Bibliografie tematiche / HARQ

Letteratura scientifica selezionata sul tema "HARQ"

Autore: Grafiati
Pubblicato: 4 giugno 2021
Ultima modifica: 1 giugno 2024

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Articoli di riviste sul tema "HARQ"

1

WANG, Yumei, Jiawei LIANG, Hao WANG, Eiji OKI e Lin ZHANG. "ePec-LDPC HARQ: An LDPC HARQ Scheme with Targeted Retransmission". IEICE Transactions on Communications E99.B, n. 10 (2016): 2168–78. http://dx.doi.org/10.1587/transcom.2016ebp3004.

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2

Yu, Wei, Fusheng Zhu, Jun Wu, Rui Wang, Haoqi Ren e Zhifeng Zhang. "HARQ-Chaotic: Analog Chaotic Code Applied in HARQ Scheme of Wireless Communication System". Wireless Communications and Mobile Computing 2019 (24 aprile 2019): 1–13. http://dx.doi.org/10.1155/2019/3728127.

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Abstract (sommario):
This paper proposes a novel symbol-level combining hybrid automatic repeat request (HARQ) scheme based on analog chaotic code and named HARQ-Chaotic. The transmitter of HARQ-Chaotic adopts analog chaotic code to encode Quadrature Amplitude Modulation (QAM) symbols of retransmission packets to combat fading and noise. As the analog chaotic code can only handle sources with amplitudes in the range of [-0.5, 0.5], QAM symbols must be scaled into this range. We derived the optimal scaling factor through theoretical analysis. A joint algorithm combining with novel soft chaotic decoder and novel soft QAM demapper is proposed for the receiver to enhance the performance of the whole communication system. We implemented HARQ-Chaotic with LDPC codes and 16-QAM/64-QAM to carry out simulations in both AWGN channels and multipath fading channels. Massive simulation results demonstrate that the proposed HARQ-Chaotic has 1dB-4dB gain over traditional HARQ-Chase combining (HARQ-CC) scheme in block error rate (BLER) performance.
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3

Rykova, Tatiana, Barış Göktepe, Thomas Schierl, Konstantin Samouylov e Cornelius Hellge. "Analytical Model and Feedback Predictor Optimization for Combined Early-HARQ and HARQ". Mathematics 9, n. 17 (31 agosto 2021): 2104. http://dx.doi.org/10.3390/math9172104.

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Abstract (sommario):
In order to fulfill the stringent Ultra-Reliable Low Latency Communication (URLLC) requirements towards Fifth Generation (5G) mobile networks, early-Hybrid Automatic Repeat reQuest (e-HARQ) schemes have been introduced, aimed at providing faster feedback and thus earlier retransmission. The performance of e-HARQ prediction strongly depends on the classification mechanism, data length, threshold value. In this paper, we propose an analytical model that incorporates e-HARQ and Hybrid Automatic Repeat reQuest (HARQ) functionalities in terms of two phases in discrete time. The model implies a fast and accurate way to get the main performance measures, and apply optimization analysis to find the optimal values used in predictor’s classification. We employ realistic data for transition probabilities obtained by means of 5G link-level simulations and conduct extensive experimental analysis. The results show that at false positive probability of 10−1, the e-HARQ prediction with the found optimal parameters can achieve around 20% of gain over HARQ at False Negative (FN) of 10−1 and around 7.5% at FN of 10−3 in terms of a mean spending time before successful delivery.
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4

Sakr, H. A., e M. A. Mohamed. "Performance Evaluation Using Smart: HARQ Versus HARQ Mechanisms Beyond 5G Networks". Wireless Personal Communications 109, n. 3 (10 giugno 2019): 1503–28. http://dx.doi.org/10.1007/s11277-019-06624-3.

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5

Bian, Hongxiu, e Rongke Liu. "Reliable and Energy-Efficient LEO Satellite Communication with IR-HARQ via Power Allocation". Sensors 22, n. 8 (15 aprile 2022): 3035. http://dx.doi.org/10.3390/s22083035.

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This paper examines reliable and energy-efficient transmission in low earth orbit (LEO) satellite communication systems. In particular, we analyze the link transmission characteristics of the LEO satellite to the ground user and model the channel as a combination of large-scale fading and small-scale fading. Based on this, we consider an incremental redundancy hybrid automatic repeat request (IR-HARQ) technique with a variable-power allocation method, and we call it the IR-HARQ-VPA scheme. In this method, the outage probability after each IR-HARQ round can be obtained through numerical integration based on the fast Fourier transform (NI-FFT). This method is suitable for any number of HARQ transmission rounds and can improve the accuracy compared with previous approximation methods. In addition, variable-power allocation based on the genetic algorithm (VPA-GA) is introduced to reduce the energy consumption. The simulation results show that the proposed IR-HARQ-VPA scheme cannot only meet the requirements of transmission reliability but also achieves higher energy efficiency than IR-HARQ with equal power (IR-HARQ-EP) transmission and a previously proposed variable-power allocation method. Moreover, the simulation results in a LEO satellite communication window also confirm the effectiveness of the proposed IR-HARQ-VPA scheme.
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6

Wu, Yue, Kuanlin Mu, Kaiyu Duan, Shishu Yin e Hongwen Yang. "On the Secure Performance of Intelligent Reflecting Surface-Assisted HARQ Systems". Entropy 25, n. 3 (17 marzo 2023): 519. http://dx.doi.org/10.3390/e25030519.

