Open Topics

Vol. 76, n° 7-8, July-August 2021
Content available on Springerlink

Motor imagery-based neuro-feedback system using neuronal excitation of the active synapses

Sumanta Bhattacharyya1,2 · Manoj K. Mukul1 · Ashish Kr. Luhach3 ·
Joel J. P. C. Rodrigues4,5

(1) BIT Mesra, Ranchi, India
(2) Cambridge Institute of Technology, Ranchi, India
(3) The PNG University of Technology, Lae, Morobe, Papua New Guinea
(4) Federal University of Piauí (UFPI), Teresina, Piauí, Brazil
(5) Instituto de Telecomunicações, Aveiro, Portugal

Abstract Neuronal excitation enables identifying the features of an electroencephalogram (EEG) signal for motor imagery detection. We propose a novel feature extraction algorithm supported by short-term cepstrum-based inverse filtration of neuronal excitation of the active synapse. The maximum power of the estimated neuronal excitation is subjected to a two-class Bayesian probabilistic classifier. The feature extraction algorithm with the Bayesian probabilistic classifier significantly improves the brain–computer interface performance compared with that of other conventional methods of EEG signal processing such as wavelet with a Bayesian classifier, autocorrelation and CSP filter with a naïve Bayes classifier over the BCI competition II and IV datasets. Consequently, this neuronal excitation feature allows the authors to develop a motor imagery neuro-feedback system; the performance of which achieves 87.2% average classification accuracy, which is 14% greater than that of the wavelet-based algorithm and 6.2% greater than that of the TRSP-based algorithm, with 53 ms of processing time allotted for each instruction in a real-time experiment. However, brain signal variation across different subjects and sessions significantly impairs decision accuracy. Our neuronal excitation base feature extraction algorithm minimizes these variations in classification accuracy.

Keywords Electroencephalogram (EEG) . Embedded system . Neuronal excitation . Neuro-feedback . Reactive frequency band (RFB) . Reverse filtration (RF) and short-time cepstrum

Analysis of discontinuous reception (DRX) on energy efficiency and transmission delay with bursty packet data traffic

Jinyan Wu1 · Jaesung Park2

(1) Department of Information Security, The University of Suwon, Wau-ri, Bongdam-eup,
Hwaseong-si, Gyeonggi-do, Korea
(2) School of Information Convergence, Kwangwoon University, Nowon-gu, Seoul, Korea

Abstract Discontinuous reception (DRX) is a way for user equipment (UE) to save energy. DRX forces a UE to turn off its transceivers for a DRX cycle when it does not have a packet to receive from a base station, called an eNB. However, if a packet arrives at an eNB when the UE is performing a DRX cycle, the transmission of the packet is delayed until the UE finishes the DRX cycle. Therefore, as the length of the DRX cycle increases, not only the amount of UE energy saved by the DRX but also the transmission delay of a packet increase. Different applications have different traffic arrival patterns and require different optimal balances between energy efficiency and transmission delay. Thus, understanding the tradeoff between these two performance metrics is important for achieving the optimal use of DRX in a wide range of use cases. In this paper, we mathematically analyze DRX to understand this tradeoff. We note that previous studies were limited in that their analysis models only partially reflect the DRX operation, and they make assumptions to simplify the analysis, which creates a gap between the analysis results and the actual performance of the DRX. To fill this gap, in this paper, we present an analysis model that fully reflects the DRX operation. To quantify the energy efficiency of the DRX, we also propose a new metric called a real power-saving (RPS) factor by considering all the states and state transitions in the DRX specification. In addition, we improve the accuracy of the analysis result for the average packet transmission delay by removing unrealistic assumptions. Through extensive simulation studies, we validate our analysis results. We also show that compared with the other analysis results, our analysis model improves the accuracy of the performance metrics.

