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IEEE 23rd International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)

作者： Aerts, Nico Moeneclaey, Marc Univ Ghent Dept Telecommun & Informat Proc B-9000 Ghent Belgium

ISBN: (纸本)9781467325691

In a cooperative network, relaying nodes transmit to the destination information that is related to the message sent by the source. In literature the performance of such networks is usually studied under the (unrealistic) assumption of perfect channel knowledge at the destination. In this paper we consider the Amplify-and-Forward protocol and assume time-varying Rice fading components. Based on pilot symbols an initial estimate of the channel parameters that correspond to the actual channel realizations is obtained, and is subsequently refined in an iterative way by also exploiting the information contained in the data part of the received signals. The iterative estimator gives rise to substantial improvements in terms of error performance and bandwidth efficiency as compared to the initial pilot-based estimate.

关键词： Cooperative communication Amplify-and-Forward sage algorithm

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MIMO Channel Measurement and Characterization for 26GHz Wave in Outdoor Scenarios 83

MIMO Channel Measurement and Characterization for 26GHz Wave...

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IEEE 83rd Vehicular Technology Conference (VTC Spring)

作者： Zhong, Zhimeng Wu, Xianyue Qu, Jingfeng Yin, Xuefeng Huawei Technol Co Ltd Shanghai Peoples R China Tongji Univ Sch Elect & Informat Engn Shanghai Peoples R China

ISBN: (纸本)9781509016983

In this paper, by using a multiple-input multiple-output (MIMO) antenna array, a channel measurement campaign in outdoor environments is introduced. The measurement campaign captures the spatial characteristics of centimeter wave (cm-wave) propagation at the center frequency of 26 GHz. By using the parametric approach of the Space-Alternating Generalized Expectation-maximization (sage) algorithm, the channel characteristics in the delay and spatial domains are extracted, and compared with the channel model below 6 GHz. Our analysis shows that the channel dispersions in the delay and directional domains are smaller at the 26 GHz. Furthermore, single-user (SU)-MIMO and multi-user (MU)-MIMO channel matrix properties are investigated, and show that the MU-MIMO channel has good orthogonal property. It implies that MU-MIMO will be one promising MIMO technique in cm-wave band.

关键词： MIMO Channel Characteristics MIMO Channel Measurement centimeter-wave propagation sage algorithm

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Methods to Perform High Velocity LTE Experiments at Low Velocities 83

Methods to Perform High Velocity LTE Experiments at Low Velo...

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IEEE 83rd Vehicular Technology Conference (VTC Spring)

作者： Lerch, Martin Rodriguez-Pineiro, Jose Garcia-Naya, Jose A. Castedo, Luis TU Wien Inst Telecommun Vienna Austria Univ A Coruna La Coruna Spain

ISBN: (纸本)9781509016983

LTE is designed to support user velocities of up to 500 km/h where experiments are expensive, time-consuming and dangerous. Fortunately, such experiments can be emulated at lower velocities by time-stretching the transmit signals. This method preserves the spatial properties of the mobile radio channel but performs a spectral compression. In this paper, we propose a new set of methods that preserve the spectral properties by inserting additional subcarriers. Next, we compare the method of time-stretching to the new set of methods by applying them to LTE downlink signals. We evaluate the properties and the main drawbacks of the proposed methods by simulations using standard-compliant LTE signals. Finally, we highlight practical aspects to be considered when implementing the proposed high speed emulation techniques.

关键词： Centimeter-wave propagation MIMO Channel Characteristics MIMO Channel Measurement sage algorithm

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Joint Data Detection and Channel Estimation for OFDM Systems in the Presence of Very High Mobility

Joint Data Detection and Channel Estimation for OFDM Systems...

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20th IEEE Symposium on Personal, Indoor and Mobile Radio Communications

作者： Panayirci, E. Senol, H. Poor, H. V. Princeton Univ Dept Elect Engn Princeton NJ 08544 USA Kadir Has Univ Dept Comp Sci Istanbul Turkey

ISBN: (纸本)9781424451234

This paper is concerned with the challenging and timely problem of joint channel estimation and data detection for orthogonal frequency division multiplexing (OFDM) systems in the presence of frequency selective and very rapidly time varying channels. The detection and estimation algorithm is based on the space alternating generalized expectation maximization (sage) technique which is particularly well-suited to multicarrier signal formats. In order to reduce the computational complexity of the algorithm, we apply the cosine orthogonal basis functions to describe the time-varying channel. It is shown that, depending on the normalized Doppler frequency, only a small number of expansion coefficients is sufficient to approximate the channel perfectly and there is no need to know the correlation function of the input signal. The proposed sage joint detection algorithm updates the data sequences in serial and the channel parameters are updated in parallel, leading to a receiver structure that also incorporates a partial interference cancelation of the interchannel interference. Computer simulations show that the cosine transformation represents the time-varying channel very effectively and the proposed algorithm has excellent symbol error rate and channel estimation performance even with a very small number of channel expansion coefficients employed in the algorithm, resulting in reduction of the computational complexity substantially.

