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As stops and pauses for separating parts of a sentence in language help to convey information, it is also possible to communicate information in communication systems not only by data payload, but also with its timing. We consider an event-triggering strategy that exploits timing information by transmitting in a state-dependent fashion to stabilize...
This study investigates the use of a popular online expression ‘skr’ by Chinese micro-blogging users on Weibo. Used originally as a hip-hop term for the sound of cars drifting tires, ‘skr’ was exploited by Chinese micro-blogging users for other meanings and functions. Data were collected from Weibo users’ postings over a month. Using the Search fun...
The theme of research was built progressively. At the beginning, the objective was to explain the relationship between stress due to e-hrm and satisfaction-productivity by using the stress model due to e-hrm to answer to the following problematic: how the stress induced by e-hrm can influence the satisfaction and the productivity of the personnel,...
In this paper, a new non-coherent chaos-based digital communication system combined short reference Quadrature chaos shift keying with orthogonal frequency division multiplexing named (OFDM-SRQCSK) is presented. This system is an extension of short reference Quadrature chaos shift keying (SR-QCSK) modulation by sending parallel information sequence...
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In the article analysis of reasons of increase reliability while transmitting signals throw communication channels with adaptive white Gaussian noise was realized. When transmitting messages over a communication channel, it becomes necessary to determine and, in some cases, improve the quality of transmitted information between remotely located subscribers. The multiplicity of solving this problem increases with the exchange of information between technological objects, where an erroneously received signal can have both small and significant irreparable consequences. The paper considers a model of a telecommunications network based on digital communication channels and a high-speed ADSL DMT subscriber line. When considering the model, we used methods for determining the energy characteristics in a digital communication channel with M-QAM modulation and calculating the error probability from the carrier/noise levels ratio. Also, we considered the calculation of the error probability in the subscriber section using a symmetrical AWG 24 cable with a diameter of 0.5 mm, depending on the length of the communication line.
This paper is concerned with a machine learning approach to cancel the interference for cognitive Internet of Things (C-IoT) in the concurrent spectrum access (CSA) model, where the C-IoT system is non-cooperative and has very limited knowledge on the interference. Our transceiver design uses an iterative processing structure, which consists of a linear estimator, a demodulation-and-decoding module, and a clustering module. In the clustering module, we employ modified expectation maximization (EM) based algorithms to estimate the interference under the knowledge of the modulation constraint (MC) of the interference. We show that this modified EM algorithm based receiver outperforms the original EM-based receiver, since the former is able to generate a more accurate clustering result by reducing the dimension of the parameter space. We further improve the performance of the iterative receiver by introducing the extrinsic information technique, with the resulting algorithm referred to as theextrinsic modulation constrained EM (Ext-MC-EM) algorithm. We show that the Ext-MC-EM algorithm based receiver considerably outperforms the counterpart iterative receivers, including the MC-EM algorithm.
Flexible and thin displays for smart devices have a large coupling capacitance between the sensor electrode of the touch screen panel (TSP) and the display electrode. This increased coupling capacitance limits the signal passband to less than 100 kHz, resulting in a significant reduction in the received signal, with a driving frequency of several hundred kilohertz used for noise avoidance. To overcome this problem, we reduced the effective capacitance at the analog front-end by connecting a circuit with a negative capacitance in parallel with the coupling capacitance of the TSP. In addition, the in-phase and quadrature demodulation scheme was used to address the phase fluctuation between the signal and the clock during demodulation. We fabricated a test chip using the 0.35 µm CMOS process and obtained a signal-to-noise ratio of 43.2 dB for a 6 mm diameter metal pillar touch input.
Low Earth Orbit (LEO) satellites are used for public networking and for scientific purposes. Communication via satellite begins when the satellite is positioned in its orbital position. Ground stations can communicate with LEO satellites only when the satellite is in their visibility region, since LEO satellites move too fast relative to a fixed point (ground station) on the Earth. The major loss in communication between the LEO satellite and the ground station is the free space loss. Free space loss varies since the distance from the ground station to the satellite varies over time. Free space loss is usually compensated through variable satellite transmit power on the downlink. This paper tries another approach on free space loss compensation, through receiver bandwidth adjustability at the ground station, in order to obtain the constant margin at the receiver. For analytical and simulation purposes, the altitudes from 600km to 1200km are considered.
In this paper, the performance of a convolutional encoded orthogonal frequency-division multiplexing (OFDM) based wireless communication system has been simulated in terms of bit error rate (BER). In FEC channel coding, the OFDM based wireless communication system incorporates a convolutional encoder under various digital modulation schemes (QAM, QPSK, 8QAM, 8PSK, 16QAM, 16PSK, 32QAM and 32PSK). The computer simulation results on BER over an Additive White Gaussian Noise (AWGN) and other fading (Rayleigh and Rician) channels demonstrate that the convolutional encoded OFDM system outperforms with QAM modulation technique as compared to other digital modulation schemes and the system is highly effective to combat inherent interferences under Rayleigh and Rician fading channels. It has been anticipated from the simulation study with synthetically generated data that the performance of the communication system degrades with the increasing of noise power.
Role of Filters in electronic devices is evident in this modern era. Filtering is a term that is used in most DSP applications to pass specific frequencies and reject other ones. There is a wide range of application areas of digital filters including image processing, voice, and video and data communication. A large number of techniques are used to design IIR filters. This paper's idea is to design, analyze and compare performance of Chebyshev I, Chebyshev II and Butterworth IIR filters using MATLAB FDA tool. Noise free signal will be rendered at the output of filter. Further effect of different parameters such as order, type of filter and cut off frequency are filter.
