Multichannel receivers from ofdm and tdma in mobile communications

This paper addresses the use of multichannel receivers for blind equalization in TDMA under frequency selective channels and OFDM systems in frequency flat fading channels. A new criteria is proposed for blind equalization of finite length mobile channels.Peer ReviewedPostprint (published version

Diversity techniques for blind channel equalization in mobile communications

A blind algorithm for channel distortion compensation is presented which can be employed in spatial or temporal diversity receivers. The proposed technique can be used in frequency selective and frequency flat fading mobile channels, using burst transmission schemes in the first case and OFDM modulation in the second one. The algorithm is base on a deterministic criteria and is suited for estimation when short sets of data are available.Peer ReviewedPostprint (published version

Transform modulations for mobile communications

A new modulation scheme called transform modulations is proposed which improves the system performance in frequency-flat fading mobile channels. They ameliorate the effect of the fadings over the transmitted signal by spreading the information in time, using a linear transform operator. The design of this scheme is discussed and its advantages are shown by means of simulations. The relationship of this scheme with OFDM modulation is also analyzed.Peer ReviewedPostprint (published version

Redundancy in block coded modulations for channel equalization based on spatial and temporal diversity

Linear block codes in the complex field can be applied in spatial and/or temporal diversity receivers in order to develop high performance schemes for (almost-) blind equalization in mobile communications. The proposed technique uses the structure of the encoded transmitted information (with redundancy) to achieve equalization schemes based on a deterministic criterion. Simulations show that the proposed technique is more efficient than other schemes that follow similar equalizer structures. The result is an algorithm that provides the design of channel equalizers in low EbNo scenarios.Peer ReviewedPostprint (published version

Blind equalization based on spatial and temporal diversity in block coded modulations

Linear block codes can be applied in spatial and/or temporal diversity receivers in order to develop high performance schemes for blind equalization in mobile communications. The proposed technique uses the structure of the encoded transmitted information (with redundancy) to achieve equalization schemes based on a deterministic criterion. Simulations show that the proposed technique is more efficient than other schemes that follow similar equalizer structures. The result is an algorithm that provides the design of blind channel equalizers in low EbNo scenarios.Peer ReviewedPostprint (published version

Diversity in mobile communications for blind detection of block-coded modulations

Spatial, temporal, and frequency diversity structures are analyzed to address the blind equalization problem in the presence of time-variant frequency selective channels. The aim of the paper is to present equalization schemes useful in front of fast changing channel responses. The best solution is a deterministic blind criterion that allows direct channel equalization and symbol detection. The main contribution of this paper is to present deterministic blind equalization schemes in CDMA systems (frequency diversity) to reduce the impact of the time-variant frequency selective channel.Peer ReviewedPostprint (published version

Estimacio de frequencia en comunicacions via satel.lit amb dfd's adaptatius

Senyal i comunicacions digitals per satèl·lit. Mètodes de descomposició en valors singulars, per estimació conjunta de freqüència i sincronisme de bit SENYAL I COMUNICACIONS DIGIPeer ReviewedPostprint (published version

El género Dictyota (Phaeophyceae: Dictyotales) en el Atlántico mexicano: análisis molecular y morfológico

