Integrated radar and communication (IRC) systems are promising in the next generation wireless communication networks. However, to realize high level security of information transmission in IRC systems is challenging ...
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ISBN:
(纸本)9781728135557
Integrated radar and communication (IRC) systems are promising in the next generation wireless communication networks. However, to realize high level security of information transmission in IRC systems is challenging due to the large transmission power and the open unguided nature of the wireless channels. In this paper, the secure precoding and artificial noise (AN) techniques are investigated to improve the secrecy rate of a multiple-input multiple-output IRC system with multiple eavesdroppers. The formulated secrecy rate maximization problem is non-convex due to the logarithmic of the determinant that exists in the objective function. Instead of using Taylor series approximation of the non-convex elements, we propose to linearize two log-det terms to tackle this challenging problem. After linearization, an alternating optimization algorithm is proposed to solve the primitive problem. Moreover, a first-order approximation is employed to handle the quadratic constraint on radar detection performance. The suboptimal secure precoding and AN scheme can be obtained for maximizing the information security transmission rate of the legitimate receiver while ensuring the performance of radar detection. Simulation results are presented to validate the performance of our proposed design.
In this letter, a compact ultra-wideband (UWB) multiple-input multiple-output (MIMO) antenna with a high isolation covering 3.1-10.6 GHz UWB bands is presented. The proposed antenna is based on planar monopoles, and t...
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ISBN:
(纸本)9787900914040
In this letter, a compact ultra-wideband (UWB) multiple-input multiple-output (MIMO) antenna with a high isolation covering 3.1-10.6 GHz UWB bands is presented. The proposed antenna is based on planar monopoles, and three band rejections are achieved by adding three Archimedes spiral electromagnetic band gap (As-EBG) structures. Isolation between two radiators is improved by suppressing the surface current flow through the T-shaped strip and triangular slot on the ground plane. The proposed antenna has a low mutual coupling of less than -20 dB over the target band (3.1-10.6 GHz). Therefore, the proposed antenna is a good candidate for UWB MIMO portable applications.
This paper considers a multicasting system in which the base station has a large number of antennas with cost-effective one-bit digital-to-analog converters and aims to send a common symbol to multiple remote users. U...
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ISBN:
(纸本)9781728143002
This paper considers a multicasting system in which the base station has a large number of antennas with cost-effective one-bit digital-to-analog converters and aims to send a common symbol to multiple remote users. Unlike the existing literature which seeks to design the one-bit precoder for a given constellation, e.g., quadrature amplitude modulation (QAM) or phase shift keying (PSK), this paper aims to jointly design the transmit one-bit precoder and the receive constellation by leveraging the concept of autoencoder, wherein the end-to-end multicasting system is modeled using a deep neural network with the one-bit precoding constraint represented by a binary thresholding layer. To deal with the issue that such a binary layer always produces a gradient of zero, and thus prevents an effective end-to-end training when using the conventional back-propagation method, this paper uses a variant of straight-through estimator which approximates the thresholding function with a properly scaled sigmoid function in the back-propagation phase. Numerical results show that, for a fixed channel scenario, the proposed autoencoder-based constellation design is superior to the conventional QAM and PSK constellations. Using the insights obtained from fixed channel scenarios, we also propose a constellation design for varying channel scenarios and numerically show that the proposed design achieves a better performance as compared to the conventional constellations.
An amplitude-phase precode method that based on a high speed ROF-MIMO system is proposed to solve the distortion problem due to the features of optical devices and link damages. This method uses the digital predistort...
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ISBN:
(数字)9781510631748
ISBN:
(纸本)9781510631748
An amplitude-phase precode method that based on a high speed ROF-MIMO system is proposed to solve the distortion problem due to the features of optical devices and link damages. This method uses the digital predistortion algorithm model,which is based on Weierstrass theorem. This could precompensation to the ROF links and reduce the influence of nonlinear characteristics of optical devices such as erbium-doped fiber amplifiers on system signal transmission, and solve the sensitivity of QAM, OFDM and other non-constant envelope modulation signals to system distortion. Then the Minimum Mean Square Error (MMSE) precoding method is used to optimize the spatial characteristics of the MIMO transmission signal to solve the signal interference problem, so as to reduce the bit error rate of the system and reduce the complexity of digital signal processing at the user terminal. The simulation results show that the bit error rate (BER) performance of ROF system with the proposed amplitude-phase precode method is lower than 4*10-4 during the transmitting 10 Gb/s 16QAM-OFDM signal in 20km standard single model fiber. The proposed scheme has the obvious lower bit error rate than the non-precode high speed ROF-MIMO system. Therefore, the proposed scheme improves the base station and antenna array coverage, at same time, reduce the complexity of terminal unit and increase the stability of the system transmission.
Visible light communication (VLC) is a promising technique in future networks due to its advantages of high data rate and licensed-free spectrum. In this paper, we apply the non-orthogonal multiple access (NOMA) techn...
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ISBN:
(纸本)9781728111902
Visible light communication (VLC) is a promising technique in future networks due to its advantages of high data rate and licensed-free spectrum. In this paper, we apply the non-orthogonal multiple access (NOMA) technique to improve the achievable sum rate of multipleinputmultiple-output (MIMO)-based multi-user visible light communication (VLC) systems. To ensure efficient and low complexity power allocation in indoor MIMO-NOMA-based VLC systems, a normalized gain difference power allocation (NGDPA) method is first proposed by exploiting users' channel conditions. We investigate the performance of an indoor 2x2 MIMO-NOMA based multi-user VLC system through numerical simulations. The obtained results show that the achievable sum rate of the 2x2 MIMO-VLC system can be significantly improved by employing NOMA with the proposed NGDPA method. It is demonstrated that NOMA with NGDPA achieves a sum rate improvement of up to 29.1% compared with NOMA with the gain ratio power allocation method in the 2 x 2 MIMO-VLC system with three users.
