The passive electronically scanned array (PESA) is widely used due to its simple structure and low cost. Its antenna weights have unit modulus and thus, only the weights phases can be controlled. PESA has limited degr...
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ISBN:
(纸本)9781665406338
The passive electronically scanned array (PESA) is widely used due to its simple structure and low cost. Its antenna weights have unit modulus and thus, only the weights phases can be controlled. PESA has limited degrees of freedom for beampattern design, where only the direction of the main beam can be controlled. In this paper we propose a novel way to improve the beamforming capability of PESA by endowing it with more degrees of freedom via the use of double phase shifters (DPS). By doing so, both the magnitude and the phase of the antenna weights can be controlled, allowing for more flexibility in the beampattern design. We also take into account the physical resolution limitation of phase shifters, and propose a method to approximate a given complex beamformer using DPS. Simulation results indicate significant beamforming improvement even at low phase resolution.
Compensation for nonlinear distortion caused by power amplifiers being driven into compression is a field that has been extensively explored by a number of authors. More complex models describing the coupled nonlinear...
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ISBN:
(纸本)9781665406338
Compensation for nonlinear distortion caused by power amplifiers being driven into compression is a field that has been extensively explored by a number of authors. More complex models describing the coupled nonlinear distortion that can occur in an active antenna array also exist. To identify these models most authors assume that the output of each power amplifier can be measured directly. For a system with many antennas over-theair identification might be favorable. The problem of identifying a system describing the joint effects of coupled nonlinear distortion over-the-air has been solved by other authors assuming model or setup simplifications. To tackle the problem with a more accurate model, an algorithm for identifying parameters of a Volterra series model describing coupled non-linear distortion in a digital radar is explored and illustrated with simulated data.
Intelligent reflecting surface (IRS) is a promising next-generation technology for increasing channel capacity and reducing power consumption. In this paper, we present a novel IRS configuration consisting of a small ...
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ISBN:
(纸本)9781665406338
Intelligent reflecting surface (IRS) is a promising next-generation technology for increasing channel capacity and reducing power consumption. In this paper, we present a novel IRS configuration consisting of a small number of active elements in an optimized L-shaped sparse array to separately estimate the channels between the base station and the IRS, and the channel between multiple user equipment and the IRS. Structured matrix completion techniques are used to attain superior direction-ofarrival estimation performance with an increased number of degrees of freedom. The training overhead is minimized in the proposed system and is not directly related to the number of IRS reflecting elements. The proposed sparse array strategy simultaneously resolves multiple sources with a high accuracy and outperforms the L-shaped uniform array counterpart using the same number of active elements. The effectiveness of the proposed strategy is confirmed using simulation results.
We present a deep reinforcement learning approach to design an automotive radar system with integrated sensing and communication. In the proposed system, sparse transmit arrays with quantized phase shifter are used to...
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ISBN:
(纸本)9781665406338
We present a deep reinforcement learning approach to design an automotive radar system with integrated sensing and communication. In the proposed system, sparse transmit arrays with quantized phase shifter are used to carry out transmit beamforming to enhance the performance of both radar sensing and communication. Through interaction with environment, the automotive radar learns a reward that reflects the difference between mainlobe peak and the peak sidelobe level in radar sensing mode or communication user feedback in communication mode, and intelligently adjust its beamforming vector. The Wolpertinger policy based actioncritic network is introduced for beamforming vector learning, which solves the dimension curse due to huge beamforming action space.
In this paper, we develop a beam tracking scheme for an orthogonal frequency division multiplexing (OFDM) Integrated Sensing and Communication (ISAC) system with a hybrid digital analog (HDA) architecture operating in...
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ISBN:
(纸本)9781665406338
In this paper, we develop a beam tracking scheme for an orthogonal frequency division multiplexing (OFDM) Integrated Sensing and Communication (ISAC) system with a hybrid digital analog (HDA) architecture operating in the millimeter wave (mmWave) band. Our tracking method consists of an estimation step inspired by radar signalprocessing techniques, and a prediction step based on simple kinematic equations. The hybrid architecture exploits the predicted state information to focus only on the directions of interest, trading off beamforming gain, hardware complexity and multistream processing capabilities. Our extensive simulations in arbitrary trajectories show that the proposed method can outperform state of the art beam tracking methods in terms of prediction accuracy and consequently achievable communication rate, and is fully capable of dealing with highly non-linear dynamic motion patterns.
This paper investigates optimal target-sensor geometries for differential received signal strength (DRSS) localization in the 2D-plane. To achieve this, theD-optimality criterion is employed, whichmaximizes the determ...