关键词： Joint data detection and channel estimation OFDM systems sage algorithm high mobility channels

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Angle of Arrival Characteristics at 20 GHz band in LOS Urban Area Street Cell Environment

Angle of Arrival Characteristics at 20 GHz band in LOS Urban...

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IEEE International Workshop on Electromagnetics - Applications and Student Innovation Competition (iWEM)

作者： Tategami, Koyo Fujimoto, Mitoshi Kitao, Koshiro Imai, Tetsuro Univ Fukui Grad Sch Engn 3-9-1 Bunkyo Fukui 9108507 Japan NTT DOCOMO INC DOCOMO R&D Ctr 3-5 Hikari No Oka Yokosuka Kanagawa 2398536 Japan

ISBN: (纸本)9781728150062

In this paper, the sage algorithm is applied to measured data acquired by the 20 GHz band channel sounder in a real urban street cell environment, and DOA (Direction of Arrival) is estimated. Then, the average arrival angles and angle spreads are calculated from the estimated results, and angle of arrival characteristics are evaluated. It is shown that the average angle of arrival gradually approaches to direction of transmitter as the distance between the transmitter and the receiver increases. Also, it is shown that the arrival angle spread in the azimuth plane tends to decrease as the distance between transmitter and receiver increases.

关键词： 5G Mobile Communication System Urban Street cell LOS Environment sage algorithm AOA characteristics

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Switching Time Optimization for Time-Division Multiplexing-based Wide-band Channel Sounding 12

Switching Time Optimization for Time-Division Multiplexing-b...

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12th International Conference on Wireless Communications and Signal Processing (WCSP)

作者： Hu, Jiayi Yin, Xuefeng Zhang, Linjian Tongji Univ Coll Elect & Informat Engn Shanghai Peoples R China Huawei Technol Co Ltd Shanghai Peoples R China

ISBN: (纸本)9781728172361

In this contribution, a solution is proposed for setting switching time of antenna array for MIMO channel sounding time-variant environment. Since the traditional coherence time is too short to support time-division multiplexing (TDM) measurements within a complete cycle, we find it possible to make use of the coherence time of individual path components of the wide-band channel as the basis for selecting switching speed, which means that the duration of the antenna array only needs to be smaller than the maximum value of the coherence time of every single multipath component (MPC) in the channel. It is recommended to apply space alternating generalized expectation maximization (sage) algorithm to assess whether the switching time we set can support channel measurement, then select a suitable one. This new method breaks through the limitation of traditional channel correlation theories and creates more possibilities for field measurements.

关键词： MIMO channel sounding coherence time sage algorithm Path-level coherence time-based TDM selection

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Augmenting the Classification of Retinal Lesions using Spatial Distribution

Augmenting the Classification of Retinal Lesions using Spati...

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33rd Annual International Conference of the IEEE Engineering-in-Medicine-and-Biology-Society (EMBS)

作者： Massey, Elizabeth M. Hunter, Andrew Lincoln Univ Sch Comp Sci Lincoln LN6 7TS England

ISBN: (纸本)9781424441228

This paper introduces sage - an algorithm that uses the spatial clustering of objects to enhance their classification. It assumes that discrete objects can be identified and classified based on their individual appearance, and further that they tend to appear in spatial clusters (for example, circinate exudates). The algorithm builds spatial distribution maps for objects and confounds for a given image, and adjusts individual object confidence levels to reflect their spatial clustering. sage may be combined with a wide range of object identification and classification methods;we demonstrate it using a Multi-Layered Perceptron (MLP) Neural Network and a Support Vector Machine (SVM) classifier types for both dark and bright retinal lesions. Using ROC analysis sage improves classifier performance as much as 83%.

关键词： Clustering algorithms Feature extraction Lesions Maximum likelihood estimation ROC analysis Retina sage algorithm SVM classifier Support vector machines Vectors circinate exudates eye image classification image classification medical image processing mult

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An Iterative sage based Semi-Blind Channel Estimation for Massive MIMO

An Iterative SAGE based Semi-Blind Channel Estimation for Ma...

