| 1. |
- Johansson, Eija, 1982, et al.
(författare)
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Interpolation based on stationary and adaptive AR(1) modeling
- 2011
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Ingår i: ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings. - 1520-6149. - 9781457705397 ; , s. 4052-4055
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Konferensbidrag (refereegranskat)abstract
- In this paper, we describe a minimal mean square error (MMSE) optimal interpolation filter for discrete random signals. We explicitly derive the interpolation filter for a first-order autoregressive process (AR(1)), and show that the filter depends only on the two adjacent points. The result is extended by developing an algorithm called local AR approximation (LARA), where a random signal is locally estimated as an AR(1) process. Experimental evaluation illustrates that LARA interpolation yields a lower mean square error than other common interpolation techniques, including linear, spline and local polynomial approximation (LPA).
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| 2. |
- Panahi, Ashkan, 1986, et al.
(författare)
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Basis pursuit over continuum applied to range-Doppler estimation problem
- 2014
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Ingår i: Proceedings of the IEEE Sensor Array and Multichannel Signal Processing Workshop. - 2151-870X. - 9781479914814 ; , s. 381-384
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Konferensbidrag (refereegranskat)abstract
- Sparse estimation and compressive sensing techniques have been recently considered for radar estimation problems. It is frequently observed that these methods are robust to model uncertainties and substantially improve performance in scenarios with a low signal-to-noise. However, since current sparsity-based techniques are computationally costly and require a suitable discretization (grid), which strongly restricts resolution, they practically receive less attention. In this work, we present an application of a new sparsity-based technique to the specific problem of range-Doppler estimation. The method, generalizing basis pursuit, is less computationally complex and its performance is independent of the grid selection. We demonstrate that the proposed technique can improve estimation performance in difficult cases, as compared to the SAGE technique.
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| 3. |
- Panahi, Ashkan, 1986, et al.
(författare)
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Wideband waveform design for robust target detection
- 2015
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Ingår i: ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings. - 1520-6149. - 9781467369978 ; 2015-August, s. 3926-3930
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Konferensbidrag (refereegranskat)abstract
- © 2015 IEEE. Future radar systems are expected to use waveforms of a high bandwidth, with an advantage of an improved range resolution. Herein, a technique to design robust wideband waveforms is developed. The context is detection of a single object with partially unknown parameters. The technique achieves an optimal detection speed for a desired resolution, maintaining a high detection performance. Many radar systems also require fast adaptation to a variable environment. Hence, the technique is devoted to rapidly design waveforms. In terms of probabilities of detection and false alarm, numerical evaluation shows the efficiency of the method when compared with a chirp signal and a Gaussian pulse.
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| 4. |
- Ström, Marie, 1984, et al.
(författare)
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Low PAPR waveform synthesis with application to wideband MIMO radar
- 2011
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Ingår i: Computational Advances in Multi-Sensor Adaptive Processing (CAMSAP), 2011 4th IEEE International Workshop on. - 9781457721052 ; , s. 5-8
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Konferensbidrag (refereegranskat)abstract
- This paper considers the problem of waveform synthesis given a desired power spectrum. The properties of the designed waveforms are such that the overall system performance is increased. The metric used to evaluate the optimality of the synthesized time domain signals is the peak-to-average power ratio (PAPR). We discuss how to synthesize waveforms using the technique of partial transmit sequence (PTS). The key point is that the gradient can explicitly be derived from the objective function. Furthermore, the result is extended by allowing the power spectrum to deviate from its original shape, yielding a further reduction in the PAPR. The method is applied to derived power spectra for wideband multiple-input-multiple-output (MIMO) radar. It is shown that the proposed technique can achieve optimal or near optimal performance with PAPR below 0.5 dB.
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| 5. |
- Ström, Marie, 1984, et al.