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Abstract (sommario):
This paper analyzes the physical layer security performance of hybrid automatic repeat request (HARQ) systems with the assistance of an intelligent reflecting surface (IRS) and aims to reveal the primary factors that enhance PLS. First, closed-form expressions for the connection outage probability (COP) and secrecy outage probability (SOP) in HARQ with chase combining (HARQ-CC) are acquired using the generalized-K (KG) distribution. Then, these two critical metrics are derived while adopting HARQ with incremental redundancy (HARQ-IR), resorting to the mixture gamma (MG) distribution and the Mellin transform. Diversity and coding gain are also addressed through an asymptotic analysis of the COP and SOP. Finally, an evaluation of the numerical results demonstrates that a greater gain in the main channel and the wiretap channel can be produced by increasing the number of meta-surfaces rather than increasing the maximum transmission number, except for the higher signal-to-noise (SNR) region of HARQ-IR where the latter is preferred. This finding provides a significant guidance for the joint configuration of IRS and HARQ to achieve secure communication.
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7

Jabi, Mohammed, Abdellatif Benyouss, Mael Le Treust, Etienne Pierre-Doray e Leszek Szczecinski. "Adaptive Cross-Packet HARQ". IEEE Transactions on Communications 65, n. 5 (maggio 2017): 2022–35. http://dx.doi.org/10.1109/tcomm.2017.2661758.

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8

Xu, Kui, Wenfeng Ma, Lei Zhu, Youyun Xu, Yuanyuan Gao, Dongmei Zhang e Wei Xie. "NTC-HARQ: Network–Turbo-Coding Based HARQ Protocol for Wireless Broadcasting System". IEEE Transactions on Vehicular Technology 64, n. 10 (ottobre 2015): 4633–44. http://dx.doi.org/10.1109/tvt.2014.2374235.

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9

Shi, Xiaoye, Haiting Zhu, Fei Ding, Zhaowei Zhang e Nan Bao. "Tradeoff-HARQ Scheme for Full-Duplex SWIPT DF Relay". Wireless Communications and Mobile Computing 2021 (25 ottobre 2021): 1–7. http://dx.doi.org/10.1155/2021/5550825.

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The SWIPT (simultaneous wireless information and power transfer) DF (decoding and forwarding) relay system could achieve the purpose of both increasing revenue and reducing expenditure. By analysing the system model and transmission characteristics of full-duplex relay, this paper optimizes the retransmission slot structure to enhance the system performance. Firstly, the state transition model is established based on the analysis of the retransmission slot structure. Secondly, the state probability of each state and the transition probability between states are calculated to obtain the total data passing rate, energy transmission efficiency, and total transmission time. Thirdly, in order to compare the performance of various HARQ (hybrid automatic repeat request) schemes more effectively, JNTP (joint normalized throughput of information transmission and energy transmission) is constructed. Monte Carlo simulations finally confirm that the proposed tradeoff-HARQ scheme outperforms the regular-HARQ scheme in terms of JNTP: the performance of the tradeoff-HARQ scheme is 0.03883 higher than that of the regular-HARQ scheme when the total power limit is 20 dB and 0.00651 higher than that of the regular-HARQ scheme when the total power limit is 30 dB.
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10

Zheng, Ya Dan, Jian Bo Li, Yong Luo, Ming Ke Dong e Jian Jun Wu. "Forced-Retransmission Based Hybrid HARQ Scheme for GEO Satellite Communications". Advanced Materials Research 846-847 (novembre 2013): 651–54. http://dx.doi.org/10.4028/www.scientific.net/amr.846-847.651.

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Abstract (sommario):
In this paper, a hybrid HARQ scheme was proposed by combing forced retransmission and traditional HARQ together, after analyzing the characteristics of satellite channel and the problem encountered when utilizing HARQ scheme in GEO satellite communication system. The forced retransmission can make a packet be correctly decoded more quickly and shorten the waiting delay. Meanwhile, to balance the delay and throughput, the proper parameters were given for the proposed hybrid scheme. Simulation results show that the proposed scheme performs well at decreasing the waiting delay, especially when SNR is low. The conclusion can be drawn that the proposed scheme can improve the HARQ performance in GEO satellite communication systems.
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Più fonti

Tesi sul tema "HARQ"

1

Kumar, Kuldeep, e Javier Perez-Ramirez. "Novel BICM HARQ Algorithm Based on Adaptive Modulations". International Foundation for Telemetering, 2011. http://hdl.handle.net/10150/595637.

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ITC/USA 2011 Conference Proceedings / The Forty-Seventh Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2011 / Bally's Las Vegas, Las Vegas, Nevada
A novel type-II hybrid automatic repeat request (HARQ) algorithm using adaptive modulations and bit-interleaved coded modulation (BICM) is presented. The algorithm uses different optimized puncturing patterns for different transmissions of the same data packet. The proposed approach exploits mapping diversity through BICM with iterative decoding. The modulation order is changed in each transmission to keep the number of symbols transmitted constant. We present new bit error rate and frame error rate analytical results for the proposed technique showing good agreement with simulation results. We compare the throughput performance of our proposed HARQ technique with a reference HARQ technique that uses different mapping arrangements but keeps the modulation order fixed. By using optimized puncturing patterns and adaptive modulations, our method provides significantly better throughput performance over the reference HARQ method in the whole signalto- noise ratio (SNR) range, and achieves a gain of 12 dB in the medium SNR region.
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2

Rauf, Zahid. "Multi-user Non-Cooperative and Cooperative Systems with HARQ". Thesis, University of Canterbury. Electrical and Computer Engineering, 2013. http://hdl.handle.net/10092/8708.