Keywords Discontinuous reception (DRX) · Bursty data packet traffic · Energy efficiency · Transmission delay

Probabilistic computation offloading and data caching assisted by mobile-edge-computing–enabled base stations

Wenhao Fan1 · Junting Han1 · Jiayi Chen1 · Yuan’an Liu1 · Fan Wu1

(1) School of Electronic Engineering, Beijing Key Laboratory of Work Safety Intelligent Monitoring, Beijing University of Posts and Telecommunications, Beijing, China

Abstract Mobile edge computing can augment the capabilities of mobile terminals (MTs) by enabling computing and caching functionalities for base stations (BSs). Because BSs have only limited computation and storage resources compared with cloud servers, they need to efficiently manage the computation offloading and data caching for MTs. In this paper, a novel scheme for efficient computation offloading and data caching assisted by mobile-edge-computing–enabled BSs (MEC-BSs) is proposed. To maximize the MT benefits in terms of reduced time and energy consumption, our scheme determines the probability that each MT offloads each type of its tasks to the MEC-BS and indicates whether the cloud data for each type of MT task is cached at the MEC-BS. A balance factor is used to flexibly adjust the tendency of the optimization between the minimization of time and energy consumption. Based on the stable probabilistic characteristics of MT tasks and the MEC-BS service, the optimization algorithm of our scheme can be executed independently and concurrently without deteriorating the system performance. The simulation results demonstrate that our scheme can largely improve the system performance and that it always outperforms other reference schemes in scenarios with multiple criteria.

Keywords Mobile edge computing · Computation offloading · Data caching · Optimization

An optimal compact time-modulated circular antenna array synthesis using krill herd optimization

Avishek Das1 · Durbadal Mandal2 · Rajib Kar2

(1) Department of Electronics and Communication Engineering, HIT, Haldia, India
(2) Department of Electronics and Communication Engineering, NIT, Durgapur, India

Abstract In this paper, an optimal far-field radiation pattern synthesis by using time modulation technique is carried out for a compact circular antenna array (CAA) design using a stochastic optimization method called krill herd (KH) optimization. A compact antenna array is achieved by reducing the inter-element spacing between the array elements, which leads to the miniaturization of the size of the array. On the other hand, an improved far-field radiation characteristic is achieved with a low side lobe level (SLL) and narrow first null beam width (FNBW). A low SLL is an essential requirement to reduce the interference with the other systems operating in the same frequency band. A narrow FNBW is necessary to obtain a high directivity. In time modulation technique, ‘time’ has the most significant role. It is considered the fourth-dimensional parameter, which plays the role of an additional degree of freedom to achieve an improved radiation pattern. The time-modulated antenna array (TMAA) radiates at various harmonic frequencies for the periodic switching time sequence. In this paper, the generation of the radiation pattern at the fundamental/central frequency only is considered. The KH algorithm is a flexible and robust search algorithm. It is applied here to find out the optimum sets of switching on-time duration for each array element and to determine the optimum inter-element separation between two array elements of the 20- and 36-element time-modulated circular antenna array (TMCAA). Particle swarm optimization (PSO) and differential evolution (DE) optimization techniques are also individually applied for the same design purpose to prove the superiority of the KH algorithm–based design. Finally, statistical analysis is performed to ensure the significance of the numerical results.

Keywords Circular antenna array · Compact antenna array · Time modulation · Side lobe level · First null beam width · Directivity · Krill herd optimization

A dynamic channel allocation protocol for medical environment

Bruno Marques Cremonezi1 · Alex Borges Vieira2 · José Augusto Nacif3 ·
Michele Nogueira1

(1) Universidade Federal do Paraná, Curitiba, Brazil
(2) Universidade Federal de Juiz de Fora, Juiz de Fora, Brazil
(3) Universidade Federal de Viçosa, Viçosa, Brazil

