A novel block sparse reconstruction algorithm is presented for direction-of-arrival (DOA) estimation in the presence of unknown mutual coupling of the monostatic multiple-input multiple-output (MIMO) radar. Consider t...
详细信息
ISBN:
(纸本)9780996007894
A novel block sparse reconstruction algorithm is presented for direction-of-arrival (DOA) estimation in the presence of unknown mutual coupling of the monostatic multiple-input multiple-output (MIMO) radar. Consider the banded complex symmetric Toeplitz structure of the unknown mutual coupling matrices (MCM) in both transmit and receive array, a new block representation model is constructed first by parameterizing the steering matrices to avoid the influence of mutual coupling and has no loss of array aperture. Then, a reduced-dimensional transformation matrix is structured to eliminate the redundant rows in the received data for reducing the computational complexity. Finally, the DOA estimation problem can be transformed into minimization constrained optimization problem. The simulation results show that the proposed algorithm outperforms the existing algorithms for DOA estimation under unknown mutual coupling conditions in monostatic MIMO radar.
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...
详细信息
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.
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 ...
详细信息
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.
Low angle target estimation is always a difficult problem for radar elevation estimation. multiple-input multiple-output (MIMO) radar can increase array degree of freedom and resolution, and improve the low angle targ...
详细信息
作者：
Liu, WendongWang, ZhaochengTsinghua Univ
Beijing Natl Res Ctr Informat Sci & Technol Dept Elect Engn Beijing 100084 Peoples R China Tsinghua Univ
Grad Sch Shenzhen Div Informat Sci & Technol Shenzhen 518055 Peoples R China
Combined with massive multiple-input multiple-output technology, beamforming can effectively compensate the high path-loss of millimeter-wave signals and hence improve the received power at user equipment (UE). In ord...
详细信息
Combined with massive multiple-input multiple-output technology, beamforming can effectively compensate the high path-loss of millimeter-wave signals and hence improve the received power at user equipment (UE). In order to establish the beam alignment between base station (BS) and UE, beam training (BT) is required to select appropriate beamforming vectors at both BS and UE sides. In general, a good trade-off between beamforming gain and BT overhead is critical to enhance the system performance. In this letter, a statistics-assisted beam training (SA-BT) scheme is proposed to reduce the BT overhead. Specifically, BS scans the candidate beams according to the descending order of the utilization frequency of each beam. Meanwhile, the BT procedure is finished when the beamforming gain at UE exceeds the pre-defined threshold. The theoretical analyses and the numerical simulations prove that the proposed scheme can reduce the BT overhead and hence improve the spectral efficiency significantly compared with the existing methodologies.
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...
详细信息
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.
In this paper, a single channel over-the-air (OTA) data acquisition approach for real-time calibration of digital predistorter in multiple-input multiple-output transmitters is proposed. By using the data acquired fro...
详细信息
ISBN:
(纸本)9781728107165
In this paper, a single channel over-the-air (OTA) data acquisition approach for real-time calibration of digital predistorter in multiple-input multiple-output transmitters is proposed. By using the data acquired from the far-field OTA tests, the output of each power amplifier (PA) can be virtually reconstructed and thus the linearization reference at the main beam direction can be accurately estimated. Digital predistortion (DPD) can therefore be effectively constructed without direct measurement at PA output. Experimental results demonstrate that the proposed scheme can accurately estimate far-field main beam data and the proposed DPD can achieve excellent linearization performance.
multiple-input multiple-output (MIMO) technique is expected to be extensively used in future wireless systems to increase capacity of wireless channels. Nevertheless, the capacity gain comes with a cost. In particular...
详细信息
ISBN:
(纸本)9789082797039
multiple-input multiple-output (MIMO) technique is expected to be extensively used in future wireless systems to increase capacity of wireless channels. Nevertheless, the capacity gain comes with a cost. In particular, multiple analog radio frequency (RF) chains are required at both the transmitter and the receiver, thereby leading to a higher implementation cost, more power consumption, and lower energy efficiency. This paper presents a receiver with only one RF chain for 2x2 MIMO transmission system. Proposed design is based on a time modulated antenna array (TMAA) with beam-steering functionality and a wideband software defined radio (SDR). Spatial streams were created by demultiplexing spectral components (sidebands) generated by periodical ON/OFF switching Number of RF chains was reduced from 2 to 1 while maintaining sufficiently low correlation of spatial streams, which is required to perform MIMO transmission. Feasibility of proposed technique is evaluated by means of experimental verification.
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...
详细信息
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.
This paper presents recent progress on portable Doppler, frequency-shift keying (FSK) and frequency-modulated continuous-wave (FMCW) radar systems for life activity sensing and human localization. It starts from a sof...
详细信息
ISBN:
(纸本)9781728108780
This paper presents recent progress on portable Doppler, frequency-shift keying (FSK) and frequency-modulated continuous-wave (FMCW) radar systems for life activity sensing and human localization. It starts from a software-based calibration technology that significantly improves the accuracy and reliability of millimeter-wave interferometry radar front-end for physiological motion and vocal vibration detection. Then, the operation principle and unique features of FSK and FMCW radar, such as RF/digital beamforming, for human-aware sensing and localization will be presented. To reject clutter noise, which is a common challenge for practical deployment of short-range radar system, intermodulation radar technique will be discussed. Then, machine learning will be presented as an efficient approach to make the radar system smart for automatic classification and decision making. Finally, challenges for biomedical radar systems and future development directions will be discussed.
暂无评论