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ISBN:
(纸本)9781665406338
This paper investigates optimal target-sensor geometries for differential received signal strength (DRSS) localization in the 2D-plane. To achieve this, theD-optimality criterion is employed, whichmaximizes the determinant of the Fisher information matrix (FIM). We observe that equiangular sensor separationmaximizes the determinant of the FIM, forming the best geometry, for equal target-sensor ranges under the assumption of identical log-normal noise variances for all sensor measurements. However, when the distances between the target and sensors are different, equiangular sensor separation cannot meet the optimal geometry condition. We provide analytical and numerical solutions for optimal geometries for the specific cases of three and four sensors with non-uniform target-sensor ranges.
Frequency diverse array (FDA)-multiple-input multiple-output (MIMO) radar is characterized by extra degreesof-freedom (DOFs) in the range domain, which can be utilized in mainlobe deceptive jammer suppression. However...
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ISBN:
(纸本)9781665406338
Frequency diverse array (FDA)-multiple-input multiple-output (MIMO) radar is characterized by extra degreesof-freedom (DOFs) in the range domain, which can be utilized in mainlobe deceptive jammer suppression. However, the jammer suppression performance degrades evidently in the presence of compound suppressive jamming signals and deceptive jammers. To this end, this paper deals with the suppression of compound interferences (including the suppressive jamming signals and deceptive jammers) in bistatic FDA-MIMO radar. At the design stage, a colocated FDA-MIMO radar is considered in node 1, while the node 2 serves as a receive-only array, which is configured as a distributed FDA-MIMO radar by combining with the transmit array in node 1. Then, a two-stage processing is performed to suppress the compound interferences, including: 1) the mainlobe maintenance processing to ensure the maximum response of the target;2) the suppression of mainlobe interferences with joint local and global processing. At the analysis stage, the output signal-to-interference-plus-noise ratio (SINR) is analyzed, and a comparison among different radar frameworks is carried out. Numerical results demonstrate the effectiveness of the proposed method in suppressing the compound interference.
This study considers the problem of detecting and locating an active talker's horizontal position from multichannel audio captured by a microphone array. We refer to this as active speaker detection and localizati...
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ISBN:
(纸本)9798350323726
This study considers the problem of detecting and locating an active talker's horizontal position from multichannel audio captured by a microphone array. We refer to this as active speaker detection and localization (ASDL). Our goal was to investigate the performance of spatial acoustic features extracted from the multichannel audio as the input of a convolutional recurrent neural network (CRNN), in relation to the number of channels employed and additive noise. To this end, experiments were conducted to compare the generalized cross-correlation with phase transform (GCC-PHAT), the spatial cue-augmented log-spectrogram (SALSA) features, and a recently-proposed beamforming method, evaluating their robustness to various noise intensities. The array aperture and sampling density were tested by taking subsets from the 16-microphone array. Results and tests of statistical significance demonstrate the microphones' contribution to performance on the TragicTalkers dataset, which offers opportunities to investigate audio-visual approaches in the future.
In this paper, we analyze the performance of dynamic time division duplexing (DTDD) in a distributed antenna array massive multiple-input multiple-output (DAA-mMIMO) system in the presence of simultaneous uplink (UL) ...
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ISBN:
(纸本)9781665406338
In this paper, we analyze the performance of dynamic time division duplexing (DTDD) in a distributed antenna array massive multiple-input multiple-output (DAA-mMIMO) system in the presence of simultaneous uplink (UL) and downlink (DL) data requirements. DTDD has been shown to substantially improve system performance in terms of spectral efficiency (SE) for cellular mMIMO systems. In the DAAenabled system, we show that the performance of DTDD depends critically on appropriately scheduling the UL/DL modes at the access points (APs) based on the localized UL/DL traffic demand. Since an exhaustive search over all possible UL/DL modes is combinatorially complex, we present a greedy algorithm to solve the AP-scheduling problem in polynomial time. Via extensive numerical experiments, we illustrate the 95%-likely sum UL-DL SE achieved by our solution, and show that DAA-mMIMO with dynamic AP-scheduling can substantially outperform TDD-based cellular as well as DAA mMIMO systems.
We study channel-aware binary-decision fusion over a shared flat-fading channel with multiple antennas at the Fusion Center (FC). This paper considers the aid of a Reconfigurable Intelligent Surface (RIS) to effective...
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ISBN:
(纸本)9781665406338
We study channel-aware binary-decision fusion over a shared flat-fading channel with multiple antennas at the Fusion Center (FC). This paper considers the aid of a Reconfigurable Intelligent Surface (RIS) to effectively convey the information of the phenomenon of interest to the FC and foster energyefficient data analytics supporting the Internet of Things (IoT) paradigm. We present the optimal rule and derive a (sub-optimal) joint fusion rule & RIS design, representing an alternative with reduced complexity and lower system knowledge required. Simulation results for performance are presented showing the benefit of RIS adoption even in a suboptimal case.
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