El género Dictyota posee aproximadamente 78 especies descritas, distribuidas en una gran variedad de ambientes templad os, subtropicales y tropicales. Como en la mayoría de las algas, la sistemática de Dictyota se ha construido principalmente bajo el enfoque del concepto morfológico de especie. Sin embargo, la alta plasticidad fenotípica que acompaña a las especies que con forman a este género, por un lado, dificulta el reconocimiento de características diagnósticas, por la sobreposición de caracteres, generando así la asignación de epítetos erróneos cuando se realiza el trabajo de identificación. Y por el otro, se hacen evidentes o se reconocen las especies cripticas. En México se han registrado 12 especies en el Atlántico mexicano. Cabe mencionar que estas especies se han determinado con trabajos que compilan solo registros o con obras en las cuales solo se realiza una breve descripción morfológica. En el presente trabajo se realizaron recolectas de especímenes de Dictyota en la zona intermareal, las cuales fueron hechas en 9 localidades del estado de Veracruz y 6 localidades del estado de Quintana Roo. Se obtuvieron 33 secuencias del gen psb A y 20 para el gen cox 1, las cuales fueron incluidas en el análisis de filogenia molecular junto con secuencias de Dictyota procedentes del GenBank. Como resultado de estos análisis se evidenció la presencia de 12 entidades taxonómicas, complementadas con análisis morfológicos, de las cuales, seis tienen correspondencia con nombres válidos (Canistrocarpuscervicornis, D.ciliolata , D. guineensis, D. jamaicensis D. mertensii y D. pinnatifida ) . Se reporta a D. canariensis como un nuevo regist ro para el A tlántico mexicano. S e describen 3 nuevas especies: D. mayae, D. pedrochei y D. chalchi uh cueyecanensis . Además, se reportan dos nuevas entidades taxonómicas: Dictyota sp. 2 y Dictyota sp. 3, quedando pendiente su circunscripción. Del presente estudio se derivaron los primeros resultados que aborda n a l género Dictyota en el Atlántico mexicano con la intención de contribuir a la comprensión y conocimiento de su filogenia con evidencias molecular es y morfológicas.Dictyota owns approximately 78 described species, distributed in a wide range of temperate, subtropical and tropical environments. As in most of the algae, the systematic of Dictyota is constructed mainly from the standpoint of morphological species concept. However, high phenotypic plasticity accompanying species that conform to this genus, difficult to recognize characteristics diagnostic for overlaying of characters, generating erroneous allocation epithets when the identification work is performed. In Mexico there have been 12 species in the Mexican Atlantic. It is noteworthy that these species have been determined on ly in compiling records or works in which only a brief morphological description is made. In this paper collecting Dictyota specimens were conducted in the intertidal zone, which were made in 9 localities in the state of Veracruz and 6 localities in the state of Quintana Roo. 33 psb A gene sequences and 20 for cox 1 gene were obtained, which were included in the analysis of molec ular phylogeny together with Dictyota sequences from GenBank. As a result of these analyzes the presence of 12 taxa was evident, complemented by morphological analysis, of which six have correspondence with valid names (Canistrocarpus cervicorni s, D. cilio lata, D. guineensis , D. jamaicensis , D. mertensii and D. pinnatifida ). D. canariensis is reported as a new record for the Mexican Atlantic. 3 new species are described. D. mayae , D. pedrochei and D. chalchi uh cueyecanensis . In addition two new taxa are repo rted: Dictyota sp.2 and Dictyota sp.3, pending their circumscription. From this study we have the first results that adress to Dictyota genus in the Mexican Atlantic with the intention of contributing to the understanding and knowledge of their phylogeny w ith molecular and morphological evidence

ADC Quantization Requirements

In this document, we analyze the impact of the quantization at the input of the demultiplexer. The required number of bits of the Analog-to-Digital-Converter (ADC) is obtained, along with the corresponding quantization losses.Preprin

Physiological and Behavioral Changes of Water Buffalo in Hot and Cold Systems: Review

This review's objective is to provide information on the mechanisms that buffaloes express during the thermoregulation process. Generally, the water buffalo is associated with warm and tropical climates. In these systems, the combination of high temperature, relative humidity, and radiation cause different physiological and behavioral changes, particularly during the summer months. Wallowing behavior in water or mud promotes heat dissipation through physical mechanisms, such as conduction, convection, and radiation. Furthermore, the provision of natural or artificial shades contributes to thermoregulation and maintains homeostasis. In production systems in cold climates, the wallowing behavior is inhibited by the water temperature, so it is important to keep the animals protected in stables to avoid the cold winds and rapid drops in temperature, causing increased illness pneumonia and sometimes death. Finally, in cold conditions, the animals require an appropriate diet since the use of energy is distributed mainly for the production of heat. Thus, heat stress and cold stress generates relevant problems in health, welfare, and productivity in water buffaloes. A comprehensive assessment of the severity of the resulting problems associated with thermal stress and specialty in cold stress in water buffaloes is necessary so far, and there's very little information about it in this species