Generalized Sidelobe Canceller Research Articles

Minimum Mutual Information-Based Linearly Constrained Broadband Signal Extraction

In this contribution, the problem of broadband acoustic signal extraction is treated as a specific source separation problem, where the desired signal components are to be separated from all remaining undesired components. For this, we exploit the generic TRIple-N Independent component analysis for CONvolutive mixtures (TRINICON) framework. The TRINICON optimization criterion is complemented with linear constraints leading to the Linearly Constrained Minimum Mutual Information (LCMMI) criterion for desired signal extraction. A general linearly constrained update rule for iterative filter optimization is derived, which can efficiently be realized in a novel Minimum Mutual Information (MMI)-Generalized Sidelobe Canceler (GSC). The general treatment of the signal extraction problem using an MMI criterion provides several advantages: Firstly, new insights into the signal extraction problem can be derived by establishing links to both the original GSC and the Multichannel Wiener Filter (MWF). Secondly, by exploiting fundamental properties characteristic for speech and audio signals, complicated and often unreliable Voice Activity Detection (VAD)-based control mechanisms become unnecessary. Thirdly, the overall realization requires only prior information of the desired source position. An evaluation of the MMI-GSC for the double-talk situation with two concurrently active speech sources under reverberant and noisy conditions demonstrates the effectiveness of this novel approach.

Adaptive set membership constant modulus algorithm with a generalized sidelobe canceler based on dynamic bounds for beamforming

In this study, we propose an adaptive set membership constant modulus (SM-CM) algorithm with a generalized sidelobe canceler (GSC) structure for blind beamforming. We develop a stochastic gradient (SG) type algorithm based on the concept of SM filtering to facilitate an adaptive implementation. The filter weights are updated only if the constraint cannot be satisfied. In addition, we also propose an extension of two schemes of time-varying bounds for beamforming with a GSC structure where we incorporate parameter and interference dependency to characterize the environment, which improves the tracking performance of the proposed algorithm in dynamic scenarios. A convergence analysis of the proposed adaptive SM filtering technique was performed. The simulation results showed that the proposed adaptive SM-CM-GSC algorithm with dynamic bounds delivered superior performance compared with previously reported methods and at a reduced update rate.

Blind RLS-Based Detection Using GSC with DF for STBC MC-CDMA Systems Under Mismatched Channel Estimation

Under Rayleigh fading channels, a common problem with blind multiuser space-time block coded (STBC) multicarrier code division multiple access (MC-CDMA) detectors is that their performance is very sensitive to the signature waveform mismatch (SWM) induced by channel estimation distortion. This paper presents a robust detector using the generalized sidelobe canceller with a double-feedback filter that effectively mitigates the channel estimation distortion for the STBC MC-CDMA system during multipath fading. Numerical simulations show that the proposed detector substantially provides robustness against small-to-medium SWM scenarios for a downlink STBC MC-CDMA system.

Application of Generalized Sidelobe Canceller and Sparse Array in Relieving Congestion in Multi-beam CDMA Systems

During operation of a cellular system, unexpected growth of traffic may develop in various regions, create traffic congestion. Among many methods to solve problem of large blocking probability, dynamic cell sectoring using smart array antenna is specially interested. In this paper, we investigate the relationship between antenna parameters (main beamwidth, sidelobe attenuation...) and blocking probability of multibeam CDMA system under the presence of hotbeam. From that, we consider deployment sectoring dynamically based on Generalized Sidelobe Canceller (GSC) structure to get blocking probability below 1%. In addition, we consider the way to decrease the complexity of array antenna using sparse array.

The Generalized Sidelobe Canceller Based on Quaternion Widely Linear Processing

We investigate the problem of quaternion beamforming based on widely linear processing. First, a quaternion model of linear symmetric array with two-component electromagnetic (EM) vector sensors is presented. Based on array's quaternion model, we propose the general expression of a quaternion semiwidely linear (QSWL) beamformer. Unlike the complex widely linear beamformer, the QSWL beamformer is based on the simultaneous operation on the quaternion vector, which is composed of two jointly proper complex vectors, and its involution counterpart. Second, we propose a useful implementation of QSWL beamformer, that is, QSWL generalized sidelobe canceller (GSC), and derive the simple expressions of the weight vectors. The QSWL GSC consists of two-stage beamformers. By designing the weight vectors of two-stage beamformers, the interference is completely canceled in the output of QSWL GSC and the desired signal is not distorted. We derive the array's gain expression and analyze the performance of the QSWL GSC in the presence of one type of interference. The advantage of QSWL GSC is that the main beam can always point to the desired signal's direction and the robustness to DOA mismatch is improved. Finally, simulations are used to verify the performance of the proposed QSWL GSC.

