1,720,996 research outputs found
Linear quadratic control of service rate allocation in a satellite network
No full textThe real-time control of multiple queues handling traffic of different nature is obtaining increasing
relevance in both the uplink and downlink of wireless telecommunication networks, characterised by the
presence of a central access point. Such is the case of satellite networks, with either on-board processing or
double-hop configuration, besides a number of terrestrial local and metropolitan wireless networks. Given a
certain amount of available bandwidth, the problem is that of deciding, within a certain time frame, the
allocation of bandwidth partitions for each traffic queue, whose packets are awaiting transmission; eventually,
this determines the transmission rates to be passed to the scheduler and to the physical layer adaptive
coding and modulation devices. In a satellite network, where this task is accomplished by a master station,
residing at the access point, it is possible to take such decisions by means of a centralised controller, based
on real-time instantaneous (in the downstream direction) or delayed (in the upstream) information on the
queues’ state. The study derives a control law to be used in this task, by adopting an approach based on
optimal linear quadratic regulation. Both cases of un-delayed and delayed information are considered. The
control laws are tested in a geo-stationary satellite scenario of digital video broadcasting – return channel via
satellite (DVB-RCS), and the queues are considered at the medium access control level. Simulation results
under real-traffic traces are also presented to highlight the effectiveness of the control and to compare
alternative solutions
Remote detection of indoor human proximity using bluetooth low energy beacons
No full textThe way people interact in daily life is a challenging phenomenon to capture and to study without altering the natural rhythm of interactions. Our work investigates the possibility of automatically detecting proximity among people, the first mandatory condition before a dyad starts interacting. We present Remote Detection of Human Proximity (ReD-HuP), an algorithm based on the analysis of Bluetooth Low Energy beacons emitted by commercial wearable tags. We validate ReD-HuP with real-world indoor settings and we compare its performance with respect to detailed ground truth data collected from a number of volunteers. Experimental results show an accuracy and F-Score metric up to 95%
A Cyber-Physical Approach to Secret Key Generation in Smart Environments
No full textUser activity monitoring is a major problem in ambient assisted living, since it requires to infer new knowledge from collected and fused sensor data while dealing with highly dynamic environments, where devices continuously change their availability and (or) physical location. In the context of the European project PERSONA, we have developed an activity monitoring sub-system characterized by high modularity, little invasiveness of the environment and good responsiveness. In this paper we first illustrate the functional architecture of the proposed solution from a general point of view, discussing the motivations of the design. Then we describe in details the software components—sensor abstraction and integration layer, human posture classification, activity monitor—and the resulting activity monitoring application, presenting also a performance evaluation
User Movements Forecasting by Reservoir Computing using Signal Streams produced by Mote-Class Sensors
No full textImpact of Evolutionary Community Detection Algorithms for Edge Selection Strategies
No full textThe combination of the edge computing paradigm with Mobile CrowdSensing (MCS) is a promising approach. However, the selection of the proper edge nodes is a crucial aspect that greatly affects the performance of the extended architecture. This work studies the performance of an edge-based MCS architecture with ParticipAct, a real-word experimental dataset. We present a community-based edge selection strategy and we measure two key-metrics, namely latency and the number of requests satisfied. We show how they vary by adopting three evolutionary community detection algorithms, TILES, Infomap and iLCD configured by changing several configuration settings. We also study the two metrics, by varying the number of edge nodes selected so that to show its benefit
Automatic virtual Calibration of Range-Based Indoor Localization Systems
No full textThe localization methods based on received signal strength indicator (RSSI) link the RSSI values to the position of the mobile to be located. In the RSSI localization techniques based on propagation models, the accuracy depends on the tuning of the propagation models parameters. In indoor wireless networks, the propagation conditions are hardly predictable due to the dynamic nature of the RSSI, and consequently the parameters of the propagation model may change. In this paper, we present an automatic virtual calibration method of the propagation model that does not require human intervention; therefore, can be periodically performed, following the wireless channel conditions. We also propose a novel RSSI-based localization algorithm that selects the RSSI values according to their strength, and uses a calibrated propagation model to transform these values into distances, in order to estimate the position of the mobile
A Novel Approach to Indoor RSSI Localization by Automatic Calibration of the Wireless Propagation Model
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