KARASAWA YOSHIO
| Emeritus Professor etc. | Emeritus Professor |
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Paper
- Propagation channel Modeling for Wideband Radio Systems
Y. Karasawa
Eu CAP2014, (Eu CAP2014, Apr. 2014, Peer-reviwed, Invited
International conference proceedings, English - 簡易型MIMO-OTAシステム信号処理部のFPGA実装と評価
中田克弘; 唐沢好男
信学論(B), vol.J97-B, 1, 51-60, Jan. 2014, Peer-reviwed
Scientific journal, Japanese - Advanced MIMO Channel Modelling for Fading Emulator with Simplified Configuration
Guijiang SUN; Y. Karasawa
Vietnam-Japan Int.Symp.Antennas and Propagation, VJISAP2013, 311-315, Jan. 2014, Peer-reviwed
International conference proceedings, English - Performance evaluation of a MIMO channel model for simplified OTA test systems
Sahrul Pasisingi; Katsuhiro Nakada; Akira Kosako; Yoshio Karasawa
EURASIP JOURNAL ON WIRELESS COMMUNICATIONS AND NETWORKING, SPRINGER INTERNATIONAL PUBLISHING AG, 2013-285, 1-10, Dec. 2013, Peer-reviwed, This paper shows performance evaluation results of the proposed multiple-input multiple-output (MIMO) channel model with simplified configuration for OTA measurement systems. The key feature of our proposal is the adoption of a simple antenna branch-controlled configuration for generating various Rayleigh fading environments composed of a number of multipath delayed waves. The scheme matches well with FPGA implementation with IF band signal processing. The channel model and its theoretical background, and the basic configuration of the measurement system are presented. From an eigenvalue analysis of the generated channel matrix, it is verified that an 8-probe antenna system can realize a very accurate multipath environment for the performance measurement of a 2 x 2 MIMO system, while a 12- or 16-probe antenna system can do the same for a 4 x 4 MIMO system.
Scientific journal, English - Experimental Evaluation of the Propagation Environment Control Function in a Double-Layered Reverberation Chamber in a MIMO-OTA System
Ichiro Oshima; Yoshio Karasawa
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E96B, 10, 2389-2398, Oct. 2013, Peer-reviwed, Reverberation chambers that easily create multipath-rich environments are suggested as test environments for the performance evaluation of multiple-input multiple-output (MIMO) terminals. However, the propagation environment characteristic is difficult to control in conventional reverberation chambers. In this paper, we propose an improved double-layered reverberation chamber to control the arrival wave distribution in addition to the cross-polarization power ratio (XPR). We show the design method of the double-layered reverberation chamber and the experimental results of the propagation environment control using our constructed measurement system.
Scientific journal, English - MIMO用偏波合成型オムニアンテナ
大島一郎; 岡崎彰; 唐沢好男
信学 論(B), vol.J96-B, 9, 1028-1036, Sep. 2013, Peer-reviwed
Scientific journal, Japanese - 2ステージ法による簡易型MIMO-OTA評価のシミュレーション手法とアンテナカップリング特性評価への応用
孫 桂江; 中田克弘; 大島一郎; 唐沢好男
信学論(B), Vol.E96-B, 7, 701-711, Jul. 2013, Peer-reviwed
Scientific journal, Japanese - A Novel High-Resolution Propagation Measurement Scheme for Indoor Terrestrial TV Signal Reception Based on Two-Dimensional Virtual Array Technique
Kazuo Morokuma; Atsushi Takemoto; Yoshio Karasawa
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E96B, 4, 986-993, Apr. 2013, We propose a novel propagation measurement scheme for terrestrial TV signal indoor reception based on a virtual array technique. The system proposed in this paper carries out two-branch recording of target signals and the reference signal. By using the signal phase reference in the reference signal, we clarify the spatial propagation characteristics obtained from the two-dimensional virtual array outputs. Outdoor measurements were performed first to investigate the validity of the proposed measurement system. The results confirm its effectiveness in accurately determining the direction-of-arrival (DOA). We then investigated the propagation characteristics in an indoor environment. The angular spectrum obtained showed clear wave propagation structure. Thus, our proposed system is promising as a very accurate measurement tool for indoor propagation analysis.
Scientific journal, English - Utilization of multiantenna full-duplex relay for post-disaster cellular network recovery
T. Taniguchi; Y. Karasawa; Nakajima,N
2013 7th European Conference on Antennas and Propagation, EuCAP, 2030-2034, Apr. 2013, Peer-reviwed
International conference proceedings, English - Error probability of opportunistic decode-and-forward relaying in nakagami-m fading channels with arbitrary m
Qinghua Shi; Y. Karasawa
IEEE Wireless Communications Letters, Institute of Electrical and Electronics Engineers Inc., 2, 1, 86-89, 2013, Peer-reviwed, We investigate the error performance of opportunistic decode-and-forward (DF) relaying in Nakagami-m fading with arbitrary m≥ 0.5. In particular, we obtain exact moment generating function (MGF) expressions in terms of Lauricella hypergeometric function (LHF) for opportunistic DF relaying with maximal ratio combining (MRC) or selection combining (SC). In the case of SC, the cumulative density function (CDF) of the receive SNR is also derived and based on the CDF, two error probability expressions for opportunistic DF relaying with SC are provided. Further, we show that the MGF expressions can be greatly simplified when average SNRs become large. From asymptotic analysis, the diversity order of opportunistic DF relaying is identified. © 2013 IEEE.
Scientific journal, English - Broadband block diagonalization method for single carrier multiuser MIMO network - A time-domain approach
Tetsuki Taniguchi; Yoshio Karasawa
2013 International Conference on Smart Communications in Network Technologies, SaCoNeT 2013, 1, 2013, Peer-reviwed, This paper presents a simple design method of single carrier broadband broadcasting weights in multiuser multiple input multiple output (MIMO) network based on the extension of block diagonalization modified for application to frequency selective channels. The proposed approach assumes time-domain processing using tapped delay line (TDL) structure, hence it can avoid the peak to average power ratio (PAPR) problem, and simultaneously, it does not require the addition of cyclic prefix which results in the reduction of data transmission rate. By using sufficient number of TDL, the components of desired signal contained in all the delay path can be utilized, and all the interferences are completely excluded in theoretical sense. In the description of design process, the relation of spatiotemporal degrees of freedom and number of streams, antennas, and tapped delay length is also discussed including the limitation of the proposed method. Then throught computer simulations, the effectiveness and typical natures of the proposed approach are verified. © 2013 IEEE.
International conference proceedings, English - 環境適応型ベースバンド無線の空 間伝送評価実験
森本勇樹; Le Manh Tien; 唐沢好男
信学論(C), J95-C, 12, Dec. 2012
Scientific journal, Japanese - On Correlated Generalized Rician Fading Based on Gaussian Class Multivariate Distributions with Generalized Correlation
Qinghua Shi; Y. Karasawa
IEEE COMMUNICATIONS LETTERS, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 16, 12, 1925-1928, Dec. 2012, Gaussian class multivariate distributions with single integral representations were recently proposed to obtain correlated fading channels with generalized correlation. In this letter, we focus on correlated generalized Rician fading channels, derived from Gaussian class multivariate distributions. We present a comprehensive investigation on the statistical properties of correlated generalized Rician fading channels. Specifically, closed-form expressions for joint probability density function (PDF), marginal PDF, power correlation, joint moment, and joint characteristic function are elaborated. These statistical characterizations help us have a better understanding of the correlated generalized Rician channels and allow for some new applications in performance analysis of diversity schemes and, particularly, maximal ratio combining over correlated fading channels with generalized correlation.
Scientific journal, English - Design and analysis of MIMO multiuser system using full-duplex multiple relay nodes
F. Tamrin, A; Rizwan; Ichiro Oshima; Yoshio Karasawa
Wireless Days, Wireless Days, Nov. 2012, Peer-reviwed
International conference proceedings, English - An accurate approximation to channel capacity of wireless communications systems
T. Taniguchi; Y. Karasawa
The 13th International Conference on Communication Systems, ICCS 2012, Nov. 2012, Peer-reviwed
International conference proceedings, English - Expaeimental Validation of Adaptiv Baseband Radio in Multipath Environment
Yuki Morimoto; Manh Tien Le; Dinh Thanh Le; Y. karasawa
Triangle Symposium on Advanced ICT 2012, TriSAI 2012, Sep. 2012, Peer-reviwed
International conference proceedings, English - Effect of coordinated base station in uplink transmission under disaster cells
T. Taniguchi; Y. Karasawa; N. Nakajima
2012 International Conference On Smart home and health Telematics, iCOST2012, Jul. 2012, Peer-reviwed
International conference proceedings, English - Arrival angle distribution control in MIMO-OTA measurement environment using double-layered reverberation chamber
Oshima, I; Karasawa, Y
Antennas and Propagation (ISAP), 2012 International Symposium on, 279-282, Jun. 2012
Scientific journal, English - Spatial Correlation Functions in Three-dimensional APS with cosn??
Wang, Y; Dang, H.L; Karasawa, Y
Antennas and Wireless Propagation Letters, IEEE, PP, 99, 1, May 2012
Scientific journal, English - Some applications of lauricella hypergeometric function F A in performance analysis of wireless communications
Qinghua Shi; Y. Karasawa
IEEE Communications Letters, 16, 5, 581-584, May 2012, Lauricella hypergeometric function (LHF) F A is often used in the performance analysis of wireless communications, especially diversity systems. In this letter, F A is applied to solve two challenging problems: (1) a product of error functions averaged over generic fading channels and (2) error probability of BPSK modulation with equal-gain combining (EGC) in independent Nakagami-m fading channels. Closed-form expressions in terms of F A are obtained. In addition, a novel and efficient approximation to F A is presented. © 2012 IEEE.
Scientific journal, English - Distributed Relay Selection for MIMO-SDM Cooperative Networks
Xuan Nam Tran; Vinh Hanh Nguyen; Thanh Tam Bui; The Cuong Dinh; Yoshio Karasawa
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E95B, 4, 1170-1179, Apr. 2012, In this paper, we Consider an amplify-and-forward cooperative wireless network in which network nodes use multiple input multiple output (MIMO) spatial division multiplexing (SDM) to communicate with one another. We examine the problem of distributed cooperative relay selection and signal combining at the destination. First, we propose three distributed relay selection algorithms based on the maximum channel gains, the maximum harmonic mean of the channel gains, and the minimum mean squared error (MSE) of the signal estimation. Second, we propose a minimum mean square error (MMSE) signal combining scheme which jointly serves as the optimal signal combiner and interference canceler. It is shown that the MSE selection together with the MMSE combining achieves the maximal diversity gain. We also show that in MIMO-SDM cooperative networks increasing the number of candidate nodes does not help to improve the BER performance as opposed to the cooperative networks where each node is equipped with only single antenna. A practical approach to implementation of the combiner based on the current wireless access network protocols will also be presented.
Scientific journal, English - Automatic Modulation Identification Based on the Probability Density Function of Signal Phase
Qinghua Shi; Y. Karasawa
IEEE TRANSACTIONS ON COMMUNICATIONS, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 60, 4, 1033-1044, Apr. 2012, Automatic modulation recognition is advantageous for wireless communication systems employing adaptive modulation, software-defined radio, and cognitive radio. In this paper, we consider a phase based maximum likelihood (ML) approach for identifying the modulation format of a linearly modulated signal. Since the optimal ML scheme is computationally intensive, we propose two approximate ML alternatives, which can offer close-to-optimal performance with reduced complexity. We then present a general performance analysis for classification of K types of modulation constellations. For K <= 5, probability of correct classification (Pcc) can be evaluated via simplified integration. In the case of K > 5, we obtain a set of upper bounds on Pcc, which provide a tradeoff between accuracy and complexity in calculating the Pcc. In addition, asymptotic behavior of phase based ML classification schemes is investigated.
Scientific journal, English - An Intuitive Methodology for Efficient Evaluation of the Nuttall Q-Function and Performance Analysis of Energy Detection in Fading Channels
Qinghua Shi; Y. Karasawa
IEEE WIRELESS COMMUNICATIONS LETTERS, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 1, 2, 109-112, Apr. 2012, We start with the computation of the Nuttall Q-function using Gauss quadrature rules. Since the integrand of the Nuttall Q-function is characterized by an exponential kernel function, the semi-infinite Gauss-Hermite quadrature is employed to efficiently calculate the tail probability involved. As such, with the help of the Gauss-Legendre quadrature, the Nuttall Q-function with arbitrary real orders can be accurately approximated in closed form. This methodology is then extended to provide closed-form approximations for other related semi-infinite integrals encountered in performance analysis of energy detection in fading channels.
Scientific journal, English - Development of a MIMO-OTA System with Simplified Configuration
Y. Karasawa; Y. Gunawan; S. Pasisingi; K. Nakada; A. Kosako
Journal of the Korean Institute of Electromagnetic Engineering and Scinece (JKIEES), 12, 1, 77-84, Mar. 2012
Scientific journal, English - 人体を伝送路として利用する通信における伝送特性の実験的検討
高崎和之; 原和樹; 前山利幸; 唐沢好男
数理科学会論文誌, vol. 13, 1, 21-26, Mar. 2012, Peer-reviwed
Scientific journal, Japanese - フェージングエミュレータ型MIMO-OTA測定システムの簡易構成法
小佐古 昂; 篠沢政宏; 唐沢好男
電子情報通信学会論文誌 B, J95-B, 2, 275-284, Feb. 2012
Scientific journal, Japanese - Performance of frequency-domain oversampling based receiver for MIMO-OFDM systems in doubly selective fading channels
Qinghua Shi
Proceedings of the International Symposium on Wireless Communication Systems, ICICS 2011, 381-385, 2012, Peer-reviwed, We are concerned with the performance of MIMO-OFDM receiver operating in a doubly selective fading channel (also called time-varying multipath fading channel). Both linear and nonlinear detection schemes are considered. In particular, frequency-domain oversampling (FDO) is employed at the receiver to take advantage of the channel diversity inherent to multipath fading channels. Simulation results demonstrate that compared with its conventional counterpart without using FDO, the FDO based receiver can offer significantly better error performance for linear as well as non-linear detection and various MIMO configurations (single or multiple antennas) under different channel conditions (quasi-static or time-varying multipath fading). © 2012 IEEE.
International conference proceedings, English - An Approximation Method for Evaluating SIMO-OFDM MRC System in Multipath Environment Where Delay Profile Exceeds the Guard Interval
Quoc-Anh Vu; Changarkame Vanmany; Anmol Bajracharya; Yoshio Karasawa
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E95B, 1, 77-86, Jan. 2012, Equivalent Transmission Path (ETP) model-based BER map method was proved to be used in fast estimating Bit Error Rate (BER) of Single-Input Single-Output Orthogonal Frequency Division Multiplexing (SISO-OFDM) system, where the delay spreading exceeds the guard interval. In this paper, we propose a method for evaluating transmission characteristics of Single-Input Multiple-Output Orthogonal Frequency Division Multiplexing (SIMO-OFDM) system with application to maximum ratio combining diversity at the reception. The simulation results show that the proposed approximation method is able to be used in estimating trasmission characteristics with high accuracy not only for SISO-OFDM system but also for SIMO-OFDM system.
Scientific journal, English - A Simple Broadband Antenna for MIMO Applications in Cognitive Radio
Dinh Thanh Le; Yoshio Karasawa
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E95B, 1, 18-26, Jan. 2012, In this paper, a simple type of printed dipole is proposed for Multi-Input Multi-Output (MIMO) applications in cognitive radio. The antenna is composed of a transmission line and a dipole. Some examinations of key factors and optimized parameters of the antenna are presented. The measured results illustrate that the proposed antenna offers a bandwidth of over 50% for Voltage Standing Wave Ratio (VSWR) less than 2, extending from 2.4 GHz to 4.0 GHz. The antenna peak gain in E-plane and radiation patterns at different frequencies are also explored. In addition, based on the proposed antenna, we introduce two simple broadband arrays for MIMO applications in cognitive radio. One has two ports and the other has four ports. Measurement results indicate that the arrays also work in a broad bandwidth. Mutual couplings between ports in each array are kept under -10 dB at the low frequencies and under -20 dB at the high frequencies of bandwidth of the arrays. Furthermore, we utilized the antenna arrays for some MIMO experiments to estimate the channel capacity in a wide frequency range.
Scientific journal, English - Design and analysis of single carrier base station cooperation system under frequency selective channel
T. Taniguchi; Y. Karasawa; N. Nakajima
Proceedings of 6th European Conference on Antennas and Propagation, EuCAP 2012, EuCAP2012, 1873-1876, 2012, Peer-reviwed, This paper investigates the effectiveness of base station cooperation (BSC) in single carrier (SC) multiantenna cellular system under frequency selective channel (FSC). The feature of this paper is to consider wideband multiuser system without frequency domain processing like the discrete Fourier transform (DFT), but instead adopting time domain operation using tapped delay line. After some weight design approaches for multiuser (multiple point to multiple point) multiple input multiple output (MIMO) system with and without BSC are described, actual effect of BSC under FSC is evaluated through computer simulations taking into account the path loss, shadowing, and fading. The results show the significant performance improvement by BSC and its problems which further need investigations. © 2012 IEEE.
