| 1. |
- Andersson, Maria, et al.
(författare)
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Recognition of Anomalous Motion Patterns in Urban Surveillance
- 2013
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Ingår i: IEEE Journal on Selected Topics in Signal Processing. - : IEEE Signal Processing Society. - 1932-4553 .- 1941-0484. ; 7:1, s. 102-110
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the unsupervised K-means clustering and the semi-supervised hidden Markov model (HMM) to automatically detect anomalous motion patterns in groups of people (crowds). Anomalous motion patterns are typically people merging into a dense group, followed by disturbances or threatening situations within the group. The application of K-means clustering and HMM are illustrated with datasets from four surveillance scenarios. The results indicate that by investigating the group of people in a systematic way with different K values, analyze cluster density, cluster quality and changes in cluster shape we can automatically detect anomalous motion patterns. The results correspond well with the events in the datasets. The results also indicate that very accurate detections of the people in the dense group would not be necessary. The clustering and HMM results will be very much the same also with some increased uncertainty in the detections.
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| 2. |
- Curic, Vladimir, et al.
(författare)
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Salience adaptive structuring elements
- 2012
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Ingår i: IEEE Journal on Selected Topics in Signal Processing. - 1932-4553 .- 1941-0484. ; 6:7, s. 809-819
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Tidskriftsartikel (refereegranskat)abstract
- Spatially adaptive structuring elements adjust their shape to the local structures in the image, and are often defined by a ball in a geodesic distance or gray-weighted distance metric space. This paper introduces salience adaptive structuring elements as spatially variant structuring elements that modify not only their shape, but also their size according to the salience of the edges in the image. Morphological operators with salience adaptive structuring elements shift edges with high salience to a less extent than those with low salience. Salience adaptive structuring elements are less flexible than morphological amoebas and their shape is less affected by noise in the image. Consequently, morphological operators using salience adaptive structuring elements have better properties.
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| 3. |
- Engelke, Ulrich, et al.
(författare)
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Psychophysiology-Based QoE Assessment : A Survey
- 2017
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Ingår i: IEEE Journal on Selected Topics in Signal Processing. - 1932-4553 .- 1941-0484. ; 11:1, s. 6-21
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Tidskriftsartikel (refereegranskat)abstract
- We present a survey of psychophysiology-based assessment for quality of experience (QoE) in advanced multimedia technologies. We provide a classification of methods relevant to QoE and describe related psychological processes, experimental design considerations, and signal analysis techniques. We summarize multimodal techniques and discuss several important aspects of psychophysiology-based QoE assessment, including the synergies with psychophysical assessment and the need for standardized experimental design. This survey is not considered to be exhaustive but serves as a guideline for those interested to further explore this emerging field of research.
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| 4. |
- Fascista, Alessio, et al.
(författare)
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RIS-aided Joint Localization and Synchronization with a Single-Antenna Receiver: Beamforming Design and Low-Complexity Estimation
- 2022
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Ingår i: IEEE Journal on Selected Topics in Signal Processing. - 1941-0484 .- 1932-4553. ; 16:5, s. 1141-1156
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Tidskriftsartikel (refereegranskat)abstract
- Reconfigurable intelligent surfaces (RISs) have attracted enormous interest thanks to their ability to overcome line-of-sight blockages in mmWave systems, enabling in turn accurate localization with minimal infrastructure. Less investigated are however the benefits of exploiting RIS with suitably designed beamforming strategies for optimized localization and synchronization performance. In this paper, a novel low-complexity method for joint localization and synchronization based on an optimized design of the base station (BS) active precoding and RIS passive phase profiles is proposed, for the challenging case of a single-antenna receiver. The theoretical position error bound is first derived and used as metric to jointly optimize the BS-RIS beamforming, assuming a priori knowledge of the user position. By exploiting the low-dimensional structure of the solution, a novel codebook-based robust design strategy with optimized beam power allocation is then proposed, which provides low-complexity while taking into account the uncertainty on the user position. Finally, a reduced-complexity maximum-likelihood based estimation procedure is devised to jointly recover the user position and the synchronization offset. Extensive numerical analysis shows that the proposed joint BS-RIS beamforming scheme provides enhanced localization and synchronization performance compared to existing solutions, with the proposed estimator attaining the theoretical bounds even at low signal-to-noise-ratio and in the presence of additional uncontrollable multipath propagation.
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| 5. |
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| 6. |
- Ghauch, Hadi, et al.