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Abstract (sommario):
The performance and reliability of wireless communication links can be improved by employing multiple antennas at both ends, thereby creating multiple-input multiple-output (MIMO) channels. However, once multiple co-channel users are added to the system it can be difficult to provide as many receive antennas as transmit antennas, resulting in a so-called overloaded (rank-deficient) system. Under overloaded conditions, maximum likelihood (ML) detection works well, but its exponential complexity prohibits its use and suboptimal linear detectors perform poorly. In this thesis, new signal processing techniques for multi-user overloaded systems using hybrid automatic repeat request (HARQ) protocols are investigated. The HARQ retransmissions are used to form virtual receive antennas, which can efficiently transform an overloaded system into a critically loaded system (i.e. a system with an equal number of transmit and receive antennas). In the first part of the thesis, a multi-user non-cooperative overloaded system is considered. At first, it is demonstrated that the suboptimal linear minimum mean square error (MMSE) detector leads to significant performance degradation compared to an ML detector for such systems. To overcome this drawback, two multi-user transmission schemes are proposed that work well under overloaded conditions. The proposed schemes allow us to apply linear multi-user detection (MUD) algorithms without requiring additional antennas or hardware chains. Monte-Carlo simulations demonstrate that the proposed schemes can result in significant gains in terms of bit-error-rate (BER) and dropped packet performance. In the second part, the performance of multiple HARQ processes for a two-hop multi-source multi-relay decode-and-forward (DF) relaying network with no direct link are analyzed. Dealing with multiple HARQ processes at each relay, a retransmission scheme is proposed that utilizes virtual antennas to achieve increased receive diversity and improved throughput compared to traditional orthogonal (time division) retransmissions. A novel forwarding strategy at the relay(s) to destination link is proposed with the objective of further improving throughput. Finally, the end-to-end outage probability and throughput efficiency of the proposed retransmission and forwarding schemes are found analytically and confirmed with Monte-Carlo simulations.
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3

Assimi, Abdel Nasser. "Diversity techniques for HARQ transmissions over frequency-selective channels". Cergy-Pontoise, 2009. http://biblioweb.u-cergy.fr/theses/09CERG0428.pdf.

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Abstract (sommario):
Nous considérons dans cette thèse le problème de la transmission fiable de données par paquets en utilisant une transmission mono-porteuse sur des canaux sélectifs en fréquence à évanouissements. Notre objectif est de concevoir des couples émetteurs-récepteurs permettant d'améliorer les performances de la détection en l'absence d'information sur le canal à la transmission et ceci en exploitant la diversité temporelle disponible dans le cadre des protocoles de retransmission hybrides (HARQ). En analysant les performances du système de transmission avec un récepteur à maximum de vraisemblance, nous établissons un critère pertinent pour l'étude des performances du système basé sur les statistiques de la distance Euclidienne à la sortie du canal sélectif en fréquence. A partir de ce cadre théorique, nous proposons un nouveau schéma de diversité entre les différentes retransmissions, nommé précodage de phase, qui permet de combattre l'interférence entre symboles pour les canaux lentement variables dans le temps. Puis, à l'aide de nos outils d'analyse, nous revisitons un autre schéma de diversité qu'est la diversité d’entrelacement. En particulier, nous soulignons le double avantage offert par ce schéma, à savoir la diversité de modulation et la réduction de l'interférence entre symboles. Nous réalisons ensuite une étude comparative entre les deux schémas de diversité précédents sous traitement itératif ou non itératif au récepteur. Enfin, nous introduisons un nouveau protocole de retransmission adaptative pour les transmissions dîtes multi-couches afin de réduire l'interférence entre couches pour les canaux rapidement variant dans le temps utilisant des informations de retour limitées
In this thesis, we consider the problem of reliable data packets transmission using single-carrier signaling over frequency-selective fading channels. Our objective is to design enhanced transceivers with improved detection performance in the absence of channel state information at the transmitter by exploiting the available time-diversity in Chase combining Hybrid Automatic Repeat reQuest (HARQ) protocols. By analyzing the performance of the transmission scheme using an optimal maximum-likelihood receiver, we establish a suitable criterion for the study of system performance based on the statistics of the Euclidean distance at the output of a frequency-selective channel. From this theoretical framework, we propose a novel transmit-diversity scheme between subsequent HARQ transmissions, called phase-precoding, which allows the mitigation of intersymbol interference for slow time-varying channels. Then, with the help of our analytical tools, we revisit another transmit-diversity scheme which is the bit-interleaving diversity scheme. In particular, we emphasize the double advantage offered by this diversity scheme including the inherent modulation diversity in addition to the intersymbol interference reduction. Subsequently, we perform a comparative study between phase-precoding and bit-interleaving diversity schemes under iterative and non-iterative receiver structures. Finally, we introduce a new adaptive retransmission protocol for a multi-layer transmission scheme for the mitigation of inter-layers interference for rapidly time-varying channels using limited feedback information
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4

Leturc, Xavier. "Resource allocation for HARQ in mobile ad hoc networks". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLT008/document.

