The tuning of proportional-integral-derivative (PID) controller is essential for any control application in order to ensure the best performance by step change or disturbance. This paper presents the tuning of PID con...
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The tuning of proportional-integral-derivative (PID) controller is essential for any control application in order to ensure the best performance by step change or disturbance. This paper presents the tuning of PID controller for single-input single-output (SISO) and multiple-input multiple-output (MIMO) control systems using tree physiology optimization (TPO). TPO is a metaheuristic algorithm inspired from a plant growth system derived based on the idea of plant architecture and Thornley model (TM). The basic principle of TM simplifies the plant growth into shoots and roots part. The plant shoots grow towards sunlight with the help of nutrients supplied by the root system in order to undergo photosynthesis process, a process of converting light photon into carbon. The carbon gain from the shoots extension will be supplied to the root system in order for the root to grow and search for water plus nutrients. As a result, the nutrients are supplied upwards towards shoot system for further extension. This concept runs iteratively in order to ensure optimum plant growth. The iterative search of shoot towards better light supported by the root counterparts leads to an optimization idea of TPO algorithm. TPO also has a unique exploration strategy due to its multiple branches and shoots that can be defined by user. This concept may improve the search mechanism with a better trade-off between diversification and intensification search. A simulation of SISO control system and an industrial application of MIMO control are applied to demonstrate the effectiveness of the proposed algorithm and compared with other optimization methods such as particle swarm optimization, Ziegler-Nichols, Tyreus-Luyben and Chien-Hrones-Reswick methods. The results clearly exhibit the capability of TPO algorithm towards finding the optimum PID parameters for SISO and MIMO process with faster settling time and better performance with respect to other methods.
In this paper, we investigate the degrees of freedom (DoF) of a multi-cell multi-user multiple-input multiple-output (MIMO) interference broadcast channel (IBC) with non-cooperation distributed base stations (BS), whe...
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In this paper, we investigate the degrees of freedom (DoF) of a multi-cell multi-user multiple-input multiple-output (MIMO) interference broadcast channel (IBC) with non-cooperation distributed base stations (BS), where each BS serves users of its corresponding cell. When all BSs simultaneously transmit their own signals over the same frequency band in the MIMO IBC, the edge users in each cell will suffer the inter-cell interference (ICI) and inter-user interference (IUI) signals. In order to eliminate the ICI and IUI signals, a distributed space time interference alignment (DSTIA) approach is proposed where each BS has only limited access to distributed moderately-delay channel state information at the transmitter (CSIT). It is shown that the DSTIA scheme can obtain the appreciate DoF gains. In addition, the DoF upper bound is asymptotically achievable as the number of antenna at each BS increases. It is shown that the DSTIA method can get DoF gains over other interference alignment schemes with delayed CSIT in literature. Moreover, the DSTIA method can attain higher DoFs than the IA schemes with global CSIT for certain antenna configurations.
Interference is usually regarded as a detrimental factor that degrades the performance of a wireless network. However, when it is used properly, the security of transmission can be effectively improved. In this paper,...
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Interference is usually regarded as a detrimental factor that degrades the performance of a wireless network. However, when it is used properly, the security of transmission can be effectively improved. In this paper, user selection and transceiver design are proposed to guarantee the secure transmission in a multiple-input multiple-output interference network with an eavesdropper. First, user selection is performed to select the most suitable user to transmit confidential information according to the topology and path loss in each time slot among all users. Then, based on user selection, the transceivers of the users are jointly designed to maximize the secrecy rate of the selected user while guaranteeing a minimum transmission rate for other users. Due to the nonconvexity of the optimization problem, it is transformed into a convex second-order cone programming with the help of successive approximations. An alternate iteration algorithm is proposed to obtain the optimal solution. The fairness of the user selection is considered, and a modified scheme is proposed to share the opportunity of secure transmission among users. Finally, simulation results are presented to show the effectiveness and efficiency of the proposed schemes.
The influences of proximity effect and complex dielectric permittivity on per-unit-length parameter matrices of three-core power line are analyzed. Based on the symmetrical structure of three-core cable, the per-unit-...
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The influences of proximity effect and complex dielectric permittivity on per-unit-length parameter matrices of three-core power line are analyzed. Based on the symmetrical structure of three-core cable, the per-unit-length parameter matrices are decomposed into common mode and differential mode parameters by phase-mode transformation. Taking the electromagnetic simulation results of finite element method as the initial values, a method of correcting per-unit-length parameters based on open-circuit impedance measurement in mode domain is proposed. Based on the theory of multi-conductor transmission line, the channel model of three-core power line in the frequency range from 30 kHz up to 15 MHz is established. The test results under the branch network show that the channel model has high accuracy, and the influence of the network structure on the impedance and transmission characteristics is further analyzed. The model can accurately take into account the coupling effect between multiple-input multiple-output channels.
Previous approaches for blind identification of space-frequency block codes (SFBCs) do not perform well for short observation periods due to their inefficient utilization of frequency-domain redundancy. This paper pro...
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Previous approaches for blind identification of space-frequency block codes (SFBCs) do not perform well for short observation periods due to their inefficient utilization of frequency-domain redundancy. This paper proposes a hypothesis test (HT)-based algorithm and a support vector machine (SVM)-based algorithm for the SFBC signals' identification over frequency-selective fading channels to exploit two-dimensional space-frequency domain redundancy. Based on the central limit theorem, space-domain redundancy is used to construct the cross-correlation function of the estimator and frequency-domain redundancy is incorporated in the construction of the statistics. The difference between two proposed algorithms is that the HT-based algorithm constructs a chi-square statistic and employs an HT to make the decision, while the SVM-based algorithm constructs a non-central chi-square statistic with unknown mean as a strongly distinguishable statistical feature and uses SVM to make the decision. Both the algorithms do not require knowledge of the channel coefficients, modulation type, or noise power, and the SVM-based algorithm does not require timing synchronization. The simulation results verify the superior performance of the proposed algorithms for short observation periods with comparable computational complexity to conventional algorithms, as well as their acceptable identification performance in the presence of transmission impairments.