International conference proceedings, English - A novel compact ultra-wideband dipole antenna
Dinh Thanh Le; Yoshio Karasawa
Proceedings of 6th European Conference on Antennas and Propagation, EuCAP 2012, EuCAP2012, 2815-2818, 2012, Peer-reviwed, A compact printed ultra-wideband dipole antenna is proposed. The antenna is integrated with a parallel transmission line and a patch. The components of the antenna are etched onto a piece of printed circuit board (PCB) with an overall size of 9 mm × 57.5 mm × 1.6 mm. The measured results of the antenna illustrate that it offers a bandwidth of over 95.5% for VSWR less than 2, covering from 3.5 GHz to 9.9 GHz. Radiation patterns, current distributions, and antenna gains at different frequencies are also explored. It is shown that the antenna has good gains, and similar radiations as those of a conventional dipole. In addition, some parametric studies of the geometric and electric parameters of the proposed antenna will be explored within further discussions to provide an inside view of antenna design. © 2012 IEEE.
International conference proceedings, English - Effect of Cooperative Base Stations and Relay Stations for Disaster Recovery in MIMO Multi-Cellular System
Tetsuki Taniguchi; Yoshio Karasawa; Nobuo Nakajima
2012 6TH INTERNATIONAL CONFERENCE ON NEXT GENERATION MOBILE APPLICATIONS, SERVICES AND TECHNOLOGIES (NGMAST), IEEE COMPUTER SOC, 141-146, 2012, It has been shown that cooperative work of base stations (BSs) is effective for the disaster recovery; namely, even if BSs in some cells are destroyed and user terminals (UTs) should communicate with another BS in a far away distance, coordination scheme of survived BSs can mitigate the degradation of link quality in disaster cells. This paper extends this scheme to relay-aided case attempting the further performance improvement; after certain time has passed from disaster, the arrival of portable relay systems could be anticipated if they are previously prepared. Allocating one relay to each cell with a defect BS, the effectiveness of relay-aided processing and influence of related parameters are evaluated from the viewpoint of cooperative transmission through computer simulations. It is shown that the use of relay is not always preferred, but under certain condition, it brings significant performance improvement in disaster cells.
International conference proceedings, English - Effect of Cooperative Base Stations and Relay Stations for Disaster Recovery in MIMO Multi-Cellular System
Tetsuki Taniguchi; Yoshio Karasawa; Nobuo Nakajima
2012 6TH INTERNATIONAL CONFERENCE ON NEXT GENERATION MOBILE APPLICATIONS, SERVICES AND TECHNOLOGIES (NGMAST), IEEE COMPUTER SOC, NGMAST, 141-146, 2012, Peer-reviwed, It has been shown that cooperative work of base stations (BSs) is effective for the disaster recovery; namely, even if BSs in some cells are destroyed and user terminals (UTs) should communicate with another BS in a far away distance, coordination scheme of survived BSs can mitigate the degradation of link quality in disaster cells. This paper extends this scheme to relay-aided case attempting the further performance improvement; after certain time has passed from disaster, the arrival of portable relay systems could be anticipated if they are previously prepared. Allocating one relay to each cell with a defect BS, the effectiveness of relay-aided processing and influence of related parameters are evaluated from the viewpoint of cooperative transmission through computer simulations. It is shown that the use of relay is not always preferred, but under certain condition, it brings significant performance improvement in disaster cells.
International conference proceedings, English - Performance Analysis of Base Station Cooperation in Multiantenna Cellular System
Tetsuki Taniguchi; Yoshio Karasawa; Nobuo Nakajima
IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E94A, 11, 2254-2262, Nov. 2011, In cellular systems, particular in the cell edge, the user terminals (UTs) are suffered from the attenuation of the signal from their target base station (BS) and the relatively strong interferences from BSs of other users. This paper investigates the performance improvement under this bad situation by BS cooperation (BSC) in the downlink scenario using multiantenna transmission assuming the perfect channel state information (CSI), and compares the effectiveness of several strategies based on a three cell model. Through computer simulations, the performance improvement by BSC is verified. Then the result is extended to multiple stream transmission utilizing the feature of multiantenna, and advantage of BSC with data sharing is shown.
Scientific journal, English - Fundamntal propagation characteristecs in a 4(m)×2(m)×2(m)-sized reverberation chamber for NINO-OTA measurements
F. Tamrin, A; Rizwan; Ichiro Oshima; Yoshio Karasawa
International Conference on Wireless Information Theory and Systems, ICWITS, Nov. 2011, Peer-reviwed
International conference proceedings, English - 小型高効率な非接触型電力・情報同時伝送方式
高崎和之; 唐沢好男
電子情報通信学会論文誌 B, J94-B, 10, 1389-1396, Oct. 2011
Scientific journal, Japanese - Analysis of Cellular System Using Coordinated Base Stations with Nonuniform and Flexible Cells
T. Taniguchi; Y. Karasawa; N. Nakajima
The 14th International Symposium on Wireless Personal Multimedia Communications. The 14th Wireless Personal Multimedia Communications Symposium (WPMC'11), 1-5, Oct. 2011
International conference proceedings, English - Performance Analysis of Coordinated Bases Stations in Multi-cellular Network Using Multistream Transmission and Different Size Cells
T. Taniguchi; Y. Karasawa; N. Nakajima
The Sixth International Conference on Systems and Networks Communications ICSNC 2011, ICSNC2011, Oct. 2011, Peer-reviwed
International conference proceedings, English - A Generalized Formula for Spatial Correlation in Three-dimensional Fading Environment
Yi Wang; Yoshio Karasawa
2011 International Symposium on Antennas & Propagation (ISAP), ISAP 2011, Oct. 2011, Peer-reviwed
International conference proceedings, English - 10 A Simplifi ed Confi guration of MIMO-OTA System for Realizing Wideband Propagationrespectively
Yoshio Karasawa; Akira
2011 International Symposium on Antennas & Propagation (ISAP), ISAP 2011, Oct. 2011, Peer-reviwed
International conference proceedings, English - 二重電波反射箱によるマルチパス伝搬環境制御
大島一郎; 唐沢好男
電子情報通信学会論文誌 B, J94-B, 9, Sep. 2011
Scientific journal, Japanese - Wideband MIMO Compact Antennaa with Tri-Polarizations
D.T. Le; M. Shinozawa; Y. Karasawa
EICE Trans. Commun, 7, Jul. 2011
Scientific journal, English - A Simple Broadband Antenna for MIMO Applications in Cognitive Radio
Dinh Thanh Le; Y. Karasawa
AP-S Symposium & USNC/URSI Meeting, AP-S Symposium & USNC/URSI Mee, Jul. 2011
International conference proceedings, English - On signal Phase Based Moudulation Classification
Qinghua Shi; Y. Karasawa
IEEE International Conference on Communications, IEEE ICC2011, Jun. 2011
International conference proceedings, English - Propagation Channel Modeling in the Mixture of NLOS and LOS Environments for MIMO-MRC System and Its Application to ITS-IVC
Yi Wang; Kenji Ito; Yoshio Karasawa
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E94B, 5, 1207-1214, May 2011, This paper presents a Multiple-Input Multiple-Output (MIMO) propagation model for independent and identically distributed (i.i.d.) channels in the mixture of none-Line-of-Sight (NLOS) and Line-of-Sight (LOS) environments. The derived model enables to evaluate the system statistical characteristics of Signal-to-Noise-Ratio (SNR) for MIMO transmission based on Maximal Ratio Combing (MRC). An application example applying the model in 2 x 2 configuration to ITS Inter-Vehicle Communication (IVC) system is introduced. We clarify the effectiveness of the proposed model by comparisons of both computer simulations and measurement results of a field experiment. We also use the model to show the better performance of SNR when applying MIMO to IVC system than SISO and SIMO.
Scientific journal, English - Statistical Analysis of MIMO Keyhole Channels under Double Rayleigh and Double Nakagami-Rice Fadings
Tetsuki Taniguchi; Yoshio Karasawa; Makoto Tsuruta
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E94B, 5, 1215-1224, May 2011, This paper gives statistical analysis of double fading channels which are typically found in keyhole MIMO (multiple input multiple output) models. First, to investigate the potential of identically distributed double Nakagami-Rice MIMO keyhole channels including LOS (line of sight) environment, the density function of SNR (signal to noise ratio) which corresponds to the only one non-zero eigenvalue of channel correlation matrix is presented. In addition to the exact expression with an infinite series form, an approximation formula with a simple monomial form derived by substituting Nakagami in formula for Rician distribution is also considered. Next, similar equations are introduced for double Rayleigh channels which have correlated branches in both the transmitter and receiver sides (independent but nonidentical case is included here). Through computer simulations, the effectiveness of the proposed formulae is verified, and in double Nakagami-Rice fading case, the advantage of the approximated formula particularly for large array size and/or large Rician factor is demonstrated.
Scientific journal, English - An Accurate and Efficient Approximation to the Gaussian Q-Function and its Applications in Performance Analysis in Nakagami-m Fading
Qinghua Shi; Y. Karasawa
IEEE COMMUNICATIONS LETTERS, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 15, 5, 479-481, May 2011, Based on the semi-infinite Gauss-Hermite quadrature rule defined in [0,infinity), we present an accurate and efficient approximation to the Gaussian Q-function, which is expressed as a finite sum of exponential functions. We then extend to address the problem of a product of Gaussian Q-functions averaged over Nakagami-m fading, ending up with a closed-form solution applicable for any real m >= 0.5. Numerical examples show that the proposed method with only N = 2 terms can give error probabilities (in closed form) that are virtually indistinguishable from the exact results obtained by numerical integration.
Scientific journal, English - A novel compact antenna for broadband MIMO
Dinh Thanh Le; Yoshio Karasawa
2011 2nd International Conference on Wireless Communication, Vehicular Technology, Information Theory and Aerospace and Electronic Systems Technology, Wireless VITAE 2011, Wireless VITAE 2011, 2011, In this paper, a simple broadband antenna in a compact size is firstly proposed. Antenna configuration and its characteristics such as VSWR, radiation patterns, and gain have been explored and discussed. The measured results illustrate that the proposed antenna offers a bandwidth of over 50% for VSWR less than 2. It also has high cross-polarization levels, and good gains varying from about 0.5 dBi to 4.5 dBi in the whole entire bandwidth. Moreover, we introduced some similar broadband antennas which also offer relative bandwidth of over 50% at different centre frequencies. These antennas can be easily obtained by adjusting some simple geometrical parameters without changing material or substrate's thickness. Secondly, we propose a simple and compact two-port broadband array which is based on the elemental design. The mutual coupling of ports of the array is kept around 10 dB at the low frequence band and around 20 dB at the high frequence area of the array's bandwidth. The proposed broadband antennas are promissing for wideband applications such as broadband MIMO systems. © 2011 IEEE.
International conference proceedings, English - Simplified configuration of fading emulator system for MIMO-OTA testing
Akira Kosako; Masahiro Shinozawa; Yoshio Karasawa
2011 2nd International Conference on Wireless Communication, Vehicular Technology, Information Theory and Aerospace and Electronic Systems Technology, Wireless VITAE 2011, Wireless VITAE 2011, 2011, OTA (Over-The-Air) system, which is one of the MIMO terminal evaluation methods, achieves real multipath fading environment around the measurement device, and it is currently being standardized. Fading emulator, one of MIMO-OTA measurement systems, can achieve the desired propagation environment around assessment area by radio waves radiated from a number of antennas placed on a circle around the terminal. This paper proposes a simplified configuration of fading emulator system, and evaluates the performance in terms of eigenvalues and channel capacity obtained by the computer simulation and experiment. © 2011 IEEE.
International conference proceedings, English - MIMO cellular systems with irregular cell geometry based on base station cooperation
Tetsuki Taniguchi; Yoshio Karasawa; Nobuo Nakajima
IEEE Vehicular Technology Conference, 1-5, 2011, In actual cellular systems, base station (BS) may not be located in the cell center because of physical restrictions. This paper investigates, assuming such a situation, the effectiveness of BS cooperation (BSC) in MIMO (multiple input multiple output) cellular system under irregular cell geometry. The cell shapes are determined by BS position based on Voronoi diagram, namely, UTs (user terminals) communicate the nearest BS. The influence of BS displacement is evaluated for several patterns using typical spatial processing algorithms. Through computer simulations, it is demonstrated that the BSC is effective under this situation, and how the BS displacement affects the system performance. © 2011 IEEE.
International conference proceedings, English - Indoor direction finding of terrestrial TV signals based on total recording
Kazuo Morokuma; Yoshio Karasawa
IEEE International Symposium on Broadband Multimedia Systems and Broadcasting, BMSB 2011 - Conference Programme, IEEE, BMSB 2011, 2011, We have shown that high-accuracy DOA estimation can be obtained by the use of a total recording technique which simultaneously records the output signals from the elements of a virtual array antenna and a reference antenna, representing the target signals and a high-quality reference signal, and performing a correlation analysis of these signals. The method proposed in this paper enables two-branch recording of the target signals and the reference signal. By adopting two-dimensional virtual array measurement, we obtained an angular spectrum in full range of 0-360. Outdoor measurements were first performed to investigate the validity of the proposed measurement method. The results confirmed its effectiveness in determining DOAs very accurately. We then investigated the system performance in an indoor environment, which is the ultimate objective of this study. The angular spectrum obtained showed five arriving waves, and allowed determination of the angular profile and the wave propagation structure. In conclusion, we have had a very accurate measurement tool for indoor propagation. © 2011 IEEE.
International conference proceedings, English - Novel Approximation for the Gaussian Q-Function and Related Applications
Qinghua Shi
2011 IEEE 22ND INTERNATIONAL SYMPOSIUM ON PERSONAL INDOOR AND MOBILE RADIO COMMUNICATIONS (PIMRC), IEEE, 2030-2034, 2011, Using the semi-infinite Gauss-Hermite quadrature rule defined in [0; infinity), we present an accurate and efficient approximation to the Gaussian Q-function, which is expressed as a finite sum of exponential functions. Based on this approximation, we address a product of Gaussian Q-functions averaged over Nakagami-m fading, ending up with a closed-form solution applicable for any real m >= 0.5. We further consider more general situations, in which the Gaussian Q-function is involved in more complicated ways. Numerical examples show that the proposed method with very few terms can give error probabilities (in closed form) that are virtually indistinguishable from the exact results obtained by numerical integration.
International conference proceedings, English - Blind channel estimation for MIMO MC-CDMA with arbitrary numbers of antennas and users
Qinghua Shi; Y. Karasawa
Proceedings of the 5th International Workshop on Signal Design and Its Applications in Communications, IWSDA'11, IWSDA 2011, 177-180, 2011, Peer-reviwed, A subspace blind channel estimation scheme is proposed for multicarrier(MC)-CDMA systems using multiple antennas. To obtain noise subspace that is essential for subspace blind channel estimation, frequency-domain over-sampling (FDO) is employed at the receiver side. A unique feature of this scheme is that it is applicable to general MC-CDMA systems without any constraint on the numbers of antennas and users. In particular, it can be applied in two challenging situations, for which existing schemes fail: (1) the number of transmit antennas is larger than the number of receive antennas
(2) the number of users is larger than the processing gain. In other cases, the proposed scheme also compare favorably with other existing schemes. © 2011 IEEE.
International conference proceedings, English - Base station cooperation in multiantenna cellular system with defect cells
Tetsuki Taniguchi; Yoshio Karasawa; Nobuo Nakajima
LAPC 2011 - 2011 Loughborough Antennas and Propagation Conference, LAPC 2011, 2011, Peer-reviwed, This paper proposes utilization of base station cooperation (BSC) in multiantenna cellular system under the situation with defect cells, namely, BSs in some cells are damaged and not working. The background idea is that user terminals (UTs) in defect cells might use a weak connection with adjacent cells, but the communication quality could be improved by cooperative transmission/reception of BSs mutually connected in backhaul. Here we make quantitative evaluation of BSC effect by computer simulations assuming two kinds of cell patterns with out-of-service BSs. The results show that BSC is effective to improve the performance degradation in defect cells. © 2011 IEEE.
International conference proceedings, English - Performance improvement of multiantenna cellular system using cooperation of base stations and relay stations
T. Taniguchi; Y. Karasawa; N. Nakajima
IEEE GLOBAL COMMUNICATIONS CONFERENCE, IEEE GLOBECOM 2010, Dec. 2010
International conference proceedings, English - MIMO-OTA Measurement Schemes for User Termunal Evaluation, Fading Emulator vs. Reverberation Chamber
Y. Karasawa
Asia-Pacific Microweve Conference, APMC2010, Workshop, Dec. 2010
International conference proceedings, English - 任意ドップラースプレッドのマルチパス環境を実現するMIMO端末特性評価用電波反射箱
篠沢政宏; パシシンギ・サハルル; アリフ・リズワン; 唐沢好男
電子情報通信学会論文誌 C, J93-C, 12, 612-621, Dec. 2010
Scientific journal, Japanese - Base Station Cooperation in Multi-Cellular Syste, Using Multi-Sttream Communications
T. Taniguchi; Y. Karasawa; N. Nakajima
5th European Conference on Circuits and Systems for Communications, ECCSC'10, Nov. 2010
International conference proceedings, English - Impact of base station location in MIMO cellular system using cooperative transmission
T. Taniguchi; Y. Karasawa; N. Nakajima
WD2010, Oct. 2010., Oct. 2010
International conference proceedings, English - Performance improvement of MIMO cellular system based on cooperative base stations
T. Taniguchi; Y. Karasawa; N. Nakajima
TriSAI2010, Oct. 2010., Oct. 2010
International conference proceedings, English - Effect of Base Station Cooperation in MIMO Cellular Systems
Y. Karasawa
2010 Workshop on Smart Info-Media Systems in Asia, SISA 2010, Sep. 2010
International conference proceedings, English - Blind Channel and Frequency Offset Estimation for OFDM via Frequency-Domain Oversampling
Qinghua Shi; Y. Karasawa
The 6th Int. Conf. Wireless Communs., Networking and Mobile Computing, WiCOM2010, Sep. 2010
International conference proceedings, English - Design and analysis of MIMO multiuser system under coexistence of direct and relay-aided links
T. Taniguchi; Y. Karasawa; N. Nakajima
The European Microwave Week, EuMW2010, Sep. 2010
International conference proceedings, English - 電磁波吸収ロックウール天井板施工による5 GHz帯及び2.4 GHz帯無線LAN伝送特性の改善
有川禎昭; 唐沢好男
電子情報通信学会論文誌 B, The Institute of Electronics, Information and Communication Engineers, 93-B, 7, 1006-1016, Jul. 2010, 本論文では室内反射環境を自在に変化できる広さ5m×5.3mの実験室において,遅延の広がりが大きいマルチパス環境を構築し,IEEE801.11aに準拠した5GHz帯無線LAN機器,及びIEEE801.11bに準拠した2.4GHz帯無線LAN機器を用いてデータ伝送実験を実施した.その結果,遅延スプレッドが200ns程度の高反射環境下ではデータレートが低下してしまう一方で電磁波吸収天井板を施工して環境を改善することによってデータレートが向上することが分かった.また,実験を通じて,遅延スプレッドとデータレートの関係を定量的に明らかにし,遅延スプレッドを100ns以内に抑圧できれば,効果として十分なことを示した.
