This paper considers a scenario in which an Alice-Bob pair wishes to communicate in secret in the presence of an active Eve, who is capable of jamming as well as eavesdropping and operates in full-duplex (FD) mode. As...
详细信息
This paper considers a scenario in which an Alice-Bob pair wishes to communicate in secret in the presence of an active Eve, who is capable of jamming as well as eavesdropping and operates in full-duplex (FD) mode. As countermeasure, Bob operates in FD mode, using a subset of its antennas to receive, and the remaining antennas to transmit jamming noise. Alice and Bob employ linear precoding, and all nodes use Gaussian code books. In that context, our goal is to maximize the achievable secrecy degrees of freedom (S.D.o.F.) of the system. We provide the optimal receive/transmit antennas allocation at Bob, based on which we determine in closed form the maximum achievable S.D.o.F. We also provide a method for constructing the precoding matrices of Alice and Bob, based on which the maximum S.D.o.F. can be achieved. We further investigate the adverse scenario in which Eve knows Bob's transmission strategy and optimizes its transmit/receive antennas allocation in order to minimize the achievable S.D.o.F. For that case, we find the worst case achievable S.D.o.F. Numerical results validate the theoretical findings and demonstrate the performance of the proposed method.
A control method for multi-input multi-output non-Gaussian random vibration test based on an improved zero-memory nonlinear transformation and an inverse system method is proposed. Compared with the classic zero-memor...
详细信息
A control method for multi-input multi-output non-Gaussian random vibration test based on an improved zero-memory nonlinear transformation and an inverse system method is proposed. Compared with the classic zero-memory nonlinear transformation method, the improved one can overcome the defect of the dynamic range loss. The inverse system method is put forward in order to control the kurtoses and the spectra for multi-input multi-output non-Gaussian random vibration test simultaneously. The main idea of inverse system method is to generate the Gaussian reference response signals first from the reference spectra, and the improved zero-memory nonlinear transformation method is utilized to obtain the non-Gaussian reference response signals with the reference kurtoses, then the continuous and stationary coupled driving signals can be derived from the relationship between the inputs and outputs of the test system. Thus, the difficulty in generation of driving signals in multi-input multi-output non-Gaussian random vibration test can be overcome. The matrix power control algorithm is introduced for the spectrum control, and a kurtosis control algorithm is set up similarly. A simulation example and an experimental test are provided in the paper, and the results illustrate the effectiveness and feasibility of the proposed control method. Copyright (c) 2017 John Wiley & Sons, Ltd.
multi-input multi-output (MIMO) is the need for recent communication system for the enhancement of channel capacity. While the number of antenna array elements increased, the spacing between the array elements and siz...
详细信息
multi-input multi-output (MIMO) is the need for recent communication system for the enhancement of channel capacity. While the number of antenna array elements increased, the spacing between the array elements and size of the antenna reduced. Hence high coupling between the elements occur, and thus the channel capacity reduced. There were several existing methods employs, however there were some limitations like reduced gain, dielectric constant, and bandwidth. So as to overcome this and to increase the performance characteristics such as bandwidth, gain of MIMO antennas and to lessen the dielectric constant of substrate material this proposed scheme is introduced. Using these considerations and requirements, an array of two-element MIMO system will be designed and developed with a less dielectric material (epsilon r<4. So in this Taconic RF-35 (dielectric constant is 3.5), Two T-Shaped antennas are employed for 2.45 GHz (ISM band) with multiple modes of operation to achieve the improved bandwidth of about - 10 db. Simulation is done by HFSS 13.0.
Power line communications (PLCs) enable new and flexible networking functions in smart grids. However, due to the high attenuation and interference, it is a great challenge for PLC to achieve reliable and high data ra...