Adaptive Beamforming Method for Turning Towed Line Array SONAR

수중의 음향 신호를 탐지하기 위하여 다양한 배열 형태를 가지는 소나가 개발되어 왔으며, 그 중 하나로 견인선배열 소나가 널리 사용된다. 견인 선배열 소나는 매우 긴 형태의 배열을 사용하므로, 회전에 의한 형상 왜곡에 의해 성능이 저하되는 단점이 있다. 이를 해결하기 위하여 회전하는 견인 선배열 소나에 대한 포물선 형태의 형상 모델을 이용하는 기법이 고안되었다. 본 논문에서는 포물선 모델을 이용하여 간섭 신호를 제거하는 적응 빔 형성기 설계 기법을 제안한다. 고안된 빔형성기 시스템은 일반화된 부엽 제거기 구조와 자가 조율 시스템에 기반을 두어 개발되었다. In order to detect underwater acoustic signals, various SONAR array types have been developed, including towed line array SONAR system (TASS). However, the TASS suffers from performance degradation which is caused by aperture deformation during a turn, because the TASS have a long-aperture array. A parabolic array model for turning TASS have been developed to solve the degradation problem occurred during a turn. In this paper, adaptive beamforming system is developed using the parabolic TASS model to cancel interference signals. The developed beamforming system is based on generalized sidelobe canceller (GSC) structure and self-tuning adaptive algorithm.

A new robust adaptive beamforming and the one-dimensional search strategy

Adaptive beamforming methods will be degraded sharply in the presence of steering vector errors. The design methods of robust adaptive beamforming become more flexible when the convex optimization technique is used. However, this leads to high computational-complexity and more difficulties for engineering applications. To solve these problems, a robust adaptive beamforming based on the least square estimation is proposed, and a laconic solution method using one-dimensional search is derived. The standard Capon beamformer (SCB) is converted to a robust least-square problem based on the principle of generalized sidelobe canceller, and is then changed into a problem of second-order program. In order to reduce the amount of computation, a one-dimensional search method is deduced using the relationship between the primal and dual problems of second-order program, and Newton iteration method is adopted to obtain the optimal solution. The computational complexity of the proposed algorithm is in the same order of magnitude as that of the SCB. Simulation results demonstrate the robustness of the proposed algorithm in the case of steering vector mismatch and snapshot deficiency.

Pre-Filtering Algorithm for Dual-Microphone Generalized Sidelobe Canceller Using General Transfer Function

Pre-Filtering Algorithm for Dual-Microphone Generalized Sidelobe Canceller Using General Transfer Function

Hybrid probabilistic adaptation mode controller for generalized sidelobe cancellers applied to multi-microphone speech enhancement

In this paper, we propose a new adaptation mode controller (AMC) for a generalized sidelobe canceller (GSC)-based speech enhancement system. Here, a likelihood ratio for target speech presence was first estimated and then utilized to estimate both the local target speech presence probability (SPP) and global SPP. Next, the estimated SPPs were applied to the design of an AMC that controlled the parameters of adaptive filters for an adaptive blocking matrix (ABM) and noise canceller (NC). In particular, the combination of local and global SPPs was applied to the AMC in the ABM, whereas only global SPPs were used for the NC. Finally, a multiple-microphone speech enhancement system was constructed on the basis of a GSC having the proposed AMC. The performance of the speech enhancement system was subsequently evaluated in terms of the perceptual evaluation of speech quality (PESQ) and the cepstral distortion (CD) for car noise conditions. It was shown from this evaluation that a speech enhancement system using the proposed AMC method provided better performance than conventional AMC methods using power ratios between the target and non-target directional signals, the inter-channel normalized cross-correlation, and the local SPPs only.

TPMS Interference Suppression Based on Beamforming Technology

The Tire Pressure Monitoring System (TPMS) displays the state of a tire on a display to inform a driver of the relevant information, by means of a sensor installed on the tire of the vehicle. When the data measured from the tire are wirelessly transmitted to a receiving antenna located in the center of the vehicle, the exact transmission of data is affected by the interference from various external electronic and electrical devices. In this paper, we suggest a minimum variance distortionless response (MVDR) beamformer based on the angle-of-arrival (AOA) vector for suppressing external interference and receiving accurate data. Although the MVDR beamformer effectively suppresses the interference, it has high computational complexity because of the calculation of an autocorrelation matrix. In order to address this issue, we also suggest a generalized sidelobe canceler (GSC) beamformer which does not have the same performance of the interference suppression to MVDR but also has low computational complexity. Since the signal from each tire can cause interference to others, we consider utilizing a unique Gold Code to each tire to minimize intertire interference and reduce power consumption of a battery installed in each tire.