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Cette thèse traite le problème de l’allocation des ressources physiques dans les réseaux ad hoc mobiles en contexte multi-utilisateurs. Nous considérons qu’un noeud du réseau, appelé gestionnaire des ressources (GR) a pour tâche d’effectuer cette allocation de ressources, et que pour ce faire, les autres noeuds lui communiquent des informations relatives aux canaux de propagations de leurs liens de communications. Ce modèle de réseaux induit un délai entre le moment où les noeuds envoient leurs informations au GR et le moment où le GR leur envoie leur allocation de ressource, ce qui rend impossible l’utilisation d’informations de canal instantanées pour effectuer l’allocation. Ainsi, nous considérons que le GR ne dispose que d’informations statistiques relatives aux canaux des différents liens de communications. De plus, nous supposons que chaque lien utilise le mécanisme de l’ARQ Hybride (HARQ). Dans ce contexte, la thèse comporte deux objectifs principaux: i) Proposer des procédures d’estimation de la statistique du canal de propagation, et plus particulièrement du facteur K du canal de Rice avec et sans effet de masquage. ii) Proposer et étudier des algorithmes d’allocation de ressources basés sur les statistiques du canal et prenant en compte l’utilisation de l’HARQ ainsi que de schéma de modulation et de codage pratique. En particulier, on cherche à maximiser des grandeurs relatives à l’efficacité énergétique du système. Les ressources à allouer à chaque lien sont une énergie de transmission et une proportion de la bande de fréquence
This thesis addresses the Resource Allocation (RA) problem in multiuser mobile ad hoc networks. We assume that there is a node in the network, called the resource manager (RM), whose task is to allocate the resource and thus the other nodes send him there channel state information (CSI). This network model induces a delay between the time the nodes send the RM their CSI and the time the RM sends them their RA, which renders impossible the use of instantaneous CSI. Thus, we assume that only statistical CSI is available to perform the RA. Moreover, we assume that an Hybrid ARQ (HARQ) mechanism is used on all the links. In this context, the objective of the thesis is twofold: i) Propose procedures to estimate the statistical CSI, and more precisely to estimate the Rician K factor with and without shadowing. ii) Propose and analyse new RA algorithms using statistical CSI and taking into account the use of HARQ and practical modulation and coding schemes. We aim to maximize energy efficiency related metrics. The resource to allocate are per-link transmit energy and bandwidth proportion
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5

Leturc, Xavier. "Resource allocation for HARQ in mobile ad hoc networks". Electronic Thesis or Diss., Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLT008.

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Abstract (sommario):
Cette thèse traite le problème de l’allocation des ressources physiques dans les réseaux ad hoc mobiles en contexte multi-utilisateurs. Nous considérons qu’un noeud du réseau, appelé gestionnaire des ressources (GR) a pour tâche d’effectuer cette allocation de ressources, et que pour ce faire, les autres noeuds lui communiquent des informations relatives aux canaux de propagations de leurs liens de communications. Ce modèle de réseaux induit un délai entre le moment où les noeuds envoient leurs informations au GR et le moment où le GR leur envoie leur allocation de ressource, ce qui rend impossible l’utilisation d’informations de canal instantanées pour effectuer l’allocation. Ainsi, nous considérons que le GR ne dispose que d’informations statistiques relatives aux canaux des différents liens de communications. De plus, nous supposons que chaque lien utilise le mécanisme de l’ARQ Hybride (HARQ). Dans ce contexte, la thèse comporte deux objectifs principaux: i) Proposer des procédures d’estimation de la statistique du canal de propagation, et plus particulièrement du facteur K du canal de Rice avec et sans effet de masquage. ii) Proposer et étudier des algorithmes d’allocation de ressources basés sur les statistiques du canal et prenant en compte l’utilisation de l’HARQ ainsi que de schéma de modulation et de codage pratique. En particulier, on cherche à maximiser des grandeurs relatives à l’efficacité énergétique du système. Les ressources à allouer à chaque lien sont une énergie de transmission et une proportion de la bande de fréquence
This thesis addresses the Resource Allocation (RA) problem in multiuser mobile ad hoc networks. We assume that there is a node in the network, called the resource manager (RM), whose task is to allocate the resource and thus the other nodes send him there channel state information (CSI). This network model induces a delay between the time the nodes send the RM their CSI and the time the RM sends them their RA, which renders impossible the use of instantaneous CSI. Thus, we assume that only statistical CSI is available to perform the RA. Moreover, we assume that an Hybrid ARQ (HARQ) mechanism is used on all the links. In this context, the objective of the thesis is twofold: i) Propose procedures to estimate the statistical CSI, and more precisely to estimate the Rician K factor with and without shadowing. ii) Propose and analyse new RA algorithms using statistical CSI and taking into account the use of HARQ and practical modulation and coding schemes. We aim to maximize energy efficiency related metrics. The resource to allocate are per-link transmit energy and bandwidth proportion
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6

Pang, Kun. "Collaborative HARQ Schemes for Cooperative Diversity Communications in Wireless Networks". Thesis, The University of Sydney, 2008. http://hdl.handle.net/2123/2559.

