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Sparse Variational Bayesian sage algorithm With Application to the Estimation of Multipath Wireless Channels

IEEE TRANSACTIONS ON SIGNAL PROCESSING 2011年第8期59卷 3609-3623页

作者： Shutin, Dmitriy Fleury, Bernard H. Princeton Univ Dept Elect Engn Princeton NJ 08544 USA Aalborg Univ Dept Elect Syst Sect Nav & Commun DK-9220 Aalborg Denmark

In this paper, we develop a sparse variational Bayesian (VB) extension of the space-alternating generalized expectation-maximization (sage) algorithm for the high resolution estimation of the parameters of relevant multipath components in the response of frequency and spatially selective wireless channels. The application context of the algorithm considered in this contribution is parameter estimation from channel sounding measurements for radio channel modeling purpose. The new sparse VB-sage algorithm extends the classical sage algorithm in two respects: i) by monotonically minimizing the variational free energy, distributions of the multipath component parameters can be obtained instead of parameter point estimates and ii) the estimation of the number of relevant multipath components and the estimation of the component parameters are implemented jointly. The sparsity is achieved by defining parametric sparsity priors for the weights of the multipath components. We revisit the Gaussian sparsity priors within the sparse VB-sage framework and extend the results by considering Laplace priors. The structure of the VB-sage algorithm allows for an analytical stability analysis of the update expression for the sparsity parameters. This analysis leads to fast, computationally simple, yet powerful, adaptive selection criteria applied to the single multipath component considered at each iteration. The selection criteria are adjusted on a per-component-SNR basis to better account for model mismatches, e. g., diffuse scattering, calibration and discretization errors, allowing for a robust extraction of the relevant multipath components. The performance of the sparse VB-sage algorithm and its advantages over conventional channel estimation methods are demonstrated in synthetic single-input-multiple-output (SIMO) time-invariant channels. The algorithm is also applied to real measurement data in a multiple-input-multiple-output (MIMO) time-invariant context.

关键词： Expectation-maximization algorithm MIMO multipath channels sage algorithm variational Bayesian methods

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Joint channel estimation, partial successive interference cancellation, and data decoding for DS-CDMA based on the sage algorithm

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IEEE TRANSACTIONS ON COMMUNICATIONS 2007年第6期55卷 1231-1241页

作者： Kocian, Alexander Land, Ingmar Fleury, Bernard H. Aalborg Univ Dept Commun Technol DK-9220 Aalborg Denmark Muscat Ctr Brila Inst Technol Muscat Oman Univ S Australia ITR Mawson Lakes SA 5095 Australia Telecommun Res Ctr Ftw A-1220 Vienna Austria

This paper deals with the derivation and optimization of an iterative receiver architecture performing joint multiuser decoding and channel estimation. We consider an asynchronous multirate convolutional coded DS-CDMA system that communicates over quasi-static flat Rayleigh fading channels. The proposed receiver is derived within the space-alternating generalized expectation-maximization (sage) framework in connection with the noise-splitting approach. The used theoretical framework guarantees convergence of the receiver, as opposed to many other iterative receiver structures. Furthermore, the noise-splitting approach provides a set of noise-weighting coefficients that can be optimized under weak constraints. The inputs to the single-user decoders are linear combinations of two kinds of soft values with weights determined by the noise-weighting coefficients. These two kinds of soft values can be interpreted as a priori information and extrinsic information, respectively, if the channels are known. In the case of unknown channels, they are asymptotically a priori and asymptotically extrinsic, i.e., they become a priori and extrinsic when the length of the observed frame tends to infinity. In most cases, the optimum coefficients lead to extrinsic or asymptotically extrinsic values fed to the input of the single-user decoders. Monte Carlo simulations show that the proposed receiver is resistant to channel estimation errors and supports high system loads.

关键词： iterative information processing iterative joint data decoding and channel estimation multiuser decoding sage algorithm

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Joint multi-dimensional channel parameter estimation schemes for DS-CDMA systems using a modified version of the sage algorithm

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IEICE TRANSACTIONS ON COMMUNICATIONS 2001年第3期E84B卷 511-519页

作者： Senhaji, YR Yamazato, T Katayama, M Ogawa, A Nagoya Univ Dept Informat Engn Grad Sch Engn Nagoya Aichi 4648603 Japan Nagoya Univ Ctr Informat Media Studies Nagoya Aichi 4648603 Japan Meijo Univ Sch Sci & Technol Dept Informat Sci Nagoya Aichi 4688502 Japan