Blind Capon-like adaptive ST-BC MIMO-CDMA receiver based on constant modulus criterion

In this paper, we present a new Capon-like blind receiver based on linearly constrained constant modulus (LCCM) criterion for the multiple-input multiple-output (MIMO) antennas system along with space–time block code (ST-BC) using direct-sequence code division multiple access (CDMA) modulation technique. A time-varying channel model with generalized sidelobe canceller (GSC) associated with the recursive least squares (RLS) algorithm is implemented to reduce the complexity of receiver design. In our derived algorithm, the parameter of constant modulus, α, relating to the desired user power is updated adaptively via stochastic gradient algorithm to track userʼs amplitude variation. Also we prove theoretically that in the two-branch filter bank receiver design the weight vector of one branch can be updated simply using the other one, which has been obtained with our proposed CM-GSC-RLS algorithm, with simple pre-calculated transform. Hence computation complexity of the proposed adaptive blind receiver can be further reduced significantly. Via intense simulations it reveals that our proposed scheme has robust performance against the userʼs acquisition inaccuracies comparing with current available algorithms.

Adaptation mode controller using multiple signal classification for GSC‐based beamforming

A new adaptation mode control method using the multiple signal classification (MUSIC) algorithm is proposed. The MUSIC algorithm is used to calculate the spatial spectral response to the direction of the target source with noisy inputs. Then, the statistical distribution of the MUSIC output is analysed and used to model the target signal presence probability. Using the probability, the filter adaptation mode of a multiple input canceller in a generalised sidelobe canceller is controlled. For performance evaluation, hidden Markov model-based speech recognition rates are measured. The results show that the proposed algorithm notably outperforms other conventional adaptation mode controllers.

Speech Enhancement with Generalized Sidelobe Canceller Based on a Coherence-based Filter for Small Microphone Arrays

为了克服传统麦克风小阵列语音增强算法噪音抑制能力有限的问题，该文提出一种基于相干性滤波器的广义旁瓣抵消器语音增强算法, 该算法基于动态平滑系数噪声谱估计来获得相干性滤波器，分别对每个阵元接收到的信号进行滤波用以抑制包括混响等噪声信号的干扰，并把滤波后的信号作为输入信号，使用基于小阵列的广义旁瓣抵消器波束形成算法抑制残余噪声信号的干扰。模拟和实际试验表明，该文提出的算法明显优于单独使用小阵列波束形成算法和相干性滤波器算法。

Combined adaptive beamforming schemes for nonstationary interfering noise reduction

This paper introduces new adaptive beamforming methods for nonstationary noise reduction, designed to be robust against broadband interfering signals. In particular, we propose combined beamforming schemes within a standard adaptive beamforming system, such as the generalized sidelobe canceller (GSC). The novelty of such combined adaptive beamformers relies on the use of different adaptive sidelobe cancelling structures which allow the system to achieve robustness in nonstationary noisy environments. The combined structures are based on the convex combination of two multiple-input single-output (MISO) adaptive systems with complementary capabilities. The whole beamformer benefits from such combination and results to be able to preserve the best properties of each system. We introduce two different adaptive schemes, whose difference lies in the way of combining the MISO systems. Moreover, we present a further adaptive beamforming scheme which generalizes the previous techniques, thus improving the robustness against nonstationary interfering signals in multisource environments. The effectiveness of the proposed systems is also assessed in a nonstationary dense multipath environment. The experiments show that the proposed combined beamforming schemes are capable of enhancing the desired signal even in the presence of nonstationary interfering signals.

MIMO radar clutter mitigation based on joint beamforming and joint domain localized processing

In this article, we propose a space–time adaptive processing scheme via a generalized sidelobe canceler (GSC) architecture for airborne multiple-input multiple-output (MIMO) radar. This scheme employs the waveforms extracted by the matched filter bank that is cascaded at the receive end and utilizes digital beamforming technique to synthesize a certain number of transmit–receive beams, therefore, the operation of target detection in clutter environment can be conducted in all the directions of the formed beams in parallel. The GSC architecture is derived to implement adaptive reduced-rank (RR) clutter mitigation in a localized angle-Doppler space based on a novel RR multistage Wiener filter algorithm. The number of iterative stages in this algorithm is automatically selected in terms of a rank decision methodology. Meanwhile, beamforming and beam selecting methods are provided for this scheme, aiming at adaptively suppressing the clutter in localized domain. This scheme reverses the unavailability of the PA-efficient joint domain localized algorithm for MIMO radar. Moreover, it adapts to MIMO radar with arbitrary transmit–receive array space ratio. Even better, the proposed scheme has lower computation complexity than the traditional sample matrix inversion algorithm. The simulation results show that the proposed algorithm provide a signal-to-interference-plus-noise ratio improvement than traditional algorithms.

