检索结果-内蒙古大学图书馆

Blind decision feedback equalisers, how to avoid degenerative solutions

SIGNAL PROCESSING 2002年第11期82卷 1675-1693页

作者： Szczecinski, LL Gei, A INRS Energy Mat & Telecommun Montreal PQ H5A 1C6 Canada Univ Chile Dept Elect Engn Santiago Chile

Decision feedback equalisers offer a good compromise between complexity and performance for channels with strong intersymbol interference. However, their blind or decision-directed adaptation may converge to degenerative solutions for which signal at the equaliser's output is independent of its input. The known algorithms proposed to solve this problem, are evaluated in this paper. It is shown that their main defect is a lack of well-defined criteria allowing the detection of degenerative solutions, so this paper introduces a criterion proved to be sufficient for reliable detection of such solutions. Using the new criterion, an algorithm of blind decision feedback equalisation, based on constrained optimisation, is proposed. The new algorithm does not admit degenerative solutions therefore should be preferred among the analysed algorithms. Also, the problem of false phase lock, characteristic of some modulations, is addressed and a solution to it is proposed. The results of the study are presented using the experimental data and simulation. (C) 2002 Elsevier Science B.V. All rights reserved.

关键词： constant modulus algorithm blind equalisation decision feedback phase tracking

来源：评论

学校读者我要写书评

暂无评论

Code-constrained blind detection of CDMA signals in multipath channels

引用

IEEE SIGNAL PROCESSING LETTERS 2002年第12期9卷 389-392页

作者： Xu, ZY Liu, P Univ Calif Riverside Dept Elect Engn Riverside CA 92521 USA

In this letter, a constant-modulus-algorithm-based multiuser detection scheme is proposed for a communication system under multipath propagation. To mitigate channel distortion and multiuser interference, we integrate multiple constraints into the optimization criterion. According to our analysis, the ability of the detector to remove all interference is ensured in the absence of noise when the constraints are properly preselected. However, in the presence of noise, the constraints highly affect the performance of the receiver. In order to optimally combine signals from different paths to achieve performance gains, those constraints can also be treated as variables and jointly optimized with the receiver, as verified by numerical examples.

关键词： constant modulus algorithm constrained optimization multiuser detection

来源：评论

学校读者我要写书评

暂无评论

Joint channel estimation and decoding of space-time block codes

Joint channel estimation and decoding of space-time block co...

引用

56th IEEE Vehicular Technology Conference

作者： Xu, CJ Le-Ngoc, T McGill Univ Dept ECE Montreal PQ H3A 2A7 Canada

ISBN: (纸本)0780374673

The channel estimation of space-time (ST) block coding transmission using the constant modulus algorithm (CMA) is investigated. The ST block coding transmission is represented by an orthogonal vector-channel model. Based on this orthogonal model, a general expression of linear decoding decision rules for ST block codes and the sufficient and necessary conditions for convergence of the CMA are derived. It is shown that the CMA directly converges to a vector-channel under the orthogonal condition. A channel estimation method using the convergence value of the CMA is proposed for ST block coding transmission systems and is suitable for 1-D signaling or 2-D signaling using a square constellation. Illustrative results show that the proposed scheme provides a better accuracy than the cross-correlated method.

关键词： transmit diversity space-time block coding channel estimation constant modulus algorithm wireless communication

来源：评论

学校读者我要写书评

暂无评论

The beamforming for an adaptive antenna system in multi-vehicles TT&C environment

The beamforming for an adaptive antenna system in multi-vehi...

引用

6th International Conference on Signal Processing

作者： Feng, WJ Zhong, YC Zhao, F Yang, SZ Chongqing Univ Chongqing 400044 Peoples R China

ISBN: (纸本)0780374886

In multi-vehicles environment, TT&C systems is realized through unified spread spectrum framework. Adaptive antenna digital beamforming technologies are used to track, measure and command objects. constant modulus array (CMA) and adaptive signal canceller estimate the direction of arrival (DOA) of every signal and use the optimum weighted vector to form the beams. The phase-weighted vectors estimated from DOA improve the processing gain as well as being utilized in the transmitting of tele-command signal to form the beam of specified object. Its processing performance is researched and simulated in this paper.

关键词： TT&C digital beamforming constant modulus algorithm

来源：评论

学校读者我要写书评

暂无评论

Performance analysis of Godard-based blind channel identification

引用

IEEE TRANSACTIONS ON SIGNAL PROCESSING 2001年第8期49卷 1757-1767页

作者： Schniter, P Casas, RA Touzni, A Johnson, CR Ohio State Univ Dept Elect Engn Columbus OH 43210 USA NxtWave Commun Langhorne PA 19047 USA Cornell Univ Dept Elect Engn Ithaca NY 14853 USA

We analyze a blind channel impulse response identification scheme based on the cross correlation of blind symbol estimates with the received signal, The symbol estimates specified are those minimizing the Godard (or constant modulus) criterion, for which mean-squared symbol estimation error bounds have recently been derived. In this paper, we derive upper bounds for the average squared parameter estimation error (ASPE) of the blind identification scheme that depend on the mean-squared error of the Wiener equalizer, the kurtoses of the desired and interfering sources, and the channel impulse response. The effects of finite data length and stochastic gradient equalizer design on ASPE are also investigated. All results are derived in a general multiuser vector-channel context.

