Topic
Adaptive beamformer
About: Adaptive beamformer is a research topic. Over the lifetime, 4934 publications have been published within this topic receiving 93100 citations.
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TL;DR: A new beamspace (BS) based on discrete cosine transform is proposed in which the medical ultrasound signals can be represented with less dimensions compared with the standard BS, and the results indicated that by keeping only two beams, the MVB in the proposed BS provides very similar resolution and also better contrast compared to the standard MVB (SMVB).
Abstract: Minimum variance beamformer (MVB) increases the resolution and contrast of medical ultrasound imaging compared with nonadaptive beamformers. These advantages come at the expense of high computational complexity that prevents this adaptive beamformer to be applied in a real-time imaging system. A new beamspace (BS) based on discrete cosine transform is proposed in which the medical ultrasound signals can be represented with less dimensions compared with the standard BS. This is because of symmetric beampattern of the beams in the proposed BS compared with the asymmetric ones in the standard BS. This lets us decrease the dimensions of data to two, so a high complex algorithm, such as the MVB, can be applied faster in this BS. The results indicated that by keeping only two beams, the MVB in the proposed BS provides very similar resolution and also better contrast compared with the standard MVB (SMVB) with only 0.44% of needed flops. Also, this beamformer is more robust against sound speed estimation errors than the SMVB.
32 citations
TL;DR: Genetic algorithm optimization method is used in this paper for the synthesis of antenna array radiation pattern in adaptive beamforming and proved its effectiveness in improving the performance of the antenna array.
Abstract: Genetic algorithm optimization method is used in this paper for the synthesis of antenna array radiation pattern in adaptive beamforming. The synthesis problem in this paper discussed is to finding the weights of the antenna array elements that are optimum to provide the radiation pattern with maximum reduction in the sidelobe level. This technique proved its effectiveness in improving the performance of the antenna array.
32 citations
Patent•
09 Feb 2009TL;DR: In this paper, the authors describe a system for transmitting signals between a transmitter and a receiver by differentially estimating channel coefficients for each of the antenna elements relative to a reference antenna element, determining beam weights to remove oscillator induced phase or offset, and applying a correction (beamforming solution) at the transmitter to make the received signal from different antenna elements to be coherently combined at the receiver.
Abstract: Systems and methods are disclosed for transmitting signals between a transmitter and a receiver by differentially estimating channel coefficients for each of the antenna elements relative to a reference antenna element; determining beam weights to remove oscillator induced phase or offset; and applying a correction (beamforming solution) at the transmitter to make the phase of the received signal from different antenna elements to be coherently combined at the receiver.
32 citations
TL;DR: The mean and variance of the complex and real and imaginary part of the averaged monopulse ratio is derived for all Swerling target models, deterministic targets, and for an arbitrary number of noncoherent averaging of time snapshots.
Abstract: Monopulse is an established array processing technique for fast and accurate angle estimation. This technique has been generalized to space-time array processing of any dimension. The statistical performance of this generalized monopulse parameter estimation has been characterized for several target fluctuation models but not for all cases. This gap is filled by this paper. We derive the mean and variance of the complex and real and imaginary part of the averaged monopulse ratio for all Swerling target models, deterministic targets (Swerling 0 case), χ2 distributed targets with 4 degrees of freedom (Swerling 3 or 4 case) including a given detection threshold, for an arbitrary number of difference beams, and for an arbitrary number of noncoherent averaging of time snapshots. For completeness we give also the already known results for Rayleigh targets (Swerling 1 or 2 case) in the same notation. From these means and variances, the performance of all kinds of parameter estimates with the generalized monopulse formula can be calculated. Applications of these statistical descriptions are presented for planar arrays and adaptive beamforming and for space-time adaptive processing (STAP) for broadband interference suppression. From these examples some interesting conclusions can be drawn.
32 citations
01 Jan 1999
TL;DR: A maximum likelihood formulation of multiuser detection with antenna arrays is introduced to provide motivation and intuition and the proposedMultiuser receiver incorporates space-time beamforming and time-domain interference cancellation.
Abstract: In CDMA systems, multiple users produce cochannel interference that is only partially mitigated by user-dependent spreading codes. Limitations in any closed-loop transmitter power control can create received power variations at the base station that are potentially large. Multichannel multiuser detectors are data-adaptive receivers that provide interference mitigation as well as spatial and temporal diversity. These receivers are discussed in the context of CDMA applications. A maximum likelihood formulation of multiuser detection with antenna arrays is introduced to provide motivation and intuition. The proposed multiuser receiver incorporates space-time beamforming and time-domain interference cancellation. Performance examples using simulated and experimental data are given along with comparisons with a variety of receiver types.
32 citations