Abstract Wireless body area networks (WBANs) is a technology that offers better methods for real-time patient health monitoring. By the year 2025, industry and academia estimate up to 3 billion wearable sensors placed in different WBANs, gathering health data from patients and sending them to medical servers. However, data transmission from WBANs to those medical servers is still a challenging task. In particular, wireless transmission can result in high latency and low throughput due to interference, which causes risks to healthcare patients. The existing solutions address wireless transmission interference inside the same WBAN or the interference that one WBAN can make on another. These solutions rarely cope with both interferences from a medical application perspective. In this article, we detail PDAC, a medical application-aware MAC-layer P rotocol for D ynamic Channel A lloC ation. At a glance, PDAC takes advantage of the existence of multiple base stations in the most common wireless network environments. In this sense, it orchestrates the cooperation among base stations, even in dense medical-hospital environments, by properly allocating co-located wireless body area networks. PDAC relies on a greedy solution for a graph coloring problem to reduce interferences and enhance data communication. According to evaluations, we observe an average increase of 30% on the system throughput and an average reduction of 40% in the system latency when compared to a baseline solution.

Keywords Channel allocation · WBAN · Allocation protocol · PDAC

Design of aperiodic spherical antenna arrays for wideband performance

Omar Elizarrarás1 · Marco A. Panduro2 · Aldo Mendez3 · Alberto Reyna3 ·
David H. Covarrubias2 · Leopoldo Garza3

(1) Unidad Académica Multidisciplinaria Río Bravo, Universidad Autónoma de Tamaulipas (UAT) Av. República Mexicana No. 1000, Fracc. Villa Hermosa, Río Bravo, Tam., México, Río Bravo, Tamaulipas, Mexico
(2) Electronics and Telecommunications Department, CICESE Research
Center, Carretera Ensenada-Tijuana No. 3918, Zona Playitas, Ensenada, Baja California, Mexico
(3) Unidad Académica Multidisciplinaria Reynosa Rodhe, Universidad
Autónoma de Tamaulipas (UAT), Carretera Reynosa-San Fernando, Reynosa, Tamaulipas, Mexico

Abstract This paper illustrates a highly nonlinear problem related to the design of aperiodic antenna arrays using spherical geometry for maximum performance. This synthesis of aperiodic spherical antenna arrays considers two design cases: (1) aperiodic arrays with a nonuniform spacing between rings assuming equal element spacings on the same ring (ASANRUE case) and (2) aperiodic arrays with a nonuniform spacing between rings and between antenna elements of the same ring (ASANRNE case). This process is carried out by using the differential evolution (DE) optimization technique with the goal of finding the optimum angular position of each element on the elevation and azimuthal planes to achieve the maximum performance in terms of the side lobe level, directivity, and number of antenna elements used in the array for three design objectives: natural response of the radiation pattern, beam scanning, and the restriction of a minimum distance among elements. The innovative contribution of this paper is the application of the differential evolution algorithm to a nontrivial and highly complex design problem: the aperiodic element distribution over a spherical antenna arrangement. The advantage of this approach with respect to the state of the art on the topic of spherical array design is that a lower side lobe level and maximum directivity for a spherical antenna array can be obtained for aperiodic element distributions with a reduced number of antenna elements and hence a smaller radius, which means less complexity and lower fabrication costs. Simulation results based on CST Microwave Studio are provided to take mutual coupling into account.

Keywords Spherical antenna array . Differential evolution . Side lobe level . Directivity .
Wide bandwidth

A compact inexpensive UWB-modified elliptic antenna including a slotted ground plane for an indoor positioning system

M. S. Karoui1,2 · N. Ghariani2 · M. Lahiani2 · H. Ghariani2

(1) Higher Institute of Applied Sciences and Technologies of Mateur, University of Cartage, Mateur, Tunisia
(2) National Engineering School of Sfax, University of Sfax, Sfax, Tunisia

