| 1. |
- Moebus, M., et al.
(författare)
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Parametrization of acoustic images for the detection of human presence by mobile platforms
- 2010
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Ingår i: ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings. - 1520-6149. - 9781424442966 ; , s. 3538-3541
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We address the problem of human detection with mobile platforms such as robots. Instead of using an optical system, we propose to employ an acoustic 2D array to reliably obtain an image of a human in a 3D spatial power spectrum which is independent of lighting conditions and uses cheap acoustic sensors. We show that humans have a distinct acoustic signature and propose to model the echoes from reflecting parts of objects in the scene by a Gaussian-Mixture- Model. When it is fitted to the acoustic image, we can extract geometric relations between the present echoes and represent the acoustic signatures in a low-dimensional parameter space. We present results based on real data measurements that demonstrate that different objects can be reconstructed from the data and discriminated. The obtained parameter space forms the basis for subsequent detection and classification of humans. ©2010 IEEE.
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| 2. |
- Seifi, Nima, 1981, et al.
(författare)
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An Efficient Signaling for Multi-mode Transmission in Multi-user MIMO
- 2010
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Ingår i: ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings. - 1520-6149. - 9781424442966 ; , s. 3402-3405
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Konferensbidrag (refereegranskat)abstract
- In this paper the downlink of a multi-user MIMO (MUMIMO)system with multi-mode transmission is considered.We propose a low-complexity algorithm for selecting usersand the corresponding number of data streams to each user,denoted as user transmission mode (UTM). The selectionis only based on the average received signal-to-noise ratio(SNR) from the base station (BS) for each user. This reducesthe overall amount of feedback for scheduling, as opposedto techniques that assume perfect instantaneous channelstate information (CSI) from all users. Analytical averagethroughput approximations are derived for each user at different UTMs. Simulation results demonstrate that the proposed algorithm provides performance close to dirty paper coding (DPC) with considerably reduced feedback.
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| 3. |
- Björnson, Emil, et al.
(författare)
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Massive MIMO systems with hardware-constrained base stations
- 2014
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Ingår i: ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings. - 1520-6149. - 9781479928927 ; , s. 3142-3146
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Konferensbidrag (refereegranskat)abstract
- Massive multiple-input multiple-output (MIMO) systems are cellular networks where the base stations (BSs) are equipped with unconventionally many antennas. Such large antenna arrays offer huge spatial degrees-of-freedom for transmission optimization; in particular, great signal gains, resilience to imperfect channel knowledge, and small inter-user interference are all achievable without extensive inter-cell coordination. The key to cost-efficient deployment of large arrays is the use of hardware-constrained base stations with low-cost antenna elements, as compared to today's expensive and power-hungry BSs. Low-cost transceivers are prone to hardware imperfections, but it has been conjectured that the excessive degrees-of-freedom of massive MIMO would bring robustness to such imperfections. We herein prove this claim for an uplink channel with multiplicative phase-drift, additive distortion noise, and noise amplification. Specifically, we derive a closed-form scaling law that shows how fast the imperfections increase with the number of antennas.
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| 4. |
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| 5. |
- Ahrens, Jens, 1978
(författare)
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Auralization of Omnidirectional Room Impulse Responses Based on the Spatial Decomposition Method and Synthetic Spatial Data
- 2019
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Ingår i: ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings. - 1520-6149. ; 2019-May, s. 146-150
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Konferensbidrag (refereegranskat)abstract
- The spatial decomposition method decomposes acoustic room impulse responses into a pressure signal and a direction of arrival for each time instant of the pressure signal. An acoustic space can be auralized by distributing the pressure signal over the available loudspeakers or head-related transfer functions so that the required instantaneous propagation direction is recreated. We present a user study that demonstrates based on binaural auralization that the arrival directions can be synthesized from random data such that the auralization is nearly indistinguishable from the auralization of the original data. The presented concept constitutes the fundament of a highly scalable spatialization method for omnidirectional room impulse responses.
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| 6. |
- Ahrens, Jens, 1978, et al.
(författare)
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Interpolation and Range Extrapolation of Sound Source Directivity Based on a Spherical Wave Propagation Model
- 2020
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Ingår i: ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings. - 1520-6149. ; 2020-May, s. 4662-4666
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Konferensbidrag (refereegranskat)abstract
- Approaches for incorporating sound source directivity into wave-based room acoustic simulations using a spherical harmonic representation have been presented recently. Normally, the directivity is measured or prescribed on a spherical surface centered at the nominal source position. In wave-based simulations, this directivity can be represented through a locally-defined driving term acting at the source location. In practice, the directivity of real-world sound sources like musical instruments or industrial machinery can only be measured approximately in terms of spatial resolution and accuracy. We show that the measurement data can be augmented such that the impairments due to the limitations of the measurement accuracy are mitigated. We revisit the previously proposed approach of only using the angle-dependent magnitude of the measured directivity together with a spherical-wave propagation model and demonstrate its potential by means of numerical simulations based on two case studies.