Scientific journal, Japanese - OFDM Symbol Detectionj Based on Frequency-Domain Oversampling
Qinghua Shi; Y. Karasawa
2010 IEEE Int. Conf. Wireless Communs. Networking and Info. Security, WCNIS 2010, Jun. 2010
International conference proceedings, English - Frequency-Domain Oversampling Based Receivers for Orthogonal Frequency Division Multiplexing: Linear MMSE and Nonlinear VBLAST Algorithms
Qinghua Shi; Y. Karasawa
2010 IEEE 71st Vehicular Technology Conference, IEEE VTC2010-Spring, May 2010
International conference proceedings, English - Robust Maximum Likelihood Classification of Quadrature Amplitude Modulation
Qinghua Shi; Y. Karasawa
The 2010 IEEE Wireless Communications and Networking Conference, IEEE WCNC 2010, Apr. 2010
International conference proceedings, English - Design of two way multiantenna af relay systems under perfect CSI
T. Taniguchi; Y. Karasawa; N. Nakajima
the 4th European Conference on Antennas and Propagation, EuCAP2010, Apr. 2010
International conference proceedings, English - Noncoherent Maximum Likelihood Classification of Quadrature Amplitude Modulation Constellations: Simplification, Analysis, and Extension
Qinghua Shi; Y. Karasawa
IEEE Transactions on Wireless Communications, 10, 4, 1312, Apr. 2010
Scientific journal, English - Advanced MIMO STBC Adaptive Array with PSAM in Fast Fading Channel
Susumu Sasaki; Supawan Annanab; Tetsuki Taniguchi; Yoshio Karasawa
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E93B, 3, 660-669, Mar. 2010, We provide an efficient transmission scheme which embeds a pilot signal in the data signal for channel state information (CSI) based on the configuration of a multiple-input multiple-output (MIMO) system using space-time block coding (STBC) with an adaptive array (AA) A computer simulation and analysis show that the proposed scheme, which combines the advantage of an Alamouti-like STBC scheme and the pilot-based AA can suppress the irreducible error due to random FM noise The proposed scheme using a pilot minimizes the decoding delay, and is highly robust against fast fading. We show that the proposed scheme can significantly increase the data transmission rate by using the transmitter diversity based on STBC. and the accuracy of the proposed technique is exemplified by a computer simulation
Scientific journal, English - 高速フェージングに耐性を有する準直交STBC伝送方式
佐々木進; イスラム・モハンマド・ザヒドル; 谷口哲樹; 唐沢好男
電子情報通信学会論文誌 B, J94-B, 2, 245-252, Feb. 2010
Scientific journal, Japanese - Design of multiuser MIMO AF relay system with interference cancellation
T. Taniguchi; N. Bin Ramli; Y. Karasawa
IWCMC 2010 - Proceedings of the 6th International Wireless Communications and Mobile Computing Conference, IWCMC 2010, 1075-1080, 2010, This paper describes design methods of multiuser MIMO (mul-tiple input multiple output) AF (amplify and forward) re-lay system. Assuming the application to multi-cellular systems, the cancellation of interuser interference is considered both in the first and second hops under perfect knowledge of CSI (channel state information). First, a maximal SINR (signal to interference plus noise ratio) approach using iterative optimization is given. Then a partial ZF (zero forcing) based method which cancels all the interferences not only in one side of transmitter or receiver, but by cooperative work of source-relay and/or relay-destination is considered both for nonseparable and separable relay weight matrices. By this operation, the restriction on the antenna number required for ZF could be released. Through computer simulations, the effectiveness of the proposed method is demonstrated. Copyright © 2010 ACM.
International conference proceedings, English - Frequency-domain oversampling based blind channel estimation for MIMO-OFDM
Qinghua Shi; Y. Karasawa; Ying Wang
12th IEEE International Conference on Communication Systems 2010, ICCS 2010, EEE ICCS 2010, 136-140, 2010, By using frequency-domain oversampling at the receiver, we propose a novel blind channel estimation scheme for multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems. Specifically, a subspace blind channel estimation approach is developed, based only on second-order statistics of the received signal. The estimated MIMO channel is nicely determined by Nt minimum eigenvectors of a Hermitian matrix, where Nt is the number of transmit antennas. Numerical results show that the proposed scheme performs significantly better than an existing linear precoding based alternative when signal-to-noise ratio is high and/or when the length of observation window (used to obtain noise subspace) is relatively large. In addition, the proposed scheme does not impose stringent requirements on the number of transmit antennas and, therefore, is applicable to general MIMO scenarios including MIMO, multiple-input single-output (MISO), singleinput multiple-output (SIMO), and single-input single-output (SISO). © 2010 IEEE.
International conference proceedings, English - Design of MIMO relay systems with interference cancellation under perfect CSI
Tetsuki Taniguchi; Nordin Bin Ramli; Yoshio Karasawa
Loughborough Antennas and Propagation Conference, LAPC 2009 - Conference Proceedings, LAPC 2009, 473-476, 08 Dec. 2009, This paper describes a design method of two-hop single and multiple relay systems in which sources, relays, and destination are equipped with multiple antenna. The existence of interference signal and perfect CSI (channel state information) condition are assumed, and the design is carried out based on the maximum SINR (signal to interference plus noise ration) criterion. For multiple relay case, array weights are designed independently between first and second hops by adopting separable weight matrices in relays. Through computer simulations, the effectiveness of the proposed methods is verified. © 2009 IEEE.
International conference proceedings, English - Design of Multiuser MIMO AF Relay System for Multi-Cellular Networks
T. Taniguchi; Y. Karasawa; N. B. Ramli
IEEE 9th Malaysia Int. Conf. Commun., MICC 2009, Dec. 2009
International conference proceedings, English - Blind Channel Estimation for OFDM and Multicarrier CDMA Systems Using Frequency-Domain Oversampling
Qinghua Shi; Y. Karasawa
The 2009 International Conference on Wireless Communications and Signal Processing, IEEE WCSP 2009, Nov. 2009
International conference proceedings, English - Weight design of AF MIMO relay system with perfect channel state information
T. Taniguchi; Y. Karasawa; N. Nakajima
9th International Conference on Intelligent Transport Systems Telecommunications, ITST 2009, 164 - 169, 20-22, Oct. 2009
International conference proceedings, English - トータルレコーディング技術に基づく 地上デジタル放送マルチパス波の到来方向・遅延時間高分解能測定法
竹本淳; 高橋宏和; 唐沢好男
信学論(B), The Institute of Electronics, Information and Communication Engineers, J92-B, 9, 1381-1389, Sep. 2009, 地上デジタル放送について,室内での受信並びに周囲に建造物が林立する環境での固定受信においては,一般に弱電界エリアであることが多く,直接波の受信が期待できないこと,マルチパス環境が顕著に影響するために伝搬環境,特に受信所望波の到来方向及び遅延時間の定量的かつ高分解能な把握が重要となる.このための到来方向推定にはアレーアンテナが有用であるが,一般的手法では複数の到来波を判定するために波数と比べアレー素子数を十分大きくする必要があるほか,すべてのブランチの信号を一括して同時に取得しなければならない.また,遅延時間の推定には受信側において既知の広帯域信号が必要になることから,実放送波を利用する到来波・遅延時間推定には有用かつ簡便な手法が確立されていない.そこで,本論文では,高SN比の信号が受信される場所と被測定環境との2点で同時収録を行い,高SN比信号を基準信号として目的信号を精密に解析する新しい測定法を提案する.本手法では,トータルレコーダ(1台)を用いて,被測定信号と高品質信号を各アレー素子について同時収録し,オフライン処理により基準・被測定双方の受信データから相関行列を作成,ここから固有値解析を行って,到来波の角度特性や遅延特性の精密な測定が可能であることを述べる.
Scientific journal, Japanese - Impact of base station cooperation in multi-antenna cellular system
T. Taniguchi; Y. Karasawa; N. Nakajima
European Wireless Technology Conference, EuWIT 2009, Sep. 2009
International conference proceedings, English - Maximum SINR Circular Weight Design of Multiple Transmitter Multiple Receiver System
T. Taniguchi; Y. Karasawa; N. Nakajima
Fourth International Conference on Systems and Networks Communications,2009, ICSNC '09, Sep. 2009
International conference proceedings, English - Macro-Diversity Scheme for a Point-to-Multipoint Communication System by means of D-STBC Method in Fast Fading Environment
Subrata Kumar Biswas; Tetsuki Taniguchi; Yoshio Karasawa
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E92B, 6, 2122-2130, Jun. 2009, In recent years, the space-time block coding (STBC) method has attracted attention to provide transmission diversity in mobile communication systems, Although the STBC method is very effective in slow fading environments, its performance in fast fading environments has yet to be clearly verified. In this paper we propose a railway radio communication system using space-time coding in cooperation with two base stations. Here, we considered the differential STBC (D-STBC) method in railway communication system to overcome difficulties caused by the fast fading environment. We have compared the performance of STBC and D-STBC method where there is frequency offset between two base stations. Moreover, we have presented the simulation result of overall performance of the system including frequency offset and transmission time delay when operating D-STBC method. The overall evaluation on this paper shows that the D-STBC method is suitable for realizing highly reliable railway communication systems.
Scientific journal, English - Improving the Capacity of OFDM via Frequency-DOmain Oversampling
Qinghua Shi; Y. Karasawa
CWIT 2009, May 2009
International conference proceedings, English - 平面境界における有限 長の不均一部によるTM平面電磁波の散乱問題の解析法
冨田正治; 坂下登美夫; 唐沢好男
信学論(C), The Institute of Electronics, Information and Communication Engineers, J92-C, 4, 142-145, Apr. 2009, この論文では,平面境界における有限長の不均一部によるTM平面電磁波の散乱問題に対して,最小二乗法的モード整合法に基づく新しい,精度の高い解析法を提案する.
Scientific journal, Japanese - AStatistical analysis of correlated MIMO channels with a pinhole
T. Taniguchi; M. Tsuruta; Y. Karasawa
(EuCAP 2009), Mar. 2009
International conference proceedings, English - An ISI Suppressing Method for SIMO-OFDM System Utilizing the Characteristic of the ETP-OFDM Model
Quoc-Anh Vu; Yoshio Karasawa
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E92B, 1, 268-276, Jan. 2009, This paper proposes a Inter-symbol Interference (ISI) suppressing method For Orthogonal Frequency Division Multiplexing (OFDM) system. In the environments where the delay spread exceeds the guard interval, the occurrence of ISI results in a degradation of system performance. A receiving method based on the Equivalent Transmission Path (ETP) model is proposed for Single-Input Multiple-Output (SIMO) OFDM system. Compared to the receiving scheme using Maximal Ratio Combining (MRC) method, the proposed one shows better performance in suppressing errors due to ISI. The paper also points out that the ETP-based model can be used for detecting the desired signal in the multi-user OFDM system. Simulation results of the system performance show the effectiveness of the proposed method over the conventional OFDM system in suppressing ISI.
Scientific journal, English - Experiment on Synchronous Timing Signal Detection from ISDB-T Terrestrial Digital TV Signal with Application to Autonomous Distributed ITS-IVC Network
Yoshio Karasawa; Taichi Kumagai; Atsushi Takemoto; Takeo Fuji; Kenji Ito; Noriyoshi Suzuki
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E92B, 1, 296-305, Jan. 2009, A novel timing synchronizing scheme is proposed for use in inter-vehicle communication (IVC) with an autonomous distributed intelligent transport system (ITS). The scheme determines the timing of packet signal transmission in the IVC network and employs the guard interval (GI) timing in the orthogonal frequency divisional multiplexing (OFDM) signal currently used for terrestrial broadcasts in the Japanese digital television system (ISDB-T). This signal is used because it is expected that the automotive market will demand the capability for cars to receive terrestrial digital TV broadcasts in the near future. The use of broadcasts by automobiles presupposes that the on-board receivers are capable of accurately detecting the GI timing data in an extremely low carrier-to-noise ratio (CNR) condition regardless of a severe multipath environment which will introduce broad scatter in signal arrival times. Therefore, we analyzed actual broadcast signals received in a moving vehicle in a field experiment and showed that the GI timing signal is detected with the desired accuracy even in the case of extremely low-CNR environments. Some considerations were also given about how to use these findings.
Scientific journal, English - MIMO小型3偏波アンテナの提案とマルチパスリッチ環境における伝送特性
篠沢政宏; N. K. Das; 谷口哲樹; 唐沢好男
信学論(B) 通信技術の未来を拓く学生論文特集号, J92-B, 1, 262-270, Jan. 2009
Scientific journal, Japanese - Frequency-domain oversampling for OFDM systems: Exploiting inter-carrier interference and multipath diversity
Qinghua Shi; Y. Karasawa
2009 9th International Symposium on Communications and Information Technology, ISCIT 2009, IEEE ISCIT 2009, 1097-1101, 2009, By using frequency-domain oversampling, we propose a frequency-domain fractionally-spaced linear minimum mean-square error (FDFS-LMMSE) receiver for Orthogonal Frequency-Division Multiplexing (OFDM) systems. The proposed FDFS-LMMSE receiver is shown to significantly outperform the conventional LMMSE receiver (without oversampling) in multipath fading channels. This is because the FDFS-LMMSE receiver is able to exploit multipath/frequency diversity inherent to the channel to improve performance. Next, based on a Gaussian approximation to inter-carrier interference (ICI), we present a semi-analytical performance analysis for the FDFS-LMMSE receiver. The accuracy of the theoretical analysis is confirmed by simulations. Finally, we study the effect of the oversampling factor on the system performance, aiming at finding an optimal oversampling factor in terms of both performance and complexity. It is found that the optimal frequency oversampling factor, usually much smaller than 2, is determined by the number of subcarriers and the number of multipath components. ©2009 IEEE.
International conference proceedings, English - Adaptive filtering for OFDM systems with frequency-domain oversampling
Qinghua Shi; Y. Karasawa
2009 15th Asia-Pacific Conference on Communications, APCC 2009, IEEE APCC 2009, 186-190, 2009, Orthogonal frequency-division multiplexing is sensitive to frequency offset between transmit and receive carriers. In this paper, frequency-domain oversampling is applied to tackle this problem. Our approach is motivated by the duality between time and frequency domains and the fact that time-domain oversampling has been successfully used to deal with timing errors. Theoretical minimum mean-square error (MSE) is first adopted as a performance measure to show that the proposed approach is robust against frequency offset, particularly when the frequency offset is within a limited range. Next, two commonly used adaptive filtering algorithms, namely, least-mean-square (LMS) and recursive least-squares (RLS), are discussed. Their performance is investigated in terms of convergence rate, steady-state MSE, and sensitivity to frequency offset. ©2009 IEEE.
International conference proceedings, English - Robust Modulation Classification Using Fractionally-Spaced Blind Equalization and Characteristic Function
Qinghua Shi; Y. Karasawa
The 12th International Symposium on Wireless Personal Multimedia Communications, WPMC 2009, 2009
International conference proceedings, English - Maximal ratio combining subband adaptive array using decision feedback approach
T. Taniguchi; N.B. Ramli; Y. Karasawa
IEEE Symp. Signal Proc. Info. Tech., (ISSPIT 2008), Dec. 2008
Scientific journal, English - トータルレコーディング技術に基づく地上デジタルテレビジョン放送信号伝送特性の精密測定法
竹本淳; 田村祐介; 唐沢好男
信学論(C), マイクロ波論文（大学発）特集, J91-C, 12, 753-763, Dec. 2008
Scientific journal, Japanese - Classification of Asynchronous High-Order QAMs
Qinghua Shi; Y. Karasawa
The Eleventh International Conference on Communications, Guangzhou, (IEEE ICCS'2008), Nov. 2008
Scientific journal, English - 環境適応型ベースバンド無線：概念提案と機能実証実験
唐沢好男; 笹木亮平; 谷口哲樹
信学論B, J91-B, 11, 1359-1368, Nov. 2008
Scientific journal, Japanese - OFDM Transmission Characteristics where the Delay Profile Exceeds the Guard Interval in Nakagami-Rice Fading Environment
Yoshio Karasawa; Changarkame Vanmany
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E91B, 10, 3262-3271, Oct. 2008, In order to evaluate the effect of Nakagami-Rice fading on Orthogonal Frequency Division Multiplex (OFDM) signal transmission when the delay profile exceeds the guard interval, a simple prediction model is developed by extending the Equivalent Transmission-Path (ETP) model for Rayleigh fading. The validity of the model is demonstrated by comparing the calculated values of BER to those obtained by computer simulation. Using the newly developed ETP-OFDM model, digital transmission characteristics of the OFDM signal ill it multipath environment when the delay profile exceeds the guard interval are shown as a function of K factor, delay spread. guard interval and OFDM symbol period.
