving 100M ads per day.TRUEpu
Analysis and Performance Improvement of Consumer-Grade Millimeter Wave Wireless Networks
Get PDFMillimeter-wave (mmWave) networks are one of the main key components in next cellular and WLANs (Wireless Local Area Networks). mmWave networks are capable of providing multi gigabit-per-second rates with very directional low-interference and high spatial reuse links. In 2013, the first 60 GHz wireless solution for WLAN appeared in the market. These were wireless docking stations under the WiGig protocol. Today, in 2019, 60 GHz communications have gained importance with the IEEE 802.11ad amendment with different products on the market, including routers, laptops and wireless Ethernet solutions. More importantly, mmWave networks are going to be used in next generation cellular networks, where smartphones will be using the 28 GHz band. For backbone links, 60 GHz communications have been proposed due to its higher directionality and unlicensed use. This thesis fits in this frame of constant development of the mmWave bands to meet the needs of latency and throughput that will be necessary to support future communications. In this thesis, we first characterize the cost-effective design of COTS (commercial off-the-shelf) 60 GHz devices and later we improve their two main weaknesses, which are their low link distance and their non-ideal spatial reuse.
It is critical to take into consideration the cost-effective design of COTS devices when designing networking mechanisms. This is why in this thesis we do the first-of-its-kind COTS analysis of 60 GHz devices, studying the D5000 WiGig Docking station and the TP-Link Talon IEEE 802.11ad router. We include static measurements such as the synthesized beam patterns of these devices or an analysis of the area-wide coverage that these devices can fulfill. We perform a spatial reuse analysis and study the performance of these devices under user mobility, showing how robust the link can be under user movement. We also study the feasibility of having flying mmWave links. We mount a 60 GHz COTS device into a drone and perform different measurement campaigns. In this first analysis, we see that these 60 GHz devices have a large performance gap for the achieved communication range as well as a very low spatial reuse. However, they are still suitable for low density WLANs and for next generation aerial micro cell stations.
Seeing that these COTS devices are not as directional as literature suggests, we analyze how channels are not as frequency stable as expected due to the large amount of reflected signals. Ideally, frequency selective techniques could be used in these frequency selective channels in order to enlarge the range of these 60 GHz devices. To validate this, we measure real-world 60 GHz indoor channels with a bandwidth of 2 GHz and study their behavior with respect to techniques such as bitloading, subcarrier switch-off, and waterfilling. To this end, we consider a Orthogonal Frequency-Division Multiplexing (OFDM) channel as defined in the IEEE 802.11ad standard and show that in point of fact, these techniques are highly beneficial in mmWave networks allowing for a range extension of up to 50%, equivalent to power savings of up to 7 dB.
In order to increase the very limited spatial reuse of these wireless networks, we propose a centralized system that allows the network to carry out the beam training process not only to maximize power but also taking into account other stations in order to minimize interference. This system is designed to work with unmodified clients. We implement and validate our system on commercial off-the-shelf IEEE 802.11ad hardware, achieving an average throughput gain of 24.67% for TCP traffic, and up to a twofold throughput gain in specific cases.Signal Theory and CommunicationsUniversidad Carlos III de Madrid, Spainpu
Atomic Appends: Selling Cars and Coordinating Armies with Multiple Blockchains
No full textIn this work we examine the fundamental problem of interoperable and interconnected blockchains. In particular, we begin by introducing the Multi-Distributed Ledger Objects (MDLO), which is the result of aggregating multiple Distributed Ledger Objects – DLO (a DLO is a formalization of the blockchain) and that supports append and get operations of records (e.g., transactions) in them from multiple clients concurrently. Next we define the AtomicAppends problem, which emerges when the exchange of digital assets between multiple clients may involve appending records in more than one DLO. We examine the solvability of this problem assuming rational and risk averse clients that may fail by crashing, and under different client utility and append models, timing models, and client failure scenarios. We show that for some cases the existence of an intermediary is necessary for the problem solution. We propose the implementation of such intermediary over a specialized blockchain, we term Smart DLO (SDLO), and we show how this can be used to solve the AtomicAppends problem even in an asynchronous, client competitive environment, where all the clients may crash.FALSEpu
Bathymetry-aided Underwater Acoustic Localization using a Single Passive Receiver
Get PDFThis paper considers the problem of estimating the trajectory of an autonomous underwater vehicle (AUV) via a single passive receiver, without any anchor nodes or receiving arrays, and with the only help of a sequence of known acoustic signals emitted by the AUV. This scenario is of interest in case multilateration-based alternatives would require the deployment of many receivers and imply exceedingly high costs, e.g., for the coverage of wide areas.
The proposed method exploits the knowledge of environmental parameters such as the sound speed profile, bathymetry and bottom sediments in order to estimate the location of the AUV, taking advantage of the spatial dependency of channel impulse responses that arises from the diverse bathymetry around the receiver. This dependency is captured by comparing channel estimates against a database of channel responses, pre-computed through an acoustic propagation model. This yields multiple likely AUV locations, which are filtered via a path tracking method similar to the Viterbi algorithm, in order to estimate the trajectory of the AUV.
Results obtained both from simulations and from a sea experiment show that the proposed method can estimate node locations and paths with a small error, especially considering the use of a single receiver.pu