关键词： blind channel identification blind deconvolution constant modulus algorithm Godard algorithm

来源：评论

学校读者我要写书评

暂无评论

Combination of Kalman filter and constant modulus algorithm with variable stepsize for the equalisation of fast-fading channels

引用

ELECTRONICS LETTERS 1998年第18期34卷 1718-1719页

作者： Pora, W Chambers, JA constantinides, AG Univ London Imperial Coll Sci Technol & Med Dept Elect Engn Signal Proc & Digital Syst Sect London SW7 2BT England

In fast-fading channels, the constant modulus algorithm (CMA) is unable to properly track the rime-variations because the magnitude of the received signal changes too rapidly. The Kalman filter (KF), however, works well in time-varying channels but needs a training sequence to operate. Therefore, a combined CMA and KF algorithm is proposed in order to utilise the advantages of both algorithms. The associated step sizes of the CMA and the KF algorithm are also varied in accordance with the magnitude of the output. Simulations are presented to demonstrate the potential of the combination.

关键词： Mobile radio systems time-variations magnitude Radiowave propagation equalisers equalisation step sizes constant modulus algorithm training sequence fading variable stepsize Kalman filters Kalman filter fast-fading channels telecommunication channels mobile communication

来源：评论

学校读者我要写书评

暂无评论

A vector constant modulus algorithm for shaped constellation equalization

引用

IEEE SIGNAL PROCESSING LETTERS 1998年第4期5卷 89-91页

作者： Yang, VY Jones, DL Univ Illinois Dept Elect & Comp Engn Urbana IL 61801 USA Univ Illinois Coordinated Sci Lab Urbana IL 61801 USA

The constant modulus algorithm (CMA), a popular method for performing blind equalization, has the drawback of failing when the input data has a Gaussian distribution or a kurtosis larger than three, This means that source shaping (which is used to increase the shaping gain) can produce data unequalizable by CMA and other important blind equalization techniques. This paper proposes a simple extension of CMA that blindly equalizes many types of shaped constellations, including those shaped by shell mapping.

关键词： blind equalization constant modulus algorithm shaped constellation shell mapping

来源：评论

学校读者我要写书评

暂无评论

Sufficient conditions for the local convergence of constant modulus algorithms

引用

IEEE TRANSACTIONS ON SIGNAL PROCESSING 2000年第10期48卷 2785-2796页

作者： Schniter, P Johnson, CR Ohio State Univ Dept Elect Engn Columbus OH 43210 USA Cornell Univ Dept Elect Engn Ithaca NY 14853 USA

The constant modulus (CM) criterion has become popular in the design of blind linear estimators of sub-Gaussian i.i.d. processes transmitted through unknown linear channels in the presence of unknown additive interference, The existence of multiple CM minima, however, makes it difficult for CM-minimizing schemes to generate estimates of the desired source (as opposed to an interferer) in multiuser environments, In this paper, we present three separate sufficient conditions under which gradient descent (GD) minimization of CIM cost will locally converge to an estimator of the desired source at a particular delay. The sufficient conditions are expressed in terms of statistical properties of the initial estimates, specifically, CM cost, kurtosis, and signal-to-interference-plus-noise ratio (SINR). Implications on CM-GD initialization methods are also discussed.

关键词： blind beamforming blind deconvolution blind equalization blind multiuser detection constant modulus algorithm Godard algorithm

来源：评论

学校读者我要写书评

暂无评论

Bounds for the MSE performance of constant modulus estimators

引用

IEEE TRANSACTIONS ON INFORMATION THEORY 2000年第7期46卷 2544-2560页

作者： Schniter, P Johnson, CR Ohio State Univ Dept Elect Engn Columbus OH 43210 USA Cornell Univ Dept Elect Engn Ithaca NY 14853 USA

The constant modulus (CM) criterion has become popular in the design of blind linear estimators of sub-Gaussian independent and identically distributed (i.i.d.) processes transmitted through unknown linear channels in the presence of unknown additive interference. In this paper, me present an upper bound for the conditionally unbiased mean-squared error (USME) of CM-minimizing estimators that depends only on the source kurtoses and the UMSE of Wiener estimators. Further analysis reveals that the extra UMSE of CM estimators can be upper-bounded by approximately the square of the Wiener (i.e., minimum) UMSE. Since our results hold for vector-valued finite-impulse response/infinite-impulse response (FIR/IIR) linear channels, vector-valued FIR/IIR estimators with a possibly constrained number of adjustable parameters, and multiple interferers with arbitrary distribution, they confirm the longstanding conjecture regarding the general mean-square error (MSE) robustness of CM estimators.

关键词： blind beamforming blind deconvolution blind equalization blind multiuser detection constant modulus algorithm Godard algorithm

来源：评论

学校读者我要写书评

暂无评论

On the convergence of blind adaptive equalizers for constant modulus signals

引用

IEEE TRANSACTIONS ON COMMUNICATIONS 2000年第5期48卷 795-803页

作者： Rupp, M Sayed, AH Univ Calif Los Angeles Dept Elect Engn Los Angeles CA 90095 USA Bell Labs Lucent Technol Holmdel NJ 07733 USA

This paper studies the behavior of the error sequence of stop-and-go variants of two adaptive blind equalizers, namely CMA2-2 and Sate's algorithm. It is shown that for transmitted signals with constant modulus gamma, the equalizer output can be made to lie within the circle of radius gamma root c infinitely often, for some value of c that is only slightly larger than one.

关键词： adaptive equalization constant modulus algorithm feedback l(2)-stability positive-real function small gain theorem

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：