Search results for " access"
showing 10 items of 776 documents
Impact of LTE’s Periodic Interference on Heterogeneous Wi-Fi Transmissions
2018
The problem of Wi-Fi and LTE coexistence has been significantly debated in the last years, with the emergence of LTE extensions enabling the utilization of unlicensed spectrum for carrier aggregation. Rather than focusing on the problem of resource sharing between the two technologies, in this paper, we study the effects of LTE's structured transmissions on the Wi-Fi random access protocol. We show how the scheduling of periodic LTE transmissions modifies the behavior of 802.11's distributed coordination function (DCF), leading to a degradation of Wi-Fi performance, both in terms of channel utilization efficiency and in terms of channel access fairness. We also discuss the applicability and…
Parity Oblivious d-Level Random Access Codes and Class of Noncontextuality Inequalities
2016
One of the fundamental results in quantum foundations is the Kochen-Specker no-go theorem. For the quantum theory, the no-go theorem excludes the possibility of a class of hidden variable models where value attribution is context independent. Recently, the notion of contextuality has been generalized for different operational procedures and it has been shown that preparation contextuality of mixed quantum states can be a useful resource in an information-processing task called parity-oblivious multiplexing. Here, we introduce a new class of information processing tasks, namely d-level parity oblivious random access codes and obtain bounds on the success probabilities of performing such task…
Rate-Splitting Random Access Mechanism for Massive Machine Type Communications in 5G Cellular Internet-of-Things
2021
The cellular Internet-of-Things has resulted in the deployment of millions of machine-type communication (MTC) devices. These massive number of devices must communicate with a single gNodeB (gNB) via the random access channel (RACH) mechanism. However, existing RACH mechanisms are inefficient when dealing with such large number of devices. To address this issue, we propose the rate-splitting random access (RSRA) mechanism, which uses rate splitting and decoding in rate-splitting multiple access (RSMA) to improve RACH success rates. The proposed mechanism divides the message into common and private messages and enhances the decoding performance. We demonstrate, using extensive simulations, t…
MAC Design for WiFi Infrastructure Networks: A Game-Theoretic Approach
2011
In WiFi networks, mobile nodes compete for accessing a shared channel by means of a random access protocol called Distributed Coordination Function (DCF). Although this protocol is in principle fair, since all the stations have the same probability to transmit on the channel, it has been shown that unfair behaviors may emerge in actual networking scenarios because of non-standard configurations of the nodes. Due to the proliferation of open source drivers and programmable cards, enabling an easy customization of the channel access policies, we propose a game-theoretic analysis of random access schemes. Assuming that each node is rational and implements a best response strategy, we show that…
How endogenous asymmetries in interregional market access trigger regional divergence
2005
International audience; We investigate how asymmetric trade patterns in differentiated products affect the regional distribution of economic activities. The asymmetry in interregional market access is an endogenous result of price competition and industry location and arises for intermediate values of trade costs. We show that the emergence of one-way trade in differentiated products gives rise to strong agglomeration forces and leads to the absorption of the smaller region's industry by the larger region. The number of spatial equilibria increases once the pattern of trade is endogenously accounted for.
El carácter contingente de las elecciones y la experiencia universitaria : riesgo y origen social
2021
Este trabajo pretende estudiar la experiencia de los estudiantes universitarios de origen social bajo en un contexto de incremento de las dificultades económicas y de endurecimiento de las condiciones institucionales en la universidad. Los momentos que se analizan son: la elección de estudios que realizan estos jóvenes, las condiciones de su paso por la universidad y su proyección de futuro en relación con las decisiones próximas que prevén tomar. Para ello se analizan entrevistas hechas a estudiantes de diferentes universidades catalanas y andaluzas. Entre los jóvenes de origen social bajo se detecta un estilo evitador del riesgo muy consciente de los obstáculos que, en un marco de incerti…
Kriterien für die Auswahl von Elektronischen Rechenanlagen für Biomedizinische Forschungsinstitute
1979
Computers are now a recognized tool in biomedical research. They are used for the evaluation of data on one hand and on the other hand for data acquisition and control of experiments. Based on our experience, some suggestions concerning the structure of a mini-computer system suitable for a research laboratory are made. According to the two major classes of application, two sets or requirements arise. We argue that it is effective to use this system for data reduction and evaluation because a large percentage of tasks require program development or at least specific input data handling. Therefore, we call for a multi-user time-sharing system which should be equipped with a set of commands t…
The importance of correct implants positioning and masticatory load direction on a fixed prosthesis
2018
Background Through the biomechanical study of dental implants, it is possible to understand the dissipation effects of masticatory loads in different situations and prevent the longevity of osseointegration. Aims: To evaluate the microstrains generated around external hexagon implants, using axial and non-axial loads in a fixed four-element prosthesis with straight implants and implants inclined at 17°. Material and Methods Three implants were modeled using CAD software following the manufacturer's measurements. Then, implants were duplicated and divided into two groups: one with straight implants and respective abutments, and the other with angled implants at 17° and respective abutments. …
A Low Cost Solution for 2D Memory Access
2006
Many of the new coding tools in the H.264/AVC video coding standard are based on 2D processing resulting in row-wise and column-wise memory accesses starting from arbitrary memory locations. This paper proposes a low cost solution for efficient realization of these 2D block memory accesses on sub-word parallel processors. It is based on the use of simple register-based data permutation networks placed between the processor and memory. The data rearrangement capabilities of the networks can further be extended with more complex control schemes. With the proposed control schemes, the networks enable row and column accesses from arbitrary memory locations for blocks of data while maintaining f…
La fossa di Danisinni, un sistema di eccesso
2014
La “fossa” di Danisinni è una depressione orografica che si estende dai margini del centro storico di Palermo fino alle emergenze monumentali delle Catacombe dei Cappuccini. Il presente studio, attraverso una sintetica disamina degli eventi salienti della storia di questo luogo, vuole delineare una possibile strategia per la riqualificazione del complesso sistema di aree verdi, proponendo nuove modalità d’accesso per connettere questo potenziale parco al centro storico della città. L’antico alveo del fiume Papireto e il sistema di gallerie delle Catacombe dei Cappuccini, appaiono come dei tracciati da riscoprire e nei quali insediare modalità d’accesso ricche ed inedite.