Scientific journal, English - Analysis and Approximation of Statistical Distribution of Eigenvalues in i.i.d. MIMO Channels under Rayleigh Fading
Tetsuki Taniguchi; Shen Sha; Yoshio Karasawa
IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E91A, 10, 2808-2817, Oct. 2008, In multiple input multiple output (MIMO) communication systems, eigenvalues of channel correlation matrices play an essential role for the performance analysis, and particularly the investigation about their behavior under time-variant environment ruled by a certain statistics is an important problem, This paper first gives the theoretical expressions for the marginal distributions of all the ordered eigenvalues of MIMO correlation matrices under i.i.d. (independent and identically distributed) Rayleigh fading environment. Then. an approximation method of those marginal distributions is presented: We show that the theory of SIMO space diversity using maximal ratio combining (MRC) is applicable to the approximation of statistical distributions of all eigenvalues in MIMO systems with the same number of diversity branches. The derived approximation has a monomial form suitable for the calculation of various performance measures utilized in MIMO systems. Through computer simulations. the effectiveness of the proposed method is demonstrated.
Scientific journal, English - An Analysis Method of Double Fading MIMO Channels Including LOS Environments
T. Taniguchi; Y. Karasawa; M. Tsuruta
(PIMRC2008), Sep. 2008
International conference proceedings, English - Multiuser Asynchronous MIMO STBC Adaptive Array Transmission Scheme in Fast Fading Channel
S. Annanab; T. Tobita; T. Taniguchi; Y. Karasawa
VTC2008-Fall, Sep. 2008
International conference proceedings, English - Asynchronous MIMO STBC adaptive array transmission scheme for multiuser over fast fading channel
Supawan Annanab; Tomonori Tobita; Tetsuki Taniguchi; Yoshio Karasawa
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E91B, 8, 2666-2673, Aug. 2008, We propose an implementation of the tapped delay line adaptive array (TDLAA) at the base station for improving the BER performance of asynchronous multi-user mobile communication over fast fading channels using multiple antennas. The data of each user at the mobile station, which applies two transmit antennas, are encoded by Space Time Block Code (STBC). The proposed scheme transmits the pilot signal and information data in alternate time slots. We derive performance criteria for designing such a scheme under the assumption that the fading is classified as fast fading. We show that the proposed scheme can suppress co-channel interference (CCI) and defeat Doppler spread effectively.
Scientific journal, English - MIMO Radio-Relay Systems for Ubiquitous Broadband Access; Multi-Keyhole Model as a Performance Analysis Tool
Y. Karasawa; M. Tsuruta; T. Taniguchi
ISIVC2008, Jul. 2008
International conference proceedings, English - Analysis Method of MIMO MRC Systems Under Nakagami m Fading Environment
T. Taniguchi; M. Tsuruta; Y. Karasawa
EW2008, Jun. 2008
International conference proceedings, English - IEICE Trans. Commun., vol.E91-B,no.6, pp.1734-1742, 2008
Performance Comparison of; Detection Methods for Combined STBC; SM Systems
IEICE Trans. Commun., vol.E91-B, 1734-1742, Jun. 2008
Scientific journal, Japanese - Performance improvement of DSTBC systems using decision feedback approach
Tetsuki Taniguchi; Yang Liu; Yoshio Karasawa
Proc. - The 3rd Int. Conf. Systems and Networks Communications, ICSNC 2008 - Includes I-CENTRIC 2008: Int. Conf. Advances in Human-Oriented and Personalized Mechanisms, Technologies, and Services, ICSNC2008, 115-120, 2008, DSTBC (differential space-time block coding) system does not require CSI (channel state information) in both transmitter and receiver sides, but its SNR (signal to noise ratio) versus BER (bit error rate) characteristic is degraded compared with original STBC scheme which utilizes CSI at the receiver. In this paper, attempting to recover this performance loss originated from the differential decoding, an improved DSTBC system is presented. In the proposed approach, data sequence after the hard decision is fed back and utilized for the channel estimation, and then the noise contained in the received signal is reduced using updated channel information before the differential decoding. Through computer simulations in fading channels assuming mobile applications, it is shown that the improved method could achieve better performance and shows higher tolerance to Doppler effect compared to conventional DSTBC. © 2008 IEEE.
International conference proceedings, English - Maximum Likelihood Based Modulation Classification for Unsynchronized QAMs
Qinghua Shi; Y. Karasawa
GLOBECOM 2008 - 2008 IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE, IEEE, GLOBECOM 2008, 2008, We consider modulation classification for quadrature amplitude modulation (QAM) formats. The received signal is assumed to be unsynchronized in both time and frequency, since in practice the receiver has little prior knowledge about the transmitted signal. To tackle this challenging problem, we propose a classifier that is based on a combination of blind time synchronization, differential processing, and maximum likelihood (ML) detection. A computationally efficient scheme is then developed. Numerical results are provided to justify our approach.
International conference proceedings, English - Broadband MIMO communication systems using spatio-temporal processing in transmitter and receiver sides
Tetsuki Taniguchi; Hoang Huy Pham; Nam Xuan Tran; Yoshio Karasawa
IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E90A, 11, 2431-2438, Nov. 2007, Peer-reviwed, This paper presents a mathematically simple method of maximum SINR (Signal to Interference plus Noise Ratio) design of broadband MIMO (Multiple Input Multiple Output) communication systems adopting TDL (Tapped Delay Line) structure for spatio-temporal processing in both transmitter and receiver sides. The weight vectors in both ends are determined alternately, optimizing one side by fixing the other, and this operation is repeated until the SINR converges. The performance of MIMO systems using the proposed approach is investigated through computer simulations, and it is demonstrated that, though it requires high computational cost, the TDL structure brings high ability to mitigate the influence of frequency selective fading, particularly when the duration of the delay profile is long. Moreover, experimental results show that the equable distribution of the resources (weights and delay units) to both arrays is better choice than the concentration of them to one side of the transmitter or receiver.
Scientific journal, English - Subband adaptive array for MIMO-STBC CDMA system
Nordin Bin Ramli; Tetsuki Taniguchi; Yoshio Karasawa
IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E90A, 10, 2309-2317, Oct. 2007, Peer-reviwed, This paper presents interference suppression using a subband adaptive array (SBAA) for uplink space-time block coding (STBC) code division multiple access (CDMA) under a frequency selective fading (FSF) channel. The proposed scheme utilizes CDMA with STBC and a receive array antenna with SBAA processing at the receiver. The received signal is converted into the frequency domain before despreading and adaptive processing is performed for each subband. A novel SBAA construction is introduced to process CDMA signals based on STBC. To improve the performance of the proposed scheme, we evaluate STBC-SBAA using spreading codes cyclic prefix (CP). Simulation results demonstrate an improved performance of the proposed system for single and multiuser environments compared to competing related techniques.
Scientific journal, English - Simple approximation of largest eigenvalue distribution in MIMO channels under Nakagami-Rice fading
Tetsuki Taniguchi; Shen Sha; Yoshio Karasawa; Makoto Tsuruta
IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E90A, 9, 1862-1870, Sep. 2007, Peer-reviwed, This paper presents an approximation method of statistical distribution of the largest eigenvalue of i.i.d. (independent and identically distributed) MIMO (multiple input multiple output) channel correlation matrices under Nakagami-Rice fading environment. The equation is actually derived for MIMO Nakagami m fading channel which is known as a good approximation of Nakagami-Rice fading, hence it well approximates the curves of the largest eigenvalue distribution of noncentral Wishart matrices. In the proposed approximation method, MIMO MRC (maximal ratio combining) system is ascribed to SIMO space diversity theory with the same number of branches, and the statistical distribution becomes a monomial gamma distribution. As a result, the derived marginal density function does not contain any special functions, and has a simple monomial gamma form which is suitable for various calculations of performance indices. Through computer simulations, it is shown that the proposed approximation formula is effective and has a better precision than conventional method.
Scientific journal, English - MIMO STBC adaptive array for fast fading channel
Supawan Annanab; Tetsuki Taniguchi; Yoshio Karasawa
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E90B, 9, 2321-2329, Sep. 2007, Peer-reviwed, We introduce a novel configuration for a multi-user Multiple-Input Multiple-Output (MIMO) system in mobile communication over fast fading channels using space-time block coding (STBC) and adaptive array. The proposed scheme adopts the simultaneous transmission of data and pilot signals which reduces control errors caused by delay of obtaining channel state information (CSI). Data and pilot signals are then encoded using a space-time block code and are transmitted from two transmit antennas. In order to overcome the fast fading problem, implementation of adaptive array using recursive least squares (RLS) algorithms is considered at the base station. Through computer simulation, it is shown that the proposed scheme in this way can overcome Doppler spread in higher frequencies and suppress co-channel interference up to N-1 users for N receiving antennas.
Scientific journal, English - On statistical distribution of eigenvalues of channel correlation matrix in MIMO multi-keyhole environment
Makoto Tsuruta; Tetsuki Taniguchi; Yoshio Karasawa
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E90B, 9, 2352-2359, Sep. 2007, Peer-reviwed, MIMO leads to dramatic improvement in channel capacity and/or link reliability of wireless systems. However, a MIMO channel has only one degree of freedom in a keyhole environment. As a result, this environment reduces achievable channel capacity and link quality. This paper proposes a MIMO repeater system, which can realize a multi-stream transmission. Although the averaged channel capacity in the MIMO repeater system is discussed in several published papers, the probability density functions of eigenvalues of correlation matrix are not analyzed. MIMO transmission performance can basically be estimated from eigenvalues of the channel correlation matrix. We derive an approximated formula for the probability density function of all eigenvalues linked to the space diversity. It is shown that the calculated values based on the proposed method agrees very well with the simulated values.
Scientific journal, English - Approximation of Largest Eigenvalue Distribution newline in Rician MIMO Channels
T. Taniguchi; S. Sha; Y. Karasawa; M. Tsuruta
IEEE 18th Inernational Symposi, Sep. 2007, Peer-reviwed
International conference proceedings, English - Largest Eigenvalue Distribution Approximation in MIMO Nakagami m Fading Channels
T. Taniguchi; M. Tsuruta; Y. Karasawa
International Symposium on Adv, Sep. 2007, Peer-reviwed
International conference proceedings, English - Performance evaluation of MIMO-STBC for inter-vehicle communications in shadowing environment by large vehicle
K. Ito; N. Suzuki; Y. Karasawa
IEEE VTC-Fall, Sep. 2007, Peer-reviwed
International conference proceedings, English - Innovative antennas and propagation studies for MIMO systems
Yoshio Karasawa
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E90B, 9, 2194-2202, Sep. 2007, Peer-reviwed, This paper reviews our recent antennas and propagation studies for MIMO systems. First we introduce a MIMO propagation channel model in which an interesting nature can be found in eigenvalue statistics from a practical viewpoint. Then we introduce multi-keyhole model which is an efficient tool for designing a MIMO repeater systems, or MIMO radio-relay systems. For realization of compact MIMO antenna systems, effectiveness of using multiple polarizations such as dual polarizations and triple polarizations is demonstrated in multipath-rich propagation environments. With application of MIMO to OFDM systems, we focus our analysis on relation between propagation and digital transmission characteristics under a severe multipath-rich environment where the delay profile exceeds the guard interval. Finally, we discuss transmission characteristics of MIMO-OFDM with maximal ratio combining (MRC) diversity in the environment.
Scientific journal, English - The high-speed human body communication systems
T. Maeyama; T. Takasaki; Y. Karasawa
414-417, Aug. 2007, Peer-reviwed
International conference proceedings, English - Performance of detectors for combined STBC-SM systems
X. N. Tran; H. C. Ho; T. Fujio; Y. Karasawa
1362-1365, Aug. 2007, Peer-reviwed
International conference proceedings, English - An ISI suppressing method for SIMO-OFDM system in the Multipath Environment where the delay profile exceeds the guard interral
Q. A. Vu; Y. Karasawa
740-743, Aug. 2007, Peer-reviwed
International conference proceedings, English - A compact tri-polarization antenna for MIMO communication systems
Y. Karasawa; M. Shinozawa
Int. URSI-B Electromagnetic Th, Jul. 2007, Peer-reviwed
International conference proceedings, English - Wideband propagation theory and modeling
Y. Karasawa
Short Course Lecture, Jun. 2007, Peer-reviwed
International conference proceedings, English - CORPS - Combined Recursion Processing of Subsets for Adaptive Array Antennas under Frequency Selective Fading
T.Taniguchi; N. Bin Ramli; Y. Karasawa
2007 IEEE 56th Vehicular Techn, Apr. 2007, Peer-reviwed
International conference proceedings, English - Spatial-temporal adaptive MIMO beamforming for frequency-selective fading channels
Huy Hoang Pham; Tetsuki Taniguchi; Yoshio Karasawa
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E90B, 3, 578-585, Mar. 2007, Peer-reviwed, Nowadays, MIMO systems are playing an important role in wireless communications. In this paper, we propose a spatial-temporal adaptive MIMO beamforming scheme for single carrier transmission in frequency-selective fading channels with the assumption of perfect channel state information (CSI) at both the transmitter and receiver. The transmit and receive weight vectors for detecting the preceding signal and the receive weight vectors for detecting the delayed signals of the preceding signal are designed by an iterative update algorithm. Based on minimum mean square error (MMSE) method, the delayed versions of the preceding signal are exploited to maximize the output signal to interference and noise ratio (SINR) instead of suppressing them at the receiver. The improvement of output SINR is useful for MIMO systems to enhance the high-quality communication in broadband wireless systems.
Scientific journal, English - Statistical multipath propagation modeling for broadband wireless systems
Yoshio Karasawa
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E90B, 3, 468-484, Mar. 2007, Peer-reviwed, This paper surveys and introduces propagation studies and models that are expected to contribute to the development of broadband wireless systems. The survey focused on theory-based propagation models, experimental measurement data useful for modeling, and transmission characteristic evaluations using propagation models. The survey did not attempt to cover all papers in the research fields, but rather took key papers for various relevant subjects and described them in some detail. The basic characteristics of multipath propagation are summarized from the viewpoints of narrow-band (NB), wide-band (WB), and ultra wide-band (UWB). Recent studies on spatio-temporal propagation models and the relationship between models and systems are introduced. To clarify the relationship between OFDM, which is a representative of wideband data transmission schemes, and wave propagation factors, problems due to large delay spread and large Doppler spread are highlighted. Finally, studies on UWB propagation measurement and propagation models are introduced.
Scientific journal, English - MIMO communication system based on wireless baseband tranmission scheme under multipath environment
Tetsuki Taniguchi; Junichi Kitagawa; Yoshio Karasawa
Second International Conference on Systems and Networks Communications, ICSNC 2007, IEEE ICSNC07, 2007, Peer-reviwed, Wireless baseband transmission (WBT) is a communication technology to radiate high rate data symbols directly from antennas without any analogue modulations. This paper describes about measurement of multiple input multiple output (MIMO) WBT system using newly developed biconical antennas to investigate its fundamental behavior under multipath environment. The experiments are carried out in anechoic chamber and measured in frequency region using voltage network analyzer (VNA). A simple processing method of frequency selective real signals for WBT MIMO system is evaluated through computer simulations using the stored results of measurement, and problems are also discussed. © 2007 IEEE.
International conference proceedings, English - Largest eigenvalue analysis in correlated MIMO Rayleigh channels
T. Taniguchi; S. Sha; Y. Karasawa
IET Seminar Digest, 2007, 11961, 2007, Peer-reviwed, This paper gives a general approximation formula of the largest eigenvalue distribution in correlated MIMO (multiple input multiple output) Rayleigh channels. The proposed formula is given by improvement of SIMO (single input single output) based analysis method of MIMO systems, and applicable to any type of correlation including the case covariance matrix has degenerated eigenvalues for which conventional exact formula could not be used. The effectiveness of the proposed equation for various correlated MIMO channels is demonstrated through computer simulations.
International conference proceedings, English - Multi-keyhole model for MIMO radio-relay systems
Y. Karasawa; M. Tsuruta; T. Taniguchi
IET Seminar Digest, 2007, 11961, 2007, Peer-reviwed, This paper introduces a multi-keyhole model for designing MIMO radio-relay systems which can realize a multi-stream transmission to an isolated area. Probability density function (PDF) of eigenvalues of channel correlation matrix in the multi-keyhole environment is highlighted. We derive an approximated formula for the probability density function of all eigenvalues connecting to a space diversity approximation. It is shown that the calculated values based on the proposed method agree very well with the simulated values.
