Papers by Alberto Tarable
Cornell University - arXiv, Jun 21, 2021
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Cornell University - arXiv, Jan 9, 2017
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2022 IEEE 15th Workshop on Low Temperature Electronics (WOLTE)
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IEEE Transactions on Wireless Communications
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ACM Transactions on Modeling and Performance Evaluation of Computing Systems, 2018
We investigate crowdsourcing algorithms for finding the top-quality item within a large collectio... more We investigate crowdsourcing algorithms for finding the top-quality item within a large collection of objects with unknown intrinsic quality values. This is an important problem with many relevant applications, such as in networked recommendation systems. The core of the algorithms is that objects are distributed to crowd workers, who return a noisy and biased evaluation. All received evaluations are then combined to identify the top-quality object. We first present a simple probabilistic model for the system under investigation. Then we devise and study a class of efficient adaptive algorithms to assign in an effective way objects to workers. We compare the performance of several algorithms, which correspond to different choices of the design parameters/metrics. In the simulations, we show that some of the algorithms achieve near optimal performance for a suitable setting of the system parameters.
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2020 IEEE Information Theory Workshop (ITW)
In this paper, we consider spatially coupled LDPC codes derived from protographs. In particular, ... more In this paper, we consider spatially coupled LDPC codes derived from protographs. In particular, we analyze the performance of the window decoder (WD), which allows reducing the complexity, the memory requirements, and the latency of the flood belief-propagation decoder. We show that the performance degradation of WD is due to the fact that it exploits a single decoding wave instead of two. This has effect both in the ideal case of infinite code length, where it may imply a threshold loss, and in the case of finite length, where it affects the slope of the BER curve in the waterfall region. We show how a forwardbackward decoder can reduce such problems at the price of a limited increase of average complexity.
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University of Copenhagen, Faculty of Science, Denmark ; Inria Saclay ; NIC Chile Research Labs, University of Chile ; IMDEA Software Institute ; CNR - IEIIT, Feb 1, 2021
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Des etudes recentes ont profite des techniques de suivi basees sur les technologies de positionne... more Des etudes recentes ont profite des techniques de suivi basees sur les technologies de positionnement d' etudier afin la mobilite humaine. Ces recherches ont revele, entre autres, une grande regularite spatio-temporelle des mouvements individuels. Sur la base de ces resultats, nous visons a repondre a la question "a quelle frequence doit-on echantillonner les mouvements humains individuels afin qu'ils puissent etre reconstruits a partir des echantillons recueillis avec un minimum de perte d'information?". Notre quete d'une reponse a conduit a la decouverte de (i) proprietes spectrales apparemment universelles de la mobilite humaine, et (ii) une loi de mise a l' echelle lineaire de l'erreur de localisation par rapport a l'intervalle d' echantillonnage. Nos resultats sont bases sur l'analyse des trajectoires GPS de 119 utilisateurs dans le monde entier. Les applications de nos resultats sont liees un certain nombre de domaines pertinents p...
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2018 2nd URSI Atlantic Radio Science Meeting (AT-RASC), 2018
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2021 XXXIVth General Assembly and Scientific Symposium of the International Union of Radio Science (URSI GASS), 2021
In massive MIMO systems, phase noise can spoil the performance of the usual receiver techniques. ... more In massive MIMO systems, phase noise can spoil the performance of the usual receiver techniques. The problem arises because of the aging of phase-noise information based on pilots. In this paper, in a realistic 5G uplink scenario, we quantify the impact of information aging and we propose an iterative receiver based on expectation-maximization (EM). Simulation results show that the iterative receiver is robust to information aging related to phase noise.
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ArXiv, 2021
We analyze a class of stochastic processes, referred to as asynchronous and semi-anonymous dynami... more We analyze a class of stochastic processes, referred to as asynchronous and semi-anonymous dynamics (ASD), over directed labeled random networks. These processes are a natural tool to describe general best-response and noisy best-response dynamics in network games where each agent, at random times governed by independent Poisson clocks, can choose among a finite set of actions. The payoff is determined by the relative popularity of different actions among neighbors, while being independent of the specific identities of neighbors. Using a mean-field approach, we prove that, under certain conditions on the network and initial node configuration, the evolution of ASD can be approximated, in the limit of large network sizes, by the solution of a system of non-linear ordinary differential equations. Our framework is very general and applies to a large class of graph ensembles for which the typical random graph locally behaves like a tree. In particular, we will focus on labeled configura...
