Multi-input Single-output Research Articles

Hierarchical robust fuzzy sliding mode control for a class of simo under-actuated systems with mismatched uncertainties

The development of the algorithms for single input multi output (SIMO) under-actuated systems with mismatched uncertainties is important. Hierarchical sliding-mode controller (HSMC) has been successfully employed to control SIMO under-actuated systems with mismatched uncertainties in a hierarchical manner with the use of sliding mode control. However, in such a control scheme, the chattering phenomenon is its main disadvantage. To overcome the above disadvantage, in this paper, a new compound control scheme is proposed for SIMO under-actuated based on HSMC and fuzzy logic control (FLC). By using the HSMC approach, a sliding control law is derived so as to guarantee the stability and robustness under various environments. The FLC as the second controller completely removes the chattering signal caused by the sign function in the sliding control law. The results are verified through theoretical proof and simulation software of MATLAB through two systems Pendubot and series double inverted pendulum.

A Deep Study on Layered Multi-Relay Non-Orthogonal Amplify-Forward Networks

The paper introduces a cross-layer design for transmission of Successive Refinement (SR) source code interplayed with non-orthogonal layered code, deployed over a half-duplex multi-relay Non-orthogonal Amplify-Forward (NAF) network. Assuming the Channel State Information (CSI) is not available at the source node, firstly the achievable layered Diversity-Multiplexing Tradeoff (DMT) curve is derived. Then, by taking Distortion Exponent (DE) as the figure of merit, several achievable lower bounds are proved and the optimal expected distortion performance under high Signal to Noise Ratio (SNR) approximation is explicitly obtained. It is shown that the proposed coding can achieve the Multi-Input Single-Output (MISO) upper bound under certain regions of bandwidth ratios, by which the optimal performance in these regions can be explicitly characterized. Further the non-orthogonal layered coding scheme is extended to a multi-hop MIMO Decode-Forward (DF) relay network and set of DE lower bounds is derived. Simulation results confirm the effectiveness of the proposed scheme under general SNR values and compared with its counterparts.

Decreasing the Single-Phase Inverter Output Voltage Distortions Caused by Impedance Networks

This article presents the possibility of decreasing the inverter output voltage distortions that are caused by the typical distortions in the output voltage pulses of an impedance network using the qZ-source as an example. DC sources, such as photovoltaic cells with the qZ-source, increase the dc voltage; an impedance network operates in the continuous current mode and the discontinuous current mode (DCM). Both of these, but particularly DCM, implement the characteristic distortions to the impedance network output pulses, which results in the distortions in the inverter output voltage. It is possible to decrease these distortions in a passive way (increasing the capacitors of the network) or by using an efficient instantaneous controller of the inverter output voltage. Two controllers—a single-input single-output PID controller and a multi-input single-output improved passivity-based controller—were compared using the experimental model voltage source inverter with the input qZ-source.

Novel hybrid approaches based on evolutionary strategy for streamflow forecasting in the Chellif River, Algeria

In this study, the feedforward neural networks (FFNNs) were proposed to forecast the multi-day-ahead streamflow. The parameters of FFNNs model were optimized utilizing genetic algorithm (GA). Moreover, discrete wavelet transform was utilized to enhance the accuracy of FFNNs model’s forecasting. Therefore, the wavelet-based feedforward neural networks (WFFNNs-GA) model was developed for the multi-day-ahead streamflow forecasting based on three evolutionary strategies [i.e., multi-input multi-output (MIMO), multi-input single-output (MISO), and multi-input several multi-output (MISMO)]. In addition, the developed models were evaluated utilizing five different statistical indices including root mean squared error, signal-to-noise ratio, correlation coefficient, Nash–Sutcliffe efficiency, and peak flow criteria. Results provided that the statistical values of WFFNNs-GA model based on MISMO evolutionary strategy were superior to those of WFFNNs-GA model based on MISO and MIMO evolutionary strategies for the multi-day-ahead streamflow forecasting. Results indicated that the performance of WFFNNs-GA model based on MISMO evolutionary strategy provided the best accuracy. Results also explained that the hybrid model suggested better performance compared with stand-alone model based on the corresponding evolutionary strategies. Therefore, the hybrid model can be an efficient and robust implement to forecast the multi-day-ahead streamflow in the Chellif River, Algeria.

