IMDEA Networks Institute Digital Repository
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Better Together: Collaborative Monitoring for Location-based Services
No full textMobile applications increasingly rely on frequent and accurate position updates-e.g., with GPS-or Wi-Fi-assisted localization techniques-to provide for functionality to their users. The service quality and acceptance of the application depend strongly on the localization accuracy and the introduced costs, in form of the resource consumption, of the used localization technique. Current mechanisms for location retrieval, however, are limited to non-mobile scenarios or still introduce high costs while obtaining the location. In this work, we propose a collaborative location retrieval service for location-based services in mobile scenarios that combines the location information of a subset of users with the connectivity information between users to enable accurate and cost-efficient location estimations. We evaluate a prototype of our solution to study the impact of service compositions in changing environments and to assess the potential of our proposed service compared to the current state-of-the-art used within location-based services. Our results reveal that, depending on the localization technique, the costs can be reduced significantly while the achieved sensing accuracy and fairness among users improves strongly at the same time.TRUEpu
How should I slice my network? A multi-service empirical evaluation of resource sharing efficiency
Get PDFBy providing especially tailored instances of a virtual network,network slicing allows for a strong specialization of the offered services on the same shared infrastructure. Network slicing has profound implications on resource management, as it entails an inherent trade-off between: (i) the need for fully dedicated resources to support service customization, and (ii) the dynamic resource sharing among services to increase resource efficiency and cost-effectiveness of the system. In this paper, we provide a first investigation of this trade-off via an empirical study of resource management efficiency in network slicing. Building on substantial measurement data collected in an operational mobile network (i) we quantify the efficiency gap introduced by non-reconfigurable allocation strategies of different kinds of resources, from radio access to the core of the network, and (ii) we quantify the advantages of their dynamic orchestration at different timescales. Our results provide insights on the achievable efficiency of network slicing architectures, their dimensioning, and their interplay with resource management algorithms.TRUEpu
Tracking mm-Wave Channel Dynamics: Fast Beam Training Strategies under Mobility
Get PDFIn order to cope with the severe path loss, millimeter-wave (mm-wave) systems exploit highly directional communication. As a consequence, even a slight beam misalignment between two communicating devices (for example, due to mobility) can generate a significant signal drop. This leads to frequent invocations of time-consuming mechanisms for beam re-alignment, which deteriorate system performance. In this paper, we propose smart beam training and tracking strategies for fast mm-wave link establishment and maintenance under node mobility. We leverage the ability of hybrid analog-digital transceivers to collect channel information from multiple spatial directions simultaneously and formulate a probabilistic optimization problem to model the temporal evolution of the mm-wave channel under mobility. In addition, we present for the first time a beam tracking algorithm that extracts information needed to update the steering directions directly from data packets, without the need for spatial scanning during the ongoing data transmission. Simulation results, obtained by a custom simulator based on ray tracing, demonstrate the ability of our beam training/tracking strategies to keep the communication rate only 10% below the optimal bound. Compared to the state of the art, our approach provides a 40% to 150% rate increase, yet requires lower complexity hardware.TRUEpu
A Privacy-Preserving Distributed Medical Insurance Claim Clearinghouse & EHR Application
No full textDOI: 10.1109/CHASE.2017.62In this paper we introduce a distributed approach to storing and processing electronic health records along with a distributed insurance claims clearinghouse. The fundamental assumption governing our work is that every system can and will be compromised, therefore, our approach improves privacy by mitigating the effect of an attack on the system when components are hacked or otherwise compromised. This improvement is achieved by separating the patient's identity from their medical and demographic data and also splitting the clearinghouse processing of the CMS-1500 insurance claim form across six processing units, these processing units are autonomous and anonymous to one another, however, are able collaborate on a common task. We use Shannon entropy to compare the performance of this distributed application to a centralized one, Shannon entropy is a measure of the information stored in the system and the information divulged when components are compromised. This distributed approach reduces the amount of entropy eliminated in the event of an attack on the clearinghouse by approximately 79%. We also compare our approach to the MyPHRMachines architecture. In our analyses we assume one component is compromised in the distributed or centralized systems.TRUEpu