International conference proceedings, English - 日本全国を対象とするM分布を用いた異積分時間降雨強度確率分布の高精度変換法
小野健一; 唐沢好男
信学論(B), J90-B, 3, 266-279, 2007, Peer-reviwed
Scientific journal, Japanese - 地上デジタル放送の移動体受信における電波信号処理型最大比合成ダイバーシチ
神田明彦; 竹本淳; P.S. Wijesena; 谷口哲樹; 唐沢好男
信学論C, 2007.12予定, 2007, Peer-reviwed
Scientific journal, Japanese - 安全係数の概念を導入したM分布近似降雨減衰確率推定法
小野健一; 唐沢好男
信学論 B, accepted, 2007, Peer-reviwed
Scientific journal, Japanese - Subband adaptive array for space-time block coding
Nordin Bin Ramli; Xuan Nam Tran; Tetsuki Taniguchi; Yoshio Karasawa
IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E89A, 11, 3103-3113, Nov. 2006, Peer-reviwed, Diversity transmission using space-time block coding (STBC) shows a degraded performance-in frequency selective fading (FSF) channel. In this paper, assuming the CSI is unknown at both transmitter and receiver while a pilot signal is available during the training period, we propose a MIMO transmission scheme using STBC by adopting subband adaptive array (SBAA) processing. The receive signal is converted into the frequency-domain and adaptive processing is done at each subband. A novel construction of SBAA is introduced to process received signal based on STBC. Simulation results demonstrate that the proposed scheme has a better performance compare to conventional STBC, and has a better performance and less computational load compare to STBC-TDLAA.
Scientific journal, English - MIMOリピータシステム評価のためのマルチキーホールモデル
鶴田誠; 唐沢好男
信学論(B)無線応用システムの進展と多様化を支えるアンテナ・伝搬の設計・解析・測定技術特集号, E89-B, 9, 1746-1754, Sep. 2006, Peer-reviwed
Scientific journal, Japanese - 交差点付近の伝搬特性を対象とする判定帰還型チャネル推定法によるMIMO-STBC車車間通信方式
伊藤健二; 伊藤修朗; 三田勝史; 唐沢好男
信学論(B), 無線応用システムの進展と多様化を支えるアンテナ・伝搬の設計・解析・測定技術特集号, J89-B, 9, 1776-1788, Sep. 2006, Peer-reviwed
Scientific journal, Japanese - Experiments on a MIMO system having dual polarization diversity branches
Nirmal Kumar; Masahiro Shinozawa; Norihisa Miyadai; Tetsuki Taniguchi; Yoshio Karasawa
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E89B, 9, 2522-2529, Sep. 2006, Peer-reviwed, This paper introduces a novel MIMO (Multiple Input Multiple Output) communication system having orthogonal dual polarization diversity branches. We have designed a dual polarized circular patch antenna which has two orthogonal polarization ports such as vertical polarization (V) and horizontal polarization (H) on its metal surface. This design makes it works as two independent antennas in multipath environments. By using two dual polarized antennas at both the transmitter and receiver, we designed a dual-polarization 4 x 4 MIMO experiment system. This system can be used to investigate the performance of various MIMO transmission methods as well as the performance of adaptive algorithms in indoor multipath environments. To investigate the performance of our experiment system, we carried out a number of MIMO transmission experiments such as space-time-coded transmission having two parallel streams and MIMO eigenmode transmission. We will show the results of those experiments and discuss the advantages of using polarization diversity in MIMO communication system for next generation broadband wireless communication.
Scientific journal, English - Wireless baseband transmission experiments
Jun-ichi Kitagawa; Tetsuki Taniguchi; Yoshio Karasawa
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E89B, 6, 1815-1824, Jun. 2006, Peer-reviwed, A baseband transmission scheme for wireless communications has been proposed and examined using a pair of discone antennas for transmission and reception. The wireless baseband transmission scheme radiates a baseband signal stream, such as non-return-to-zero (NRZ), return-to-zero (RZ), or Manchester encoded signals, directly from an antenna. Namely, a carrier in terms of a sinusoidal radio wave or light wave is not used in the transmission. In experiments, baseband pulses generated with a data generator were radiated directly from the discone antenna, and received waveforms were observed with a digital storage oscilloscope. The experiments showed that wireless baseband transmission is realisable when using antennas with a flat amplitude spectrum and a linear phase characteristic, such as discone antennas, over a given band. Manchester encoding is promising for this wireless baseband transmission.
Scientific journal, English - Design of MIMO communication systems using tapped delay line structure in receiver side
T Taniguchi; HH Pham; NX Tran; Y Karasawa
IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E89A, 3, 670-677, Mar. 2006, This paper presents a simple method to determine weights of single carrier multiple input multiple output (MIMO) broadband communication systems adopting tapped delay line (TDL) structure in receiver side for the effective communication under frequency selective fading (FSF) environment. First, assuming the perfect knowledge of the channel matrix in both arrays, an iterative design method of transmitter and receiver weights is proposed. In this approach, both weights are determined alternately to maximize signal to noise plus interference ratio (SINR) by fixing the weight of one side while optimizing the other, and this operation is repeated until SINR converges. Next, considering the case of uninformed transmitter, maximum SINR design method of MIMO system is extended for space time block coding (STBC) scheme working under FSF. Through computer simulations. it is demonstrated that the proposed schemes achieves higher SINR than conventional method with delay-less structure, particularly for the fading with long duration.
Scientific journal, English - 気象庁の１分間降水量データを用いた日本各地における1分間降雨強度特性と最適な近似分布モデルに関する考察
小野健一; 唐沢好男
信学論B, J89-B, 3, 361-372, 2006
Scientific journal, Japanese - 降雨減衰確率推定手法の精度向上を目的とした降雨強度のn乗の空間相関特性に関する考察
小野健一; 唐沢好男
信学論(B), J89-B, 10, 1998-2011, 2006, Peer-reviwed
Scientific journal, Japanese - 実信号解析を用いた無線ベースバンド伝送のマルチパス環境下での伝送特性
北川淳一; 谷口哲樹; 唐沢好男
信学論(C), マイクロ波論文（大学発）特集号, J89-C, 12, 1066-1078, 2006, Peer-reviwed
Scientific journal, Japanese - Design of MIMO Communication Systems Using tapped Delay Line Structure in Receiver Side for STBC Transmission under Frequency Selective Fading
T. Taniguchi; H. H. Pham; N. X. Tran; Y. Karasawa
International Conference on Si, 2006, Peer-reviwed
International conference proceedings - Spatial-temporal adaptive MIMO beamforming for high-quality transmission over frequency-selective fading channels
Huy Hoang Pham; Tetsuki Taniguchi; Yoshio Karasawa
Proceedings of the Advanced International Conference on Telecommunications and International Conference on Internet and Web Applications and Services, AICT/ICIW'06, 2006, 82, 2006, Peer-reviwed, In this paper, we propose a spatial-temporal adaptive MIMO beamforming scheme for single carrier transmission in frequency-selective fading channels with an assumption of perfect channel state information (CSI) at both transmitter and receiver sides. The transmit and receive weight vectors are estimated by using an iterative update algorithm to detect the preceding signal and its delayed versions. The preceding signal and its delayed versions after detection are combined with the minimum mean square error (MMSE) criterion to maximize the output SINR at the receiver side. This improvement of output SINR is useful for MIMO systems to complement the high-quality for increasing high data rate transmission in broadband wireless communication. © 2006 IEEE.
International conference proceedings, English - A Novel MIMO-STBC Scheme for Inter-Vehicle Communications at intersection
K. Ito; N. Itoh; K. Sanda; Y. Karasawa
IEEE VTC-2006, 2006, Peer-reviwed
International conference proceedings, English - Wireless Baseband Transmission MIMO Communication System
T. Taniguchi; J. Kitagawa; Y. Karasawa
The 2006 IEEE International Co, 2006, Peer-reviwed
International conference proceedings, English - Multirate Multicode MIMO-STBC CDMA System with Subband Adaptive Array Processing
Nordin Bin Ramli; Tetsuki Taniguchi; Y. Karasawa
145-153, 2006, Peer-reviwed
International conference proceedings, English - Spatio-temporal MIMO systems for multiuser communications under frequency selective fading
Tetsuki Taniguchi; Nordin Bin Ramli; Yoshio Karasawa
International Conference on Digital Telecommunications 2006, ICDT'06, 2006 International Conference, 2006, Peer-reviwed, This paper presents multiple input multiple output (MIMO) system adopting spatio-temporal processing in both transmitter and receiver sides for multiuser communication under frequency selective fading (FSF). The proposed system assumes the perfect channel state information (CSI) at the base station (BS), and all the weights are computed at BS and then fed back to mobile stations (MSs). The weights of both sides are calculated circularly based on maximum SINR criterion fixing the weights in one side of BS or MS during the optimization of the other side. Computer simulations are carried out to verify the effectiveness and the performance of the proposed scheme. © IEEE.
International conference proceedings, English - BER characteristics of the wireless baseband transmission under multipath environments
J. Kitagawa; T. Taniguchi; Y. Karasawa
3rd IEEE VTS Asia Pacific Wire, 2006, Peer-reviwed
International conference proceedings, English - Subband Adaptive Array for MIMO-CDMA Space-Time Block Coded System
N. Bin Ramli; T. Taniguchi; Y. Karasawa
14th European Signal Processin, 2006, Peer-reviwed
International conference proceedings, English - A design method of single carrier spatio-temporal MIMO systems with reduced computational cost
T. Taniguchi; N. Bin Ramli; Y. Karasawa
IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, The 17th IEEE International Sy, 2006, Peer-reviwed, This paper presents a design method of multiple input multiple output (MIMO) communication system using spatio-temporal processing with the reduced computational cost working under frequency selective fading (FSF) environment. Instead of conventional simultaneous design of all the weights in the system, weights in transmitter and receiver are divided into several groups, and the optimization is carried out group by group as a reduced scale problem. The grouping scheme gives us the flexibility of the design regarding both the performance and computational cost. The computer simulations are carried out to investigate the performance of the proposed method and to provide useful information for the actual design. ©2006 IEEE.
International conference proceedings, English - Subband Adaptive Array for Space-Time Block Coded Multirate Multicode MIMO CDMA System
Nordin Bin Ramli; Tetsuki Taniguchi; Yoshio Karasawa
2006 International Symposium o, 2006, Peer-reviwed
International conference proceedings, English - On Statistical Distribution of the Largest Eigenvalue of Channel Correlation Matrix in MIMO Multi-Keyhole Environment
Makoto TSURUTA; Tetsuki TANIGUCHI; Yoshio KARASAWA
2006 International Symposium o, 2006, Peer-reviwed
International conference proceedings, English - Adaptive beamforming for MIMO space-time block coding over fast fading channel
S. Annanab; T. Taniguch; Y. Karasawa
2006 International Symposium o, 2006, Peer-reviwed
International conference proceedings, English - Analysis of scattering problem by an imperfection of finite extent in a plane surface
M Tomita; T Sakashita; Y Karasawa
IEICE TRANSACTIONS ON ELECTRONICS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E88C, 12, 2177-2191, Dec. 2005, In this paper, a new method based on the mode-matching method in the sense of least squares is presented for analyzing the two dimensional scattering problem of TE plane wave incidence to the infinite plane surface with an arbitrary imperfection of finite extent. The semi-infinite upper and lower regions of that surface are a vacuum and a perfect conductor, respectively. Therefore the discussion of this paper is developed about the Dirichlet boundary value problem. In this method, the approximate scattered wave is represented by the integral transform with band-limited spectrum of plane waves. The boundary values of those scattered waves are described by only abscissa z and Fourier spectra are obtained by applying the ordinary Fourier transform. Moreover, new approximate functions are made by inverse Fourier transform of band-limited those spectra. Consequently, the integral equations of Fredholm type of second kind for spectra of approximate scattered wave functions are derived by matching those new functions to exact boundary value in the sense of least squares. Then it is shown analytically and numerically that the sequence of boundary values of approximate wave functions converges to the exact boundary value, namely, the boundary value of the exact scattered wave in the sense of least squares when the profile of imperfection part is described by continuous and piecewise smooth function at least. Moreover, it is shown that this sequence uniformly converges to exact boundary value in arbitrary finite region of the boundary and the sequence of approximate wave functions uniformly converges to the exact scattered field in arbitrary subdomain in the upper vacuum domain of the boundary in wider sense when the uniqueness of the solution of the Helmholtz equation is satisfied with regard to the profile of the imperfection parts of the boundary.
Scientific journal, English - Modeling and analysis of OFDM transmission characteristics in Rayleigh fading environment in which the delay profile exceeds the guard interval
Y Karasawa; N Gejoh; T Izumi
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E88B, 7, 3020-3027, Jul. 2005, In order to assess the effect of multipath fading on Orthogonal Frequency Division Multiplex (OFDM) signal transmission when the delay profile exceeds the guard interval, a simple prediction model is developed based on the Equivalent Transmission-Path (ETP) model. This model, which is described in this paper, is referred to as the ETP-OFDM-statistical model. The validity of the model is demonstrated by comparing the calculated digital transmission characteristics to results obtained by computer simulation. Using the newly developed ETP-OFDM-statistical model, digital transmission characteristics of the OFDM signal in a multipath environment when the delay profile exceeds the guard interval are shown as a function of delay spread, guard interval and OFDM symbol period.
Scientific journal, English - MIMO propagation channel modeling
Y Karasawa
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E88B, 5, 1829-1842, May 2005, This paper provides an overview of research in channel modeling for multiple-input multiple-output (MIMO) data transmission focusing on a radio wave propagation. A MIMO channel is expressed as an equivalent circuit with a limited number of eigenpaths according to the singular-value decomposition (SVD). Each eigenpath amplitude depends on the propagation structure not only of the path direction profiles for both transmission and reception points but also of intermediate regions. Inherent in adaptive control is the problem of instability as a hidden difficulty. In this paper these issues are addressed and research topics on MIMO from a radio wave propagation viewpoint are identified.
Scientific journal, English - Spatio-temporal equalization for space-time block coded transmission over frequency selective fading channel with co-channel interference
XN Tran; T Taniguchi; Y Karasawa
IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E88A, 3, 660-668, Mar. 2005, In this paper, we propose a spatio-temporal equalizer for the space-time block coded transmission over the frequency selective fading channels with the presence of co-channel interference (CCI). The proposed equalizer, based on the tapped delay line adaptive array (TDLAA), performs signal equalization and CCI suppression simultaneously using the minimum mean square error (MMSE) method. It is to show that our scheme outperforms the previous two-stage combined adaptive antenna and delayed decision feedback sequence estimator (DDFSE) approach. Weal so show that performance can be further improved if the synchronization between the preceding and delayed paths is achieved.
Scientific journal, English - Multiuser MIMO beamforming for single data stream transmission in frequency-selective fading channels
HH Pham; T Taniguchi; Y Karasawa
IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E88A, 3, 651-659, Mar. 2005, In this paper, we propose a multiple-input multiple-output (MIMO) beamforming scheme for a multiuser system in frequency-selective fading channels. The maximum signal-to-noise and interference ratio (MSINR) is adopted as a criterion to determine the transmit and receive weight vectors. In order to maximize the output SINR over all users, two algorithms for base station are considered: the first algorithm is based on the receive weight vector optimization and the second algorithm is based on an iterative update of both transmit and receive weight vectors. Based on the result of single user MIMO beamforming, we analyze the interference channels cancellation ability of multiuser MIMO system. The first algorithm is a simple method and the second algorithm is a performative solution. Through computer simulations, it is shown that multiuser communication system is achievable using the proposed methods in frequency-selective fading condition.
Scientific journal, English - Adaptive algorithm based on accumulated signal processing for fast fading channels with application to OFDM mobile radio
PS Wijesena; T Taniguchi; Y Karasawa
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E88B, 2, 568-574, Feb. 2005, In this paper, we propose an adaptive algorithm based on accumulated signal processing, which could be applicable to Post-FFT-type OFDM adaptive array antennas. Proposed scheme calculates the weight of each element at a particular instant t, by considering both post- and pre-received symbols. Because of the use of additional forthcoming information on channel behavior in the weight calculation scheme, one can expect an improved performance in fast fading conditions by using the proposed adaptive algorithm. This paper also discusses the application of the proposed adaptive algorithm to OFDM adaptive array. In OFDM application, a few subchannels are being used to transmit pilot symbols, and at the receiver, the proposed adaptive algorithm is applied to those pilot subchannels, and interpolates the weights for the data subchannels which are allocated between the pilot subchannels. Finally, the system performance improvement with the application of the proposed adaptive algorithm is verified by computer simulation.
Scientific journal, English - An MMSE Detector for Multiuser Space-Time Block Coded OFDM
X. N. Tran; T. Fujino; Y. Karasawa
IEICE Trans. Commun., Special Section on Multi-carrier Signal Processing Techniques for Next Generation Mobile Communications, E88-B, 1, 141-149, 2005
English - 気象庁1分間降水量データを用いた1分間降雨強度累積分布の高精度推定法
小野健一; 西村安由; 中間浩一; 斎藤研次; 野本真一; 唐沢好男
信学論B, 信学論B, 2005, Peer-reviwed
Scientific journal, Japanese - レイリーフェージング環境における広帯域信号の瞬時レベル変動に関する理論解析
井上隆; 唐沢好男
信学論B, 2005
Japanese - An Approximation of Eigenvalue Distribution in i.i.d MIMO Channels under Rayleigh Fading
T. Taniguchi; S. Sha; Y. Karasawa
The 2005 IEEE Workshop on Stat, 2005, Peer-reviwed
International conference proceedings, English - Comparison of Isotropic and Directive Adaptive Array Antennas in OFDM Mobile Reception of Terrestrial Digital Television
P.S.Wijesena; T. Taniguchi; Y. Karasawa
vol.2, 531-534, 2005, Peer-reviwed
International conference proceedings, English - Statistical Distribution of Eigenvalues of Correlation Matrices in i.i.d MIMO Channels under Rayleigh Fading
T. Taniguchi; S. Sha; Y. Karasawa
C02-03, 2005, Peer-reviwed
International conference proceedings, English - 仲上-ライスフェージング環境におけるMIMO チャネル行列の第１固有値の簡易計算法
鶴田誠; 唐沢好男
信学論B、ワイヤレスパーソナル通信におけるアンテナ・伝搬の最新技術特集号, The Institute of Electronics, Information and Communication Engineers, J87-B, 9, 1486-1495, Sep. 2004, 本論文では,直接波を合む仲上-ライスフェージング環境におけるMIMO伝搬チャネルにおける相関行列の第1固有値の確率分布を精度良く計算する簡易な方法を提案する.提案した近似式で求めた結果を計算機シミユレーション結果と比較し,良い精度で一致していることを示す.また,仲上-ライスフェージング環境におけるテャネル容量を示し,同環境においては,第1固有値が支配的になり,最大比合成伝送が有益であることを明らかにする.
