This work analyses the performance-complexity tradeoff for different direction of arrival (DoA) estimation techniques. Such tradeoff is investigated taking into account uniform linear array structures. Several DoA estimation techniques have been compared, namely the conventional Delay-and-Sum (DS), Minimum Variance Distortionless Response (MVDR), Multiple Signal Classifier (MUSIC) subspace, Estimation of Signal Parameters via Rotational Invariance Technique (ESPRIT), Unitary-ESPRIT and Fourier Transform method (FT-DoA). The analytical formulation of each estimation technique as well the comparative numerical results are discussed focused on the estimation accuracy versus complexity tradeoff. The present study reveals the behavior of seven techniques, demonstrating promising ones for current and future location applications involving DoA estimation, especially for 5G massive MIMO systems. 2 an electromagnetic wave into a voltage. The electromagnetic waves are necessary for wireless communications systems implementation. Array signal processing applications include radar and wireless communication systems with electromagnetic waves and sonar, seismic event prediction, microphone sensors with mechanical waves [1]-[3]. In a typical application, an incoming wave is detected by an array, the associated signals at different sensors in space can be processed to extract various types of information including their direction of arrival (DoA). The array model is illustrated in Fig. 1. Moreover, the spatial-temporal estimation and filtering capability can be exploited for multiplexing co-channel users and rejecting harmful co-channel interference that may occur because of jamming or multipath effects. DoA algorithms can be divided into three categories: extrema-searching techniques [4]-[10], polynomial-rooting techniques [11] and matrix-shift techniques [12], [13]. The matrix-shift techniques utilize estimates of the signal subspace whereas most extrema-searching techniques and most polynomial-rooting techniques use estimates of its orthogonal complement, often referred to as noise subspace.The DoA estimation process has been extensively researched since the 1980s, but the research area remains active, mainly due to recent and newly field of applications [14], [15]. Recent studies are mostly focused on specific applications and new approaches to the subject in order to improve performance while decrease computational complexity as well. For some DoA applications it is necessary to estimate the location of sources near and far from the array. For instance, in [16] and [17] DoA techniques are discussed for far-field and near-field sources. To achieve greater accuracy in DoA, a large number of antennas are required, and this is not always feasible, either by physical space or cost limitations.

Introduction: A methodology was developed for implementing closed-loop control algorithms and for evaluating the behavior of a system, considering certain component restrictions used in laboratory implementation. Methods:Mathematical functions representing a model of the biological system were used for knee extension/fl exion movements. A Proportional Integral Derivative (PID) controller and another one using the root locus method were designed to control a patient's leg position by applying functional electrical stimulation (FES). The controllers were simulated in Matlab and ISIS Proteus. After the simulations were performed, the codes were embedded in a microcontroller, and tests were conducted on a paraplegic volunteer. To the best of the authors' knowledge, this is the fi rst time that ISIS Proteus software resources have been used prior to implementing a closed-loop system designed to control the leg position of patients. Results: This method obviates the application of initial controller tests directly to patients. The response obtained in the experiment with a paraplegic patient complied with the specifi cations set in terms of the steady-state error, the settling time, and the percentage overshoot.The proposed procedure was successfully applied for the implementation of a controller used to control the leg position of a paraplegic person by electrical muscle stimulation. Conclusion: The methodology presented in this manuscript can contribute to the implementation of analog and digital controllers because hardware limitations are typically not taken into account in the design of controllers.

Abstract This work presents an alternative methodology for analysis and testing of some systems with closed loop control using DSP's. First identifies the transfer function that describes the behavior of the plant, then projected to the controller and then embedded on the independents DSP's. Thus, implementing the controller in hardware, it allows the designer encounters limitations actual implementation often not foreseen in the design phase and the plant model embedded on another, it's not necessary to use the actual plant this phase controller design. In this work we used this methodology in design and implementation of a controller for a DC motor. The responses of the simulations were compared with the actual responses, indicating a good perspective on the use of the proposed methodology. The algorithms and systems have been developed in MATLAB / Simulink, which offers programming block, easy to use, versatile and can also be embedded directly into the DSP. Keywords Method, Control, DSP, Code Composer and PID.Resumo Este trabalho propõe uma alternativa metodológica para análise e experimentação de alguns sistemas com controle em malha fechada utilizando DSP's. Primeiramente identifica-se a função de transferência que descreve o comportamento da planta, posteriormente projeta-se um controlador e em seguida embarca-os em DSP's independentes. Desta forma, implementando o controlador em hardware, permite-se que o projetista se depare com limitações reais de implementação, muitas vezes não previstas na fase de projeto e embarcando o modelo da planta em outro, não se faz necessário o uso a planta real nesta fase de projeto do controlador. Neste trabalho foi utilizada esta metodologia no projeto e implementação de um controlador para um motor de corrente contínua. As respostas da simulações foram confrontadas com as respostas reais, indicando uma boa perspectiva na utilização da metodologia proposta. Os algoritmos e sistemas foram elaborados no MATLAB/Simulink, que oferece uma programação em blocos, de fácil utilização, versátil e também podem ser embarcados diretamente nos DSP's por meio do Code Composer. Palavras-chave IntroduçãoUm sistema real muitas vezes pode ser representado por um modelo matemático.Com este modelamento se obtém um sistema analítico semelhante ao real, permitindo assim o desenvolvimento de um controlador adequado.É importante utilizar, nas etapas de desenvolvimento de controladores, métodos que preveem seu comportamento dentro de um sistema.Normalmente são utilizadas algumas plataformas de simulação poderosas, como MATLAB/Simulink, capazes de analisar a resposta temporal de sistemas controlados.Contudo, quando o controlador simulado é implementado em um dispositivo, como um microcontrolador ou um DSP (Processador Digital de Sinais), muitas vezes não obtém-se êxito.Isto pode ocorrer por diversos motivos, o componente escolhido não ter tão elevada capacidade de processamento como MATLAB, o algoritmo utilizado no controlador não ser adequado, as limitações dos periféricos, como conversor an...