2,254 research outputs found
Rainfall Map from Attenuation Data Fusion of Satellite Broadcast and Commercial Microwave Links
Full text linkThe demand for accurate rainfall rate maps is growing ever more. This paper proposes a novel algorithm to estimate the rainfall rate map from the attenuation measurements coming from both broadcast satellite links (BSLs) and commercial microwave links (CMLs). The approach we pursue is based on an iterative procedure which extends the well-known GMZ algorithm to fuse the attenuation data coming from different links in a three-dimensional scenario, while also accounting for the virga phenomenon as a rain vertical attenuation model. We experimentally prove the convergence of the procedures, showing how the estimation error decreases for every iteration. The numerical results show that adding the BSL links to a pre-existent CML network boosts the accuracy performance of the estimated rainfall map, improving up to 50% the correlation metrics. Moreover, our algorithm is shown to be robust to errors concerning the virga parametrization, proving the possibility of obtaining good estimation performance without the need for precise and real-time estimation of the virga parameters
Deep Reinforcement Learning for URLLC data management on top of scheduled eMBB traffic
Full text linkWith the advent of 5G and the research into beyond 5G (B5G) networks, a novel and very relevant research issue is how to manage the coexistence of different types of traffic, each with very stringent but completely different requirements. In this paper we propose a deep reinforcement learning (DRL) algorithm to slice the available physical layer resources between ultra-reliable low-latency communications (URLLC) and enhanced Mobile BroadBand (eMBB) traffic. Specifically, in our setting the time-frequency resource grid is fully occupied by eMBB traffic and we train the DRL agent to employ proximal policy optimization (PPO), a state-of-the-art DRL algorithm, to dynamically allocate the incoming URLLC traffic by puncturing eMBB codewords. Assuming that each eMBB codeword can tolerate a certain limited amount of puncturing beyond which is in outage, we show that the policy devised by the DRL agent never violates the latency requirement of URLLC traffic and, at the same time, manages to keep the number of eMBB codewords in outage at minimum levels, when compared to other state-of-the-art schemes.This work has been submitted to the IEEE for possible publicatio
Power and Subcarrier Allocation in 5G NOMA-FD Systems
No full textIn this article, we study the problem of power and channel allocation for multicarrier non-orthogonal multiple access (NOMA) full duplex (FD) systems. In such a system there are multiple interfering users transmitting over the same channel and the allocation task is a non-convex and extremely challenging problem. Following a block coordinated descent approach, we propose two algorithms based on the decomposition of the original allocation problem in lower-complexity sub-problems, which can be solved in the Lagrangian dual domain with a great reduction of the computational load. Numerical results show the effectiveness of the proposed approach, which outperforms other schemes designed to address NOMA-FD allocation and attains performance similar to the optimal solution with much lower complexity
A quasi-optimal clustering algorithm for MIMO-NOMA downlink systems
Full text linkIn this letter we consider a resource allocation problem for multi-user MIMO non orthogonal multiple access (MU-MIMO-NOMA) downlink transmissions. Under the NOMA paradigm, users are organized in clusters of strong/weak pair and our aim is to find an optimal clustering, beamforming and power allocation scheme to minimize the power transmitted subject to a rate constraint for each user. Since the joint optimization problem is intractable, we split it in three sub-problems: clustering, which is formulated as a mixed integer linear programming (MILP) problem, beamforming and power allocation. Simulations results show that the our proposed scheme greatly outperforms both the classical OMA scheme and state-of-the-art NOMA techniques
Analisi archeozoologiche nei contesti sacri: il caso degli animali di Ascoli – Lu Battente
No full textIl contributo intende trattare l’analisi dei resti ossei di due sepoltue: un suino (Sus domesticus) e un
bovino (Bos taurus), rinvenuti nel 2016 durante lo svolgimento di sondaggi archeologici preventivi
nei pressi di Ascoli, in località Lu Battente. La ricerca è stata condotta ponendo particolare
attenzione al trattamento ed alle modalità di deposizione dei due scheletri, poiché la
documentazione materiale, recuperata a poca distanza dagli animali, suggeriva una connotazione
sacra dell’area, assiduamente frequentata fra la fine del IV e gli inizi del III sec. a.C. I fotopiani e le
foto di dettaglio dei singoli distretti ossei prodotti in fase di scavo sono stati funzionali per
evidenziare la connessione anatomica del suino e le fasi di smembramento del bovino. Tali strategie
di deposizione sono state successivamente osservate in relazione alle dimensioni delle fosse e alle
tracce antropiche riscontrate sui resti ossei, al fine di individuare le cause della morte e il trattamento
delle carcasse. L’analisi delle ossa, in particolare della dentatura, ha permesso di appurare la giovane
età dei due esemplari (6-7 mesi per il suino e 7-10 per il bovino); questo dato ha reso difficile la
determinazione del loro genere, permettendo di avanzare ipotesi solamente per il bovino
3-D Rain Rate Estimation from Integrated Measurements of Commercial Wireless and Satellite Links: an Overview
Full text linkIn the last decade, various algorithms have been developed to provide accurate rainfall maps from measurements
of rain-induced attenuation on commercial wireless links (CWLs).