A modified version of the sage algorithm is presented for joint delay-azimuth-attenuation parameters' estimation in a multiuser DS-CDMA system. The introduced modification consists of using different time interval lengths wizen calculating the time correlations for optimizing the different channel parameters. This modification was proposed for the purpose of a further reduction in the algorithm's computational weight in case of receiving sufficiently resolvable waves. Specifically, we found that short interval windows are sufficient for estimating delays and azimuth angles, which is quite effective in reducing the computational burden in their optimization processes. As for the estimation of the attenuation parameters, a longer time window, equal to the preamble length, is considered for more accurate estimation. Also two other estimators are proposed. The first one combining the modified sage with a sequential estimation of the attenuation parameters, suitable for slowly varying channels. Another one, similar to the first, and primarily designed to alleviate the influence of present strong interferers. Through a numerical example, the performances of the three presented estimation schemes, in terms of their near-far resistance, are compared. And it is shown that the proposed second combined estimator outperforms the modified sage in environments with high MAI levels.

关键词： channel parameter estimation EM algorithm sage algorithm Cramer-Rao lower bound maximum-likelihood estimation

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Robust DoA estimation by extension of the sage algorithm: algorithm description and trails results

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IEE PROCEEDINGS-MICROWAVES ANTENNAS AND PROPAGATION 2006年第6期153卷 568-572页

作者： Tyler, N. Allen, B. Aghvami, A. H. Kings Coll London Ctr Telecommun Res London WC2B 5RL England Univ Oxford Dept Engn Sci Oxford OX1 3PJ England

By extending the space-alternating generalised expectation-maximisation (sage) parameter estimation algorithm to include a novel cost variant process, the robustness of direction of arrival (DoA) estimation from the sage algorithm is shown to improve. A novel extension to the standard sage algorithm that enhances the parameter estimation process is first introduced. Field trials that have been conducted using an adaptive antenna to verify the performance of this algorithm are presented. Results show that the extended sage algorithm improves DoA performance compared to standard sage by 5 degrees, when operating in an urban environment.

关键词： Parameter estimation trails sage algorithm algorithms urban environment Direction of arrival estimation adaptive antenna

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Direction of arrival (DOA) parameter estimation with the sage algorithm

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SIGNAL PROCESSING 2004年第3期84卷 619-629页

作者： Verhaevert, J Van Lil, E Van de Capelle, A Katholieke Univ Leuven Div ESAT TELEMIC B-3001 Louvain Belgium

In this study, we investigate the estimation of the relative delay, the azimuth and elevation angle and the complex amplitude of a known received signal with the space alternating generalised expectation (sage) maximisation algorithm. This optimisation algorithm is used to replace the high-dimensional optimisation procedure, necessary to compute the joint maximum likelihood estimate of the parameters using several separate maximisation processes, which can be performed sequentially. Spherical arrays provide wide scan coverage with low grating lobe levels. Because a uniform antenna element distribution on this spherical surface gives rise to the smallest variations in received signal levels over the whole angular space, a uniform distribution of antennas on a sphere is used. For this completely general three-dimensional array, we have for the first time investigated the resolution of the sage algorithm, the convergence and the bit error rate as a function of the signal to noise ratio. We will show that this algorithm is a powerful tool that can be applied successfully for high-resolution parameter extraction. (C) 2003 Elsevier B.V. All rights reserved.

关键词： smart antennas DOA maximum likelihood sage algorithm

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Precise DOA Estimation Using sage algorithm with a Cylindrical Array

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IEICE TRANSACTIONS ON COMMUNICATIONS 2008年第11期E91B卷 3784-3787页

作者： Takanashi, Masaki Nishimura, Toshihiko Ogawa, Yasutaka Ohgane, Takeo Hokkaido Univ Grad Sch Informat Sci & Technol Sapporo Hokkaido 0600814 Japan

A uniform circular array (UCA) is a well-known array configuration which can accomplish estimation of 360 degrees field of view with identical accuracy. However, a UCA cannot estimate coherent signals because we cannot apply the SSP owing to the structure of UCA. Although a variety of studies on UCA in coherent multipath environments have been done, it is impossible to estimate the DOA of coherent signals with different incident polar angles. Then, we have proposed Root-MUSIC algorithm with a cylindrical array. However, the estimation performance is degraded when incident signals arrive with close polar angles. To solve this problem. in the letter, we propose to use sage algorithm with a cylindrical array. Here, we adopt a CLA Root-MUSIC for the initial estimation and decompose two-dimensional search to double one-dimensional search to reduce the calculation load. The results show that the proposal achieves high resolution with low complexity.

关键词： DOA estimation cylindrical array coherent signals sage algorithm

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LTE Ranging Measurement Using Uplink Opportunistic Signals and the sage algorithm 27

LTE Ranging Measurement Using Uplink Opportunistic Signals a...

