COEFFICIENT QUANTIZATION EFFECTS ON NEW FILTERS BASED ON CHEBYSHEV FOURTH-KIND POLYNOMIALS

The aim of this paper is to construct non-recursive filters, extensively used type of digital filters in digital signal processing applications, based on Chebyshev orthogonal polynomials. The paper proposes the use of the fourth-kind Chebyshev polynomials as functions in generating new filters. In this kind, low-pass filters with linear phase responses are obtained. Comprenhansive study of the frequency response characteristics of the generated filter functions is presented. The effects of coefficient quantization as one type of quantization that influences a filter characteristic are investigated here also. The quantized-coefficient errors are considered based on the number of bits and the implementation algorithm

WAVE DIGITAL MODELS OF IDEAL AND REAL TRANSFORMERS

In this paper, a generalization of the wave digital models of ideal transformer is done, aiming to increase a number of types of structures that can be modeled by using wave digital filter theory. Wave digital networks are described in details and developed here based on scattering parameter formalism and two-port networks of parallel or series adaptors

Applications of artificial neural networks for calculation of the Erlang B formula and its inverses

Abstract In this article, a novel approach to calculate the Erlang B formula and its inverses is proposed. It is based on application of artificial neural networks (ANNs). Namely, ANNs are trained to calculate the Erlang B call blocking probability as well as to solve the inverse problem, i.e. to calculate the required number of channels or the maximum amount of traffic for the given call blocking probability. Comparing to direct calculation of Erlang B formula, computational efficiency is significantly increased, while the accuracy is maintained. As far as the calculation of Erlang B inverse values is considered, as there is a lack of exact mathematical formulas, the proposed approach provides the closed‐form mathematical expressions

Doherty Amplifier Linearity Test for Fifth Generation Signals

In this paper, the linearity of a fabricated microstrip Doherty amplifier in asymmetrical topology (ADA) is experimentally tested for the fifth generation signals. The measurement set-up contains a Matlab programming platform, a signal generator, and a vector signal analyzer. The Matlab development platform and the signal generator are used for the generation of the 5G FBMC, UFMC, and FOFDM signals. The 5G signal spectra are measured by the vector signal analyzer at the input and output of the Doherty amplifier. The output spectra of the 5G signals for different input power levels gained in measurements are compared to the simulated results

Combination of Digital Second-Order Linearization Technique and DPD Compensation Technique - Concept and Results

In this paper, a single stage broadband power amplifier operating at 3.5 GHz central frequency is linearized in simulation by the technique that combines two linearization approaches: 1. the digital technique that uses the second-order baseband nonlinear signals which modulate the second harmonic of signal carrier and 2. one iteration of the DPD Compensation technique. Linearization results are obtained and analyzed for 5G signal modulation forms FBMC, FOFDM, and UFMS with 50 MHz useful channel bandwidth for various signal power levels. The output spectrum achieved by the combined technique is compared for the cases when two linearization techniques are applied independently

Evaluation of the Dual-Band PA Nonlinear Behavior for 5G Signals

In this paper, the assessment of the digital linearization technique’s influence on a dual-band power amplifier was carried out. The linearization technique requires utilization of the second-order nonlinear signals in the baseband which modulate the second harmonic of the carrier. The dual-band power amplifier (PA) operates concurrently at two widely spaced frequencies, 2.1 GHz and 5 GHz. The linearization of the dual-band is executed in simulation for both considered frequency bands independently. Results accomplished through the linearization process for various output power levels were acquired for FBMC, FOFDM and UFMC signals, which represent modulation forms for the 5G systems

Post-anaesthesia pulmonary complications after use of muscle relaxants (POPULAR): a multicentre, prospective observational study

Background Results from retrospective studies suggest that use of neuromuscular blocking agents during general anaesthesia might be linked to postoperative pulmonary complications. We therefore aimed to assess whether the use of neuromuscular blocking agents is associated with postoperative pulmonary complications. Methods We did a multicentre, prospective observational cohort study. Patients were recruited from 211 hospitals in 28 European countries. We included patients (aged ≥18 years) who received general anaesthesia for any in-hospital procedure except cardiac surgery. Patient characteristics, surgical and anaesthetic details, and chart review at discharge were prospectively collected over 2 weeks. Additionally, each patient underwent postoperative physical examination within 3 days of surgery to check for adverse pulmonary events. The study outcome was the incidence of postoperative pulmonary complications from the end of surgery up to postoperative day 28. Logistic regression analyses were adjusted for surgical factors and patients’ preoperative physical status, providing adjusted odds ratios (ORadj) and adjusted absolute risk reduction (ARRadj). This study is registered with ClinicalTrials.gov, number NCT01865513. Findings Between June 16, 2014, and April 29, 2015, data from 22803 patients were collected. The use of neuromuscular blocking agents was associated with an increased incidence of postoperative pulmonary complications in patients who had undergone general anaesthesia (1658 [7·6%] of 21694); ORadj 1·86, 95% CI 1·53–2·26; ARRadj –4·4%, 95% CI –5·5 to –3·2). Only 2·3% of high-risk surgical patients and those with adverse respiratory profiles were anaesthetised without neuromuscular blocking agents. The use of neuromuscular monitoring (ORadj 1·31, 95% CI 1·15–1·49; ARRadj –2·6%, 95% CI –3·9 to –1·4) and the administration of reversal agents (1·23, 1·07–1·41; –1·9%, –3·2 to –0·7) were not associated with a decreased risk of postoperative pulmonary complications. Neither the choice of sugammadex instead of neostigmine for reversal (ORadj 1·03, 95% CI 0·85–1·25; ARRadj –0·3%, 95% CI –2·4 to 1·5) nor extubation at a train-of-four ratio of 0·9 or more (1·03, 0·82–1·31; –0·4%, –3·5 to 2·2) was associated with better pulmonary outcomes. Interpretation We showed that the use of neuromuscular blocking drugs in general anaesthesia is associated with an increased risk of postoperative pulmonary complications. Anaesthetists must balance the potential benefits of neuromuscular blockade against the increased risk of postoperative pulmonary complications