(författare)
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Robust transceiver design for wideband MIMO radar utilizing a subarray antenna structure
- 2013
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Ingår i: Signal Processing. - : Elsevier BV. - 0165-1684. ; 93:12, s. 3541-3552
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we investigate the possibility to suppress interference in wideband multiple-input multiple-output radar. The idea is to employ tunable filters at the transmitter and the receiver sides, and to derive filter coefficients that result in optimal transmitted signals from a system performance point of view, for a given radar scenario. The system performance is measured in signal-to-interference-and-noise ratio (SINR) at the receiver output, from which the filter properties are derived. The focus is to suppress active jamming interference, and especially deceptive jamming interference. We discuss two ways to derive the transmit and the receive filters. Each procedure utilizes two different power constraints related to the transmit filters. To incorporate imperfections in the given scenario, a robust extension to the design problem is proposed. Two different robust methods are evaluated: one that utilizes a Taylor series expansion of the SINR, and one that exploits a worst-case SINR maximization. Numerical validation illustrates the possibility to suppress interference without actually forming a spatial null in the direction towards interference, and the necessity to design transmit filters that are robust to uncertainties in the given scenario. (C) 2013 Elsevier B.V. All rights reserved.
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| 6. |
- Ström, Marie, 1984, et al.
(författare)
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Transmit and receive filter optimization for wideband MIMO radar
- 2011
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Ingår i: Computational Advances in Multi-Sensor Adaptive Processing (CAMSAP), 2011 4th IEEE International Workshop on. - 9781457721052 ; , s. 9-12
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Konferensbidrag (refereegranskat)abstract
- In this paper, we discuss the possibility to suppress interference for wideband multiple-input-multiple-output (MIMO) radar, using only the temporal properties of the signals. The idea is to use tunable filters each connected to a wideband waveform generator, and to derive the optimal power spectral density (PSD) of the resulting signals in a known environment. The metric used to evaluate the enhancement in the system performance is the signal-to-noise and interference ratio (SNIR), from which the optimal transmit and receive filter properties are derived. We discuss two optimization approaches: one alternating and one joint algorithm. Each method is separated into two cases: for a total power constraint and for an individual power constraint on the transmit filters, respectively. Numerical validation illustrates the possibility to suppress the interference in the temporal domain, without actually forming a spatial null in the direction of the interference.
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| 7. |
- Ström, Marie, 1984, et al.
(författare)
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Wideband Waveform and Receiver Filter Bank Design for Clutter Suppression
- 2015
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Ingår i: IEEE Journal on Selected Topics in Signal Processing. - : Institute of Electrical and Electronics Engineers (IEEE). - 1941-0484 .- 1932-4553. ; 9:8, s. 1366-1376
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Tidskriftsartikel (refereegranskat)abstract
- Modern wideband radar systems with long integration time, equipped with arbitrarily waveform generators, raise a demand for advanced signaling transmission schemes. In this paper, we propose two algorithms to select transmit waveforms and receiver filters. The techniques are based on a clutter suppression criterion. For the first algorithm, we employ an optimized filter bank, and for the second algorithm, we use a matched filter bank. Clutter suppression is achieved by minimizing the correlation between receiver filters and interfering clutter echoes. The algorithm, for the optimized filter bank, is extended to adapt the transmission scheme and receiver filters to a time-evolving scenario. Adaptation parameters are based on estimates of a clutter map and detected target characteristics. To estimate the clutter map we propose a Kalman filter, whereas target parameters are calculated using a least-squares fit to data. The efficiency of the algorithms and the adaptation scheme are visualized through a numerical simulation.
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| 8. |
- Ström, Marie, 1984, et al.
(författare)
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Wideband waveform design for clutter suppression
- 2014
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Ingår i: Proceedings of the IEEE Sensor Array and Multichannel Signal Processing Workshop. - 2151-870X. - 9781479914814 ; :Art. no. 6882399, s. 297-300
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Konferensbidrag (refereegranskat)abstract
- Modern signal generators offer the capability to synthesize arbitrary wideband waveforms for radar and sonar applications. This makes it possible to optimize signals for specific purposes or scenarios. Herein, we discuss how to design a wideband waveform for clutter suppression. We formulate an optimization in terms of mainlobe and sidelobe properties of the ambiguity function, then we provide an approximate solution based on convex relaxation. Numerical evaluation shows the advantage of selecting a smart signal compared to a conventional waveform design. The advantages are shown as a lower probability of false alarm and a higher probability of correct target detection.
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