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27th European Signal Processing Conference (EUSIPCO)

作者： Pin, A. Rinaldo, R. Tonello, A. Marshall, C. Driusso, M. Biason, A. Dalla Torre, A. Univ Udine DPIA Udine Italy Univ Klagenfurt Klagenfurt Austria U Blox Reigate England U Blox Sgonico Italy

ISBN: (纸本)9789082797039

With the increase of services that need accurate location of the user, new techniques that cooperate with the Global Navigation Satellite System (GNSS) are necessary. GNSS suffers poor performance in indoor and dense urban environments, due to high signal attenuation and severe multipath propagation. The current release of the 3rd Generation Partnership Project (3GPP) LTE specification, supports the Uplink Time Difference Of Arrival (UTDOA) localization technique, which uses as reference the Sounding Reference Signal (SRS). Local Measurement Units (LMUs) devices use knowledge of the SRS to perform time difference measures. This paper studies the possibility of performing radio localization using a new UTDOA technique that exploits the uplink Demodulation Reference Signal (DM-RS) in 4G Long Term Evolution (LTE) cellular networks. We point out the advantages of our proposal and evaluate its feasibility by measuring the distance between two antennas using real DM-RS signals generated by an LTE module.

关键词： LTE Time Difference of Arrival Ranging Measure Opportunistic Positioning Uplink DM-RS sage algorithm

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Performance Improvement of DOA Estimation Using Radio Holography by sage algorithm

Performance Improvement of DOA Estimation Using Radio Hologr...

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International Symposium on Antennas and Propagation (ISAP)

作者： Nakajima, Yuto Kikuma, Nobuyoshi Sakakibara, Kunio Nagoya Inst Technol Dept Elect & Mech Engn Nagoya Aichi 4668555 Japan

ISBN: (纸本)9788957083048

The radio holography can perform the direction-of-arrival (DOA) estimation of radio waves with a simple array system. In this paper, we incorporate sage algorithm into the radio holography to reduce the cross-correlation between multiple incoming waves which deteriorates the estimation accuracy. It is demonstrated that the estimation performance of the proposed method is improved.

关键词： Array antenna DOA estimation radio holography MUSIC sage algorithm

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Performance Improvement of Localization of Radio Sources by using Spatial Smoothing Processing in Near-field DOA-Matrix Method with sage algorithm

Performance Improvement of Localization of Radio Sources by ...

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IEEE MTT-S International Conference on Microwaves for Intelligent Mobility (ICMIM)

作者： Kikuma, Nobuyoshi Tanaka, Kensuke Sakakibara, Kunio Nagoya Inst Technol Dept Elect & Mech Engn Nagoya Aichi 4668555 Japan

ISBN: (纸本)9781509043545

This paper deals with the near-field DOA-Matrix method with sage algorithm, which is applied for source localization using a uniform linear array antenna. In this paper, we investigate the effect of spatial smoothing processing (SSP) on the performance of the near-field DOA-Matrix method with sage algorithm. The computer simulation using electromagnetic field analysis shows the SSP improves the source localization performance with the help of sage algorithm especially when the sources are correlated with each other.

关键词： Near-field source localization DOA-Matrix method sage algorithm Spatial smoothing processing Electromagnetic field analysis

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Improved sage algorithm for PET image reconstruction using rescaled block-iterative method

Improved SAGE algorithm for PET image reconstruction using r...

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26th Annual International Conference of the IEEE-Engineering-in-Medicine-and-Biology-Society

作者： Zhu, HQ Zhou, J Shu, HZ Li, SY Luo, LM Southeast Univ Dept Biol Sci & Med Engn Nanjing 210096 Peoples R China

ISBN: (纸本)0780384393

Iterative reconstruction methods such as the expectation maximization maximum likelihood (EMML) method can be accelerated by using a resealed block-iterative (RBI) algorithm. It was demonstrated that the space-alternating generalized expectation-maximization (sage) algorithm is superior to the EMML due to the following facts: (1) The hidden data spaces can be appropriately chosen and then be used in sage algorithm to speed up the convergence rate. (2) sage algorithm updates the parameters sequentially which makes its M-step to be treated more easily. In this paper, we present a novel algorithm that combines the RBI algorithm with sage algorithm. The convergence property of RBI-sage is discussed, and the image quality is assessed with mean absolute error and chi-square error. The experimental results show that the proposed method is more effective than the sage algorithm even if the projection data includes statistic noise.

关键词： block-iterative algorithm sage algorithm image reconstruction convergence properties

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