Data Conversion in Area-Constrained Applications: the Wireless Network-on-Chip Case

Network-on-Chip (NoC) is currently the paradigm of choice to interconnect the different components of System-on-Chips (SoCs) or Chip Multiprocessors (CMPs). As the levels of integration continue to grow, however, current NoCs face significant scalability limitations and have prompted research in novel interconnect technologies. Among these, wireless intra-chip communications have been under intense scrutiny due to their low latency broadcast and architectural flexibility. Thus far, the practicality of the idea has been studied from the RF front-end and the network interface perspectives, whereas little to no attention has been placed on another essential component: the data converters. This article aims to fill this gap by providing a comprehensive analysis of the requirements of the scenario, as well as of the current performance and cost trends of Analog-to-Digital Converters (ADCs). Based on Murmann's data, we demonstrate that ADCs will not be a roadblock for the realization of wireless intra-chip communications although current designs do not meet their demands fully.Comment: Presented at DCIS 201

Channel Characterization for Chip-scale Wireless Communications within Computing Packages

Wireless Network-on-Chip (WNoC) appears as a promising alternative to conventional interconnect fabrics for chip-scale communications. WNoC takes advantage of an overlaid network composed by a set of millimeter-wave antennas to reduce latency and increase throughput in the communication between cores. Similarly, wireless inter-chip communication has been also proposed to improve the information transfer between processors, memory, and accelerators in multi-chip settings. However, the wireless channel remains largely unknown in both scenarios, especially in the presence of realistic chip packages. This work addresses the issue by accurately modeling flip-chip packages and investigating the propagation both its interior and its surroundings. Through parametric studies, package configurations that minimize path loss are obtained and the trade-offs observed when applying such optimizations are discussed. Single-chip and multi-chip architectures are compared in terms of the path loss exponent, confirming that the amount of bulk silicon found in the pathway between transmitter and receiver is the main determinant of losses.Comment: To be presented 12th IEEE/ACM International Symposium on Networks-on-Chip (NOCS 2018); Torino, Italy; October 201

Fault Tolerance in Programmable Metasurfaces: The Beam Steering Case

Metasurfaces, the two-dimensional counterpart of metamaterials, have caught great attention thanks to their powerful control over electromagnetic waves. Recent times have seen the emergence of a variety of metasurfaces exhibiting not only countless functionalities, but also a reconfigurable or even programmable response. Reconfigurability, however, entails the integration of tuning and control circuits within the metasurface structure and, as this new paradigm moves forward, new reliability challenges may arise. This paper examines, for the first time, the reliability problem in programmable metamaterials by proposing an error model and a general methodology for error analysis. To derive the error model, the causes and potential impact of faults are identified and discussed qualitatively. The methodology is presented and instantiated for beam steering, which constitutes a relevant example for programmable metasurfaces. Results show that performance degradation depends on the type of error and its spatial distribution and that, in beam steering, error rates over 10% can still be considered acceptable

Characterizing the Communication Requirements of GNN Accelerators: A Model-Based Approach

Relational data present in real world graph representations demands for tools capable to study it accurately. In this regard Graph Neural Network (GNN) is a powerful tool, wherein various models for it have also been developed over the past decade. Recently, there has been a significant push towards creating accelerators that speed up the inference and training process of GNNs. These accelerators, however, do not delve into the impact of their dataflows on the overall data movement and, hence, on the communication requirements. In this paper, we formulate analytical models that capture the amount of data movement in the most recent GNN accelerator frameworks. Specifically, the proposed models capture the dataflows and hardware setup of these accelerator designs and expose their scalability characteristics for a set of hardware, GNN model and input graph parameters. Additionally, the proposed approach provides means for the comparative analysis of the vastly different GNN accelerators.Comment: ISCAS 202

Comportamiento en vivero de nueve variedades de café injertada sobre Coffea canephora en San Ramón (Chanchamayo)

Universidad Nacional Agraria La Molina. Facultad de Agronomía. Departamento Académico de FitotecniaEl presente trabajo se realizó en el fundo “La Genova” de la Universidad Nacional Agraria La Molina, con el objetivo de comparar nueve variedades de café injertadas sobre Coffea canephora en San Ramón (Chanchamayo). El café es el cultivo de mayor área de producción del país, además de ser internacionalmente reconocido por su alta calidad. Las variedades que se evaluaron en este ensayo son: Laurina IAC 870, Catuai Vermelho IAC 144, Catuai Vermelho IAC 99, Catuaí Amarelo IAC 86, Caturra Amarelo Col. 8 IAC 476, Bourbon Vermelho IAC 662, Caturra Vermelho IAC 477, Obata IAC 1669-20 y Limani. Esta última, es una variedad que se cultiva localmente, y los ocho restantes son variedades de café introducidas desde Brasil. El injerto se hizo a todas las variedades, utilizando como patrón al cultivar Robusta que es una Coffea canephora, ya que esta es conocida por tener resistencia a Meloidogyne spp.. Los parámetros evaluados son: número de hojas, altura de planta, diámetro de tallo, esta evaluación se realizó en cuatro ocasiones y cada 30 días, en donde la primera evaluación se hizo después del injerto y repique. El peso fresco y peso seco se evaluó al término de la cuarta evaluación en el laboratorio “José Calzada Benza” del IRD – Selva de la UNALM en el fundo “La Génova”. Se demuestra que el tratamiento Caturra Vermelho IAC 477/Robusta con inóculo, obtuvo el mayor número de hojas. En el parámetro, altura de planta los tratamientos Obata IAC 1669-20 con inóculo y Laurina IAC 870 alcanzaron una mayor altura. Para el caso del diámetro de tallo se encontró que el tratamiento Catuaí Vermelho IAC 144/Robusta con inóculo obtuvo el mayor diámetro de tallo. El mayor peso fresco total y el peso seco total (secado en estufa a 75° por 48 horas) lo consiguió Caturra Vermelho IAC 477/Robusta con inóculo.Tesi