This letter is on the energy efficient precoder design in multi-user multiple-input multiple-output systems which is also robust with respect to the imperfect channel state information at the transmitters. In other wo...
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This letter is on the energy efficient precoder design in multi-user multiple-input multiple-output systems which is also robust with respect to the imperfect channel state information at the transmitters. In other words, we design the precoder matrix associated with each transmitter to maximize the general energy efficiency of the network. We investigate the problem in two conventional cases. The first case considers the statistical characterization for the channel estimation error that leads to a quadratically constrained quadratic program with a semi-closed-form solution. Then, we turn our attention to the case which considers only the uncertainty region for the channel estimation error;this case eventually results in a semi-definite program.
This letter studies the fully decentralized optimization of the preceding matrices for the downlink of multiple-input-multiple-output cache-enabled ultra-dense radio access network. To avoid signalling exchange betwee...
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This letter studies the fully decentralized optimization of the preceding matrices for the downlink of multiple-input-multiple-output cache-enabled ultra-dense radio access network. To avoid signalling exchange between coordinated edge radio access nodes (RANs), we first construct a virtual downlink cache-enabled ultra-dense radio access network. Following, a new concept of signal-to-interference-leakage-plusnoise ratio is defined. Based on this concept, a virtual weighted sum rate maximization problem is formulated to optimize the precoders. We then propose a computationally efficient decentralized optimization algorithm that achieves stationary point to the problem. Numerical results show that the proposed algorithm can achieve more than 96.15% of the performance of the centralized optimization without any signalling exchange between coordinated edge RANs for multiple-input single-output cases.
Visible light communication (VLC) systems are inherently signal-to-noise ratio (SNR) limited due to link budget constraints. One favourable method to overcome this limitation is to focus on the pre-log factors of the ...
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Visible light communication (VLC) systems are inherently signal-to-noise ratio (SNR) limited due to link budget constraints. One favourable method to overcome this limitation is to focus on the pre-log factors of the channel capacity. multiple-input multiple-output (MIMO) techniques are therefore a promising avenue of research. However, inter-channel interference in MIMO limits the achievable capacity. Spatial modulation (SM) avoids this limitation. Furthermore, the performance of MIMO systems in VLC is limited by the similarities among spatial channels. This limitation becomes particularly severe in intensity modulation/direct detection (IM/DD) systems because of the lack of phase information. The motivation of this paper is to propose a system that results in a multi-channel transmission system that enables reliable multi-user optical MIMO SM transmission without the need for a precoder, power allocation algorithm or additional optics at the receiver. A general bit error performance model for the SM system is developed for an arbitrary number of light-emitting diodes (LEDs) in conjunction with pulse amplitude modulation. Based on this model, an LED array structure is designed to result in spatially separated multiple channels by manipulating the transmitter geometry. This article is part of the theme issue 'Optical wireless communication'.
In this paper, we investigate the detection performance for MIMO signals in a wireless full-duplex (FD) relaying network, in which the diversity techniques, including maximal ratio transmission (MRT) at source and max...
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In this paper, we investigate the detection performance for MIMO signals in a wireless full-duplex (FD) relaying network, in which the diversity techniques, including maximal ratio transmission (MRT) at source and maximal ratio combining (MRC) at destination, are applied. Especially, we rigorously study the impact of hardware impairment (HI) at all nodes and the residual self-interference (RSI) at the FD relay (FDR), which have not mentioned in previous works. Here, the closed-form expressions of key performance factors such as outage probability (OP), throughput, and symbol error rate (SER) of the considered MIMO-FDR system with HI are derived mathematically. All analytical expressions are validated by Monte Carlo simulations. Numerical results demonstrate a strong impact of HI on OP, throughput, and SER of the MIMO-FDR system in comparison with the ideal (ID) MIMO-FDR system, especially at high data rate. The combination of HI and RSI prevents OP and SER of the MIMO-FDR system from going lower than some error floors even at high signal-to-noise ratio (SNR) regime. However, by using MRT/MRC techniques with larger number of transmit antennas at source than the number of receive antennas at destination, the OP and SER performance in HI condition can be significantly improved. (C) 2020 Elsevier B.V. All rights reserved.
The most popular technique used for high data rate services in 4G scenario is MIMO-OFDM. Space-time block codes have been recommended for high diversity gain in MIMO communication systems. Due to comparatively simpler...
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The most popular technique used for high data rate services in 4G scenario is MIMO-OFDM. Space-time block codes have been recommended for high diversity gain in MIMO communication systems. Due to comparatively simpler design and less decoding complexity orthogonal STBCs are very attractive. In this paper, we propose a novel adaptive companding method for peak to average power ratio reduction in IEEE 802.16 standards used in 4G wireless mobile communications with orthogonal space time block coded MIMO-OFDM systems. This is obtained by fixing compander parameters independently for statistically unrelated symbols in OFDM waveform and according to the features of input symbols. The bit error rate performance analysis of the proposed system under Rayleigh fading MIMO channel conditions has also been presented. Simulation results showed that the proposed method performs better for a given PAPR preset value and a slight improvement in the BER performance was observed over fixed compander.
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