A New Variable Forgetting Factor-Based Bias-Compensation Algorithm for Recursive Identification of Time-Varying Multi-Input Single-Output Systems With Measurement Noise

This article proposes a new variable forgetting factor (VFF) bias-compensated recursive least-squares (BCRLS) algorithm for the recursive identification of complex time-varying multi-input single-output (MISO) systems with measurement noise. It extends a previously developed real-valued BCRLS algorithm to complex signals and introduces new self-calibrated VFF and noise variance estimation schemes for tracking time-varying systems. The proposed VFF scheme offers faster tracking speed, especially for sudden system changes, while achieving a low steady-state (SS) mean square error (MSE) in a stationary environment. Moreover, the mean and mean square deviation of the complex RLS algorithm under zero-mean white Gaussian output additive noise are performed, from which the variance of the additive noise can be estimated. To mitigate the effect of finite-sample number, a self-calibration scheme is proposed to refine the FF at the SS and hence MSE. Simulations show that the proposed self-calibrated VFF-BCRLS algorithm offers improved tracking speed in sudden system changes and offers smaller MSE over the conventional BCRLS algorithm. Applications to real-world data for pH value prediction of a pH neutralization process and temperature prediction of a glass furnace also demonstrate the effectiveness of the proposed algorithm. The good performance and efficient implementation make it an attractive alternative to other conventional methods for system identification in control and optimization processes and other possible applications.

An online predictive control method with the temperature based multivariable linear regression model for a typical chiller plant system

As many studies prefer to focus on the accuracy of prediction models in model-based problems of chiller plants, the practicality and feasibility of the models used for field applications are often compromised for a superior performance. We herein present an online predictive control method based on linear regression model for a typical chiller plant from the perspective of real-time application to optimize its overall performance and energy consumption. A multi-input–single-output (MISO) controller is developed for predicting the global coefficient of performance (COP) of the chiller plant to reflect integral characteristics and interactions of components based on the multivariable linear regression (MLR) model. The input variables are much easier to obtain in a practical system compared to variables such as water flow and part load ratio, thereby rendering an excellent model capable of easy implementation and duplication. The performance of this approach is tested and evaluated in a real chiller plant system by comparing it to that obtained using a local control strategy. The results of this study indicate that the online predictive control strategy can enhance the global COP values by 5.35% on average and reduce electricity consumption by 2.70% daily compared to the local control strategy.

Performance analysis of FSO coherent BPSK systems over Rician turbulence channel with pointing errors.

We investigate the performance of coherent free-space optical (FSO) system in terms of bit error rate (BER) evaluation by adopting the modified Rician distribution based coherent channel model which allows taking into consideration the composite effects of both Rician turbulence, including amplitude fluctuation and optical phase distortion, and pointing errors (PEs). By expanding the Rician distribution, a mathematically traceable expression of the probability density function (PDF) for the composite channel is derived in the form of the Meijer-G function. Based on the composite channel PDF, the exact BER expression is obtained, allowing the analysis of BER performance for single-input single-output (SISO) links. This analysis is extended to single-input multi-output (SIMO) links with maximal ratio combining (MRC). With the help of the moment generating function (MGF), the exact BER expression can be simplified into a single integral, facilitating the analysis with high accuracy and reducing calculation complexity. Engineering insights including high-SNR approximated channel PDF, asymptotic BER expression, coding and diversity gains, are investigated and cross-validated for both SISO and SIMO links. Through both analytical and numerical verifications, the impairment due to PEs as well as the effect of modal compensation on the BER performance are discussed in detail, unveiling the fact that their inner relations should be taken into account for optimization. These verify the effectiveness of our models for both SISO and SIMO links with a wide range of different conditions and can be feasibly applied for different types of coherent FSO links.

Fundamental Applicability of Spatial Modulation: High-SNR Limitation and Low-SNR Advantage