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Abstract (sommario):
Wireless technology is experiencing spectacular developments, due to the emergence of interactive and digital multimedia applications as well as rapid advances in the highly integrated systems. For the next-generation mobile communication systems, one can expect wireless connectivity between any devices at any time and anywhere with a range of multimedia contents. A key requirement in such systems is the availability of high-speed and robust communication links. Unfortunately, communications over wireless channels inherently suffer from a number of fundamental physical limitations, such as multipath fading, scarce radio spectrum, and limited battery power supply for mobile devices. Cooperative diversity (CD) technology is a promising solution for future wireless communication systems to achieve broader coverage and to mitigate wireless channels’ impairments without the need to use high power at the transmitter. In general, cooperative relaying systems have a source node multicasting a message to a number of cooperative relays, which in turn resend a processed version message to an intended destination node. The destination node combines the signal received from the relays, and takes into account the source’s original signal to decode the message. The CD communication systems exploit two fundamental features of the wireless medium: its broadcast nature and its ability to achieve diversity through independent channels. A variety of relaying protocols have been considered and utilized in cooperative wireless networks. Amplify and forward (AAF) and decode and forward (DAF) are two popular protocols, frequently used in the cooperative systems. In the AAF mode, the relay amplifies the received signal prior to retransmission. In the DAF mode, the relay fully decodes the received signal, re-encodes and forwards it to the destination. Due to the retransmission without decoding, AAF has the shortcoming that noise accumulated in the received signal is amplified at the transmission. DAF suffers from decoding errors that can lead to severe error propagation. To further enhance the quality of service (QoS) of CD communication systems, hybrid Automatic Repeat-reQuest (HARQ) protocols have been proposed. Thus, if the destination requires an ARQ retransmission, it could come from one of relays rather than the source node. This thesis proposes an improved HARQ scheme with an adaptive relaying protocol (ARP). Focusing on the HARQ as a central theme, we start by introducing the concept of ARP. Then we use it as the basis for designing three types of HARQ schemes, denoted by HARQ I-ARP, HARQ II-ARP and HARQ III-ARP. We describe the relaying protocols, (both AAF and DAF), and their operations, including channel access between the source and relay, the feedback scheme, and the combining methods at the receivers. To investigate the benefits of the proposed HARQ scheme, we analyze its frame error rate (FER) and throughput performance over a quasi-static fading channel. We can compare these with the reference methods, HARQ with AAF (HARQ-AAF) and HARQ with perfect distributed turbo codes (DTC), for which correct decoding is always assumed at the relay (HARQ-perfect DTC). It is shown that the proposed HARQ-ARP scheme can always performs better than the HARQ-AAF scheme. As the signal-to-noise ratio (SNR) of the channel between the source and relay increases, the performance of the proposed HARQ-ARP scheme approaches that of the HARQ-perfect DTC scheme.
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7

Pang, Kun. "Collaborative HARQ Schemes for Cooperative Diversity Communications in Wireless Networks". School of Electrical & Information Engineering, The University of Sydney, 2008. http://hdl.handle.net/2123/2559.

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Abstract (sommario):
Master of Philosophy
Wireless technology is experiencing spectacular developments, due to the emergence of interactive and digital multimedia applications as well as rapid advances in the highly integrated systems. For the next-generation mobile communication systems, one can expect wireless connectivity between any devices at any time and anywhere with a range of multimedia contents. A key requirement in such systems is the availability of high-speed and robust communication links. Unfortunately, communications over wireless channels inherently suffer from a number of fundamental physical limitations, such as multipath fading, scarce radio spectrum, and limited battery power supply for mobile devices. Cooperative diversity (CD) technology is a promising solution for future wireless communication systems to achieve broader coverage and to mitigate wireless channels’ impairments without the need to use high power at the transmitter. In general, cooperative relaying systems have a source node multicasting a message to a number of cooperative relays, which in turn resend a processed version message to an intended destination node. The destination node combines the signal received from the relays, and takes into account the source’s original signal to decode the message. The CD communication systems exploit two fundamental features of the wireless medium: its broadcast nature and its ability to achieve diversity through independent channels. A variety of relaying protocols have been considered and utilized in cooperative wireless networks. Amplify and forward (AAF) and decode and forward (DAF) are two popular protocols, frequently used in the cooperative systems. In the AAF mode, the relay amplifies the received signal prior to retransmission. In the DAF mode, the relay fully decodes the received signal, re-encodes and forwards it to the destination. Due to the retransmission without decoding, AAF has the shortcoming that noise accumulated in the received signal is amplified at the transmission. DAF suffers from decoding errors that can lead to severe error propagation. To further enhance the quality of service (QoS) of CD communication systems, hybrid Automatic Repeat-reQuest (HARQ) protocols have been proposed. Thus, if the destination requires an ARQ retransmission, it could come from one of relays rather than the source node. This thesis proposes an improved HARQ scheme with an adaptive relaying protocol (ARP). Focusing on the HARQ as a central theme, we start by introducing the concept of ARP. Then we use it as the basis for designing three types of HARQ schemes, denoted by HARQ I-ARP, HARQ II-ARP and HARQ III-ARP. We describe the relaying protocols, (both AAF and DAF), and their operations, including channel access between the source and relay, the feedback scheme, and the combining methods at the receivers. To investigate the benefits of the proposed HARQ scheme, we analyze its frame error rate (FER) and throughput performance over a quasi-static fading channel. We can compare these with the reference methods, HARQ with AAF (HARQ-AAF) and HARQ with perfect distributed turbo codes (DTC), for which correct decoding is always assumed at the relay (HARQ-perfect DTC). It is shown that the proposed HARQ-ARP scheme can always performs better than the HARQ-AAF scheme. As the signal-to-noise ratio (SNR) of the channel between the source and relay increases, the performance of the proposed HARQ-ARP scheme approaches that of the HARQ-perfect DTC scheme.
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8

Mafra, Samuel Baraldi. "Uso de cooperação em redes cognitivas baseadas em retransmissões HARQ". reponame:Repositório Institucional da UFPR, 2012. http://hdl.handle.net/1884/37399.

