Computation reduction for turbo decoding through window skipping

A simple and effective technique to skip the computation of reliable portions of a frame (windows) for turbo code decoding is proposed. The proposed criterion relies on a very simple approximation of cross-entropy measure by means of thresholding. This criterion features negligible complexity and low-memory requirements. Simulation results show that, in the best case, up to 20% of windows can be skipped with no error-rate degradation. Such a significant computation reduction can be exploited to directly reduce the power consumption as well

MEDEA: A Hybrid Shared-memory/Message-passing Multiprocessor NoC-based Architecture

The shared-memory model has been adopted, both for data exchange as well as synchronization using semaphores in almost every on-chip multiprocessor implementation, ranging from general purpose chip multiprocessors (CMPs) to domain specific multi-core graphics processing units (GPUs). Low-latency synchronization is desirable but is hard to achieve in practice due to the memory hierarchy. On the contrary, an explicit exchange of synchronization tokens among the processing elements through dedicated on-chip links would be beneficial for the overall system performance. In this paper we propose the Medea NoC-based framework, a hybrid shared-memory/message-passing approach. Medea has been modeled with a fast, cycle-accurate SystemC implementation enabling a fast system exploration varying several parameters like number and types of cores, cache size and policy and NoC features. In addition, every SystemC block has its RTL counterpart for physical implementation on FPGAs and ASICs. A parallel version of the Jacobi algorithm has been used as a test application to validate the metodology. Results confirm expectations about performance and effectiveness of system exploration and design

Caractérisation de l'aptitude au frittage des poudres d'alumine par émission exoélectronique photostimulée (OSEE).

National audienc

Computation reduction for turbo decoding through window skipping

A simple and effective technique to skip the computation of reliable portions of a frame (windows) for turbo code decoding is proposed. The proposed criterion relies on a very simple approximation of cross-entropy measure by means of thresholding. This criterion features negligible complexity and low-memory requirements. Simulation results show that, in the best case, up to 20% of windows can be skipped with no error-rate degradation. Such a significant computation reduction can be exploited to directly reduce the power consumption as well

The stackelberg minimum spanning tree game on planar and bounded-treewidth graphs

The Stackelberg Minimum Spanning Tree Game is a two-level combinatorial pricing problem introduced at WADS’07. The game is played on a graph, whose edges are colored either red or blue, and where the red edges have a given fixed cost. The first player chooses an assignment of prices to the blue edges, and the second player then buys the cheapest spanning tree, using any combination of red and blue edges. The goal of the first player is to maximize the total price of purchased blue edges. We study this problem in the cases of planar and bounded-treewidth graphs. We show that the problem is NP-hard on planar graphs but can be solved in polynomial time on graphs of bounded treewidth

Logic-in-Memory: A Nano Magnet Logic Implementation

In most computational systems memory access rep- resents a relevant bottleneck for circuits performance. The execution speed of algorithms is severely limited by memory access time. An emerging technology like NanoMagnet Logic (NML), where its magnetic nature leads to an intrinsic memory ability, represents therefore a very promising opportunity to solve this issue. NanoMagnet Logic is the ideal candidate to implement the so called Logic-In-Memory (LIM) architecture. But how is it possible to organize an architecture where logic and memory are mixed and not separated entities? In this paper we try to address this issue presenting our recent developments on LIM architectures. We originally conceived a LIM architecture without considering any technological con- straints. Here we present the first adaptation of that architecture to NanoMagnet Logic technology. The architecture is based on an array of identical cells developed on three virtual layers, one for logic, one for memory and one for information routing. These three virtual layers are mapped on two physical layers exploiting all our recent improvements on NanoMagnet Logic technology, which are validated with the help of low level simulations. The structure has been tested implementing two different algorithms, a sort algorithm and an image manipulation algorithm. A complete characterization in terms of area and power is reported. The structure here presented is therefore the first step of an ongoing effort directed toward the development of truly innovative architecture

Red Devonian trilobites with green eyes from Morocco and the silicification of the trilobite exoskeleton

Latest Emsian (Early Devonian) sediments at the famous mud−mound− and trilobite−locality Hamar Laghdad (Tafilalt, Morocco) yielded some red−coloured remains of phacopid trilobites. Closer examination revealed that the eyes of these phacopids are often greenish in colour. EDX−analyses showed that the lenses retained their original calcitic composition, possibly greenish due to Fe−impurities, while most of the exoskeleton was silicified. The silicified parts contain elevated concentrations of iron which causes the red colour. This phenomenon is explained by the porosity of the exoskeleton in contrast to the homogeneous and massive construction of the lenses and their Mg−content. These incompletely silicified trilobites enabled a reconstruction of the silicification process in trilobites. Their diagenetic alteration probably occurred as a result of events associated with the Cretaceous transgression

Muon accelerators

We introduce a new phylogenetic reconstruction algorithm which, unlike most previous rigorous inference techniques, does not rely on assumptions regarding the branch lengths or the depth of the tree. The algorithm returns a forest which is guaranteed to contain all edges that are: 1) sufficiently long and 2) sufficiently close to the leaves. How much of the true tree is recovered depends on the sequence length provided. The algorithm is distance-based and runs in polynomial time