详细信息
Power line communications (PLCs) enable new and flexible networking functions in smart grids. However, due to the high attenuation and interference, it is a great challenge for PLC to achieve reliable and high data rate transmissions. Thus, we propose a multiple-inputmultiple-output (MIMO) architecture to improve the reliability and data rate for PLC networks. In viewing the data rate requirements of in-home PLC network systems, we develop a precoding scheme to maximize the system throughput. In harmonizing to the proposed precoding scheme, the closed-form of the sum data rate of the PLC-MIMO channel is derived. To improve the communication reliability, we propose a partial transmission sequence (PTS) based algorithm to mitigate the noise in PLC channels. The closed-form of the symbol error rate (SER) is derived according to the probability density function of the impulsive noise in PLC channels. Simulation results demonstrate that the proposed precoding scheme achieves a better throughput when compared to the conventional precoding schemes. Furthermore, the PTS-based noise mitigation algorithm significantly improves the SER performance of PLC links.
In this article, we present an investigation into the use of faster-than-Nyquist (FTN) signaling in multiple-inputmultiple-output (MIMO) covert communications with a multi-antenna warden. We formulate an optimization...
详细信息
In this article, we present an investigation into the use of faster-than-Nyquist (FTN) signaling in multiple-inputmultiple-output (MIMO) covert communications with a multi-antenna warden. We formulate an optimization problem to maximize the covert rate subject to the covertness and transmit power constraints. Due to the dimensional expansion of variables, solving the formulated problem by conventional convex optimization method incurs unaffordable computational overhead. To circumvent this issue, we propose a low-complexity linear precoding and equalization method to nullify the energy leakage towards the warden while decoupling the MIMO FTN signaling into independent substreams simultaneously, and allocate the power by a new scaled water-filling approach. Numerical results validate the superiority of FTN signaling in MIMO covert communications over the Nyquist counterpart, and also show the effectiveness of our proposed scheme, which merely causes minor performance loss compared to the optimal baseline.
This paper considers a scenario in which a source-destination pair needs to establish a confidential connection against an external eavesdropper, aided by the interference generated by another source-destination pair ...
详细信息
This paper considers a scenario in which a source-destination pair needs to establish a confidential connection against an external eavesdropper, aided by the interference generated by another source-destination pair that exchanges public messages. The goal is to compute the maximum achievable secrecy degrees of freedom (S.D.o.F) region of a MIMO two-user wiretap network. First, a cooperative secrecy transmission scheme is proposed, whose feasible set is shown to achieve all S.D.o.F. pairs on the S.D.o.F. region boundary. In this way, the determination of the S.D.o.F. region is reduced to a problem of maximizing the S.D.o.F. pair over the proposed transmission scheme. The maximum achievable S.D.o.F. region boundary points are obtained in closed form, and the construction of the precoding matrices achieving the maximum S.D.o.F. region boundary is provided. The proposed expressions are functions of the number of antennas at each terminal, and apply to any number of antennas, thus constituting an advancement over prior works that have considered only fixed antenna configurations.
This paper investigates the control method for multi-input multi-output non-stationary non-Gaussian random vibration test with the specified references composed of stationary power spectra, moving root mean square dis...
详细信息
This paper investigates the control method for multi-input multi-output non-stationary non-Gaussian random vibration test with the specified references composed of stationary power spectra, moving root mean square distributions and moving kurtosis distributions. The objective of random vibration test is to force the response signals of test structure to satisfy the specified references within tolerances. An inverse system method in time domain is used to guarantee the control of response time-frequency characteristics independently and simultaneously. The evolutionary spectrum theory is utilized to establish the matrix representation of non-stationary non-Gaussian input-output relationships of a linear dynamic system in frequency domain. To analyze a non-stationary non-Gaussian vibration signal, two sets of random numbers named moving root mean square and moving kurtosis are used to modulate a stationary random signal. The transformation process theory is utilized to obtain moving root mean square and moving kurtosis by a moving root mean square distribution and a moving kurtosis distribution respectively. The control algorithms are presented to update the drive signals according to the deviations between responses and references. A numerical example by a cantilever beam and a biaxial vibration test are carried out and the results demonstrate the feasibility and validity of the proposed methods. (C) 2019 Elsevier Ltd. All rights reserved.
This paper investigates and quantifies the advantages of a Full-Duplex (FD) transmitter/receiver pair in improving the secrecy rate of the system. We consider a linear precoder design for a multiple-inputmultiple-out...