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Abstract (sommario):
Orientador : Prof. Dr. Evelio Martín Garcia Fernández
Co-orientador : Prof. Dr. Richard Demo Souza
Dissertação (mestrado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduação em Engenharia Elétrica. Defesa: Curitiba, 20/04/2012
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Nesta dissertação é avaliado o uso de cooperação em uma rede cognitiva baseada em HARQ, onde a rede secundária aproveita as oportunidades originadas nas retransmissões do enlace primário. O objetivo principal é propor técnicas com o uso de comunicação cooperativa para conseguir uma transmissão da rede secundária com taxas maiores que as alcançadas na literatura, sem prejudicar significativamente o desempenho da rede primária. Na dissertação são feitas comparações em termos da vazão do sistema entre os protocolos de codificação. Além disso, avalia-se o efeito da linha de visada e do número de relays cooperando. As simulações demonstram que é possível o enlace secundário se comunicar com altas taxas mantendo uma mínima interferência no enlace primário com o uso de cooperação. Com os nós da rede secundária bem próximos entre si e do transmissor primário é possível obter taxas maiores que as alcançadas pela rede primária. Palavras chave: Comunicação cooperativa, redes cognitivas, HARQ, múltiplos relays, codificação por repetição, codificação paralela, Nakagami-m.
Abstract: This dissertation evaluates the use of cooperation in a cognitive network based on HARQ, where the secondary link exploits the retransmissions of the primary link. The main objective is to propose techniques with the use of cooperative communication to achieve a transmissions rates of the secondary link higher than those achieved in the literature, without significantly harming the performance of the primary network. Comparisons are made in terms of throughput between the coding protocols. The effect of line of sight and the number of cooperating relays is also evaluated. The simulations show that it is possible for the secondary link to communicate with high transmission rates while causing a minimum interference on the primary link with the use of cooperation. When the secondary link nodes are very close to each other and nearby the primary transmitter, it is possible to achieve higher rates than those achieved by the primary link. Key words: Cooperative communications, cognitive networks, HARQ, multiple relay, repetition coding, parallel coding, Nakagami-m.
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Burich, Mariano Eduardo. "A cross layer analysis of harq protocols in wireless networks". Universidade Tecnológica Federal do Paraná, 2017. http://repositorio.utfpr.edu.br/jspui/handle/1/2570.

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Este trabalho estuda as potenciais melhorias na eficiência energética e vazão do método híbrido de requisição automática de retransmissão (Hybrid Automatic Retransmission Request, HARQ). A análise inclui as camadas física (PHY) e de acesso ao meio (MAC). É investigada a relação de compromisso gerada pelo HARQ, o qual demanda uma menor potência de transmissão para uma certa probabilidade de falha alvo ao custo de mais acessos ao canal. Uma vez que a competição para acesso ao canal na camada MAC é bastante custosa em termos de energia e atraso, os resultados mostram que a utilização do HARQ leva a uma grande melhoria de performance devido ao menor número de nós competidores – uma consequência da redução na potência de transmissão necessária. Contra-intuitivamente, esta análise leva à conclusão que retransmissões podem diminuir o atraso, melhorando a performance do sistema. Finalmente, são também investigados valores ótimos para o número de retransmissões permitidas, visando maximizar vazão ou/e eficiência energética.
This work studies the potential improvements in terms of energy efficiency and throughput of a hybrid automatic retransmission request (HARQ) mechanism. The analysis includes both the physical (PHY) and medium access (MAC) layers. We investigate the trade-off provided by HARQ, which demands reduced transmit power for a given target outage probability at the cost of more accesses to the channel. Since the competition for channel access at the MAC layer is very expensive in terms of energy and delay, our results show that HARQ leads to great performance improvements due to the decrease in the number of contending nodes – a consequence of the reduced required transmit power. Counter-intuitively, our analysis leads to the conclusion that retransmissions may decrease the delay, improving the system performance. Finally, we investigate the optimum values for the number of allowed retransmissions in order to maximize either the throughput or the energy efficiency.
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Maagh, Stefan. "Performance analysis of the HARQ dynamic decode-and-forward protocol". Thesis, Edinburgh Napier University, 2015. http://researchrepository.napier.ac.uk/Output/8849.