Spatial modulation (SM) is viewed as a promising multi-antenna technology for future communications. Numerous works on SM have been done on the specific optimized designs and performance analysis mainly based on high signal-to-noise ratio (SNR) union bound approximation. However, the existing information-theoretical investigation indicates that SM is more efficient in low SNR regimes. Therefore, the most prominent potential of SM with respect to the error performance is still not well understood. As a first step to filling this void, we consider the fundamental applicability of SM in multi-antenna channels. On the one hand, for high SNR regimes, by developing the optimal structure of multi-input single-output (MISO) and proposing efficient multiple-input multiple-output (MIMO) transmission schemes, we prove that the performance limits of SM-MISO and SM-MIMO with respect to the received minimum Euclidean distance (MED) can be outperformed even by single radio-frequency chain transmission. On the other hand, for the low-SNR regimes, we show the respective optimality of: 1) SM for single-user energy-based noncoherent massive MIMO (ED-MaMIMO) channels; and 2) dual SM of multi-user ED-MaMIMO which collaboratively modulates data onto both the indexes of transmitter antennas and those of the users. In addition, the dual SM for multiuser ED-MaMIMO has a practically important property that partial coordination via user index modulation can be as useful as full one. Our analytical findings and numerical results strongly suggest that more attention should be paid to the low-SNR behavior and designs of SM rather than the currently popular MED optimization in high-SNR regimes. This paper points out a direction, towards which SM should evolve, and also shows that combination of SM with the users' index modulation can be very useful for designing the optimal finite-alphabet nonorthogonal multiple-access.

Symbol-Level Hybrid Precoding in mmWave Multiuser MISO Systems

Recently, symbol-level precoding has emerged as a novel efficient solution in multi-user multi-antenna downlink systems, since it can exploit multi-user interference (MUI) and transform it into useful signal. In this correspondence, we attempt to apply symbol-level precoding into the well-known hybrid precoding architecture in multi-user multi-input single-output (MU-MISO) millimeter wave (mmWave) communication systems. Particularly, we aim to design the symbol-varying digital precoder and the analog precoder with low-resolution phase shifters (PSs) to optimize symbol detection performance under the transmit power constraint and the discrete phase constraint. To handle this difficult joint optimization problem, we propose to minimize the Euclidean distance between the optimal fully-digital precoder and the hybrid precoder. An efficient iterative algorithm is developed to solve this problem. Simulation results demonstrate the advantages of symbol-level precoding and validate the effectiveness of our proposed symbol-level hybrid precoding algorithm.

Joint power allocation and power splitting for MISO SWIPT RSMA systems with energy-constrained users

Simultaneous wireless information and power transfer (SWIPT) has been widely used in multi-input single-output (MISO) systems to transmit information and energy simultaneously from the base station (BS) towards the users. The traditional approach used in the literature is based on space-division multiple access (SDMA) method by using the multi-user linear precoding technique, where the information decoding is done by considering the multi-user interference as noise. Recently, the novel rate-splitting multiple access (RSMA) method, based on partially decode the multi-user interference and partially treat that interference as noise, has been shown to outperform the SDMA method in multi-user MISO systems. Motivated by the superior performance of RSMA, we consider a multi-user MISO SWIPT system applying the RSMA method, where multiple energy-constrained users are equipped with a power-splitting structure to harvest energy and decode information simultaneously. In particular, we investigate the optimal precoders and power-splitting ratios design to minimize the total transmit power at the BS, subject to constraints of the minimum data rate for users, minimum energy harvesting by users, and maximum power at the BS. The proposed solution for the formulated non-convex problem is based on two phases. First, we convert the non-convex problem into bilevel programming where the upper optimization problem is solved by using particle swarm optimization. Second, we propose two algorithms to solve the inner optimization problem based on a semidefinite relaxation method or a successive interference cancellation method. Numerical results show that RSMA achieves significant improvement over SDMA in reducing the total transmit power.

The identification of gearbox vibration using the meshing impacts based demodulation technique

Gearboxes are at the heart of most rotating machines and they are considered as one of the main sources of vibration. As a key element in rotating machines, it is important to extract the gearbox vibration part from the mechanical system signal to assess the health state of the gearbox. In general, the gear meshing frequency part contains rich information which reflects its health state. In this paper, the authors find that in some cases when gearboxes work under heavy load, the meshing frequency part cannot be detected easily from the frequency spectrum. We think that the meshing frequency part may be modulated to the higher frequency band as the meshing impacts. To prove this point, a Multi-Input Single-Output (MISO) model is proposed to identify the local resonance excited by gear meshing impacts. In our method, a Meshing Impact Energy Distribution (MIED) graph is obtained through iteration to determine the demodulated frequency band. Experimental vibration data acquired form a healthy gearbox are illustrated to validate the performance of the proposed method. The forklift is taken as an example in the paper. Forklifts usually work in heavy load condition, and the gearbox vibration of a forklift is generally mixed with the ignition impacts of the diesel engine. The experiment result shows that for forklift machine system working in heavy load condition, its meshing frequency part of gearbox vibration signal is modulated into high frequency band. Further, the result shows that the proposed method is good at extracting the meshing frequency component when it is modulated into high frequency band especially when it is in heavy load condition.

A New FGMOS UCCII and SIMO Type Universal Filter Application

DOI: 10.26650/electrica.2019.19006 A new floating gate MOS (FGMOS) universal current conveyor (UCCII) is proposed to have the properties of simplifier circuit topology, simpler signal processing and wider input swing. Since the FGMOS transistors are used in the proposed UCCII circuit, the number of transistors is reduced and the topology of the circuit is simplified because it is easier to get arithmetic operations in circuits by using FGMOS transistors when compared to conventional MOS transistors. At the same time, using FGMOS differential amplifier structure in the input stage of the FGMOS UCCII circuit increased the input signal swing resulting both an increase in the linearity of the circuit and an improvement in the voltage following properties. A single input multi output (SIMO) type universal filter application is given to show the versatility of the UCCII block. Both the proposed FGMOS UCCII circuit and filter circuit are simulated with SPICE program by using 0.35µm technology parameters. When the simulation results are analyzed it is seen that that the FGMOS UCCII circuit reached the expected improvements according to the MOS equivalent circuit and expected to be used in linearly tunable filters. Cite this article as : Keles S, Keles F, Kuntman HH. A New FGMOS UCCII and SIMO Type Universal Filter Application. Electrica 2019; 10.26650/electrica.2019.19006.

Voltage differencing transconductance amplifier based fractional order multiple input single output universal filter

In this paper a Voltage Differencing Transconductance Amplifier (VDTA) based Voltage Mode (VM) Multi Input Single Output (MISO) Fractional Order filter (FOF) providing all five filter responses is presented. The proposed FOF is designed using single VDTA and two fractional Capacitors (FC). The FC is implemented using RC ladder network; component values of which are computed using Carlson rational approximation. For illustration, FC of 0.5 order has been implemented using first, second and third iterations of Carlson approximation, which results in different integer order approximation functions. The ladder component values for all iterations are computed using MATLAB. The effect of different iterations on FOF behavior is also studied. The proposed FOF is verified through Cadence Virtuoso simulations using 0.18 µm CMOS technology.

Design and implementation of a SIMO DC–DC converter

Multiport converters have tremendous performance over conventional solutions that employ multiple single converters in multi-input and multi-output applications. Furthermore, they provide the most economic operation and improve the performance of the system. Hence, in the recent past, a lot of development and research have been carried out for developing the single-input–multi-output (SIMO) converters in various aspects which are presented in the study. These topologies have some assumptions which are made on the charging of inductor current and design of duty cycle for achieving multiple outputs. In this study, an SIMO DC–DC converter is proposed. It independently regulates both the outputs at different voltage levels and none of the assumptions are made on the basis of inductor charging currents (iL1 > iL2 or iL1 < iL2). Cross-regulation problems do not exist, so the output voltage V01 (V02) is not influenced by the variation of load current i02 (i01), also the proposed converter has the ability to avoid the common grounding problems between the outputs. Low-power (200 W) prototype circuit is developed to verify the feasibility of the proposed converter and the experimental results are validated with simulation results.

Compensating rain induced impairments in terrestrial FSO links using aperture averaging and receiver diversity

In this paper, we investigate the performance of a free space optical link considering the deteriorations caused by heavy rain. The applicability of receiver diversity and aperture averaging techniques to compensate the rain-induced impairments is analyzed on the basis of outage probability and signal to noise ratio at varying rain intensities. A 10-Mbps on-off keying modulated optical signal is taken as the test signal for which rain specific attenuation is calculated using a laboratory testbed having controlled rainfall conditions up to 250 mm/h. A 15-m single input multi output) optical link with selection combining technique at the receiver is used to observe diversity gain. Significant diversity improvement by a factor of 1.35 is observed by comparing the results with the conventional single input single output link. Experimental observations with and without aperture averaging shows average SNR gain of 1.58 and outage probability reduction of 12.3%.

On the duality between array beam-formers and MU-MISO precoders

Multi-user transmission, whereby users share time and frequency resources has been an active research area in the past decade in which the uniform linear array (ULA) was proposed and implemented for its model simplicity and easy implementation. This paper studies the performance of different methods used in ULA environment and their implication to multiuser multi-input single-output (MU-MISO) scenario where the channel is considered AWGN and Rayleigh fading (slow flat fading channel). The noise power level and the effect of multipath are investigated based on the assumption that the paths have the same loss exponent and the same length (i.e. the power of the received signal are the same from different paths). The results show that the best method dependent on numerous variables, the most important being the signal to noise ratio (SNR) and the number of multipath received from each source. The implementation of these methods in MU-MISO environment reveals that they can be successfully adopted for MU-MISO. It is observed that any method applicable to ULA scenario, is also applicable to MU-MISO scenario.