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IEEE Global Communications Conference

作者： Khushboo Mawatwal Debarati Sen Rajarshi Roy Indian Institute of Technology

ISBN: (纸本)9781509013296

In this paper, we have proposed an iterative space-alternating generalized expectation maximization (sage) based semi-blind channel estimation technique for massive multiple-input multiple-output (MIMO) system in multi-cell pilot contamination prone scenario. The benefits of massive MIMO depend largely on the accuracy of channel state information (CSI) available at the base station (Transmitter). The proposed method improves the accuracy of conventional pilot based minimum mean squared error (MMSE) estimator by iteratively updating the estimate with the help of sage algorithm. The received data signals are incorporated along with the received pilot signals to obtain an improved channel estimate without the additional pilot symbols, which in turn improves the spectral efficiency of the system. Most of the existing estimators reported in the literature assume full knowledge of large scale fading coefficients of the interfering cells which is practically infeasible and incurs heavy overheads. The proposed estimator overcomes this problem with the help of an estimate obtained from the received samples. The proposed algorithm converges in almost one iteration, and achieves significant improvement over the existing pilot based estimator reported in the literature.

关键词： Channel estimation Massive MIMO sage Semi-blind MMSE sage semiautomatic ground environment channel estimation Mini Mental State Examination channel blind estimation multiple input multiple output systems sage algorithm Pilots data signal

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Modeling the ultrasonic testing echoes by a combination of particle swarm optimization and Levenberg-Marquardt algorithms

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MEASUREMENT SCIENCE AND TECHNOLOGY 2017年第6期28卷 065001-065001页

作者： Gholami, Ali Honarvar, Farhang Moghaddam, Hamid Abrishami K N Toosi Univ Technol Fac Mech Engn NDE Lab 7 Pardis StMollasadra AveVanak Sq Tehran Iran K N Toosi Univ Technol Fac Elect Engn MVMIP Lab Shariati Ave Tehran Iran

This paper presents an accurate and easy-to-implement algorithm for estimating the parameters of the asymmetric Gaussian chirplet model (AGCM) used for modeling echoes measured in ultrasonic nondestructive testing (NDT) of materials. The proposed algorithm is a combination of particle swarm optimization (PSO) and Levenberg-Marquardt (LM) algorithms. PSO does not need an accurate initial guess and quickly converges to a reasonable output while LM needs a good initial guess in order to provide an accurate output. In the combined algorithm, PSO is run first to provide a rough estimate of the output and this result is consequently inputted to the LM algorithm for more accurate estimation of parameters. To apply the algorithm to signals with multiple echoes, the space alternating generalized expectation maximization (sage) is used. The proposed combined algorithm is robust and accurate. To examine the performance of the proposed algorithm, it is applied to a number of simulated echoes having various signal to noise ratios. The combined algorithm is also applied to a number of experimental ultrasonic signals. The results corroborate the accuracy and reliability of the proposed combined algorithm.

关键词： ultrasonic testing asymmetric Gaussian chirplet model (AGCM) Levenberg-Marquardt (LM) particle swarm optimization (PSO) sage algorithm

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Opportunistic channel estimation with LTE signals of limited bandwidth for positioning applications

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EURASIP JOURNAL ON WIRELESS COMMUNICATIONS AND NETWORKING 2023年第1期2023卷 72页

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 Univ Sussex Brighton And Hove England U Blox Italy Sgon Italy

The positioning problem is interesting in a variety of applications, especially in indoor environments or in urban canyons, where the position information obtainable with traditional Global Navigation Satellite Systems is limited. In this paper, we deal with the problem of estimating, for the purposes of positioning, the time of arrival (TOA) and the angle of arrival (AOA) by processing LTE 3GPP signals, with particular attention to the uplink signals. The main contribution of this paper is the definition of new opportunistic methods to estimate the TOA and the AOA using the upstream demodulation reference signal (DM-RS) instead of the Sounding Reference Signal. We will show that the use of DM-RS and of estimation algorithms such as the Space-Alternating Generalized Expectation-Maximization and the Iterative Adaptive Approach for Amplitude and Phase estimation (IAA-APES) allows an efficient estimate of the parameters, in spite of the small, occupied bandwidth.

关键词： LTE Time difference of arrival Ranging measure Opportunistic positioning Uplink DM-RS sage algorithm

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