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The explosive growth of data traffic in wireless communication systems comes together with the urgent need to minimize its environmental and financial impact. Therefore, the main objective in the field of green radio communication is to improve the energy efficiency of wireless communication systems with respect to the future performance demands on the wireless communication infrastructure. In this context, recent research in cooperative and cognitive communication techniques attracts particular attention. While cognitive radio improves spectral efficiency by enhanced spectrum utilization, cooperative communication techniques achieve remarkable gains in spectral efficiency by enabling the terminals to share their resources. In particular, creating virtual multi-antenna arrays by antenna sharing enables exploitation of spatial diversity gains and multiplexing gains within a network of single antenna terminals. This technique is particularly attractive for mobile wireless networks, since power and space constraints often prohibit the integration of multiple antennas into mobile terminals. This work studies the performance of the hybrid automatic repeat-request (HARQ) dynamic decode-and-forward (DDF) protocol in the half-duplex relay channel. The reason behind exploration of the HARQ-DDF protocol is that it achieves the optimal performance in terms of the diversity-multiplexing tradeoff (DMT) and the diversity-multiplexing-delay tradeoff(DMDT). However, DMT and DMDT are evaluated as the signal-to-noise ratio (SNR) approaches infinity. In practice, key performance measures are the fixed-rate outage probability and delay-limited throughput achieved at the SNR expected during operation. To this end, it is common practice to give the performance of the DDF protocol as a function of the source-to-destination channel SNR (SD-SNR). In this dissertation the focus is to study the performance of the HARQ-DDF protocol measured as a function of the SNR as seen at the destination (D-SNR). This approach enables the performance comparison with the HARQ-SISO and the HARQ-MISO protocol from an energy efficiency perspective on the system level. Furthermore, a novel variant of the HARQ-MISO protocol, the hybrid repeat-with-diversity-request (HARDQ) MISO protocol, is introduced. Considering outage probability as measure of reliability, closed-form solutions and simulation results show that the HARDQ-MISO and the HARQ-DDF protocol outperform the HARQ-MISO protocol from an energy efficiency point of view. From a delay-limited throughput point of view the HARQ-MISO protocol is beneficial. It is demonstrated that code-rate assignment allows to achieve significant performance gains in terms of delay-limited throughput. Furthermore, reducing the decoding cost using code-rate assignment techniques comes together with only negligible performance loss.
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Libri sul tema "HARQ"

1

Hart, Emma. Emma Hart: A long hard look. Edinburgh: The Fruitmarket Gallery, 2018.

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Weverbergh, Louis Julien. Hard tegen hart: Het literaire klimaat in Vlaanderen. Antwerpen: Houtekiet, 1992.

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Ben-Bassat, Yehuda. Har-ṭov: Moshavah mevudedet be-"Hare Yehudah". [Israel]: Yehudah Ben Basaṭ, 2008.

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Dalvi, Jayavant Dvarkanath. Harī-ap, Harī! = Hurry-up, Hari! : vinodī-upahāsagarbha-camatkṛtipūrṇa, dona aṅkī svatantra nāṭaka. Mumbaī: Mêjesṭika Prakāśana, 1987.

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Organisation for Economic Co-operation and Development. Competition Committee., a cura di. Fighting hard-core cartels: Harm, effective sanctions and leniency programmes. Paris, France: OECD, 2002.

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Hart Crane's harp of evil: A study of Orphism in The bridge. Troy, N.Y: Whitston Pub. Co., 1986.

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Hara-hara vyaṅgye. Naī Dillī: Prabhāta Prakāśana, 1999.

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Kuṇṭe, Jagannātha. Narmade'' hara hara. Puṇe: Prājakta Prakāśana, 2005.

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Hara-hara Gaṅge. Naī Dillī: Vidyā Vihāra, 2013.

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Tsuruta, Mayu. Hare nochi hare. Tōkyō: Kadokawa Shoten, 1996.

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Capitoli di libri sul tema "HARQ"

1

Rykova, Tatiana, Barış Göktepe, Thomas Schierl e Cornelius Hellge. "Analytical Model of Early HARQ Feedback Prediction". In Lecture Notes in Computer Science, 222–39. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-65729-1_20.

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Li, Xun, Zhangdui Zhong, Yong Niu e Hong Zhou. "Backoff HARQ for Contention-Based Transmission in 5G Uplink". In Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 284–91. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-14657-3_28.

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Wu, Xi, Jiaqi Tang e Yan Zhang. "Performance Analysis of Collaborative HARQ Protocol with Distributed Codes". In LISS 2014, 55–60. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-43871-8_9.

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Kim, Dongwook, e Namgi Kim. "Improving User Throughput with Interleaved-HARQ in OFDM Systems". In Future Generation Information Technology, 52–58. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-35585-1_7.

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Bhuvaneswari, P., e L. Nithyanandan. "Improving Energy Efficiency in Cooperative MIMO with HARQ-CC Mechanism". In Advances in Intelligent Systems and Computing, 15–27. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-5029-4_2.

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Abd Aziz, Azlan, Mohammed Ahmed Magzoub Albashier, Azwan Mahmud, Mohamad Yusoff Alias e Nurul Asyiqin Amir Hamzah. "Physical Layer Security Using Scrambled BCH with Adaptive Granular HARQ". In Proceedings of the Multimedia University Engineering Conference (MECON 2022), 58–67. Dordrecht: Atlantis Press International BV, 2022. http://dx.doi.org/10.2991/978-94-6463-082-4_8.

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Hu, Youjun, Jian Jiao, Rui Zhang, Shaohua Wu, Shushi Gu e Qinyu Zhang. "Performance Analysis of MIMO-HARQ Schemes in LTP for Space Information Networks". In Lecture Notes in Electrical Engineering, 101–8. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-10-6571-2_13.

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Hu, Tianze, Lei Xie, Huifang Chen, Hongda Duan e Kuang Wang. "Improved Incremental Freezing HARQ Schemes Using Polar Codes over Degraded Compound Channels". In Communications and Networking, 316–30. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-41114-5_24.

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Gao, Yuan, Peng Xue, Yi Li, Hongyi Yu, Xianfeng Wang e Shihai Gao. "Implementation and Performance Analysis of HARQ in 3GPP LTE System-Level Simulation". In Lecture Notes in Electrical Engineering, 1583–91. New York, NY: Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4614-4981-2_173.

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Gao, Yuan, Yi Li, HongYi Yu e ShiHai Gao. "Modeling and Analysis of MU-CoMP HARQ in 3GPP LTE System Level Simulation". In Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 250–64. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-29157-9_24.