Experience: An Open Platform for Experimentation with Commercial Mobile Broadband Networks
Get PDFOpen experimentation with operational Mobile Broadband (MBB) networks in the wild is currently a fundamental requirement of the research community in its endeavor to address the need of innovative solutions for mobile communications. Even more, there is a strong need for objective data about stability and performance of MBB (e.g., 3G/4G) networks, and for tools that rigorously and scientifically assess their status. In this paper, we introduce the MONROE measurement platform: an open access and flexible hardware-based platform for measurements and custom experimentation on operational MBB networks. The MONROE platform enables accurate, realistic and meaningful assessment of the performance and reliability of 11 MBB networks in Europe. We report on our experience designing, implementing and testing the solution we propose for the platform. We detail the challenges we overcame while build- ing and testing the MONROE testbed and argue our design and implementation choices accordingly. We describe and exemplify the capabilities of the platform and the wide variety of experiments that external users already perform using the system.TRUEpu
Data-driven Evaluation of Anticipatory Networking in LTE Networks
Get PDFAnticipatory networking is a recent branch of network optimization that exploits contextual information to improve resource allocation decisions based on prediction. While some anticipatory networking concepts have been proposed in the literature, understanding of the potential real-world gains is so far very limited. Future mobile networks will likely integrate such mechanisms, and thus it is of paramount importance to understand the actual performance improvements and in which scenarios they can be realized. Analyzing a month-worth of LTE control channel information collected in four urban locations, we show how anticipatory networking can enhance current LTE networks. First, we propose a comprehensive optimization framework encompassing different forecasting solutions. Then, we provide a thorough analysis of the aggregated network traffic and the contributions of individual users. In particular, we show that predictable traffic accounts for more than 95% of the total traffic volume and that simple prediction and optimization techniques allow network operators to save 50% of the resources and/or on average more than double the offered data rate in our data set.TRUEpu
LTESS-track: A Precise and Fast Frequency Offset Estimation for low-cost SDR Platforms
Get PDFThe availability of very cheap RTL-SDR "dongle" devices has unleashed the popularity of Software-Defined Radio (SDR) projects in the last years, both among academics and hobbyists. The main success factors are the very affordable price (<25 USD), ease of use and wide availability of open-source SDR software. One important performance aspect of SDR receivers is related to the accuracy and stability of the Local Oscillator (LO). We present LTESS-track, an LO frequency offset evaluation method that relies on the Synchronization Signals (SS) transmitted by LTE base stations as reference. We compare LTESS-track with other publicly available tools for frequency offset estimation and show that our method can perform reliable measurements in less than 1 second, orders of magnitude faster than software publicly available. We leverage LTESS-track to assess the actual LO performances of two popular RTL-SDR models with and without Temperature Controlled Local Oscillator (TCXO). The experimental results show that the latest generation of RTL-SDR (with TCXO), despite being very low cost, has surprising excellent LO stability, well within the maximum tolerance of 1 ppm declared in the specifications.TRUEpu
Formalizing Distributed Ledger Objects
Get PDFIn his PODC’2017 keynote address, Maurice Herlihy pointed out that despite the hype about blockchains and distributed ledgers, no formal abstraction of these objects has been proposed. To face this issue, in this paper we provide a proper formulation of a distributed ledger object. In brief, we define a ledger object as a sequence of records, and we provide the operations and the properties that such an object should support. We then provide a variation of the ledger – the validated ledger – which requires that each record in the ledger satisfies a particular validation rule. A (validated) ledger is distributed if it is implemented on top of multiple (possibly geographically dispersed) computing devices.TRUEpu
Controlled Flooding of Fountain Codes
Get PDFWe consider a multihop network where a source node must reliably deliver a set of data packets to a given destination node. To do so, the source applies a fountain code and floods the encoded packets through the network, until they reach their destination or are lost in the process.
We model the probability that the destination can recover the original transmissions from the received coded packets as a function of the network topology and of the code redundancy, and show that our analytical results predict the outcome of simulations very well.
These results are employed to design distributed forwarding policies that achieve a good tradeoff between the success probability and the total number of transmissions required to advance a packet towards the destination.
We finally develop in detail the case where intermediate relays can inject additional redundancy in the network, provided that they have successfully decoded the source packets.pu