QAM to Circular Isomorphic Constellations

in 8th Advanced Satellite Multimedia Systems Conference (ASMS/SPSC), Palma de Mallorca, Spain, 2016 (2016, September)

Employing high order constellations is inevitable in order to achieve higher spectral efficiency in satellite communication systems. In DVB-S2X standard, constellations with up to 256 points have been ... [more ▼]

Employing high order constellations is inevitable in order to achieve higher spectral efficiency in satellite communication systems. In DVB-S2X standard, constellations with up to 256 points have been included. However, optimizing such high order constellations is a difficult task. In this paper we propose a very simple constellation design based on the radial map from QAM constellations to non-uniform APSK constellations. Our method provides a systematic way to generate a family of optimized high order constellations. We show that gains larger than 0.5 dB can be obtained with respect to the DVB-S2X constellations with 256 points. Even though the proposed constellations are essentially sub-optimal (in terms of maximizing the mutual information), they provide a very competitive test benchmark for the performance of high order constellations. Moreover, the proposed construction potentially allows for an efficient one-dimensional soft detection by an inverse mapping to the QAM. Finally, further optimization techniques are discussed. [less ▲]

QASBA 2013: Proceedings of the 2013 International Workshop on Quality Assurance for Service-Based Applications

Book published by ACM (2013)

QKD parameter estimation by two-universal hashing leads to faster convergence to the asymptotic rate

in Quantum (2021)

This paper proposes and proves security of a QKD protocol which uses two-universal hashing instead of random sampling to estimate the number of bit flip and phase flip errors. This protocol dramatically ... [more ▼]

This paper proposes and proves security of a QKD protocol which uses two-universal hashing instead of random sampling to estimate the number of bit flip and phase flip errors. This protocol dramatically outperforms previous QKD protocols for small block sizes. More generally, for the two-universal hashing QKD protocol, the difference between asymptotic and finite key rate decreases with the number $n$ of qubits as $cn^{-1}$, where $c$ depends on the security parameter. For comparison, the same difference decreases no faster than $c'n^{-1/3}$ for an optimized protocol that uses random sampling and has the same asymptotic rate, where $c'$ depends on the security parameter and the error rate. [less ▲]

QM7-X, a comprehensive dataset of quantum-mechanical properties spanning the chemical space of small organic molecules

in Scientific Data (2021), 8(43),

We introduce QM7-X, a comprehensive dataset of 42 physicochemical properties for ≈4.2 million equilibrium and non-equilibrium structures of small organic molecules with up to seven non-hydrogen (C, N, O ... [more ▼]

We introduce QM7-X, a comprehensive dataset of 42 physicochemical properties for ≈4.2 million equilibrium and non-equilibrium structures of small organic molecules with up to seven non-hydrogen (C, N, O, S, Cl) atoms. To span this fundamentally important region of chemical compound space (CCS), QM7-X includes an exhaustive sampling of (meta-)stable equilibrium structures—comprised of constitutional/structural isomers and stereoisomers, e.g., enantiomers and diastereomers (including cis-/trans- and conformational isomers)—as well as 100 non-equilibrium structural variations thereof to reach a total of ≈4.2 million molecular structures. Computed at the tightly converged quantum-mechanical PBE0+MBD level of theory, QM7-X contains global (molecular) and local (atom-in-a-molecule) properties ranging from ground state quantities (such as atomization energies and dipole moments) to response quantities (such as polarizability tensors and dispersion coefficients). By providing a systematic, extensive, and tightly-converged dataset of quantum-mechanically computed physicochemical properties, we expect that QM7-X will play a critical role in the development of next-generation machine-learning based models for exploring greater swaths of CCS and performing in silico design of molecules with targeted properties. [less ▲]

QoE-Oriented Resource Allocation Design Coping with Time-Varying Demands in Wireless Communication Networks

in IEEE 96st Vehicular Technology Conference, London-Beijing, Sept. 2022 (2022)

QoS-Constrained Sum-Harvested Energy Maximization in OFDMA-based Wireless Cooperative Networks

Scientific Conference (2018, December)

We investigate the performances of the time-switching (TS) and power-splitting (PS) based energy harvesting models in a two-hop relay assisted network where the end-users are capable of decoding ... [more ▼]

