| 41. |
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| 42. |
- Mecklenbräuker, Christoph F., et al.
(författare)
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Eigenbeam transmission over line-of-sight MIMO channels for fixed microwave links
- 2011
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Ingår i: Proceedings - ITG/IEEE Workshop on Smart Antennas (WSA). - 9781612840741
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Konferensbidrag (refereegranskat)abstract
- We propose and analyze eigenbeam transmission over line-of-sight (LOS) multiple-input multiple-output (MIMO) channels with linear reception. In particular, we consider fixed point-to-point microwave links for which the singular value decomposition of the LOS MIMO channel matrix is analytically derived. We demonstrate that the Tx eigenbeams can be defined without channel state information at the transmitter and that the beams admit an insightful physical interpretation. We also evaluate the performance of a lattice-reduction aided linear receiver through numerical simulations.
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| 43. |
- Moebus, Marco, et al.
(författare)
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Parameterization of Acoustic Signatures in Ultrasound Images for the Detection of Human Presence by Autonomous Vehicles
- 2010
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Ingår i: Proceedings of ICASSP 2010.
-
Konferensbidrag (refereegranskat)abstract
- We address the problem of human detection for autonomousvehicles. Instead of using an optical system, we propose toemploy an acoustic 2D array to reliably obtain an image of ahuman in a 3D spatial power spectrum which is independentof lighting conditions and uses cheap ultrasound sensors.We show that humans have a distinct acoustic signature andpropose to model the echoes from reflecting parts of objectsin the scene by a Gaussian-Mixture-Model. When the model is fitted to the acoustic image, it is straightforward toobtain geometric relations between the present echoes andrepresent 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 obtainedparameter space can then be the basis for subsequent detection and classification of humans.
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| 44. |
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| 45. |
- Ngia, Lester S.H. 1965, et al.
(författare)
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Adaptive neural nets filter using a recursive Levenberg-Marquardt search direction
- 1998
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Ingår i: Proc. Asilomar Conf. Signals, Systems, Computers, 01 Nov 1998-04 Nov 1998. ; 1, s. 697-701
-
Konferensbidrag (refereegranskat)abstract
- This paper proposes a recursive Levenberg-Marquardt (LM) search direction as the training algorithm for non-linear adaptive filters, which use multi-layer feed forward neural nets as the filter structures. The neural nets can be considered as a class of non-linear adaptive filters with transversal or recursive filter structures. In the off-line training, the LM method is regarded as an intermediate method between the steepest descent (SD) and Gauss-Newton (GN) methods, and it has better convergence properties than the other two methods. In the echo cancellation experiments, the recursive LM algorithm converges faster and gives higher echo return loss enhancement (ERLE) than the recursive SD and GN algorithms.
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| 46. |
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| 47. |
- Ozcelikkale, Ayca, 1982, et al.
(författare)
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MIMO Linear Precoder Design with Non-Ideal Transmitters
- 2015
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Ingår i: Proceedings of the International Symposium on Wireless Communication Systems. - 2154-0217 .- 2154-0225. ; , s. 681-685
-
Konferensbidrag (refereegranskat)abstract
- We investigate the linear precoder design problem for multiple-input multiple-output (MIMO) channels under non-ideal transmitter hardware.We consider two different non-ideal hardware models: i) an additive noise model in which the level of the noise at an antenna is proportional to the signal power at that antenna, ii) an additive precoder error model. We focus on the problem of minimizing mean-square error at the receiver under transmit power constraints at the transmitter. For the first hardware impairment model, this scenario leads to a non-convex formulation for which we propose a block-coordinate descent technique. The proposed method has a convergence guarantee and provides rank-constrained solutions.For the second model, analytical expressions for the optimum designs are provided. We compare the performance of our hardware impairment aware designs with that of designs developed with ideal hardware assumptions. Our results suggest that significant gains can be obtained by the proposed designs for sufficiently high signal-to-noise ratio values.
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| 48. |
- Ozcelikkale, Ayca, 1982, et al.
(författare)
-
Performance Bounds for Remote Estimation with an Energy Harvesting Sensor
- 2016
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Ingår i: IEEE International Symposium on Information Theory - Proceedings. - 2157-8095. - 9781509018062 ; 2016-August, s. 460-464
-
Konferensbidrag (refereegranskat)abstract
- Remote estimation with an energy harvesting sensor with a limited data buffer is considered. The sensor node observes an unknown correlated circularly wide-sense stationary (c.w.s.s.) Gaussian field and communicates its observations to a remote fusion center using the energy it harvested. The fusion center employs minimum mean-square error (MMSE) estimation to reconstruct the unknown field. The distortion minimization problem under the online scheme, where the sensor has only access to the statistical information for the future energy packets is considered. We provide performance bounds on the achievable distortion under a slotted block transmission scheme, where at each transmission time slot, the data and the energy buffer is completely emptied. Our bounds provide insight to the trade-off between the buffer sizes and the achievable distortion. These trade-offs illustrate the insensitivity of the performance to the buffer size for signals with low degree of freedom and suggest performance improvements with increasing buffer size for signals with relatively higher degree of freedom.
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| 49. |
- Ozcelikkale, Ayca, 1982, et al.
(författare)
-
Simultaneous Information and Power Transfer with Transmitters with Hardware Impairments
- 2016
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Ingår i: Proceedings of the International Symposium on Wireless Communication Systems. - 2154-0217 .- 2154-0225. - 9781509020614 ; 2016-October, s. 114-118
-
Konferensbidrag (refereegranskat)abstract
- We investigate the performance of a communication system with simultaneous wireless information and power transfer capabilities under non-ideal transmitter hardware. We adopt an experimentally validated additive noise model in which the level of the noise at an antenna is proportional to the signal power at that antenna. We consider the linear precoder design problem and focus on the problem of minimizing the mean-square error under energy harvesting constraints. This set-up, in general, constitutes a non-convex formulation. For the single antenna information user case, we provide a tight convex relaxation, i.e. a convex formulation from which an optimal solution for the original problem can be constructed. For the general case, we propose a block coordinate descent technique to solve the resulting non-convex problem. Our numerical results illustrate the effect of hardware impairments on the system.
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| 50. |
- Ozcelikkale, Ayca, 1982, et al.
(författare)
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Transmission Strategies for Remote Estimation under Energy Harvesting Constraints
- 2016
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Ingår i: European Signal Processing Conference. - 2219-5491. - 9780992862657 ; , s. 572-576
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Konferensbidrag (refereegranskat)abstract
- We consider the remote estimation of a time- correlated field using an energy harvesting (EH) sensor. The sensor observes the unknown field and communicates its observa- tions to a remote fusion center using an amplify-forward strategy. We consider the design of optimal transmission strategies in order to minimize the mean-square error (MSE) at the fusion center. Contrary to traditional approaches, the degree of correlation between the field values constitutes an important aspect of our formulation. We provide the optimal power allocation strategies for a number of illustrative scenarios, including the circularly wide-sense stationary (c.w.s.s.) signals with static correlation coefficient and the sampled low-pass c.w.s.s. signals. Based on these results, we propose low-complexity policies for the general case. Numerical evaluations illustrate the performance of the optimal and the low-complexity policies.
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