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IJCA Proceedings on Mobile and Embedded Technology International Conference 2013, Feb 22, 2013
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Abstract: A general method for the evaluation of the symbol er-ror probability (SER) of UWB syste... more Abstract: A general method for the evaluation of the symbol er-ror probability (SER) of UWB systems with various kind of mod-ulation schemes (N-PAM, M-PPM, Bi-Orthogonal), in presence of multipath channel, multiuser and strong narrowband interference, is presented. This method is shown to be able to include all the principal multiaccess techniques proposed so far for UWB, time hopping (TH), direct sequence (DS) and optical orthogonal codes (OOC). A comparison between the performance of these multiple access and modulation techniques is given, for both ideal Rake re-ceiver and minimum mean square error (MMSE) equalizer. It is shown that for all the analyzed multiple access schemes, a Rake receiver exhibits a high error floor in presence of narrow-band interference (NBI) and that the value of the error floor is in-fluenced by the spectral characteristics of the spreading code. As expected, an MMSE receiver offers better performance, represent-ing a promising candidate for UWB systems....
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Photonics in Switching and Computing 2021, 2021
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We analyze a class of stochastic processes, referred to as asynchronous and semi-anonymous dynami... more We analyze a class of stochastic processes, referred to as asynchronous and semi-anonymous dynamics (ASD), over directed labeled random networks. These processes are a natural tool to describe general best-response and noisy best-response dynamics in network games where each agent, at random times governed by independent Poisson clocks, can choose among a finite set of actions. The payoff is determined by the relative popularity of different actions among neighbors, while being independent of the specific identities of neighbors. Using a mean-field approach, we prove that, under certain conditions on the network and initial node configuration, the evolution of ASD can be approximated, in the limit of large network sizes, by the solution of a system of non-linear ordinary differential equations. Our framework is very general and applies to a large class of graph ensembles for which the typical random graph locally behaves like a tree. In particular, we will focus on labeled configura...
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We present bounds and a closed-form high-SNR expression for the capacity of multiple-antenna syst... more We present bounds and a closed-form high-SNR expression for the capacity of multiple-antenna systems affected by Wiener phase noise. Our results are developed for the scenario where a single oscillator drives all the radio-frequency circuitries at each transceiver (common oscillator setup), the input signal is subject to a peak-power constraint, and the channel matrix is deterministic. This scenario is relevant for line-of-sight multiple-antenna microwave backhaul links with sufficiently small antenna spacing at the transceivers. For the 2 by 2 multiple-antenna case, for a Wiener phase-noise process with standard deviation equal to 6 degrees, and at the medium/high SNR values at which microwave backhaul links operate, the upper bound reported in the paper exhibits a 3 dB gap from a lower bound obtained using 64-QAM. Furthermore, in this SNR regime the closed-form high-SNR expression is shown to be accurate.
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— For high data rate applications, the implementation of iterative turbo-like decoders requires t... more — For high data rate applications, the implementation of iterative turbo-like decoders requires the use of parallel architectures posing some collision-free constraints to the reading/writing process from/into the memory. This consideration applies to the two main classes of turbo-like codes, i.e., turbo codes and low-density parity-check codes. Contrary to the literature belief, we prove in this paper that there is no need for an ad hoc code design to meet the parallelism requirement, because, for any code and any choice of the scheduling of the reading/writing operations, there is a suitable mapping of the variables in the memory that grants a collision-free access. The proof is constructive, i.e., it gives an algorithm that obtains the desired collision-free mapping. The algorithm is applied to two simple examples, one for turbo codes and one for low-density parity-check codes, to illustrate how the algorithm works. Index Terms — LDPC codes, memory mapping, parallel implementatio...
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We investigate crowdsourcing algorithms for finding the top-quality item within a large collectio... more We investigate crowdsourcing algorithms for finding the top-quality item within a large collection of objects with unknown intrinsic quality values. This is an important problem with many relevant applications, for example in networked recommendation systems. The core of the algorithms is that objects are distributed to crowd workers, who return a noisy and biased evaluation. All received evaluations are then combined, to identify the top-quality object. We first present a simple probabilistic model for the system under investigation. Then, we devise and study a class of efficient adaptive algorithms to assign in an effective way objects to workers. We compare the performance of several algorithms, which correspond to different choices of the design parameters/metrics. In the simulations we show that some of the algorithms achieve near optimal performance for a suitable setting of the system parameters.
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— The pragmatic approach to coded continuous-phase modulation (CPM) is proposed as a capacity-ach... more — The pragmatic approach to coded continuous-phase modulation (CPM) is proposed as a capacity-achieving lowcomplexity alternative to the serially-concatenated CPM (SC-CPM) coding scheme. In this paper, we first perform a selection of the best spectrally-efficient CPM modulations to be embedded into SC-CPM schemes. Then, we consider the pragmatic capacity (a.k.a. BICM capacity) of CPM modulations and optimize it through a careful design of the mapping between input bits and CPM waveforms. The so obtained schemes are cascaded with an outer serially-concatenated convolutional code to form a pragmatic coded-modulation system. The resulting schemes exhibit performance very close to the CPM capacity without requiring iterations between the outer decoder and the CPM demodulator. As a result, the receiver exhibits reduced complexity and increased flexibility due to the separation of the demodulation and decoding functions. I.
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Papers by Alberto Tarable