Further Study on Robust Adaptive Beamforming With Optimum Diagonal Loading

Elnashar, Ayman; Elnoubi, S.; El-Mikati, H.A.

doi:10.1109/tap.2006.886473

Cited by 154 publications

(72 citation statements)

References 26 publications

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“…Although method to compute the optimal weight vector, and the second-order cone (SOC) programming-based approach is used to solve the original problem. Ayman Elnashar et al make use of the diagonal loading technique to implement the robust beamformer [24], but the optimal value of diagonal loading level is not solved exactly, alternatively, the diagonal loading technique is integrated into the adaptive update schemes by means of optimum variable loading technique. R. G. Lorenz and S. P. Boyd also solve the similar beamformer by the Lagrange multiplier techniques [23], but they express the weight vector and the array manifold as the direct sum of the corresponding real and imaginary components.…”

Section: Robust Approaches For Signal Direction Mismatchmentioning

confidence: 99%

Robust Beamforming and DOA Estimation

Liu¹

2012

Fourier Transform Applications

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Section: Robust Approaches For Signal Direction Mismatchmentioning

confidence: 99%

Robust Beamforming and DOA Estimation

Liu¹

2012

Fourier Transform Applications

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“…The effect of MC is taken into account by using a distortion matrix model [8][9][10][11][12][13][14]. According to this model, we insert a mutual coupling matrix (MCM) C in the data model for the received signal as follows:…”

Section: Performance Analyses Of Array Beamformers With MC Effectsmentioning

confidence: 99%

“…However, some uncertainties in the spatial information result in a mismatch between the steering vector and the direction vector of the desired signal. Many results have been reported on how to improve the performance of the steered beam beamformers against the mismatch [3][4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

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Performance Analysis of Antenna Array Beamformers With Mutual Coupling Effects

Lee

Chen²

2011

PIER B

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Abstract-Antenna array beamformers suffer from performance deterioration in the presence of mutual coupling (MC) between array sensors. In this paper, we present a theoretical analysis in terms of the output signal-to-interference-plus-noise ratio (SINR) for the performance of antenna array beamformers under MC effects. Based on the model of a distortion matrix to encapsulate the MC effects, a closed-form expression for the SINR is derived that is shown to accurately predict the SINR obtained in simulations. This theoretical formula is valid for any distortion matrix estimated from collected measurement data. The SINR formulas provide insights into the influence of the MC effects on the performances of the linearly constrained minimum variance (LCMV) beamformer and the eigenspace-based (ESB) beamformer. It is shown that the ESB beamformer outperforms the LCMV beamformer under MC effects. Moreover, we derive the formulas for computing the eigenvalues of signal correlation matrix under MC effects. Simulation results are presented for confirming the validity of the theoretical results.

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“…Another effective diagonal loading technique [26] has been the widely used approach of enhancing robustness against mismatch errors and correlated noise. The main drawback of this method is that there is uncertainty as to how to precisely choose the optimal value of the diagonal loading factor [27]. In [28], Wang et al utilize a blind variablediagonal loading (VDL) multiuser detector, based on the concept of optimizing the worst-case performance over properly chosen bounded uncertainty sets that are determined by a bounding probability, to provide further robustness against small-to-medium prior signal modeling errors in MC-CDMA systems.…”

Section: Introductionmentioning

confidence: 99%

Blind ICA detection based on second-order cone programming for MC-CDMA systems

Jen

Jou

2014

EURASIP J. Adv. Signal Process.

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The multicarrier code division multiple access (MC-CDMA) technique has received considerable interest for its potential application to future wireless communication systems due to its high data rate. A common problem regarding the blind multiuser detectors used in MC-CDMA systems is that they are extremely sensitive to the complex channel environment. Besides, the perturbation of colored noise may negatively affect the performance of the system. In this paper, a new coherent detection method will be proposed, which utilizes the modified fast independent component analysis (FastICA) algorithm, based on approximate negentropy maximization that is subject to the second-order cone programming (SOCP) constraint. The aim of the proposed coherent detection is to provide robustness against small-to-medium channel estimation mismatch (CEM) that may arise from channel frequency response estimation error in the MC-CDMA system, which is modulated by downlink binary phase-shift keying (BPSK) under colored noise. Noncoherent demodulation schemes are preferable to coherent demodulation schemes, as the latter are difficult to implement over time-varying fading channels. Differential phase-shift keying (DPSK) is therefore the natural choice for an alternative modulation scheme. Furthermore, the new blind differential SOCP-based ICA (SOCP-ICA) detection without channel estimation and compensation will be proposed to combat Doppler spread caused by time-varying fading channels in the DPSK-modulated MC-CDMA system under colored noise. In this paper, numerical simulations are used to illustrate the robustness of the proposed blind coherent SOCP-ICA detector against small-to-medium CEM and to emphasize the advantage of the blind differential SOCP-ICA detector in overcoming Doppler spread.

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Further Study on Robust Adaptive Beamforming With Optimum Diagonal Loading

Cited by 154 publications

References 26 publications

Robust Beamforming and DOA Estimation

Robust Beamforming and DOA Estimation

Performance Analysis of Antenna Array Beamformers With Mutual Coupling Effects

Blind ICA detection based on second-order cone programming for MC-CDMA systems

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