详细信息
This paper investigates and quantifies the advantages of a Full-Duplex (FD) transmitter/receiver pair in improving the secrecy rate of the system. We consider a linear precoder design for a multiple-inputmultiple-output Gaussian wiretap channel, which comprises two legitimate nodes, i.e., Alice and Bob, operating in FD mode and exchanging confidential messages in the presence of a passive eavesdropper. Using the sum secrecy degrees of freedoms (sum SDoFs) as metric, we formulate an optimization problem with respect to Alice's and Bob's precoding matrices. In order to solve this problem, we first propose a cooperative secrecy transmission scheme, whose feasible set is sufficient to achieve the maximum sum SDoF. Based on that feasible set, we then determine in closed form the maximum achievable sum SDoF and also provide a method for constructing the precoding matrix pair, which achieves the maximum sum SDoF. The latter pair would be near-optimal in terms of the achievable secrecy sum rate in the high signal-to-noise ratio (SNR) regime. By providing the maximum achievable sum SDoF as a function of the number of antennas, one could select the optimal system parameters to further maximize the achievable sum SDoF. We use simulations to evaluate the performance of the proposed precoding matrices in realistic channel scenarios and at various levels of the SNR.
A novel transceiver antenna selection (TRAS) strategy selecting a pair of antennas for transmission and reception at terminal sources for full-duplex amplify-forward multi-input multi-output two way relay networks is ...
详细信息
A novel transceiver antenna selection (TRAS) strategy selecting a pair of antennas for transmission and reception at terminal sources for full-duplex amplify-forward multi-input multi-output two way relay networks is proposed. Antenna pair is selected in accordance with maximum and second maximum signal to self-interference-plus-noise ratio between the sources and relay, where the terminal sources and relay are full-duplex. Unlike reciprocal channel gains, forward and backward paths between the sources and relay are taken to be different. With four different antenna selection (AS) scenarios, the exact sum outage probability (SOP) for fading self-interference (SI) and the exact, approximated, and asymptotic SOP expressions for nonfading SI over Rayleigh fading channels are derived and validated via Monte Carlo simulation technique. The proposed AS strategy uses all antenna space for either transmission or reception which results in a reduction in total number of antennas at each terminal node. It is shown that performance can be significantly improved by usage of offered TRAS strategy at terminal sources. For example, up to 25 dB gain is obtained for five antennas at the sources with respect to no selection case of two antennas. In addition, it outperforms the selection strategy using maximum paths from two divided antenna sets at each source, where one set is only used for transmission and the other one for reception. The diversity order of the system is proven to be dependent on SI and varies between zero and minimum of the total number of antennas of two sources minus 1. For different SI values, optimum power allocations are demonstrated and factors affecting optimum relay location are also elaborated. Each AS scenario produces the lowest SOP for different combinations of SI occurrences, power allocations, and relay locations.
The problem of joint beamforming and power allocation for cognitive multi-input multi-output systems is studied via game theory. The objective is to maximize the sum utility of secondary users (SUs) subject to the pri...
详细信息
The problem of joint beamforming and power allocation for cognitive multi-input multi-output systems is studied via game theory. The objective is to maximize the sum utility of secondary users (SUs) subject to the primary user (PU) interference constraint, the transmission power constraint of SUs, and the signal-to-interference-plus-noise ratio (SINR) constraint of each SU. In our earlier work, the problem was formulated as a non-cooperative game under the assumption of perfect channel state information (CSI). Nash equilibrium (NE) is considered as the solution of this game. A distributed algorithm is proposed which can converge to the NE. Due to the limited cooperation between the secondary base station (SBS) and the PU, imperfect CSI between the SBS and the PU is further considered in this work. The problem is formulated as a robust game. As it is difficult to solve the optimization problem in this case, existence of the NE cannot be analyzed. Therefore, convergence property of the sum utility of SUs will be illustrated numerically. Simulation results show that under perfect CSI the proposed algorithm can converge to a locally optimal pair of transmission power vector and beamforming vector, while under imperfect CSI the sum utility of SUs converges with the increase of the transmission power constraint of SUs.
暂无评论