Japanese - 遅延の広がりがガードインターバルを超えるマルチパス環境におけるMIMO構成OFDMの伝送特性
Xa Nguyen; 谷口哲樹; 唐沢好男
信学論B、ワイヤレスパーソナル通信におけるアンテナ・伝搬の最新技術特集号, J87-B, 9, 1467-1476, Sep. 2004
Japanese - 遺伝的アルゴリズムを用いたmin-max規範に基づくアレーアンテナの設計法
岡本直樹; 谷口哲樹; 唐沢好男
信学論B、ワイヤレスパーソナル通信におけるアンテナ・伝搬の最新技術特集号, The Institute of Electronics, Information and Communication Engineers, J87-B, 9, 1372-1382, Sep. 2004, 伝搬波が球面波とみなされるような近接場を想定してアレーアンテナを設計する場合,複雑な非線形最適化問題を解く必要がある.特に,不連続な評価関数を用いた場合,従来のこう配型アルゴリズムの適用は困難である.本論文ではこのような場合にも有効な方法として遺伝的アルゴリズム(GA)を用いたアレーアンテナの設計法について検討を行う.ここではアレーに比較的距離が近い平面に対して受信スポットのみを照射できるように,min-max規範に基づき最適重みを決定する.更に,より効率良く探索を行うために,パラメータフリーGAの適用並びに焼きなまし法(SA)とGAを併用したハイブリッドGAについて検討する.計算機シミュレーションより,提案手法によって良好な結果が比較的簡単な手続きで得られることを示す.
Japanese - MIMO最大比合成伝送における制御不安定問題とその対策―60GHz帯車車間通信を例にして―
竹本亮一; 谷口哲樹; 唐沢好男
信学論B、ワイヤレスパーソナル通信におけるアンテナ・伝搬の最新技術特集号, J87-B, 9, 1477-1485, Sep. 2004
Japanese - OFDM伝送特性評価用等価伝送路モデルに用いるBERマップの簡易作成法
和泉隆亮; 下条則之; 唐沢好男
信学論B、ワイヤレスパーソナル通信におけるアンテナ・伝搬の最新技術特集号, J87-B, 9, 1514-1523, Sep. 2004
Japanese - The weights determination scheme for MIMO beamforming in frequency-selective fading channels
HH Pham; T Taniguchi; Y Karasawa
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E87B, 8, 2243-2249, Aug. 2004, Smart or adaptive antennas promise to provide significant space-time communications against fading in wireless communication systems. In this paper, we propose multiple-input multiple-output (MIMO) beamforming for frequency-selective fading channels to maximize the Signal-to-Noise and Interference Ratio (SINR) based on an iterative update algorithm of transmit and receive weight vectors with prior knowledge of the channel state information (CSI) at both the transmitter and receiver. We derive the necessary conditions for an optimum weight vector solution and propose an iterative weight update algorithm for an optimal SINR reception. The Maximum Signal-to-Noise (MSN) method, where noise includes the additive gaussian noise and interference signals, is used as a criterion. The proposed MIMO with M x N arrays allows the cancellation of M + N - 2 delayed channels. Computer simulations are presented to verify our analysis. The results show that significant improvements in performance are possible in wireless communication systems.
Scientific journal, English - Subband adaptive array for DS-CDMA mobile radio
XN Tran; T Omata; T Taniguchi; Y Karasawa
EURASIP JOURNAL ON APPLIED SIGNAL PROCESSING, HINDAWI PUBLISHING CORPORATION, 2004, 3, 418-426, Mar. 2004, We propose a novel scheme of subband adaptive array (SBAA) for direct-sequence code division multiple access (DS-CDMA). The scheme exploits the spreading code and pilot signal as the reference signal to estimate the propagation channel. Moreover, instead of combining the array outputs at each output tap using a synthesis filter and then despreading them, we despread directly the array outputs at each output tap by the desired user's code to save the synthesis filter. Although its configuration is far different from that of 2D RAKEs, the proposed scheme exhibits relatively equivalent performance of 2D RAKEs while having less computation load due to utilising adaptive signal processing in subbands. Simulation programs are carried out to explore the performance of the scheme and compare its performance with that of the standard 2D RAKE.
Scientific journal, English - Beam-Space Adaptive Array Antenna for Suppressing the Doppler Spread in OFDM Mobile Reception
P. S. Wijesena; Y. Karasawa
IEICE Trans. Commun., E87-B, 1, 20-28, Jan. 2004
English - Maximum SINR Design Method of MIMO Communication Systems Using Tapped Delay Line Structure in Receiver Side
T. Taniguchi; H. H. Pham; N. X. Tran; Y; Karasawa
59th IEEE Semiannual Vehicular, 2004, Peer-reviwed
International conference proceedings, English - Wireless Baseband Transmission Experiments
J. Kitagawa; T. Taniguchi; Y. Karasawa
1, 101-104, 2004, Peer-reviwed
International conference proceedings, English - Subband Adaptive Array for Space Time Block Coding
N. Ramli; X. N. Tran; T. Taniguchi; Y. Karasawa
1, 289-292, 2004, Peer-reviwed
International conference proceedings, English - Adaptive Algorithm Based on Accumulated Signal Processing for Fast Fading Channel
P. S. Wijesena; T. Taniguchi; Y. karasawa
2, 653-656, 2004, Peer-reviwed
International conference proceedings, English - Analysis of Scattering Problem by An Imperfection of Finite Extent in A Plane Surface
M. Tomita; Y. Karasawa
1, 577-580, 2004, Peer-reviwed
International conference proceedings, English - MIMO STBC Data Transmission Scheme for Inter-vehicle Communications at 60GHz in ITS
S. Annanab; Y. karasawa; T. Taniguchi; P. Tangtisanon
1, 329-332, 2004, Peer-reviwed
International conference proceedings, English - An Experiment on MIMO System Having Dual Polarization Diversity Branches
N. K. Das; M. Shinozawa; N. Miyadai; T. Taniguchi; Y. karasawa
1, 341-344, 2004, Peer-reviwed
International conference proceedings, English - Performance of Space-Time Block Coded CDMA Systems with Adaptive Beamforming
X. N. Tran; A. Rajapakshe; T. Fujino; Y. Karasawa
1, 285-288, 2004, Peer-reviwed
International conference proceedings, English - Maximum SINR Design and Performance Analysis of MIMO Communication Systems with Tapped Delay Line Structure
T. Taniguchi; H. H. Pham; X. N. Tran; Y. Karasawa
The 15th IEEE International Pe, 2004, Peer-reviwed
International conference proceedings, English - MIMO Beamforming for High-Bit-Rate Transmission over Frequency-Selective Fading Channels
H. H. Pham; T. Taniguchi; Y. Karasawa
The International Symposium on, 2004, Peer-reviwed
International conference proceedings, English - Adaptive Beamforming for Multiuser Space-Time Block Coded Systems
X. N. Tran; T. Taniguchi; Y. Karasawa
The International Symposium on, 2004, Peer-reviwed
International conference proceedings, English - An MMSE Detector for Multiuser Space-Time Block Coded OFDM
X. N. Tran; T. Fujino; Y. Karasawa
9 International OFDM-Workshop, 2004, Peer-reviwed
International conference proceedings, English - An Experiment on MIMO System having Three Orthogonal Polarization Diversity Branches in Multipath-rich Environment
N. K. Das; T. Inoue; T. Taniguchi; Y. Karasawa
IEEE VTC Fall, 2004, Peer-reviwed
International conference proceedings, English - On Performance of Multiuser OFDM Systems with Transmit Diversity
X. N. Tran; T. Fujino; Y. Karasawa
The IEEE Symposium on Signal P, 2004, Peer-reviwed
International conference proceedings, English - Multimode Transmission Scheme for MIMO Systems Under Frequency Selective Fading
T. Taniguchi; H. H. Pham; Y. Karasawa
C4.6, 2004, Peer-reviwed
International conference proceedings, English - An Adaptive Array Antenna Based on the IQ-Division Bandpass Sampling
S. Sasaki; T. Taniguchi; Y. Karasawa
IEICE Trans. Commun., E86-B, 12, 3483-3490, Dec. 2003
English - 屋内電波吸収壁によるマルチパス抑圧効果とディジタル伝送特性改善に関する等価伝送路モデルによる解析
下条則之; 唐沢好男
信学論B, J86-B, 12, 2522-2532, Dec. 2003
Japanese - MIMO伝搬チャネルモデリング
唐沢好男
信学論B、電磁界解析手法とアンテナ・伝搬における設計技術特集号, J86-B, 9, 1706-1720, Sep. 2003
Scientific journal, Japanese - 仲上ライスフェージング伝搬路におけるダイバーシチ合成後のフェージング抑圧特性の理論解析
井上隆; 唐沢好男
信学論B, 電磁界解析手法とアンテナ・伝搬における設計技術特集号, J86-B, 9, 1963-1970, Sep. 2003
Japanese - 最大比合成によるフェージング抑圧性能の解析法―共分散行列の固有値に等しい値を含む場合―
井上隆; 唐沢好男
信学論B, 電磁界解析手法とアンテナ・伝搬における設計技術特集号, J86-B, 9, 1981-1988, Sep. 2003
Japanese - アレーアンテナブランチ間に相関が存在する場合のMIMOチャネル相関行列の最大固有値分布推定
付鑑宇; 谷口哲樹; 唐沢好男
信学論B, 電磁界解析手法とアンテナ・伝搬における設計技術特集号, J86-B, 9, 1971-1980, Sep. 2003
Japanese - 独立にレイリー分布するMIMOチャネルにおける最大比合成伝送特性の簡易推定法
付鑑宇; 谷口哲樹; 唐沢好男
信学論B, 電磁界解析手法とアンテナ・伝搬における設計技術特集号, J86-B, 9, 1963-1970, Sep. 2003
Japanese - A Multistage Blind Adaptive Array Antenna for Multiuser Signal Detection in Asynchronous SS Systems
Y. Kamiya; K. Ochiai; Y. Karasawa
IEICE Trans. Commun., E86-B, 8, 2414-2424, Aug. 2003
English - Subband Adaptive Array for Multirate Multicode DS-CDMA Systems
X. N. Tran; T. Taniguchi; Y. Karasawa
IEICE Trans. Fundamentals, Special Section on Multi-dimensional Mobile Information Networks, E86-A, 7, 1611-1618, Jul. 2003
English - A Simple Calculation Method on Spatial Distribution of Error Occurrence due to ISI Based on the ETP Model －Application to Indoor Propagation Environments
N. Gejoh; Y. Karasawa
IEICE Trans. Commun., E86-B, 2, 809-817, Feb. 2003
Research society, English - Spatial Optical Signal Processing Beam Forming Network for 2-Dimennsional Beam Steering
K. Inagaki; Y. Karasawa
IEICE Trans. on Electron., Special issue on "Recent Progress in Microwave and Millimeter-wave Photonics Technologies", 2003
English - Subband Adaptive Array for Multirate Multicode DS-CDMA Systems
X. N. Tran; T. Taniguchi; Y. Karasawa
IEEE Topical Conference on Com, 2003, Peer-reviwed
International conference proceedings, English - Eigenvalue Decomposition Based Recursive Least-Squares Algorithm for OFDM Communications over Fast Time-Varying Channels
P. S. Wijesena; T. Taniguchi; Y. Karasawa
IEEE Topical Conference on Com, 2003, Peer-reviwed
International conference proceedings, English - A Design Method of MIMO Communication System with Robustness to Eigenvector Mismatch Problem
T. Taniguchi; R. Takemoto; X. N. Tran; Y. Karasawa
IEEE International Symposium o, 2003, Peer-reviwed
International conference proceedings, English - Theoretical Analysis of Subband Adaptive Array Combining Cyclic Prefix Data Transmission Scheme
X. N. Tran; T. Taniguchi; Y. Karasawa
IEICE Trans. Commun., E85-B, 12, 2610-2621, Dec. 2002
Research society, English - Subband Adaptive Array for DS-CDMA Mobile Radio
X.N.Tran; T.Omata; T.Taniguchi; Y.Karasawa
Interim International Symposium on Antennas and Propagation (ISAP), Yokosuka Research Park, Japan, Nov. 2002
International conference proceedings, English - Beam-Space Adaptive Array Antenna for Suppressing the Doppler Spread in OFDM Mobile Reception
Pubudu S.Wijesena; Y.Karasawa
Interim International Symposium on Antennas and Propagation (ISAP), Yokosuka Research Park, Japan, 37-40, Nov. 2002
International conference proceedings, English - Theoretical Analysis of Subband Adaptive Array Combining Cyclic Prefix Data Transmission Scheme
X.N.Tran; T.Taniguchi; Y.Karasawa
8th IEEE International Conference on Communication Systems, Singapore, Nov. 2002
International conference proceedings, English - Multipath Propagation Theory and Modeling in Wideband Mobile Radio: The"ETP Model", Connecting "Propagation" and "Systems"
Y. Karasawa
The Radio Science Bulletin (Invited Paper), 302, 5-15,26, Sep. 2002
Research society, English - Space-Time Adaptive Downlink Beamforming for Frequency Division Duplex in DS-CDMA Mobile Radio
H.H.Pham; Y.Karasawa
APCC2002, Indonesia, R01-21, 85-88, Sep. 2002
International conference proceedings, English - Software antenna with algorithm diversity
Y.Karasawa
URSI-GA'02, Maastricht (invited), Aug. 2002
International conference proceedings, English - Performance Analysis of Subband Adaptive Array in Multipath Fading Environment
X.N.Tran; T.Taniguchi; Y.Karasawa
the 2002 IEEE AP-S International Symposium and USNC/URSI National Radio Science Meeting, San Antonio, Texas, USA., 1, 610-613, Jun. 2002
International conference proceedings, English - Analysis and Evaluation of Subband Adaptive Array under Multipath Fading Condition
T.Taniguchi; X.N.Tran; Y.karasawa
IEEE Vehicular Technology Conference (VTC2002 Spring), 3.4.1.1, Birmingham, AL, May 2002
International conference proceedings, English - Spatial optical beam-forming network for receiving-mode multibeam array antenna - Proposal and experiment
O Shibata; K Inagaki; Y Karasawa; Y Mizuguchi
IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 50, 5, 1425-1430, May 2002, This paper proposes an array antenna for multibeam reception with a beam-forming network (BFN) that uses spatial optical signal processing and also presents experimental results. In this antenna, signals received at individual antenna elements are converted to optical signals, and are optically divided from the directions of signal arrival by, means of optical spatial Fourier transformation, and then the optical signals are reconverted into microwave signals at the BFN. In this BFN, to maintain optical path-length conditions, an optical integrated circuit is employed. We have experimentally investigated the optical signal processing performances of the BFN for multibeam reception. The experimental results show that optical beam direction is changed according to the signal arrival direction of an array antenna. Two multiple RF signals with different phase distributions are separated. The sidelobe level of the optical signal is reduced when amplitude distributions of optical signals are Chebyshev distributions. We also present the signal transmission behavior of this BFN. The measured carrier-to-noise-ratio degradation of this BFN is 2 dB at BER = 10(-6) when 118.125-Mb/s QPSK modulated signal is input into the BFN.