This paper analyzes the performance of multi-user multiple-input multiple-output (MU-MIMO) systems, with a finite phase-shift keying (PSK) input alphabet. The achievable sum rate is investigated for two precoding tech...
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ISBN:
(纸本)9781538676462
This paper analyzes the performance of multi-user multiple-input multiple-output (MU-MIMO) systems, with a finite phase-shift keying (PSK) input alphabet. The achievable sum rate is investigated for two precoding techniques, namely: 1) zero forcing (ZF) precoding, 2) constructive interference (CI) precoding. In light of this, new analytical expressions for the average sum rate are derived in the two scenarios, and Monte Carlo simulations are provided throughout to confirm the analysis. Furthermore, based on the derived expressions, a power allocation scheme that can ensure fairness among the users is also investigated. The results in this paper demonstrate that, the CI strictly outperforms the ZF scheme, and the performance gap between the considered schemes depends essentially on the system parameters.
The recent emergence of spatial modulation (SM) as a new modulation concept maneuvers the random and unique properties of the multiple-input multiple-output (MIMO) wireless channels. In this paper, an enhancement in S...
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ISBN:
(纸本)9781728106601
The recent emergence of spatial modulation (SM) as a new modulation concept maneuvers the random and unique properties of the multiple-input multiple-output (MIMO) wireless channels. In this paper, an enhancement in SM scheme is proposed by innovative usage of quadrature amplitude modulation (QAM) to add layers which fully exploit both the signal and spatial domains. Layered spatial modulation (LSM) controls the preset rotated signals with normalized amplitudes to classify the layers and to identify the transmitted symbols at the transceiver by completely avoiding inter-channel interference (ICI). High spectral efficiency can be achieved with the addition of only one transmit antenna for each layer by the LSM scheme. Simulation results show that the proposed method has significant improvement in spectral efficiency and bit-error-rate (BER) performance as compared to other MIMO schemes.
In this paper, we consider the problem of multiple-input multiple-output (MIMO) free-space optical communications under the Poisson photon-counting detection model. Aiming for high bit rate objectives, we consider the...
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In this paper, we consider the problem of multiple-input multiple-output (MIMO) free-space optical communications under the Poisson photon-counting detection model. Aiming for high bit rate objectives, we consider the spatial-multiplexing (SMux) solution with M-ary pulse-position modulation, where we propose appropriate optimal and suboptimal decoders and evaluate their complexities. Such novel decoder designs are needed, since the widely spread Gaussian noise-based MIMO decoders are not suitable for the Poisson model. We also carry out an asymptotic performance analysis. This analysis guides a candidate constellation confinement where transmissions are limited to some selected information vectors of the multi-dimensional SMux constellation. This confinement meets the objective of compromising the multiplexing gains for the sake of improved error-rates. The analyzed SMux solutions with both the unconfined and confined constellations transmit at higher data rates compared with the existing single-aperture systems, MIMO systems with repetition coding, and MIMO systems based on spatial modulation.
multiple-input multiple-output (MIMO) system has achieved significant benefits by applying optimum detection techniques. Maximum likelihood (ML) detection technique improves the error rate performance of MIMO system a...
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multiple-input multiple-output (MIMO) system has achieved significant benefits by applying optimum detection techniques. Maximum likelihood (ML) detection technique improves the error rate performance of MIMO system at optimum level but with enhanced complexity. Therefore, we have considered minimum mean square error-ordered successive interference cancellation with candidate detection to approach the performance of ML with reduced complexity. The proposed system performance is analyzed in composite Weibull-gamma fading and additive white generalized Gaussian noise (AWGGN) scenario. Some special cases of WG fading and AWGGN yield the simplified results.
We consider a multiantenna transmission system where the transmitter and receiver respectively have M and two antennas. Specifically, zero-forcing precoding is employed at the transmitter based on a possibly imperfect...
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We consider a multiantenna transmission system where the transmitter and receiver respectively have M and two antennas. Specifically, zero-forcing precoding is employed at the transmitter based on a possibly imperfect channel state information (CSI). The channel estimation is carried out at the transmitter using pilot signals sent from the receiver. Adopting a dual-stream transmission structure, the error performance of the system is enhanced by resorting to signal space diversity (SSD). The performance of the proposed system with binary phase shift keying modulation is studied under a slow flat Rayleigh fading scenario with uncorrelated transmit antennas and correlated receive antennas. We separately examine two cases: the perfect CSI and imperfect CSI at the transmitter. In the former scenario, we provide an exact closed-form expression on the bit error probability (BEP) of the proposed approach. A tight approximation on the BEP of the proposed scheme is presented for the latter scenario. The case with distinct channel estimation qualities for the two subchannels is also considered in the second scenario. The proper rotation angles for the BPSK signal constellation are analytically obtained such that the derived expressions on the BEP are minimized under both cases. We show that the inclusion of SSD into the original scheme yields a noteworthy improvement on the BEP performance with only an insignificant increase in complexity and no additional use of bandwidth/time slots. It is also shown that the proposed technique is more immune against the channel estimation errors as compared to the original method. (C) 2018 Elsevier B.V. All rights reserved.
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