Abstract Within the present article, an original inexpensive UWB-modified elliptic antenna including slots in its ground plane is presented. This antenna with the FR4-epoxy substrate has a very modest size of 21 × 24 × 1.6mm3. The measured results confirm that the suggested antenna has an impedance bandwidth (|S11|< − 10 dB) of 134.13%, which expands from 3.1 to 15.72 GHz, covering the entire UWB frequency range and reaching a maximum gain of approximately 9.5 dBi at 14 GHz with an average value equal to 3.3 dBi throughout the functional frequency band and a maximum radiation efficiency of 97% obtained for the frequency 8.3 GHz with an average value equal to 94% over the whole frequency band. Excellent accordance between the simulation and measurement is observed. This antenna presents an approximately omni-directional radiation diagram in some directions, a dipole-like radiation pattern at lower frequencies and a quasi-stable group delay through the operating band, making the antenna relevant for most useful UWB applications, especially for indoor localization. Impedance matching is performed by employing two ellipses with diverse semi-major axes ″a″ as radiating patches and by optimizing the size, number, and position of the inserted slots in the downsized ground plane. Detailed information on the simulation and experimental results is provided and discussed.

Keywords UWB antenna · Slotted ground plane · Elliptic patch · Omni-directional · High gain ·
Indoor positioning

Virtual sensors: an industrial application for illumination attributes based on machine learning techniques

Michalis Drakoulelis1 · Gabriel Filios1,2 · Vasilis Georgopoulos Ninos3 ·
Ioannis Katsidimas1,2 · Sotiris Nikoletseas1,2

(1) Department of Computer Engineering and Informatics, University of Patras, Patras, Greece
(2) Computer Technology Institute and Press “Diophantus”, Athens, Greece
(3) Athenian Brewery S.A. Patras Plant, Patras, Greece

Abstract Nowadays, the Internet of Things is a technology used in a wide range of applications, empowering fields such as the smart city, smart transportation, and the manufacturing industry. Their growing number increases the demand for robust and intelligent solutions providing relevant data, while relying on as few resources as possible. To this end, it is essential to search for techniques and solutions that can achieve a high level of quality of service, using the least hardware and cost. Machine learning can tackle the challenge by generating virtual data. It aims on replicating a sensor’s activity by utilizing real data from a subset of sensors. Such a task could be difficult with existing means, while the proposed approach might reduce it to a trivial calculation. In a similar fashion, it is possible to use simulation models for data analysis and model validation, by feeding the existing simulation models with varying conditions and comparing the results with the real ones. The current work aims to utilize the virtual IoT paradigm, in order to immerse and test everyday applications in realistic conditions and constraints. Finally, a prototype’s implementation in real-life use cases is discussed, such as the illumination in an industrial environment.

Keywords Virtual sensor · Light sensor · Machine learning

Low-power DSSS transmitter and its VLSI implementation

M. Jayasanthi1 · R. Kalaivani2

(1) Department of ECE, PSG Institute of Technology and Applied Research, Coimbatore, India
(2) Department of ECE, Erode Sengunthar Engineering College, Erode, India

Abstract An interesting area of application in wireless data communication is direct-sequence spread spectrum (DSSS). Spread spectrum communication techniques make the signals more robust against interference and jamming. These are based on a concept that narrowband signal is scrambled before transmission in such a way that the signals occupy a much larger part of the radio frequency spectrum. As the digital and the analogue system components are required on the same substrate in today’s mixed-signal chips, the DSSS transmitter system is proposed to be implemented in field-programmable gate array (FPGA)–based platforms and application-specific integrated circuits (ASICs). With a low-power very large-scale integration (VLSI) architecture, sophisticated processing of wide-bandwidth DSSS systems can be exploited in FPGAs/ASICs. In this article, binary pseudo-noise (PN) sequences are generated using a low-power linear feedback shift register (LFSR) in order to spread transmit signals extensively. The proposed low-power design of LFSR and DSSS transmitter with implementation results is illustrated in this paper. Dynamic power dissipation of the proposed DSSS transmitter is reduced up to 15% and 15.6% when compared to the conventional LFSR and the Gold code–based systems respectively. The proposed hardware is implemented in 180-nm technology and operates at 15.36-MHz frequency.

Keywords Latches · Linear feedback shift register · Low-power DSSS transmitter · Spread spectrum communication · Field-programmable gate array