| 1. |
- Asztély, David, et al.
(författare)
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A Generalized Array Manifold Model for Local Scattering in Wireless Communications
- 1997
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Ingår i: Proceedings of IEEE International Conference on Acoustics, Speech, and Signal Processing. ICASSP-97. - : IEEE. ; , s. 4021-4024
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Konferensbidrag (refereegranskat)abstract
- In wireless communication scenarios, local scatterers in the vicinity of the mobile sources cause angular spreading. As a result, the spatial signatures will not belong to the conventional array manifold parameterized by direction of arrival (DOA) alone. A parameterized model for spatial signatures applicable in scenarios with localscattering is presented. Several algorithms that exploit this model are proposed, and the performance of signal waveform estimators using the model is investigated via simulations. It is demonstrated that considerable gain may result as compared with using the conventional plane wave model.
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| 2. |
- Asztély, David, et al.
(författare)
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Auto Calibration for Signal Separation with Uniform Linear Arrays
- 1997
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Konferensbidrag (refereegranskat)abstract
- In this paper, the problem of signal waveform estimation using a uniform linear array with unknown receiver gain and phase responses is considered. As is well known, it is not possible to uniquely estimate directions-of-arrival(DOAs) and receiver gain and phase simultaneously. For steering vector and signal separation this ambiguity is notcritical. An ESPRIT-like solution is presented, and the proposed method is examined on data collected with an antenna array in a suburban environment.
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| 3. |
- El-Jaby, S., et al.
(författare)
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ISSCREM: International Space Station cosmic radiation exposure model
- 2013
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Ingår i: IEEE Aerospace Conference Proceedings. - 1095-323X. - 9781467318112
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Konferensbidrag (refereegranskat)abstract
- A semi-empirical model is derived from operational data collected aboard the International Space Station (ISS) with the U.S. tissue equivalent proportional counter (TEPC). The model provides daily and cumulative mission predictions of the operational dose equivalent that space-crew may receive from galactic cosmic radiation (GCR) and trapped radiation (TR) sources as a function of the ISS orbit. The parametric model for GCR exposure correlates the TEPC dose equivalent rate to the cutoff rigidity at ISS altitudes while the TR parametric model relates this quantity to the mean atmospheric density at the crossing of the South Atlantic Anomaly (SAA). The influences of solar activity, flux asymmetry inside the SAA, detector orientation, and position aboard the ISS on the dose equivalent have been examined. The model has been successfully benchmarked against measured data for GCR and TR exposures to within ±10% and ±20%, respectively, over periods of time ranging from a single day to a full mission. In addition, preliminary estimates of the protection quantity of effective dose equivalent have been simulated using the PHITS Monte Carlo transport code. These simulations indicate that the TEPC dose equivalent is a conservative estimate of the effective dose equivalent.
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| 4. |
- Jansson, Magnus, et al.
(författare)
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Robust Weighted Subspace Fitting in the Presence of Array Model Errors
- 1998
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Ingår i: Proceedings IEEE International Conference on Acoustics, Speech, and Signal Processing. - : IEEE. ; , s. 1961-1964
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Konferensbidrag (refereegranskat)abstract
- Model error sensitivity is an issue common to all high resolution direction of arrival estimators. Much attention has been directed to the design of algorithms for minimum variance estimation taking only finite sample errors into account. Approaches to reduce the sensitivity due to array calibration errors have also appeared in the literature. Herein, a weighted subspace fitting method for a wide class of array perturbation models is derived. This method provides minimum variance estimates under the assumption that the prior distribution of the perturbation model is known. Interestingly enough, the method reduces to the WSF (MODE) estimator if no model errors are present. On the other hand, when model errors dominate, the proposed method turns out to be equivalent to the “model-errors-only subspace fitting method”. Unlike previous techniques for model errors, the estimator can be implemented using a two-step procedure if the nominal array is uniform and linear, and it is also consistent even if the signals are fully correlated.
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| 5. |
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| 7. |
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| 8. |
- Swindlehurst, Andrew Lee, et al.
(författare)
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Application of MUSIC to Arrays with Multiple Invariances
- 2000
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Ingår i: Proceedings IEEE International Conference on Acoustics, Speech, and Signal Processing. - : IEEE. ; , s. 3057-3060
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Konferensbidrag (refereegranskat)abstract
- This paper describes generalizations of the MUSIC and root-MUSIC algorithms for direction of arrival (DOA) estimation to arrays composed of multiple translated subarrays. The advantage of these new approaches is that the DOAs can be estimated using either a one-dimensional search or by rooting a polynomial, as opposed to a multidimensional search as required by the multiple invariance (MI)-ESPRIT algorithm. While MI-MUSIC and root-MI-MUSIC are not statistically efficient like MI-ESPRIT, they do perform better than a single invariance implementation of ESPRIT, and are thus better suited for finding the initial conditions required by the MI-ESPRIT search.
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| 9. |
- Swindlehurst, Andrew Lee, et al.
(författare)
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Some Experiments with Array Data Collected in Actual Urban and Suburban Environments
- 1997
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Ingår i: Proceedings of Signal Processing Advances in Wireless Communications, SPAWC 97. - : IEEE. ; , s. 301-304
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Konferensbidrag (refereegranskat)abstract
- We compare the performance of several algorithms for signal separation based on actual mobile cellular radiodata. The data were collected by base stations in two different environments: using an eight element lineararray on a hillside overlooking a suburban area, and using a four element square array at the top of a ten story building in a dense urban area. Calibration data were available for one of the arrays used for the suburban data, allowing for performance comparisons between DOA-based and blind signal separators. Experiments were conducted with three different types of signal waveforms: sinewaves, simple FM waveforms, and π/4-DQPSK signals, each of which necessitated the use of a different performance metric. We focus on the results obtained for cases where the data were approximately low rank, with little delay spread (although not all data sets from the urban environment were of this type)
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