Iterative joint frequency offset and channel estimation for OFDM systems using first and second order approximation algorithms

[[abstract]]To implement an algorithm for joint estimation of carrier frequency offset (CFO) and channel impulse response (CIR) in orthogonal frequency division multiplexing (OFDM) systems, the maximum-likelihood criterion is commonly adopted. A major difficulty arises from the highly nonlinear nature of the log-likelihood function which renders local extrema or multiple solutions for the CFO and CIR estimators. Use of an approximation method coupled with an adaptive iteration algorithm has been a popular approach to ease problem solving. The approximation used in those existing methods is usually of the first order level. Here, in addition to a new first order approximation method, we also propose a second order approximation method. Further, for the part of the adaptive iteration algorithm, we adopt a new technique which will enable performance improvement. Our first order approximation method is found to outperform the existing ones in terms of estimation accuracies, tracking range, computation complexity, and convergence speed. As expected, our second order approximation method provides an even further improvement at the expense of higher computation complication.[[notice]]補正完畢[[journaltype]]國外[[incitationindex]]SCI[[booktype]]紙本[[booktype]]電子版[[countrycodes]]DE

Biosensors Based on Nanomaterials: Transducers and Modified Surfaces for Diagnostics

The use of nanoparticles has opened a new era in the development of nanobiosensors capable of achieving analytical responses that compete with the most powerful instrumental techniques. Nanobiosensors are devices that allow analytical determinations through a specific action event between an analyte ofinterest and a bio-recognition molecule. These recognition molecules as enzymes,antibodies, nucleic acids, and aptamers are studied in detail in this chapter. The role of nanomaterials in biosensors is described in a separate section since they play a central role, allowing the understanding of their physicochemical properties such as quantum confinement, surface plasmon resonance, magnetic properties, and the effect of area increase. In addition, a brief review is provided about some basic concepts for the integration of the sensor components and their function in sensing systems found in the literature. Subsequently, a classification is proposed to summarize its fundamental characteristics, mechanism of operation, analytical characteristics, advantages, and disadvantages. Then, the main nanobiosensor types found in the literature are detailed, and specific explanations are given, e.g., those based on the determination of electrical, piezoelectric, colorimetric, fluorescent, and chemiluminescent properties. Likewise, the functioning of recently developed nanobiosensors is discussed, such as those based on local (SERS). Also, the applications of nanobiosensors in different fields of biomedicine and their fundamental importance to advance in the diagnosis of multiple pathologies as cancer are detailed. Finally, we discuss the state of the art and the future perspectives of scientific development.Fil: Romero, Marcelo Ricardo. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; ArgentinaFil: Picchio, Matías Luis. Universidad Nacional de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin