In this work, a generalization of the Smith Predictor (SP) is proposed to control linear time-invariant (LTI) time-delay single-inputsingle-output (SISO) systems. Similarly to the SP, the combination of any stabilizi...
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In this work, a generalization of the Smith Predictor (SP) is proposed to control linear time-invariant (LTI) time-delay single-inputsingle-output (SISO) systems. Similarly to the SP, the combination of any stabilizing output-feedback controller for the delay-free system with the proposed predictor leads to a stabilizing controller for the delayed system. Furthermore, the tracking performance and the steady-state disturbance rejection capabilities of the equivalent delay-free loop are preserved. In order to place this contribution in context, some modifications of the SP are revisited and recast under the same structure. The features of the proposed scheme are illustrated through simulations, showing a comparison with respect to the corresponding delay-free loop, which is here considered to be the ideal scenario. In order to emphasize the feasibility of this approach, a successful experimental implementation in a laboratory platform is also reported. (C) 2017 ISA. Published by Elsevier Ltd. All rights reserved.
Many approaches to build a wiretap channel (WTC) by multi-input multi-outputsystem have been introduced. Different from those approaches, the authors propose a feedback method combined with the low-density parity-che...
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Many approaches to build a wiretap channel (WTC) by multi-input multi-outputsystem have been introduced. Different from those approaches, the authors propose a feedback method combined with the low-density parity-check (LDPC) codes for building the WTC I (WTC-I) to achieve unconditional security under single-input single-output system by the soft decision decoding. The novel approach establishes the WTC-I on both the binary symmetric channel and binary input additive white Gaussian noise channel. In order to keep the eavesdropper be fully ignorant about the secret information, randomness is added to the feedback signals from the destination by taking advantage of feedback. In addition, the message to be sent is encoded by the LDPC codes such that it can be correctly decoded by a legitimate receiver. Furthermore, the secret information transmission capacity can be improved by the soft decision decoding.
Spectral efficiency, energy efficiency, and security are cornerstones for the upcoming 5G systems. In this study, the issue of how the energy and spectral efficiency of multiuser massive multiple-input multiple-output...
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Spectral efficiency, energy efficiency, and security are cornerstones for the upcoming 5G systems. In this study, the issue of how the energy and spectral efficiency of multiuser massive multiple-input multiple-output (Ma-MIMO) systems are affected in the presence of a secrecy constraint is addressed. The performance of the two most prominent linear precoding techniques, the matched filter (MF) and zero-forcing (ZF) precoders, for secure downlink multiuser Ma-MIMO in the presence of multi-antenna passive eavesdropper is investigated. The authors consider three performance metrics, namely, the achievable ergodic secrecy rate, the secrecy spectral efficiency (SSE), and the secrecy energy efficiency (SEE), assuming perfect and imperfect channel state information. The tradeoff between SSE and SEE is also studied. Moreover, the authors derive tight lower bounds on the achievable ergodic secrecy rate for MF and ZF precoding techniques. The derived lower bounds provide insights on the tradeoff between the SSE and SEE. It is shown that ZF precoder outperforms MF precoder at high transmit power, whereas at very low transmit power, MF outperforms ZF. Moreover, it is shown that using large number of transmit antennas can improve the SSE and the SEE with orders of magnitude compared to a single-input single-output system.
The control of time-delayed perturbed systems is easy when time delay affects systeminputs or outputs. In the more difficult case when system states are affected, CRONE (fractional order) control-system design (CSD) ...
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The control of time-delayed perturbed systems is easy when time delay affects systeminputs or outputs. In the more difficult case when system states are affected, CRONE (fractional order) control-system design (CSD) methodology can be adapted and used. Stability analysis is achieved using interval analysis. An academic time-delayed system is used to illustrate the robust CSD methodology and the robust stability analysis. In order to provide a reduced-order robust controller, a reduced-order Pade approximation of the nominal system is selected as the nominal plant.
This paper proposes a new blind sequence estimation method for single-inputsingle-output (SISO) systems utilizing an optimal trellis search, which is performed by, a channel-independent Viterbi algorithm (CIVA). In c...
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This paper proposes a new blind sequence estimation method for single-inputsingle-output (SISO) systems utilizing an optimal trellis search, which is performed by, a channel-independent Viterbi algorithm (CIVA). In contrast to the traditional Viterbi algorithm that requires accurate channel estimation, CIVA does not require channel coefficients. Instead, the metrics are calculated from a bank of test vectors designed off-line. The proposed algorithm has outstanding performance under most of the channel conditions. Specifically, it does not suffer from ill-conditioned channels. In addition, it does not depend on channel correlation estimation and, therefore, has fast convergence. Simulations demonstrate its superior performance over even most training-based equalization algorithms.
In this paper, a simple scheme to estimate frequency responses of linear time-invariant single-inputsingle-output (SISO) systems based on closed-loop step response data is investigated. The method uses only a single ...
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ISBN:
(纸本)9781424453634
In this paper, a simple scheme to estimate frequency responses of linear time-invariant single-inputsingle-output (SISO) systems based on closed-loop step response data is investigated. The method uses only a single set of step response data of plants under closed-loop operating conditions. The input and output of a plant are filtered by a simple bandpass filter, and the frequency response of the plant is obtained with the Discrete Fourier Transforms (DFTs) of the filtered input and output signals. The validity of the proposed method is illustrated through simulations and experiments.
In this work we present a case fir dynamic spectrum sharing between different operators in systems with carrier aggregation (CA) which is an important feature in 3GPP LTE-A systems. Cross-carrier scheduling and sensin...
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ISBN:
(纸本)9781479930838
In this work we present a case fir dynamic spectrum sharing between different operators in systems with carrier aggregation (CA) which is an important feature in 3GPP LTE-A systems. Cross-carrier scheduling and sensing are identified as key enablers for such spectrum sharing in LTE-A. Sensing is classified as Type 1 sensing and Type 2 sensing and the role of each in the system operation is discussed. The more challenging Type 2 sensing which involves sensing the interfering signal in the presence of a desired signal is studied for a single-inputsingleoutputsystem. Energy detection and the most powerful test are formulated. The probability of false alarm and of detection are analyzed for energy detectors. Performance evaluations show that reasonable sensing performance can be achieved with the use of channel state information, making such sensing practically viable.
This manuscript presents an iterative learning control strategy for a class of single-inputsingle-output (SISO) nonlinearly parameterized systems with unknown time-varying state delays and actuator faults. Based on s...
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ISBN:
(纸本)9781728159225
This manuscript presents an iterative learning control strategy for a class of single-inputsingle-output (SISO) nonlinearly parameterized systems with unknown time-varying state delays and actuator faults. Based on some basic assumptions and the property of the state delays and actuator faults of the SISO nonlinear system, we design the P-type iterative learning reliable controller to deal with the nonlinearity caused by the time-delays term and actuator faults. And then, a composite energy function(CEF) is used to show the convergence property of the state tracking error. Finally, a numerical simulation is used to verify the correctness and effectiveness of control scheme.
During the reachability phase, the sliding mode control is sensitive to external disturbances and uncertainties. In this paper, we propose to determine the coefficients of the sliding function using the technique of L...
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ISBN:
(纸本)9781479917587
During the reachability phase, the sliding mode control is sensitive to external disturbances and uncertainties. In this paper, we propose to determine the coefficients of the sliding function using the technique of Linear Matrix Inequalities. This technique leads to an optimal choice of sliding function. Using the proposed sliding function, a discrete second order sliding mode control is presented. The control law is based on an input-output model. Simulation results demonstrate that the proposed strategy leads to an optimal performances in terms of the reduction of the reachability phase and the chattering phenomenon.
During the reachability phase, the sliding mode control is sensitive to external disturbances and uncertainties. In this paper, we propose to determine the coefficients of the sliding function using the technique of L...
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ISBN:
(纸本)9781479917594
During the reachability phase, the sliding mode control is sensitive to external disturbances and uncertainties. In this paper, we propose to determine the coefficients of the sliding function using the technique of Linear Matrix Inequalities. This technique leads to an optimal choice of sliding function. Using the proposed sliding function, a discrete second order sliding mode control is presented. The control law is based on an input-output model. Simulation results demonstrate that the proposed strategy leads to an optimal performances in terms of the reduction of the reachability phase and the chattering phenomenon.
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