We investigate the performances of the time-switching (TS) and power-splitting (PS) based energy harvesting models in a two-hop relay assisted network where the end-users are capable of decoding information and harvesting energy concurrently. In particular, we consider joint resource allocation and relay selection to realize Simultaneous Wireless Transmission of Information and Energy (Wi-TIE) in a multi-carrier multi-user cooperative system where the relays employ the amplify-and-forward (AF) protocol. First, we formulate based on the TS and PS Wi-TIE architectures an optimization problem to maximize the sum of energy harvested at the end-users, taking into consideration each user's quality-of-service (QoS) requirement as well as power constraints at the transmit and relaying nodes. We then solve the formulated problem to optimize the users' Wi-TIE splitting factors along with relay-user coupling, sub-carrier-user assignment, sub-carrier pairing, and power allocation. Finally, we demonstrate the benefits of the proposed framework via numerical results. [less ▲]

QRNG Entropy as a Service(EaaS) Platform for Quantum-Safe Entropy and key Delivery

Report (2023)

Random numbers [1] are widely used in numerical computing, statistical simulation, random sampling, etc. The security of random numbers is getting more attention. In addition to random numbers ... [more ▼]

Random numbers [1] are widely used in numerical computing, statistical simulation, random sampling, etc. The security of random numbers is getting more attention. In addition to random numbers, information and network environment security [2] are also very important in real life, such as the generation of verification code for login, QR code for online payment, etc. All random numbers that involve important identity information must have extremely high security to protect personal privacy from being leaked or illegally stolen. At present, the mechanism for generating random numbers by computers is at risk of being attacked which is subject that the generated random numbers may be predicted in some cases. Random number generation (RNG) [3] has always been one of the biggest problems. The problem with classic random number generators, i.e., pseudorandom number generators, consists in the possibility to know the deterministic process of pseudorandom generation by unwanted persons. This may result, in the case of cryptography, in compromising a myth of security. Another problem may be the incorrect handling of the generated sequence—mostly in cryptographic uses, the generated random sequence is applied once. Its multiple usage may lead to a security breach (e.g., in the case of the OTP cipher, a sufficiently long key should be truly random and used once in that protocol, otherwise it will be possible to break the code). [less ▲]

Qu’est-ce qu’un diplomate calviniste au XVIe siècle ? Le cas de Philippe de Marnix de Sainte-Aldegonde

Scientific Conference (2009)

Qu'est-ce qu'un Luxembourgeois? Histoire de la nationalité luxembourgeoise du Code Napoléon à nos jours: une histoire sous influence française, belge et allemande

in Reuter, Antoinette; Ruiz, Jean-Philippe (Eds.) Retour de Babel. Itinéraires, mémoires et citoyenneté (2007)

Qu'est-ce qu'une archive du Web?

Book published by OpenEdition Press (2019)

Bien que le Web ait seulement trente ans, son patrimoine est déjà pléthorique : la fondation Internet Archive a collecté plus de 345 milliards de pages web depuis 1996. Cette fondation, qui fut l’un des ... [more ▼]

Bien que le Web ait seulement trente ans, son patrimoine est déjà pléthorique : la fondation Internet Archive a collecté plus de 345 milliards de pages web depuis 1996. Cette fondation, qui fut l’un des pionniers de l’archivage du Web, n’est pas seule à préserver et collecter aujourd’hui ce patrimoine dit « nativement numérique ». Au cours des années 2000, plusieurs pays ont en effet lancé de tels archivages, souvent confiés aux bibliothèques nationales, et cette tendance ne cesse de s’affirmer depuis. Ces initiatives introduisent des ruptures : dans la notion même d’archive, mais aussi dans les pratiques des professionnels des bibliothèques et du patrimoine, tout comme dans celles des chercheurs. Cet ouvrage se propose d’initier le lecteur aux enjeux humains et techniques de l’archivage de la Toile, de la collecte à l’analyse en passant par la création et le partage de corpus ou encore le cadre législatif. Il étudie de manière pragmatique cet archivage, en essayant de rendre palpable à la fois sa fabrique (technique, institutionnelle, juridique), la relation que ses acteurs entretiennent avec les publics et les évolutions qu’ont connues les collectes en une vingtaine d’années. Ce livre s’intéresse également à la manière dont les archives du Web, outre leur rôle patrimonial, peuvent aujourd’hui être exploitées par différents acteurs, notamment à des fins de recherche. [less ▲]