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| 7. |
- Ahrens, Jens, 1978, et al.
(författare)
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The Far-Field Equatorial Array for Binaural Rendering
- 2021
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Ingår i: ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings. - 1520-6149. ; 2021-June, s. 421-425
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Konferensbidrag (refereegranskat)abstract
- We present a method for obtaining a spherical harmonic representation of a sound field based on a microphone array along the equator of a rigid spherical scatterer. The two-dimensional plane wave de-composition of the incoming sound field is computed from the microphone signals. The influence of the scatterer is removed under the assumption of distant sound sources, and the result is converted to a spherical harmonic (SH) representation, which in turn can be rendered binaurally. The approach requires an order of magnitude fewer microphones compared to conventional spherical arrays that operate at the same SH order at the expense of not being able to accurately represent non-horizontally-propagating sound fields. Although the scattering removal is not perfect at high frequencies at low harmonic orders, numerical evaluation demonstrates the effectiveness of the approach.
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| 8. |
- Alegría, Juan Vidal, et al.
(författare)
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Cell-Free Massive MIMO: Exploiting The Wax Decomposition
- 2022
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Ingår i: 2022 IEEE International Conference on Acoustics, Speech, and Signal Processing, ICASSP 2022 - Proceedings. - 1520-6149. - 9781665405409 ; 2022-May, s. 5393-5397
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Konferensbidrag (refereegranskat)abstract
- Cell-free massive multiple-input multiple-output (MIMO) consists of a large set of distributed access points (APs) serving a number of users. The APs can be far from each other, and they can also have a big number of antennas. Thus, decentralized architectures have to be considered so as to reduce the interconnection bandwidth to a central processing unit (CPU) and make the system scalable. On the other hand, the APs in a heterogeneous network might have limited processing capabilities and fully-decentralized processing may not be available. In a recent paper, a trade-off between level of decentralization and decentralized processing complexity has been identified. Furthermore, a novel matrix decomposition - the WAX decomposition - which, if applicable to the channel matrix, allows for exploitation of said trade-off without loss of information. The results on WAX decomposition are only available for random channel matrices without specific structures, while in a cell-free massive MIMO scenario the channel can have sparse structures. In this work, we study the applicability of WAX decomposition to cell-free massive MIMO with its implications to the above-mentioned trade-off.
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| 9. |
- Alegría, Juan Vidal, et al.
(författare)
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Modular binary tree architecture for distributed large intelligent surface
- 2021
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Ingår i: International Conference on Acoustics, Speech, and Signal Processing (ICASSP). - 1520-6149. - 9781728176055 - 9781728176062 ; 2021-June, s. 4865-4869
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Konferensbidrag (refereegranskat)abstract
- Large intelligent surface (LIS) is a technology that extends massive MIMO by considering an even greater number of antennas distributed throughout vast areas. In order to be able to implement this technology, it is crucial to consider decentralized architectures so as to make the whole system scalable. We consider a LIS divided into several LIS panels of smaller size, which can be located far away from each other. We present a modular architecture that allows combining different LIS panels using a binary tree. This architecture is also valid in a cell-free massive MIMO scenario. We make use of a newly defined matrix decomposition, the WAX decomposition, to define the modules that are used within our architecture. We also study the lossless dimensionality reduction in the data to be processed, which can be achieved using our proposed architecture.
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| 10. |
- Axell, Erik, et al.
(författare)
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Spectrum Sensing of Orthogonal Space-Time Block Coded Signals with Multiple Receive Antennas
- 2010
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Ingår i: Proceedings of the IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781424442959 - 9781424442966 ; , s. 3110-3113
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We consider detection of signals encoded with orthogonal space-time block codes (OSTBC), using multiple receive antennas. Such signals contain redundancy and they have a specific structure, that can be exploited for detection. We derive the optimal detector, in the Neyman-Pearson sense, when all parameters are known. We also consider unknown noise variance, signal variance and channel coefficients. We propose a number of GLRT based detectors for the different cases, that exploit the redundancy structure of the OSTBC signal. We also propose an eigenvalue-based detector for the case when all parameters are unknown. The proposed detectors are compared to the energy detector. We show that when only the noise variance is known, there is no gain in exploiting the structure of the OSTBC. However, when the noise variance is unknown there can be a significant gain.
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