(författare)
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Subspace Estimation and Decomposition for Large Millimeter-Wave MIMO Systems
- 2016
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Ingår i: IEEE Journal on Selected Topics in Signal Processing. - : Institute of Electrical and Electronics Engineers (IEEE). - 1932-4553 .- 1941-0484. ; 10:3, s. 528-542
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Tidskriftsartikel (refereegranskat)abstract
- Channel estimation and precoding in hybrid analog-digital millimeter-wave (mmWave) MIMO systems is a fundamental problem that has yet to be addressed, before any of the promised gains can be harnessed. For that matter, we propose a method (based on the well-known Arnoldi iteration) exploiting channel reciprocity in TDD systems and the sparsity of the channel's eigenmodes, to estimate the right (resp. left) singular subspaces of the channel, at the BS (resp. MS). We first describe the algorithm in the context of conventional MIMO systems, and derive bounds on the estimation error in the presence of distortions at both BS and MS. We later identify obstacles that hinder the application of such an algorithm to the hybrid analog-digital architecture, and address them individually. In view of fulfilling the constraints imposed by the hybrid analog-digital architecture, we further propose an iterative algorithm for subspace decomposition, whereby the above estimated subspaces, are approximated by a cascade of analog and digital precoder/combiner. Finally, we evaluate the performance of our scheme against the perfect CSI, fully digital case (i.e., an equivalent conventional MIMO system), and conclude that similar performance can be achieved, especially at medium-to-high SNR (where the performance gap is less than 5%), however, with a drastically lower number of RF chains (similar to 4 to 8 times less).
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| 7. |
- Gokceoglu, Ahmet, et al.
(författare)
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Spatio-Temporal Waveform Design for Multiuser Massive MIMO Downlink With 1-bit Receivers
- 2017
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Ingår i: IEEE Journal on Selected Topics in Signal Processing. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 1932-4553 .- 1941-0484. ; 11:2, s. 347-362
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Tidskriftsartikel (refereegranskat)abstract
- Internet-of-Things (IoT) refers to a high-density network of low-cost, low-bitrate terminals and sensors where low energy consumption is also one central feature. As the power budget of classical receiver chains is dominated by the high-resolution analog-to-digital converters (ADCs), there is a growing interest toward deploying receiver architectures with reduced bit or even 1-bit ADCs. In this paper, we study waveform design, optimization, and detection aspects of multiuser massive MIMO downlink, where user terminals adopt very simple 1-bit ADCs with oversampling. In order to achieve spectral efficiency higher than 1 bit/s/Hz per real dimension, and per receiver antenna, we propose a two-stage precoding structure, namely, a novel quantization precoder followed by maximum-ratio transmission or zero-forcing-type spatial channel precoder which jointly form the multiuser multiantenna transmit waveform. The quantization precoder outputs are designed and optimized, under appropriate transmitter and receiver filter bandwidth constraints, to provide controlled intersymbol interference enabling the input symbols to be uniquely detected from 1-bit quantized observations with a low-complexity symbol detector in the absence of noise. An additional optimization constraint is also imposed in the quantization precoder design to increase the robustness against noise and residual interuser interference (IUI). The purpose of the spatial channel precoder, in turn, is to suppress the IUI and provide high beamforming gains such that good symbol error rates can be achieved in the presence of noise and interference. Extensive numerical evaluations illustrate that the proposed spatio-temporal precoder-based multiantenna waveform design can facilitate good multiuser link performance, despite the extremely simple 1-bitADCsin the receivers, hence being one possible enabling technology for the future low-complexity IoT networks.
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| 8. |
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| 9. |
- Hu, R., et al.
(författare)
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Automotive Squint-forward-looking SAR : High Resolution and Early Warning
- 2021
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Ingår i: IEEE Journal on Selected Topics in Signal Processing. - : Institute of Electrical and Electronics Engineers (IEEE). - 1932-4553 .- 1941-0484. ; , s. 1-1
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Tidskriftsartikel (refereegranskat)abstract
- Forward-looking automotive radars can sense long-distant targets to enable early warning, but the lateral resolution is limited. Synthetic aperture radar (SAR) techniques can achieve very high azimuth resolution, but cannot resolve targets in the forward direction. As a trade-off, squint-forward-looking SAR (SFL-SAR) can perform 2D imaging on a distant area squint to the moving direction, providing both high resolution and early warning. In this paper, we analyzed and derived the constraints of automotive SFL-SAR to satisfy both required resolution and braking distance. Simulations and imaging results verified the analysis.
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| 10. |
- Jorswieck, Eduard A, et al.
(författare)
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Introduction to the Issue on Game Theory in Signal Processing
- 2012
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Ingår i: IEEE Journal on Selected Topics in Signal Processing. - : Institute of Electrical and Electronics Engineers (IEEE). - 1932-4553 .- 1941-0484. ; 6:2, s. 73-75
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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