نشریه صنایع الکترونیک
سال دهم شماره 3 (پیاپی 39، پاییز 1398)

Cognitive Radars have the advantage of reducing tracking error, compared to the classical radars, using adaptive waveform design in each transmission with respect to the dynamic parameters of the target. The main idea of this paper is to use this superiority to propose a new paradigm in system design of radars. First, a classic system design of a test bench radar is studied in this paper. In this design paradigm, antenna specifications is determined based on tracking error requirements. In this, we propose to determine the antenna specifications and beamwidth based on the angular resolutions and to use cognitive radars capabilities for reducing the tracking errors. Comparing these two design, we find out that considering a constant tracking error, using cognitive radar elements would lead to a serious reduction in antenna elements in phased arrays radar, and thus, a reduction in cost of the radar. This reduction in array element numbers, depending on the value of angular accuracy and angular resolution, might be as much as half.

The Smart Grid is a large-scale electric power grid by using digital technology that integrates the components of power generations (producers and consumers) in order to enhance the reliability, security, and efficiency by utilizing sensing, processing, measurement, and control. Now, the technologies should lie on the abstract mathematics firmly to model and control the operations. Game theory is a mathematical tool to model systems with Multi-agents (rational decision-makers). Game theory models the behavior of independent and rational agents which in they want to maximize their profits. To this end, we model the behavior of agents and the possible behaviors profit. In the new system, users are able to generate the required energy from renewable energy sources such as solar panels, electric generators, and so forth. Hence, in these complex systems, we would make the use of the mathematical tools to model the interactions and features between agents. In this paper, three basic questions will be answered which I) Why cooperation between agents is valuable. II) Which forms of cooperation are forming and III) Why and how game theory can model the cooperation. In the following, we survey a number of Game theory-based applications especially cooperative game theory to solve relevant problems in Smart Grid. The applications of the Game theory have been presented in three scopes: Micro-grid, Demand Side Management (DSM), and Communications that we will describe them in detail in the following.

Detecting chaos in severe noisy environments and also detecting chaos from noise are important issues in many areas of science and engineering. In this paper, a new criterion for distinguishing noise from noise is first presented, and a new method is proposed to detect chaos in noisy environment from noise based on auto-correlation coefficient of energy distribution. Finally, another method for chaos detection from noise in heavy noisy environments based on energy distribution in different frequency bands using the Discrete Wavelet Transform (DWT) is proposed. A new chaotic oscillator based on memristive devices (memristor and memcapacitor) with up to 50% white gaussian noise, is used as a practical case study to validate the results. This method is capable of detecting chaos in noisy environments of Gaussian noise and color noise. A new chaotic oscillator based on memristive devices is used as a practical case study to validate the results. Simulation results are used to show the main points of the paper.

Along with increasing in the number of telecommunication standards, the demand for multi-standard transmitters / receivers has been raised. The aim of this paper is to design and simulate an LNA that covers the full band of UWB and involve the available standards as well. Accordingly, the main design parameters including noise, gain, input matching, current level, and voltage level are determined so as to achieve an effective operation in the band of 3.1 GHz to 10.6 GHz. The proposed structure is a differential common-gate associated with the gain-boosting and current-reused techniques. Applying the proposed common-gate structure in the LNA in CMOS 0.18μm technology, the power consumption achieves a considerable reduction compared to other LNA counterparts. In addition, the noise figure is reduced to 1.8dB with a gain of 12.8 dB to 13.6 dB, a linearity of -7dBm is achieved, and the input reflection coefficient is reduced to less than -10 dB.

In this paper, a high sensitive piezoresistive intracranial MEMS (Micro Electro Mechanical system) pressure sensor was analyzed and designed for pressure rage of 0-225 mmHg (0-0.05 MPa). This sensor is designed to diagnose disease like Parkinson, brain edema, brain tumor along with other brain problems that could be seriously harmful to the patient. The MEMS technology can create a small size and high sensitive system in order to minimize the brain damages and complications. Enforcing pressure on diaphragm changes the piezoresistor’s resistance and causes a variation in output voltage. In the new sensor, however, the size and material of the diaphragm along with the structure of piezoresistors have been modified. Different materials were investigated and as a result, a substance with the highest tensile strength was chosen. Then the design was done for 4 piezoresistors forming a Wheatstone bridge while two of them are longitudinal without turn and the others are lateral containing a turn. The simulation was done using the finite element method for different piezoresistor lengths with same size. According to the results, a sensitivity of 206.1164 µv/mmHg is achieved with a completely linear output which shows a significant improvement compared with previous works. Furthermore, one of the important feature of this design is all materials used in new structure, including wires and piezoresistors, are biocompatible.

With the widespread use of Voice over IP (VoIP) technology to transmit multimedia such as voice and video, Session Initiation Protocol (SIP) has been the focus of many research. To establish a secure communication channel between the two parties using SIP, authentication of the parties is of the utmost importance. Many research has been done on authentication protocols in recent years, including the lightweight VoIP authentication scheme presented by Zhang et al. In this article, we first prove that Zhang's authentication scheme is not robust against known-session-specific temporary information attack and does not meet the security requirement of perfect forward secrecy. In addition, we present a lightweight and efficient authentication protocol and show that the proposed protocol is resistant to various attacks and is capable of meeting essential security requirements such as perfect forward secrecy and user anonymity. We have also examined the performance of the proposed protocol in terms of computational complexity and have shown that the proposed method has less computational complexity compared to most similar methods. Finally, we prove the correctness of the proposed protocol with Scyther and Proverif tools.

A low-profile wideband conical beam antenna which uses two concentric annular ring slots in substrate integrated waveguide (SIW) technology is presented. First, a single ring antenna is considered and then the effect of introducing the second slot on bandwidth is investigated and high bandwidth is achieved. A brief parametric study for different slot width is presented. A prototype of the proposed antenna is fabricated and measured. The measured reflection coefficient is in good agreement with simulation. The theoretical result is also provided for S11 to validate the simulation and measurement results. The proposed antenna shows 30% bandwidth in 17 GHz center frequency (|S11

Direct Sequence Spread Spectrum is a solution for providing security and jamming resistance in wireless communications. Using long spreading codes is a good idea for making DSSS more secure and reliable. In this paper, common methods of long code acquisition are reviewed and discussed analytically and numerically. The effect of residual frequency and coherent integration time on their probability of detection and mean acquisition time in an AWGN channel are simulated and computational burden of each algorithm is roughly obtained. From theoretical point of view, in addition to restating the expressions of the methods in uniform framework for AWGN channel, performance analysis for averaging based methods in AWGN channel are carried out. Also the effect of multipath Rayleigh channel on detection performance of the methods are modelled mathematically and simulated. Beside good agreement between theory and simulation, the results show that Dual folding method provide better trade-off between time and detection performance and passing through a typical fading channel causes a few dBs drop in the performance of the methods. This paper provides a comparison between acquisition techniques of long codes so as choosing a method for a specific application while considering trade-offs between metrics would be feasible.