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...
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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.
In this paper, the problem of detection and joint estimation of range, azimuth and elevation of multiple targets in a multiple-input multiple-output stepped-frequency continuous wave radar system is investigated. Two ...
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ISBN:
(纸本)9781728189420
In this paper, the problem of detection and joint estimation of range, azimuth and elevation of multiple targets in a multiple-input multiple-output stepped-frequency continuous wave radar system is investigated. Two iterative deterministic algorithms are illustrated and their accuracy is assessed on the basis of the raw data acquired from a commercial radar device. Our results evidence that these algorithms achieve similar accuracies, but at the price of substantially different computational efforts.
As one of the potential candidate technologies for sixth generation (6G), visible light communication (VLC) can provide indoor communication services with high data rate when combined with multiple-inputmultiple-outp...
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ISBN:
(纸本)9781665442664
As one of the potential candidate technologies for sixth generation (6G), visible light communication (VLC) can provide indoor communication services with high data rate when combined with multiple-input multiple-output (MIMO). In this paper, we first study the impact of precoding on zonotopes model of channel and then derive the capacity of VLC-MIMO with precoding when the number of transmitters is greater than receivers. Based on the zonotopes graph, two design principles for VLC-MIMO optimal precoding are obtained. Simulation results show that the commonly used radio frequency (RF)-MIMO precodings can hardly catch the capacity lower bound. The optimal precoding in RF may not be optimal in VLC.
In this paper, the problem of power allocation for a multiple-input multiple-output two-way system is investigated in underlay Cognitive Radio (CR) set-up. In the CR underlay mode, secondary users are allowed to explo...
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ISBN:
(纸本)9781479920037
In this paper, the problem of power allocation for a multiple-input multiple-output two-way system is investigated in underlay Cognitive Radio (CR) set-up. In the CR underlay mode, secondary users are allowed to exploit the spectrum allocated to primary users in an opportunistic manner by respecting a tolerated temperature limit. The secondary networks employ an amplify-and-forward two-way relaying technique in order to maximize the sum rate under power budget and interference constraints. In this context, we formulate an optimization problem that is solved in two steps. First, we derive a closed-form expression of the optimal power allocated to terminals. Then, we employ a strong optimization tool based on particle swarm optimization algorithm to find the power allocated to secondary relays. Simulation results demonstrate the efficiency of the proposed solution and analyze the impact of some system parameters on the achieved performance.
The communication bottleneck of over-the-air federated learning (OA-FL) lies in uploading the gradients of local learning models. In this paper, we study the reduction of the communication overhead in the gradients up...
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ISBN:
(纸本)9798350310900
The communication bottleneck of over-the-air federated learning (OA-FL) lies in uploading the gradients of local learning models. In this paper, we study the reduction of the communication overhead in the gradients uploading by using the multiple-input multiple-output (MIMO) technique. We propose a novel sparse-coded multiplexing (SCoM) approach that employs sparse-coding compression and MIMO multiplexing to balance the communication overhead and the learning performance of the FL model. We derive an upper bound on the learning performance loss of the SCoM-based MIMO OA-FL scheme by quantitatively characterizing the gradient aggregation error. We show that the optimal number of multiplexed data streams to minimize the upper bound is given by the minimum of the numbers of transmit and receive antennas. We then formulate an optimization problem of designing precoding and post-processing matrices to minimize the gradient aggregation error, and develop an efficient algorithm to solve the problem. The numerical results indicate the effectiveness of the proposed SCoM approach.
A relay and antenna selection scheme is proposed for multiple-input multiple-output decode-and-forward cooperative networks, where multiple antennas are installed at the grid-powered source, the battery-powered relays...