Scientific journal, English - Compoundモードが入射する場合に方向性結合器の解析
冨田正治; 唐沢好男
信学論C, J85-C, 3, 204-205, Mar. 2002, Peer-reviwed
Scientific journal, Japanese - サイクリックプレフィックスを付加したデータ伝送方式とサブバンド信号処理型アダプティブアレー
唐沢好男; 篠澤政宏
信学論B, J85-B, 1, 90-96, Jan. 2002, Peer-reviwed
Scientific journal, Japanese - スペクトル拡散通信システムにおいてビーム形成、等化及び逆拡散を同時に行うCMAアダプティブアレーの構成
神谷幸宏; 田野哲; 水口芳彦; 片山正昭; 小川明; 唐沢好男
信学論A, J85-A, 1, 31-41, Jan. 2002, Peer-reviwed
Scientific journal, Japanese - ３つのコアから構成される方向性結合器のcompoundモードの入射時における解析
冨田正治; 唐沢好男
電学論A, 122-A, 5, 511-512, 2002
Research society, Japanese - 突発的に発生する強い干渉波に耐性を有するソフトウェアアンテナ－アレーアンテナ相関行列第２固有値のパワーインバージョン特性を利用した－
畑中芳隆; 唐沢好男
信学論C, J85-B, 7, 1086-1094, 2002
Research society, Japanese - Performance Analysis of Subband Adaptive Array in Multipath Fading Environment
X. N. Tran; T. Taniguchi; Y. Karasawa
IEICE Trans. Fundamentals, E85-A, 8, 1798-1806, 2002
Research society, English - マルチパス環境における直交周波数分割多元接続方式（OFDMA）のスループット特性に関する基礎的検討
付鑑宇; 唐沢好男
電子情報通信学会論文誌B, J85-B, 11, 1884-1894, 2002
Research society, Japanese - 遅延の広がりがガードインターバルを超えるマルチパス環境におけるOFDM伝送特性の等価伝送路モデルによる解析
下条則之; 唐沢好男
電子情報通信学会論文誌B, J85-B, 11, 1904-1912, 2002
Research society, Japanese - Fundamental Analysis on Throughput Characteristics of Orthogonal Frequency Division Multiple Access (OFDMA) in Multipath Propagation Environments
J.Fu; Y.Karasawa
The IEEE Annual Vehicular Technology Conference (VTC2002-Fall), 2002
International conference proceedings, English - Analysis of indoor radio propagation and wideband digital transmission characteristics based on the equivalent transmission-path model with ray tracing
Y. Karasawa; N. Gejoh
APMC2001, Taipei, Dec. 4-7,2001. (to be presented), (invited), Dec. 2001, Peer-reviwed
International conference proceedings, English - Performance analysis of subband arrays
YM Zhang; K Yang; MG Amin; Y Karasawa
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E84B, 9, 2507-2515, Sep. 2001, Peer-reviwed, Several subband array methods have been proposed as useful means to perform joint spatio-temporal equalization in digital mobile communications. These methods can be applied to mitigate problems caused by the inter-symbol interference (ISI) and co-channel interference (CCI). The subband array methods proposed so far can be classified into two major schemes: (1) a centralized feedback scheme and (2) a localized feedback scheme. In this paper, we propose subband arrays with partial feedback scheme, which generalize the above two feedback schemes. The main contribution of this paper is to derive the steady-state mean square error (MSE) performance of subband arrays implementing these three different feedback schemes. Unlike the centralized feedback scheme which can be designed to provide the optimum equalization performance, the subband arrays with localized and partial feedback schemes are in general suboptimal. The performance of these two suboptimal feedback schemes depends on the channel characteristics, the filter banks employed, and the number of subbands.
Scientific journal, English - Downlink Transmit Beamforming in FDD Cellular System
Y. Amano; T. Inoue; Y. Karasawa
Wireless Personal Multimedia Communications Conference Proceedings (WPMC'01), Denmark, Sep. 2001
International conference proceedings, English - Downlink Transmit Beamforming in FDD Cellular System
Y. Amano; T. Inoue; Y. Karasawa
Wireless Personal Multimedia Communications Conference Proceedings (WPMC'01), Sep. 2001, Peer-reviwed
International conference proceedings, English - Multipath Propagation Theory and Modeling in Wideband Mobile Radio -Connecting "Propagation" and "Systems" by "ETP model"-
Y. Karasawa
2001 Asia-Pacific Radio Science Conference (AP-RASC'01), Tokyo, 160, Aug. 2001, Peer-reviwed
International conference proceedings, English - "Experiments on Propagation Characteristic Improvement in Data Transmission for 2.4-GHz-band 11Mbps wireless LAN by Using Rock-Wool Ceiling Panel Wave Absorber"
H. Hatanaka; M. Ohtsubo; S. Arikawa; H. kojima; Y. Karasawa
Progress in Electromagnetics Research Symposium (PIERS 2001), Osaka, Jul. 2001, Peer-reviwed
International conference proceedings, English - Analysis of Directional Coupler of Rectangular Waveguides for Fundamental Compound Mode Incidence
M. Tomita; Y. Karasawa
Progress in Electromagnetics Research Symposium (PIERS 2001), Osaka, Jul. 2001, Peer-reviwed
International conference proceedings, English - サイクリックプレフィックスを付加したデータ転送方式とサブバンド信号処理型アダプティブアレー
唐沢好男; 篠澤政宏
信学技報，SST2000-95, A・P2000-229, RCS2000-229, MW2000-220, 51-56, Mar. 2001, Peer-reviwed
Scientific journal, Japanese - 環境適応性に優れたワイヤレスアクセス方式 : OFDMA（直交周波数分割多元接続方式）-そのイメージと電波伝搬を中心とした研究課題-
唐沢好男; 付鑑宇
URSI-F分科会 第452回会合資料，2001.3.16, Mar. 2001
Japanese - サイクリックプレフィックスを付加したデータ転送方式とサブバンド信号処理型アダプティブアレー
唐沢好男; 篠澤政宏
2001年電子情報通信学会総合大会, B-1-79, 97, Mar. 2001
Japanese - 電磁波吸収ロックウール天井板の誘電率測定
有川禎昭; 大坪雅人; 畑中英之; 小島英俊; 唐沢好男
2001年電子情報通信学会総合大会, B-4-59, 374, Mar. 2001
Japanese - 等価伝送路モデルを用いた符号間干渉誤り発生空間分布の簡易な計算法-屋内伝搬環境を例として-
下条則之; 唐沢好男
信学技報，A・P2000-200, 33-40, Feb. 2001
Japanese - 等価伝送路モデルを用いた符号間干渉波誤り発生空間分布の簡易な計算法-屋内伝搬環境を例として-
下条則之; 唐沢好男
電波研連F分科会, 第449回, 1-14, Nov. 2000
Japanese - 矩形導波路から構成される方向性結合器の解析
冨田正治; 唐沢好男
電磁界理論研究会, EMT-00-107, 49-60, Oct. 2000
Japanese - 広帯域移動通信の多重波伝搬理論とモデリング
唐沢好男
信学会アンテナ，伝搬における設計，解析手法ワークショップ（第19回）, 1-153, Sep. 2000
Japanese - Performance Analysis of Subband Arrays
Y. Zhang; K. Yang; Y. Karasawa
International Symposium on Antennas and Propagation（ISAP2000），Fukuoka, Japan, 903-906, Aug. 2000
English - Analysis of Scattering and Coupling Problem of Directional Coupler for Rectangular Dielectric Waveguides
M. Tomita; Y. Karasawa
International Symposium on Antennas and Propagation（ISAP2000），Fukuoka, Japan, 409-412, Aug. 2000
English - Development of an Adaptive Array Based on Subband Signal Processing
Y. Kamiya; S. Denno; Y. Mizuguchi; M. Katayama; A. Ogawa; Y. Karasawa
Fifth International Symposium on Antennas and Propagation EM Theory（ISAPE2000），Beijing, China, Aug. 2000
English - AD変換器の量子化誤差とフリッピングがアレーアンテナの受信性能に与える影響について
篠澤政宏; 唐沢好男
信学会ソフトウェア無線研究会，SR0013，2000.07.21, 1-8, Jul. 2000
Japanese - Theoretical analysis on the performance of optimal combining for multipath waves distributed in spatial and time domains
T Inoue; Y Karasawa
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E83B, 7, 1426-1434, Jul. 2000, This paper theoretically analyzed the performance of the RAKE combining (in the time domain), maximal ratio combining (in the spatial domain), and two-dimensional RAKE combining (in the spatial and time domains) techniques for multipath fading environments, where multipath waves ate distributed in the spatial and time domains. The analysis was based on a diversity combining technique that employed the eigenvalues of the covariance matrix between branch signals. It was found that the performance of the fading mitigation was normalized by the beamwidth of an army antenna, for various parameters such as the number of antenna elements, angular spread, and angle of arrival.
Scientific journal, English - Software receiver technology and its applications
T Yokoi; Y Iki; J Horikoshi; K Miwa; Y Karasawa; A Fukuda; J Takada; Y Kuroda; T Shiokawa; Y Furuya; S Suzuki; Y Senba; Y Yamada; H Harada; Y Suzuki; K Araki
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E83B, 6, 1200-1209, Jun. 2000, It is expected that software receivers will be widely available for radio communication, broadcasting and ra dio monitoring applications because they are able to be equipped with multimode, multirate and multiband functions in a single hardware platform. This paper describes the basic techniques required for software receivers for both hardware and software. The evaluation items and methods were studied and some evaluations done with an experimental software receiver model fabricated for radio monitoring applications. Future concepts in radio communication, broadcasting and radio monitoring applications where software receivers are thought to be suitable, were studied, and problems for realization identified.
Scientific journal, English - Algorithm diversity in a software antenna
Y Karasawa; Y Kamiya; T Inoue; S Denno
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E83B, 6, 1229-1236, Jun. 2000, A software antenna, which will bo a key device realizing flexible and highly reliable wireless communications systems, is inherently matched with software defined radios (SDR). In this paper first, key technologies on the software antenna are introduced. The technologies contain i) how to recognize the radio environment, ii) how to determine the optimum adaptive signal processing algorithm and iii) how to reconfigure the digital beamforming circuit. Then, an image of a software antenna with reconfiguration eigenvector-beamspace configuration is presented. Finally, by assuming various propagation conditions, per formance of the software antenna in terms of algorithm diversity is demonstrated.
Scientific journal, English - Propagation Channel Modeling for LMSS and HAPS, - A step to realize a virtual urban city for channel simulation and system design
K. Minamisono; Y. Karasawa
（invited）AP2000, Davos, Switzerland, Paper, 0129, Apr. 2000
English - Interactive studies on antennas, propagation and systems in wideband mobile communications
Y. Karasawa
（invited）AP2000, Davos, Switzerland, Paper, 0644, Apr. 2000
English - New configuration of full-blind CMA adaptive array applicable to spread spectrum systems
Y. Kamiya; M. Katayama; A. Ogawa; Y. Karasawa
AP2000, Davos, Switzerland, Paper, 0639, Apr. 2000
English - 方形断面を有する光導波路に対する方向性結合器の解析
冨田正治; 唐沢好男
電子情報通学会論文誌, J83-C, 3, 234-235, Mar. 2000
Japanese - 等価伝送路モデルによる広帯域ディジタル伝送特性の解析
唐沢好男
2000年信学総合大会（招待発表）, 通信1, SB-1-4, 709, Mar. 2000
Japanese - 電波吸収ロックウール天井板を用いた2.4GHz帯無線LAN伝搬特性改善実験結果
畑中英之; 大坪雅人; 有川禎昭; 小島英俊; 唐沢好男
2000年信学総合大会, 通信1, B-4-18, 321, Mar. 2000
Japanese - Formulation of opatial correlation statistics in Nakagami-Rice fading environments
Y. Karasawa; H. Iwai
IEEE Trans. Antennas & Propagation, 48, 1, 277-284, Jan. 2000
Scientific journal, English - 周波数に依存しない送受信ナルビームフォーミング
関口高志; 唐沢好男
電子情報通信学会論文誌, J83-B, 1, 31-38, Jan. 2000
Japanese - Wideband beamspace adaptive array utilizing FIR fan filters for multibeam forming
T Sekiguchi; Y Karasawa
IEEE TRANSACTIONS ON SIGNAL PROCESSING, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 48, 1, 277-284, Jan. 2000, We propose a wideband beamspace adaptive array that uses FIR fan filters to construct a multibeam forming network. We also describe a method for designing such FIR fan filters. Approximation is achieved by combining spectral transformation and the window method such that the beam patterns including the sidelobe characteristics of the resulting fan filters are virtually frequency independent. This is a requirement of beamforming networks used in multibeam forming. Fan filters designed with the proposed method are used to demonstrate that the beam-space adaptive array can suppress interference signals having a wide fractional bandwidth and that the array has fast convergence.
English - K .Fujimoto and J. R. James（Ed）: Mobile Antenna Systems Handbook（2nd Edition），5.2 Digital Beamforming Antennas in Mobile Communications
Y. Karasawa
Artech House 2000, 2000
English - ITSミリ波車車間通信の路面反射フェージングとスペースダイバーシチに関する基礎的検討
唐沢好男
信学論B, J83-B, 4, 518-524, 2000
Japanese - 大規模アレーアンテナにおいて最大比合成を簡易に実現する方法
唐沢好男; 神谷幸宏
信学論B, J83-B, 6, 866-871, 2000
Japanese - Analysis of scattering and coupling problem of directional coupler for rectangular dielectric waveguides
M. Tomita; Y. Karasawa
Progress in Electromagnetics Research, 29, 295-320, 2000, In this paper, scattering and coupling problems of the directional coupler for the dielectric rectangular waveguides are analyzed by the mode-matching method in the sense of least squares for the fundamental mode incidence. This directional coupler is composed of three parallel dielectric rectangular waveguides cores which are placed at equal space in the dielectric medium. Namely, respective cores are core regions of three respective rectangular waveguides. The central rectangular core among them has periodic groove structures of finite extent on its two surfaces which face each other and other two waveguide cores are perfect. In the central waveguide, the fundamental mode is incident from perfect part toward the periodic structure of this waveguide. The power of the incident mode to the central waveguide is coupled to other two waveguides through periodic groove structure. The coupled mode propagates in the other waveguides to the same or opposite direction for the direction of the incident mode when the Bragg condition is selected appropriately. The method of this paper results in the integral equations of Fredholm type of the second kind for the unknown spectra of scattered fields. The results of the first order approximate solutions of the integral equations are presented in this paper.
Scientific journal, English - サブバンド信号処理に基づくアダプティブアレーアンテナの開発
神谷幸宏; 田野 哲; 水口芳彦; 片山正昭; 小川 明; 唐沢好男
信学論（A）, J83-A, 12, 1413-1424, 2000
Japanese - 広帯域移動通信の多重波伝搬理論とモデリング：-等価伝送路モデルによる「伝搬」と「システム」の橋渡し-
唐沢好男
信学論B（招待論文）, J83-B, 12, 1651-1660, 2000
Japanese - Enhancement of the ETP Model : How to Calculate BER Due to ISI for Wide-Band Digital Transmission in Nakagami - Rice Fading Environments
Y. Karasawa; H. Iwai
IEEE Trans. Vehicul .Tech., 49, 6, 2000
English - 統計モデルをベースとしたリアルタイム移動伝搬環境生成
唐沢好男; 井上隆
信学誌（電子情報通信を支えるシミュレーション技術特集号）, 83, 11, 884-888, 2000
Japanese - A Software Antenna: Reconfigurable Adaptive Arrays Based on Eigenvalue Decomposition
Y. Kamiya; Y. Karasawa; S. Denno; Y. Mizuguchi
IEICE Trans. Commun., E82-B, 12, 2012-2020, Dec. 1999
English - ITSミリ波車車間通信の路面反射フェージングとスペースダイバーシチに関する基礎的検討
唐沢好男
信学技報, A・P99-124, 1-8, Oct. 1999
Japanese - A Beamspace Adaptive Array for Multipath Signals Distributed in Time and Space Domains
Y. Kamiya; Y. Karasawa
PIMRC '99, Osaka Japan, 37-41, Sep. 1999
English - Theoretical Analysis on the Level Variation Properties of Wideband Signals in the Rayleigh Fading Environments
T. Inoue; Y. Karasawa
PIMRC '99, Osaka Japan, 1263-1267, Sep. 1999
Japanese - 大規模アレーアンテナにおいて最大比合成を簡易に実現する方法
唐沢好男; 神谷幸宏
信学技報, A・P99-105, 95-100, Sep. 1999
Japanese - Mobile, Terrestrial, and Satellite Propagation Modeling
Y. Karasawa; F. Perez-Fontan
Review of Radio Science，1996-1999，Oxford Univ., 443-457, Aug. 1999
Scientific journal, English - Software Antennas Adapting to Environment Kaleidoscopically
Y.Karasawa
URSI XXVI-th General Assembly, Toronto Canada,（invited）, 213(C4.6), Aug. 1999
Japanese - LMSS Propagation Channel Modelling: Dynamic Models
Y.Karasawa
URSI XXVI-th General Assembly, Toronto Canada,（invited）, 328(F1.7), Aug. 1999
Japanese - What are Key Propagation Parameters Affecting Wideband Digital Transmission Characteristics?
Y.Karasawa
URSI XXVI-th General Assembly, Toronto Canada,（invited）, 871(WSF1.2), Aug. 1999
English - スペクトル拡散通信システムにおいてビーム形成，等化及び逆拡散を同時に行う完全ブラインド型CMAアダプティブアレーの構成
神谷幸宏; 田野 哲; 水口芳彦; 片山正昭; 小川明; 唐沢好男
信学技報, A・P99-69, 13-18, Aug. 1999
Japanese - 時間及び周波数領域信号処理を行う適応型アレーアンテナの種々の構成における特徴比較と収束特性改善
神谷幸宏; 唐沢好男
電子情報通信学会論文誌, J82-A, 6, 867-874, Jun. 1999
Japanese - マルチパス環境におけるアレーアンテナの空間信号処理に関する考察：空間信号処理３兄弟：スペースダイバーシチ・アダプティブアレー・MUSIC法の動作と解析手法に見るアナロジー
唐沢好男; 井上 隆; 神谷幸宏
第435回URSI-F分科会, Jun. 1999
Japanese - A DBF self-beam steering array antenna for mobile satellite applications using beam-space maximal-ratio combination
R Miura; T Tanaka; A Horie; Y Karasawa
IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 48, 3, 665-675, May 1999, This paper proposes a diversity-receiving array antenna scheme achieved by digital beamforming (DBF) for the purpose of self-beam steering toward the unknown direction-of-arrival (DOA) of a modulated signal in a mobile satellite communications environment, This scheme uses a multibeam former with a spatial fast Fourier transform (FFT) for the received baseband signals to coarsely acquire the attenuated signal, It also uses a self-phasing processor (SPP) applied to the multibeam outputs for precise acquisition and tracking. In the SPP, maximal-ratio combining is achieved with simple digital numerical operations in the complex baseband, allowing for rapidity and stability in beamforming, As a result, the array antenna steers its receiving beam toward the DOA automatically without the need for nonlinear optimization methods. Moreover, the beam is steered toward the DOA of multipath signals according to their signal levels, leading to the optimal cophase recombination of all correlated signals, which improves the quality of the total receiving signal. This paper discusses the scheme, and its performance is evaluated by computational simulation and experiments conducted in a radio anechoic chamber.