These solutions are able to give precise results but they also require dense terrestrial microwave networks,
which have non negligible installation and operating costs.
A cheaper alternative for rainfall estimation is represented by broadcast satellites links (BSLs).
However, estimation of the rain-induced attenuation on satellite links requires complex signal processing
techniques, due to the physical structure of these links. Furthermore, to the best of authors’ knowledge, data
provided by satellite links only cannot be used to properly estimate a precise rainfall map of an area.
To overcome these problems, we studied a mixed approach based on data given by both CML and BSL, able
to provide a three-dimensional (3-D) rain rate map of a monitored area.
The proposed joint approach gives us remarkable appealing advantages:
1. Efficiency: both CWLs and BSLs exploit already existing wireless infrastructure, at no extra costs for the
required equipments, the installation and operating conditions.
2. Coverage: CWL coverage can be improved by including satellite terminals already installed at domestic
premises for TV reception. Additionally, more satellite devices can be purposely installed in areas not
adequately covered by terrestrial microwave links, where the deployment of conventional methods of observation,
as rain gauges and weather radars, is impractical.
3. Diversity: measuring the signal levels coming from different links, terrestrial and satellite, provides a
diversity gain which is the key to improve the accuracy and reliability of the overall joint system.
4. Accuracy: the numerical results obtained by simulations corroborate the effectiveness of the proposed
mixed 3-D strategy and quantify the improvements over the conventional systems based on CWLs only.
end{itemize}
Our contribution lies in the description of the data processing schemes developed to retrieve these maps.
In particular, the first part consist in pointing out the problems connected to the satellites links and a signal
processing approach able to provide precise data of estimated rainfall.
Then, a summary of the algorithm will given and preliminary results obtained by the proposed approach will
be presented, in order to show the effectiveness of our approach
3-D Rain Rate Estimation from Integrated Measurements of Commercial Wireless and Satellite Links
Full text linkIn the last decade, various algorithms have been developed to provide accurate rainfall maps from measurements of
rain-induced attenuation on commercial wireless links (CWLs), such as [1]. These solutions provide precise results but
they also require dense terrestrial microwave networks, which have non negligible installation and operating costs. A
cheaper alternative for rainfall estimation is represented by broadcast satellites links (BSLs). However, to the best of
authors’ knowledge, these approaches are able to estimate the rainfall rate on a single point only [2]–[4]. To gain all the
benefits provided by both the cited schemes, we propose an adaptation of the state-of-the-art algorithm in [1] which
is able to integrate the data provided by both the CWLs and BSLs, yielding a three-dimensional (3-D) rain rate map
of a monitored area.
Our contribution lies in the technical description of the data processing schemes developed to retrieve these maps,
with particular interest in the 3-D system model. In the following, we summary the machinery of our approach. Let us
consider a monitored zone, where N = Nw + Ns communication links are active, with Nw and Ns are the number of
CWLs and BSLs, respectively. It is worth noting that rain is assumed only present below the 0 C isotherm height. We
divide then the vertical dimension into H fixed heights, from ground level up to the 0 C isotherm height. Hence, by
implementing the algorithm in [1] for each height, we obtain a set of H rain maps, one for each height value, yielding
to a 3-D description of the phenomena.
The effectiveness of novel approach is assessed using a simulator able to set up a configuration of the coordinates
for both CWL and BSL terminals, and an instance of a simulated rain in a randomly-generated position. Preliminary
results are given in Figures 1 and 2 which illustrate different scenarios in the presence of the same rain conditions. In
the scenario of Fig. 1, the estimation is performed using only 21 CWLs, while Fig. 2 presents the estimation results
using 13 BSLs and 8 CWLs. Though the position of the rain column with diameter 3 km is correctly estimated in
both cases, it can be nevertheless noted that the joint utilization of both CWL and BSL provides a more accurate
estimation of the rain intensity.
To show a more general prove of effectiveness, the near-to-the-ground RMSE between actual and estimated rain rate
is plotted for different scenarios. In Fig. 3, the RMSE is shown as a function of the number of wireless links, randomly
chosen from the arrangement presented in Fig. 1. The curves are plotted for different numbers of satellite receivers,
i.e., 0, 4, 8 and 16 randomly-positioned on the maps. It is apparent that even a few number of satellites can be of great
help in reducing the RMSE
The Poem of Memory. "Triumphi"
No full textWriting of the "Triumphi" Fabio Finotti finds that its author undercuts a medieval idea of ascent to God in the structural progression from Love to Chastity, Death, Fame, Time, and Eternity. Here Petrarch programmatically counters Dante, transforming a universal, eschatological vision into a subjective, cultural and psychological experience
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