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Atti di convegni sul tema "HARQ"

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Rahmati, Mehdi, e Dario Pompili. "uwMIMO-HARQ". In the 10th International Conference. New York, New York, USA: ACM Press, 2015. http://dx.doi.org/10.1145/2831296.2831323.

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El-Khamy, Mostafa, Jungwon Lee e Inyup Kang. "Soft Turbo HARQ combining". In ICC 2013 - 2013 IEEE International Conference on Communications. IEEE, 2013. http://dx.doi.org/10.1109/icc.2013.6655474.

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Sethuraman, Vignesh, Hairuo Zhuang e Shahab Sanayei. "HARQ over correlated fading". In 2012 50th Annual Allerton Conference on Communication, Control, and Computing (Allerton). IEEE, 2012. http://dx.doi.org/10.1109/allerton.2012.6483400.

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Cheng, K. W., e J. C. Chen. "Dynamic Pre-Allocation HARQ (DP-HARQ) in IEEE 802.16j Mobile Multihop Relay (MMR)". In ICC 2009 - 2009 IEEE International Conference on Communications. IEEE, 2009. http://dx.doi.org/10.1109/icc.2009.5198958.

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Jin, Shan, Zhaoyang Zhang, Yuzhou Shang e Jue Wang. "MPPP-HARQ: A HARQ Scheme with Multi-Packet Retransmission and Packet-wise Polarization". In 2021 IEEE 94th Vehicular Technology Conference (VTC2021-Fall). IEEE, 2021. http://dx.doi.org/10.1109/vtc2021-fall52928.2021.9625526.

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Weitkemper, Petra, e Hidekazu Taoka. "Adaptive HARQ with Memoryless Relays". In 2011 IEEE Vehicular Technology Conference (VTC Fall). IEEE, 2011. http://dx.doi.org/10.1109/vetecf.2011.6093080.

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Liang, Chulong, Jin Xu, Qiujin Guo e Jun Xu. "Soft HARQ for 5G Downlink". In 2020 International Wireless Communications and Mobile Computing (IWCMC). IEEE, 2020. http://dx.doi.org/10.1109/iwcmc48107.2020.9148379.

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Shirvanimoghaddam, Mahyar, Hossein Khayami, Yonghui Li e Branka Vucetic. "Dynamic HARQ with Guaranteed Delay". In 2020 IEEE Wireless Communications and Networking Conference (WCNC). IEEE, 2020. http://dx.doi.org/10.1109/wcnc45663.2020.9120547.

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Kim, Seong Hwan, Tumula V. K. Chaitanya e Tho Le-Ngoc. "HARQ with Chase-Combining (HARQ-CC) for Uplink Transmission in Large-Antenna-Array Multicell Systems". In 2016 IEEE 83rd Vehicular Technology Conference (VTC Spring). IEEE, 2016. http://dx.doi.org/10.1109/vtcspring.2016.7504266.

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Liu, Fang, Xiaoming She e Lan Chen. "HARQ based Scheduling for Wireless Network". In 2007 IEEE 18th International Symposium on Personal, Indoor and Mobile Radio Communications. IEEE, 2007. http://dx.doi.org/10.1109/pimrc.2007.4394486.

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Rapporti di organizzazioni sul tema "HARQ"

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Farmer, Matthew S. Afghan Tortoise, Korean Hare: Advising in Hard and Soft Cultures. Fort Belvoir, VA: Defense Technical Information Center, gennaio 2010. http://dx.doi.org/10.21236/ada539027.

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Campbell, John, Stefano Giglio e Christopher Polk. Hard Times. Cambridge, MA: National Bureau of Economic Research, luglio 2010. http://dx.doi.org/10.3386/w16222.

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Mckie, Jim. HARE: Final Report. Office of Scientific and Technical Information (OSTI), gennaio 2012. http://dx.doi.org/10.2172/1037585.

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He, Daqing, e Dina Demner-Fushman. HARD Experiment at Maryland: From Need Negotiation to Automated HARD Process. Fort Belvoir, VA: Defense Technical Information Center, gennaio 2006. http://dx.doi.org/10.21236/ada456302.

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Canavan, G. H. Radiation from hard objects. Office of Scientific and Technical Information (OSTI), febbraio 1997. http://dx.doi.org/10.2172/469098.

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Sedillo, James Daniel. 1L Harp Chassis Pics. Office of Scientific and Technical Information (OSTI), novembre 2015. http://dx.doi.org/10.2172/1226134.

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Liberti, José María, e Mitchell Petersen. Information: Hard and Soft. Cambridge, MA: National Bureau of Economic Research, settembre 2018. http://dx.doi.org/10.3386/w25075.

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Leeper, Eric. Fiscal Analysis is Darned Hard. Cambridge, MA: National Bureau of Economic Research, dicembre 2015. http://dx.doi.org/10.3386/w21822.

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Markley, F., M. Davidson, J. Keller, G. Foster, A. Pla-Dalmau, J. Harmon, E. Biagtan et al. Development of radiation hard scintillators. Office of Scientific and Technical Information (OSTI), novembre 1993. http://dx.doi.org/10.2172/10158512.

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Klasky, Marc, Balasubramanya Nadiga, Jennifer Disterhaupt, Elena Guardincerri, James Carroll, Luke Pfister, Luke Hovey et al. Hydrodynamic and Radiographic Toolbox (HART). Office of Scientific and Technical Information (OSTI), maggio 2020. http://dx.doi.org/10.2172/1632670.

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