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[IEEE 2018 IEEE 5G World Forum (5GWF) - Silicon Valley, CA, USA (2018.7.9-2018.7.11)] 2018 IEEE 5G World Forum (5GWF) - Downlink Performance of MRT-BD in Multiuser Massive MIMO with Low Resolution ADCs
摘要： The multiuser massive MIMO (multi-input multi-output) system using low-resolution analog-to-digital converters (ADCs) in the uplink is to realize low cost and power consumption demands, which, however, reduce the signal quality. Beamforming as a signal processing technique can supply high throughputs in the MIMO systems. In this paper, we investigate the robustness of low-resolution ADCs against the interference among the different streams in the uplink and the different users in downlink systems respectively, and propose the maximum ratio transmission - block diagonalization (MRT-BD) scheme as a kind of beamforming to evaluate the effects of low-resolution ADCs in the full digital massive MIMO system. The preliminary conclusion is that the MRT-BD scheme achieves our anticipation to make the rate achievable, even more than it in the infinite-resolution (no quantization) of BD case can be approached using ADCs with only a few bits of resolution.
关键词： MRT-BD,Massive MIMO,low-resolution ADCs
更新于2025-09-23 15:21:21
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[IEEE ICASSP 2018 - 2018 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP) - Calgary, AB (2018.4.15-2018.4.20)] 2018 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP) - Dithered Beamforming for Channel Estimation in Mmwave-Based Massive Mimo
摘要： In this work we consider the challenging problem of channel estimation at the receiver of a massive multiple-input multiple-output system with hybrid analog/digital beamforming and low-resolution quantization. We propose a dithered beamforming architecture, where random control signals are injected to the analog part of the receiver beamformer and to the analog-to-digital converters to introduce randomness into the signal capturing process and combat the stair-case quantization effects. The statistical properties of the dithered output are captured via an Expectation-Maximization approximation of the maximum a-posteriori estimator. A low-complexity algorithm is proposed which exhibits performance close to the oracle-based least-squares estimation of the sparse channel.
关键词： low resolution analog-to-digital converter (ADC),hybrid analog/digital beamforming,millimeter wave (mmWave) massive MIMO
更新于2025-09-23 15:19:57
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[IEEE 2019 International Conference on Computing, Electronics & Communications Engineering (iCCECE) - London, United Kingdom (2019.8.22-2019.8.23)] 2019 International Conference on Computing, Electronics & Communications Engineering (iCCECE) - Detailed Analysis of IRIS Recognition Performance
摘要： Iris recognition is a well-known biometric identification system which distinguishes authentic and imposter individuals based on the features of their irides. It employs stringent statistical analyses of the features of irides due to the fact that each person has a unique iris, just like a fingerprint. In this work, the approach adopted towards the iris recognition problem is through an exhaustive and careful analysis of the statistical properties of the iris images and the randomness of spurious noise effects. The ability to differentiate two different templates from each other improves with the increase in the number of the degrees of freedom (DOF). The DOF depends on the encoding schemes utilized and moreover, it is hypothesized that the encoding schemes used in themselves could influence the recognition performance. The CASIA (Chinese Academy of Sciences Institute of Automation) version 1 database of iris images used in this study has been modified by the addition of artificial noise in order to simulate practical real life in situ noisy iris capture environments. The classical and state-of-the-art segmentation techniques have been compared, determining whether they are superior to the others under several conditions. The 1D, 2D Gabor filters and the short window implementation were all tested. The conclusion was that the 2D Gabor Filters produce a lower equal error rate (EER), higher accuracy and decidability than by using the one-dimensional log Gabor filter. After modifying the one-dimensional log Gabor filters, a lower EER and higher accuracy was found as the noise level increased. This makes the modified 1D log Gabor Filters a better proposition in noisy conditions. The generated iris templates have a predetermined theoretical value of DOF and from the statistical analysis, an experimental value can be determined. The relation between these values can be used as a metric to compare different databases.
关键词： CASIA iris image database,decidability,equal error rate,degrees of freedom,recognition,accuracy,iris encoding,low-resolution images,CASIA-iris segmentation
更新于2025-09-16 10:30:52
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Low‐resolution fiber‐optic Raman spectroscopy for bladder cancer diagnosis: A comparison study of varying laser power, integration time, and classification methods
摘要： In our previous work, we have demonstrated the great diagnostic potential of a low‐resolution Raman sensing system for bladder cancer through ex vivo experiments. Before forwarding this technique into clinical applications, the system's performance under different experimental conditions must be thoroughly understood. In this paper, a comparison study of this system under different experimental conditions and post‐experiment analysis methods is presented. The different experiment conditions includes two major parts: (a) varying the incident laser power at sample from 30 to 150 mW (30‐mW interval) with fixed integration time of 1 s; (b) varying integration time of 1 s, 2 s, 3 s, and 5 s, with a fixed incident laser power of 150 mW. A total number of 2,916 spectra were collected on 42 bladder tissue specimens under different experimental conditions. Three principal component analysis (PCA)‐based classification methods, including linear discriminant analysis (LDA), support vector machine (SVM), and artificial neural network (ANN), are used in this study for comparison. Results show that increasing the incident laser power has little influence on the overall prediction accuracy; increasing the integration time from 1 to 5 s has a clear improvement on the prediction accuracy; PCA–ANN outperforms PCA–LDA and PCA–SVM consistently under the parameter settings in this study.
关键词： Raman spectroscopy,low resolution,bladder cancer,PCA
更新于2025-09-11 14:15:04
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[IEEE 2018 25th IEEE International Conference on Image Processing (ICIP) - Athens, Greece (2018.10.7-2018.10.10)] 2018 25th IEEE International Conference on Image Processing (ICIP) - Fused Discriminative Metric Learning for Low Resolution Pedestrian Detection
摘要： Low resolution (LR) is one of the most challenging factor in pedestrian detection. In this paper, we propose a fused discriminative metric learning (F-DML) approach for low resolution pedestrian detection without explicit super resolution. We firstly learn a discriminative high resolution (HR) feature space as target space. Then, an optimal Mahanalobis metric is learned to transform the LR feature space into a new LR classification space, which largely preserves the discriminative structure of the HR feature space. Finally, a weighted K-nearest neighbors classifier is applied in the LR classification space which inherits good discrimination from HR feature space. A new training strategy is proposed to find the fewest and most representative LR-HR exemplars. In addition, we build a new dataset for the evaluation of low resolution pedestrian detection methods. Extensive experimental results demonstrate that the proposed approach performs favorably against the state-of-the-art methods.
关键词： Metric learning,Pedestrian detection,Low resolution
更新于2025-09-09 09:28:46