Coordinated adaptive beamformer over distributed antenna network

The spatial diversity of distributed network demands the individual filter to accommodate the topology of interference environment. In this paper, a type of distributed adaptive beamformer is proposed to mitigate interference over coordinated antenna arrays network. The proposed approach is formulated as generalized sidelobe canceller (GSC) structure to facilitate the convex combination of neighboring nodes’ weights, and then it is solved by unconstrained least mean square (LMS) algorithm due to simplicity. Numerical results show that the robustness and convergence rate of antenna arrays network can be significantly improved in strong interference scenario. And they also clearly illustrate that mixing vector is optimized adaptively and adjusted according to the spatial diversity of the distributed nodes which are placed in different power of received signals to interference ratio (SIR) environments.

Distributed Multiple Constraints Generalized Sidelobe Canceler for Fully Connected Wireless Acoustic Sensor Networks

This paper proposes a distributed multiple constraints generalized sidelobe canceler (GSC) for speech enhancement in an <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> -node fully connected wireless acoustic sensor network (WASN) comprising <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> microphones. Our algorithm is designed to operate in reverberant environments with constrained speakers (including both desired and competing speakers). Rather than broadcasting <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> microphone signals, a significant communication bandwidth reduction is obtained by performing local beamforming at the nodes, and utilizing only transmission channels. Each node processes its own microphone signals together with the N + P transmitted signals. The GSC-form implementation, by separating the constraints and the minimization, enables the adaptation of the BF during speech-absent time segments, and relaxes the requirement of other distributed LCMV based algorithms to re-estimate the sources RTFs after each iteration. We provide a full convergence proof of the proposed structure to the centralized GSC-beamformer (BF). An extensive experimental study of both narrowband and (wideband) speech signals verifíes the theoretical analysis.

Beam Width Performance of the Adaptive Beam Former Based on Pseudo-Interference Technique

In this paper, we examine the beam width performance of the recently addressed robust Capon beam formers. This adaptive array employs the estimated steering vector, injected noise, and pseudo-interference to provide robustness against direction mismatch. With the generalized side lobe canceller (GSC) as the underlying structure, we first derive the effect of angular mismatch on the estimated interference correlation matrix. Then, a simple approximate expression is presented for output signal-to-interference-plus-noise-ratio (SINR) of this new beam former. Based on this expression, the angular beam width of this robust beam former is investigated. Simulation results verify the analytically predicted performance.

Adaptive blind receivers for MC-CDMA communication systems

In this paper, we propose three adaptive blind algorithms for multiuser multicarrier code division multiple-access systems in multipath fading channels. The proposed adaptive blind receivers are based on the property of the discreteness of the input data symbol and are updated in every symbol interval. We also use the concept that the variance of the output signal approaches to the variance of the desired signal to get the cost function. The three proposed receiver structures are the traditional finite impulse response FIR structure, the despreading DES filter structure and the generalized sidelobe canceller GSC structure. The advantage of the FIR filter is that the length of the filter weights does not have to be the same length as the spreading code. For the DES filter, the combination of the adaptive weight and the despreading code has the simplest structure than the other two proposed receiver structures. The constrained GSC filter is superior to the other two proposed receiver structures in the environments dominated by multiple-access interference. By this constraint, the blind GSC filter can guarantee to converge to the desired solution. Simulation results are given to show the effectiveness and comparison of the proposed adaptive blind receivers. Copyright ©2012 John Wiley & Sons, Ltd.

Linear Receiver for the Uplink in Distributed Antenna Systems

We consider the uplink of a distributed antenna system (DAS) in the presence of interference and unknown oscillator offsets, which lead to synchronization errors. For this scenario, we develop a linear receiver which maximizes the output signal-to-interference-plus-noise ratio (SINR). Specifically, we first propose a new structured generalized sidelobe canceller (SGSC) formulation for the commonly used minimum-variance receiver, and derive a general framework to improve the robustness of a linear receiver when oscillator offsets exist. Then a new linear receiver is proposed in closed-form based on the proposed robust SGSC and a ridge regression technique. It is shown by simulations that the proposed linear receiver can provide very robust SINR performance and excellent symbol error rate (SER) performance in the existence of interference and unknown oscillator offsets.