Constellation-Optimal Beamformers for Multiuser MISO Broadcast Visible Light Communications

In this paper, we design energy-efficient space constellations for multiuser multi-input single-output visible light communication broadcast systems with channel state information (CSI) at the receiver in the three scenarios: 1) with CSI at the transmitter (CSIT); 2) with statistical CSIT; and 3) without CSIT. By utilizing the cooperation of multiuser interference, optimal multidimensional additively uniquely decomposable constellation groups are designed to optimize the received worst case performance metrics of all users subject to two commonly used power constraints, i.e., average and peak optical power constraints. The resulting optimal designs are proved to be pulse amplitude modulated with an optimal beamformer, which can be efficiently attained by numerical search for Scenarios 1 and 2 and be given in a closed form for Scenario 3. One of the common significant advantages of these designs is the fast demodulation of the sum signal from a noisy received signal, since these optimal designs result in an equivalent ideal scalar AWGN channel. Comprehensive computer simulations demonstrate that our designs significantly outperform traditional zero-forcing, minimum mean square error, and time-division methods.

Deterministic pilot design for structured sparse channel estimation in MISO systems

To reduce the pilot overhead, compressive sensing techniques have been widely adopted for sparse channel estimation. In this paper, we explore the spatial common sparsity across different channels and investigate the deterministic pilot design with superimposed pattern for the downlink channel estimation in multi-input single-output systems. Previous works generally allocate pilots randomly when using the superimposed pilots to estimate the jointly sparse channels, which is storage-hungry and time-consuming. For the joint optimization of pilot locations and symbols, this paper proposes two pilot design schemes, named by Algorithms 1 and 2, to minimize the intrablock and interblock coherence simultaneously. Algorithm 1 sequentially optimizes pilot locations and symbols, while Algorithm 2 integrates the allocation of pilot symbols into the optimization of pilot locations and alternately optimizes the pilot locations and symbols. Both schemes can flexibly select the design criteria to ensure the small intrablock and interblock coherence. Simulation results show that the proposed pilot designs outperform the existing ones in terms of channel estimate mean-squared-error and bit-error-rate.

Realization of DTMOS based CFTA and multiple input single output biquadratic filter application

Analog filters can be found in everything from mobile phones to disk drives, from audio systems to power supplies, from telecommunications to broadband internet connection. Analog filters can be formed from a variety of active elements. In this study, the Dynamic Threshold Voltage MOSFET (DTMOS) based Current Follower Transconductance Amplifier (CFTA) active element has been suggested and a multi input single output (MISO) universal biquadratic filter has been obtained with this active element. The proposed circuit operates with ±0.2 V supply voltages and consumes 140 µW power and electronically tunable. All five filtering responses have been realized by selecting the different input signals. All simulations have been performed with LTSpice program using the Predictive Technology Model (PTM) 45 nm Level 54 CMOS process parameters. Analysis of AC/DC, noise, Monte Carlo, temperature, total harmonic distortion (THD) proves that the circuit operates in harmony with the theory. With Monte Carlo analysis, it has been observed that the filter achieves stable output against both passive element and process parameter tolerance. It is hoped that the proposed active element and the filter will be useful in ultra-low voltage, low power, and low frequency analog signal applications.

Design and Implementation of Biquad Filters Using CMOS Circuit Based Active Elements

This paper mainly concentrates on a new kind of CMOS implementation based on Current Differencing Current Conveyer (CD-CC). The grate CMOS circuit effort is fulfilled by introducing a new kind of biquad filter. The proposed filter employs two CD-CC circuits and four passive elements. The filter is designed depending on Multi Input Single Output (MISO) configuration and realizes all filter functions identified by current mode (Low pass, Band pass, High pass, Band Stop, and all Pass) filter. In addition, the behavior of the proposed filter circuit has been tested and simulated then it results in sound outcomes. This test has been achieved by using the current mode application example, which consists of two (CDCCs) and four passive elements with multi- inputs and a single output. Finally, the filters are simulated using TSMC 0.35 μm technology. Moreover, the theoretical analyses agree with PSPICE simulation results.