Energy efficiency of mmWave massive MIMO precoding with low-resolution DACs

With the congestion of the sub-6 GHz spectrum, the interest in massive multiple-input multiple-output (MIMO) systems operating on millimeter wave spectrum grows. In order to reduce the power consumption of such massive MIMO systems, hybrid analog/digital transceivers and application of low-resolution digital-to-analog/analog-to-digital converters have been recently proposed. In this work, we investigate the energy efficiency of quantized hybrid transmitters equipped with a fully/partially-connected phase-shifting network composed of active/passive phase-shifters and compare it to that of quantized digital precoders. We introduce a quantized single-user MIMO system model based on an additive quantization noise approximation considering realistic power consumption and loss models to evaluate the spectral and energy efficiencies of the transmit precoding methods. Simulation results show that partially-connected hybrid precoders can be more energy-efficient compared to digital precoders, while fully-connected hybrid precoders exhibit poor energy efficiency in general. Also, the topology of phase-shifting components offers an energy-spectral efficiency trade-off: active phase-shifters provide higher data rates, while passive phase-shifters maintain better energy efficiency.Comment: Published in IEEE Journal of Selected Topics in Signal Processin

General scalar products in the arbitrary six-vertex model

In this work we use the algebraic Bethe ansatz to derive the general scalar product in the six-vertex model for generic Boltzmann weights. We performed this calculation using only the unitarity property, the Yang-Baxter algebra and the Yang-Baxter equation. We have derived a recurrence relation for the scalar product. The solution of this relation was written in terms of the domain wall partition functions. By its turn, these partition functions were also obtained for generic Boltzmann weights, which provided us with an explicit expression for the general scalar product.Comment: 24 page

Optimizing the choice of microsatellite markers for fingerprinting eucalyptus

In this study we have analyzed the information provided by 17 publicly available Eucalyptus microsatellite (SSR) markers (Brondani et al. 1998, 2002; Jones et al. 2002; Steane et al. 2001) in the context of genetic identification within a sample of 140 individuals from an elite collection (denoted hereafter base) of RAIZ genetic improvement population

Estimativa do parentesco numa população de melhoramento de Eucalyptus globulus através de microsatélites nucleares

É situação comum desconhecer-se o grau de parentesco entre a população na origem da maioria dos programas de melhoramento genético de espécies florestais. Para resolver este problema, desenvolvemos um protocolo de avaliação do parentesco utilizando 125 indivíduos e 16 microssatélites, da população base ou de referência (PR) de Eucalyptus globulus do RAIZ. Através da recombinação gamética in silico foram simulados 105 indivíduos com diferentes graus de parentesco: descendentes de autopolinização, meiosirmãos, irmãos completos e indivíduos não aparentados. Por simulação Monte-Carlo foram calculados o valor médio e a variância associada à média dos diferentes grupos de parentesco, com quatro coeficientes de similaridade genética. Compararam-se as funções densidade dos diferentes grupos de parentesco, obtidas com quatro coeficientes de parentesco, utilizando o valor crítico correspondente à intercepção das funções densidade dos indivíduos não aparentados e dos meios-irmãos. O estimador escolhido foi aplicado à PR. Detectaram-se 4,4% de pares de indivíduos potencialmente aparentados, com um erro de tipo II de 8%. Inferimos também, o parentesco de um conjunto de 24 clones elite e encontrámos 4 pares que são potencialmente aparentados. Futuros cruzamentos entre estes indivíduos deverão ser evitados