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ISBN:
(纸本)9781509038237;9781509038220
A relay and antenna selection scheme is proposed for multiple-input multiple-output decode-and-forward cooperative networks, where multiple antennas are installed at the grid-powered source, the battery-powered relays and the grid-powered destination. In order to prolong the network lifetime and avoid the serious degradation of the network performance, the residual energy in the battery of each battery-powered relay is also considered for the relay and antenna selection, besides the channel conditions between the transmitting antennas and the receiving antennas. Another important feature of the proposed scheme lies in the variable number of transmitting antennas selected for data forwarding. The performance of the proposed scheme, in terms of average channel capacity and average network lifetime, is validated by Monte Carlo simulations. The simulation results show that the proposed scheme is superior to the compared scheme in the network performance. Most of all, the network lifetime is significantly prolonged.
In this paper, we investigate an intelligent reflecting surface (IRS) aided millimeter wave (mmWave) secure communication system. To maximize the secrecy rate at the legitimate receiver, we jointly optimize the active...
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ISBN:
(纸本)9781665495080
In this paper, we investigate an intelligent reflecting surface (IRS) aided millimeter wave (mmWave) secure communication system. To maximize the secrecy rate at the legitimate receiver, we jointly optimize the active hybrid precoding at the transmitter and passive precoding at the IRS. Since the optimization problem is non-convex, an alternating optimization based algorithm is proposed, i.e., we iteratively solve digital baseband precoding, analog radio frequency precoding or one of the reflection coefficients with the others fixed. Simulation results show that our proposed algorithm can effectively improve the security performance of the system.
Differential codebook precoding is known as a capacity-achieving precoding scheme when the channel variation is slow. However, at medium to high channel variation speeds the differential codebook optimized for low cha...
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ISBN:
(纸本)9781479915323
Differential codebook precoding is known as a capacity-achieving precoding scheme when the channel variation is slow. However, at medium to high channel variation speeds the differential codebook optimized for low channel variation speeds performs poorly compared to other precoding schemes, thereby limiting its application to practical systems. In this paper, we apply an alternating codebook technique to differential precoding to improve its robustness to high channel variability. The basic idea is creating multiple (instead of single) differential codebooks optimized for various channel variation speeds, and alternating these codebooks over time providing a virtually larger differential codebook, containing various precoding matrices optimized for different speeds, without the need for additional feedback overhead. Simulation results show that the proposed alternating differential codebook scheme not only retains the superior performance of differential precoding at low channel variation rate but, at the same time, reduces the sensitivity to high speed channel variations, resulting in a more practical precoding scheme.
We study outage performance of a downlink multiple-input multiple-output non-orthogonal multiple access (MIMO-NOMA) in dual hop amplify-and-forward (AF) relay communication system over frequency non-selective and slow...
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ISBN:
(纸本)9781538605851
We study outage performance of a downlink multiple-input multiple-output non-orthogonal multiple access (MIMO-NOMA) in dual hop amplify-and-forward (AF) relay communication system over frequency non-selective and slow fading channels with Nakagami-m distribution. In the network, the base station (BS) and mobile users equipped by multi-antenna communicate by the help of fixed gain AF relay with single antenna. In the network, transmit antenna selection (TAS) and maximal ratio combining (MRC) diversity techniques are employed at the BS and mobile users, respectively. Exact closed-form outage probability is derived. Analytical results are validated by Monte Carlo simulations.
This paper proposes an autoencoder based multiple-input multiple-output (MIMO) communication system. The proposed autoencoder learns and optimizes for only line of sight (LOS) component of Rician channel. In addition,...
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ISBN:
(纸本)9784885523281
This paper proposes an autoencoder based multiple-input multiple-output (MIMO) communication system. The proposed autoencoder learns and optimizes for only line of sight (LOS) component of Rician channel. In addition, we adopt multi-dimensional constellation (MDC) in autoencoder, where it is obtained during learning process of autoencoder by adjusting hyperparameter. Simulation results show that our proposed autoencoder using MDC achieves better symbol error rate (SER) performance compared to conventional communication system which uses quadrature amplitude modulation (QAM) constellation. Furthermore, we confirmed that although proposed autoencoder is learned for only LOS component, it can be applied to random Rician flat fading channels with fading components and channel variation terms.
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