Scientific journal, English - 仲上-ライスフェージング環境におけるダイバーシチ合成のフェージング抑圧特性の理論解析
井上 隆; 唐沢好男
信学技報, RCS99-3, 13-18, Apr. 1999
Japanese - 電波伝搬ハンドブック「第12章:多重波伝搬理論、第22章:移動体衛星通信の電波伝搬」を担当執筆
リアライズ社, 1999
Japanese - 広帯域ワイヤレス通信のソフトウェアアンテナ技術
トリケップス, 1999
Japanese - 低軌道周回衛星通信システム「第6章 パーソナル衛星通信の電波伝搬」を担当執筆
電子情報通信学会, 1999
Japanese - 広帯域移動通信における電波伝搬とシステムの接点を探る
電子情報通信学会誌, 81, 8, 830-837, 1998
Japanese - The software antenna: A new concept of kaleidoscopic antenna in multimedia radio and mobile computing era
Y Karasawa; T Sekiguchi; T Inoue
IEICE TRANSACTIONS ON COMMUNICATIONS, IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, E80B, 8, 1214-1217, Aug. 1997, Based on a recent remarkable development of digital beamforming (DBF) antenna technologies, we propose a new concept of kaleidoscopic antenna, we call it ''software antenna,'' which is a more general one extending DBF schemes. The software antenna instantly reconfigures itself adapting its software and hardware to changes in the radio-environment. To realize the software antenna, the development of high-speed reconfigurable FPGAs is indispensable. As an intelligent antenna, we believe the software antenna could play a key role in the days of software radio having a function of mobile computing.
English - Cycle slip in clock recovery on frequency-selective fading channels
Y Karasawa; T Kuroda; H Iwai
IEEE TRANSACTIONS ON COMMUNICATIONS, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 45, 3, 376-383, Mar. 1997, The mechanism and fundamental nature of the ''cycle slip phenomenon'' in clock recovery, which triggers the occurrence of burst-type irreducible errors in frequency-selective fading conditions, are theoretically clarified for PSK transmission systems with a coherent detection scheme, The appropriateness of the theory is identified through measurement by means of a fading simulator and a 64 kb/s QPSK modem, Moreover, a simple formula for predicting the frequency of cycle slip occurrence in Rayleigh-fading environments is developed, the accuracy of which is confirmed by means of computer simulation.
Scientific journal, English - The equivalent transmission-path model - A tool for analyzing error floor characteristics due to intersymbol interference in Nakagami-Rice fading environments
Y Karasawa; T Kuroda; H Iwai
IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 46, 1, 194-202, Feb. 1997, A very simple but general scheme for calculating irreducible bit error rate (BER) (namely, BER door) due to intersymbol interference in frequency-selective Nakagami-Rice fading environments has been developed, The scheme, which we call the equivalent transmission-path model, plays a role in connecting wave propagation with digital transmission characteristics in a general manner, Through computer simulations assuming various types of delay profiles, we first identify key parameters of Nakagami-Rice fading dominating principally the occurrence of irreducible errors, and we develop a simple method for the calculation of irreducible BER utilizing the nature of the key parameters, Then we examine the accuracy of the scheme for various types of phase-shift keying (PSK) transmission systems, Finally, based on tile scheme, we show calculation examples of BER door characteristics in line-of-sight fading environments.
Scientific journal, English - Analysis on Availability Improvement in LMSS by Means of Satellite Diversity Based on a Three-State Propagation Channel Model
IEEE Trans. on Vehicul. Tech., 47, 4, 1047-1056, 1997
English - Ka-band Earth-Space Propagation Research in Japan(invited)
Proceedings of the IEEE, 85, 6, 821-842, 1997
English - Analysis on Cycle Slip in Clock Recovery on Transmission-Path Model.
IEICE Trans. on Communications, E79B, 12, 1900-1910, 1996
English
MISC
- 伝搬モデルで遊ぶ
唐沢 好男
Sep. 2012, 電子情報通信学会論文誌 B pp., J95-B, 9, 1141, Japanese, Introduction other - ITS車車間通信の研究開発動向と課題：～安全運転を支援する電 波カーブミラー～
唐沢好男
Nov. 2009, 目黒会, CHOFU Network, vol. 21, 2, 11-13, Japanese, Introduction other - 地上デジタル放送波伝搬の新しい測定法 ～パソコントータルレコーディングとその応用
唐沢好男; 竹本淳
Sep. 2009, 電波技術協会報 FORN, 270, 16-19, Japanese, Introduction other, 20001629502 - 実験と理論
唐沢好男
Mar. 2009, 日立国際 電興技報, 9, 5-1, English, Introduction other - 実験と理論
唐沢好男
Mar. 2009, 日立国際 電気技報, 9, 5-1, Japanese, Introduction other - 放射パターン測定に基づくアレーアンテナ素子間結合特性
大島一郎; 佐々木克守; 田中幸男; 高橋行隆; 唐沢好男
Nov. 2007, 電興技報, 42, 7-12, Japanese, Introduction other - 伝搬モデルの作り方－ OFDM伝送特性評価用広帯域伝搬モデルを例として －
唐沢好男
Jun. 2007, 信学会通信ソサイエティマガジン（B-plus）,, 2007 夏号, 67-75, Japanese, Introduction other - MIMOのふしぎ探検
唐沢好男
Dec. 2006, 電興技報, 40, English, Introduction other - 広帯域移動通信の多重波伝搬理論とチャネルモデリングの研究
唐沢好男
Apr. 2006, ICF機関誌, 24, 6-7, Japanese, Introduction other - MIMO: アレーアンテナを用いる究極の情報伝送技術
唐沢好男
May 2005, 情報通信 Bulletin, KEC, 24, 1-4, Japanese, Introduction other - MIMO その実力に迫る
唐沢好男
2005, 島田理化技報, 16, 16, 6-14, Japanese, Introduction other, 10028991769 - UWBの動向
唐沢好男
Dec. 2003, 目黒会報, 第46回移動体通信研究会, 15-3号, 14-16, Japanese, Introduction other - 遅延スプレッドと相関帯域幅：どちらが本質？
唐沢好男
Sep. 2003, 信学論B, 電磁界解析手法とアンテナ・伝搬における設計技術論文特集, Vol.J86-B, No.9, 2009, Japanese, Introduction other
Books and other publications
- Mobile Antenna Systems Handbook (3rd Edition)
K. Fujimoto; J. R. Jame
English, Joint work, 2.2 Fundamentals in Land Mobile Propagations, Artech House, Nov. 2008 - 電子情報通信学会編、アンテナ工学ハンドブック（改訂版）
Japanese, Joint work, 第１３章 電波伝搬：章主任, オーム社, Nov. 2008 - アンテナ・無線ハンドブック
後藤尚久; 伊藤精彦; 中川正雄
Japanese, Editor, II編「電波伝搬」（編主任）のうち、「ダイバーシチ技術」。「MIMOチャネルモデル」、「移動体衛星通信の電波伝搬」の章（及び節）を担当執筆, オーム社, 2006 - 無線技術とその応用: 第4巻; 新世代ワイヤレス技術（第3章MIMO）
唐沢好男
Japanese, Joint work, 丸善, Mar. 2004 - ディジタル移動通信の電波伝搬基礎
唐沢好男
Japanese, コロナ社, Mar. 2003 - Mobile Antenna Systems Handbook (2nd Edition)(分担執筆)
Y.Karasawa
English, Joint work, Artech House, 2000 - 広帯域ワイヤレス通信のソフトウェアアンテナ技術（監修・分担執筆）
唐沢好男
Japanese, Joint work, トリケップス, Mar. 1999 - 電波伝搬ハンドブック
唐沢好男
Japanese, Joint work, リアライズ社, Jan. 1999 - 低軌道周回衛星通信システム
唐沢好男
Japanese, Joint work, 電子情報通信学会（コロナ社）, 1999 - エンサイクロペディア電子情報通信ハンドブック「第4-24編 電波伝搬」編主任
電子情報通信学会
Dictionary or encycropedia, Japanese, オーム社, 1998
Lectures, oral presentations, etc.
- 伝搬モデルで遊ぶ
唐沢 好男
Invited oral presentation, Japanese, 電子情報通信学会
Sep. 2012 - 簡易な構成による広帯域アンテナ
レ・ディン・タン; 唐沢好男
Oral presentation, Japanese, 信学技報,A･P2010-124
Dec. 2010 - MIMOフェージングエミューレータ型OTAシステムの簡易構成法 ～マルチパス遅延波環境生成を特徴とする～
唐沢好男; 小佐古 昂; 清水昌彦
Oral presentation, Japanese, 信学技報,A･P2010-131
Dec. 2010 - 屋内MIMOリレー伝送におけるマルチキーホール効果のレイトレーシング解析
宮部達志; 唐沢好男; 本間尚樹
Oral presentation, Japanese, 信学技報,AP2010-78
Oct. 2010 - MIMO-OTAフェージングエミュレータの簡易構成法に関する検討
小佐古 昂; パシシンギ サハルル; 唐沢好男
Oral presentation, Japanese, 信学技報,AP2010-89
Oct. 2010 - Impact of Base Station and Relay Station Cooperation in MIMO Cellular System
谷口哲樹; 唐沢好男; 中嶋信生
Oral presentation, English, 信学技報,信学ソ大
Sep. 2010 - 二重反射箱による偏波制御
大島一郎; 唐沢好男
Oral presentation, Japanese, 電子情報通信学会,信学ソ大
Sep. 2010 - 電力と情報を同時に伝送する電極の構造について
高崎和之; 唐沢好男
Oral presentation, Japanese, 電子情報通信学会,信学ソ大
Sep. 2010 - MIMOフェージングエミュレータの簡易構成法とチャネル固有値特性
小佐古昂; 唐沢好男
Oral presentation, Japanese, 電子情報通信学会,信学ソ大
Sep. 2010 - Fandamental study on base station cooperation in MIMO cellular systems using multistream transmission
谷口哲樹; 唐沢好男; 中嶋信生
Oral presentation, English, 信学技報
Aug. 2010 - 直接ならびリレーリンクを用いたマルチアンテナ・マルチユーザー通信システムの完全チャネル情報下における設計と解析
谷口哲樹; 唐沢好男; 中嶋信生
Oral presentation, English, 信学技報
Jul. 2010 - フェージングシュミレーター型MIMO-OTA測定系の構成法に関する比較検討
小佐古昂; Psisingi Sahrul; 唐沢好男
Oral presentation, Japanese, 日本学術会議,第545回URSI-F会合
Jun. 2010 - 任意ドップラースプレッドのマルチパス環境を実現するMIMO端末特性評価用電波反射箱
篠沢政宏; パシシンギ・サハルル; アリフ・リズワン; 唐沢好男
Oral presentation, Japanese, 信学技報
Jun. 2010 - ＭＩＭＯ通信用コンパクトアンテナ
レ・ディン・タン; 篠沢政宏; 唐沢好男
Oral presentation, Japanese, 信学技報
Jun. 2010 - 「サイクルスリップ物語」
唐沢好男
Invited oral presentation, Japanese, AP-S Japan Chapter, IEEE
Jun. 2010 - MIMO-OTA試験に垂直面到来波広がりが与える影響の端末傾きへの依存性
尾林秀一; 大石崇文; 柏木一平; 唐沢好男
Oral presentation, Japanese, 信学技報,信学ソ大
Jun. 2010 - Design of Multiuser MIMO AF Realy System
谷口哲樹; ノルディン・ビン・ラムリ; 唐沢好男
Oral presentation, Japanese, 信学技報
May 2010 - 基地局協調ＭＩＭＯセルラーシステムの協調効果
唐沢好男; 谷口哲樹; 中嶋信生
Oral presentation, Japanese, 信学技報
Mar. 2010 - 人値通信における非接触形電極を介した人体伝送特性
原和輝; 高崎和之; 唐沢好男
Oral presentation, Japanese, 電子情報通信学会,総合大会
Mar. 2010 - トータルレコードを用いたMBCホットスポットの追跡
亀井利久; 若林良二; 長澤正氏; 唐沢好男; 小野寺紀明
Oral presentation, Japanese, 電子情報通信学会,総合大会
Mar. 2010 - Design of Multiuser MIMO AF Realy System
谷口哲樹; ノルディン・ビン・ラムリ; 唐沢好男
Oral presentation, Japanese, 電子情報通信学会,総合大会
Mar. 2010 - 基地局協調ＭＩＭＯセルラーシステムの協調効果
唐沢好男; 谷口哲樹; 中嶋信生
Oral presentation, Japanese, 信学技報
Mar. 2010 - ＭＩＭＯ末端特性評価のための電波環境構築法に関する考察[Ⅳ],～フェージングエミュレータ方式のチャネル固有値特性～
アリャファル・ザーラ; 唐沢好男
Oral presentation, Japanese, 信学技報,信学技報
Feb. 2010 - ＭＩＭＯ末端特性評価のための電波環境構築法に関する考察[Ⅲ],～動的フェージング環境を実現する電波反射箱におけるチャネル特性評価～
パシシンギ・サハルル; アリフ・リズワン; 篠沢政宏; 唐沢好男
Oral presentation, Japanese, 信学技報,信学技報
Feb. 2010 - 垂直面到来波広がりを考慮した端末用MIMOアンテナOTA評価法の検討
尾林秀一; 大石宗文; 唐沢好男
Oral presentation, Japanese, 信学技報,信学技報 A･P研
Feb. 2010 - 電波伝搬視点に立った基地局協調システムの物理限界
唐沢好男; 谷口哲樹; 中嶋信生
Oral presentation, Japanese, 信学技報,信学技報
Nov. 2009 - A new concept of baseband radio
Y. Karasawa
Invited oral presentation, English, IEEE Int,conf,advanced Tech.commun ATC 2009, Haiphong,Vietnam, International conference
Oct. 2009 - How to create propagation environment for MIMO performnce evaluation of user terminals
Y. Karasawa
Invited oral presentation, English, Joint UET-SEU seminer on Applied Science and info. commun. Tech. ASICT 2009, Hanoi, Vietnam, International conference
Oct. 2009 - 環境適応型ベースバンド無線の実験検証
森本勇樹; 唐沢好男
Oral presentation, Japanese, 信学技報,信学技報
Oct. 2009 - Weight Design of MIMO AF Relay System
谷口哲樹; 唐沢好男; 中嶋信生
Oral presentation, English, 信学ソ大,信学ソ大
Sep. 2009 - ITS車車間通信のSIMO/MIMOレイトレーシング官位計算法
J.T.J.Napitupulu; 唐沢好男
Oral presentation, English, 信学ソ大,信学ソ大
Sep. 2009 - ITS-IVC Propagation Channel Model for MIMO-STBC Transmissin at an Intersection where a Large Vihicle Shadows the Oncomming Car
王軼; 伊藤健二; 唐沢好男
Oral presentation, English, 信学ソ大,信学ソ大
Sep. 2009 - MIMOフェージングエミュレータのチャンネル固有値特性の評価
Zahra Ariyafar; 唐沢好男
Oral presentation, Japanese, 信学ソ大,信学ソ大
Sep. 2009 - 環境適応型ベースバンド無線伝送システム
森本勇樹; 唐沢好男
Oral presentation, Japanese, 信学ソ大,信学ソ大
Sep. 2009 - MIMO AFリレーシステムのウェイトに関する検討
谷口哲樹; 唐沢好男; 中嶋信生
Oral presentation, English, 信学技報
Aug. 2009 - MIMO端末特性評価のための電波環境構築法に関する考察[Ⅱ]
唐沢好男
Oral presentation, Japanese, 信学技報
Aug. 2009 - ITS車車間通信の研究開発動向と課題：安全運転を支援する電 波カーブミラー
唐沢好男
Oral presentation, Japanese, 目黒会
Aug. 2009 - Subband Adaptive Array with Reduced Pilot Signal Using Maximal Ratio Combining Scheme
T. Taniguchi; N. B. Ramli; Y. Karasawa
Keynote oral presentation, English, Int. Conf. Commun., (ICC '09), International conference
Jun. 2009 - MIMO端末特性評価のための電波環境構築法に関する考察と提案
唐沢好男
Oral presentation, Japanese, 日本学術会議
Jun. 2009 - GPSトータルレコーディングの開発－マルチパスによる位置推定精度劣化の評価手段として－
小佐古昂; 土屋潤三; 高崎和之; 唐沢好男; 小松覚
Oral presentation, Japanese, 信学技報
May 2009 - An Elementary Analysis on Base Station Cooperation in Multi-antena Cellular System
谷口哲樹; 唐沢好男; 中嶋信生
Oral presentation, English, 信学技報
May 2009 - 3次元空間到来波環境における空間相関特性
ダン フン レー; 唐沢好男
Oral presentation, Japanese, 信学技報
Apr. 2009 - Statistical analysis of correlated MIMO channels with a pinhole under Rayleigh fading environment
T. Taniguchi; M. Tsuruta; Y. Karasawa; Statistical analysis of correlated; MIMO channels with; a; pinhole under Rayleigh fading envi; 信学技報
Oral presentation, English, 信学技報
Mar. 2009 - Analysis of correlated MIMO channels with a pinhole under NLOS environmen
谷口哲樹; 鶴田誠; 唐沢好男
Oral presentation, English, 2009信学総大
Mar. 2009 - GPSトータルレコーディングシステムの開発
小佐古昂; 土屋潤三; 高崎和之; 唐沢好男; 小松覚
Oral presentation, Japanese, 2009信学総大
Mar. 2009 - GPSトータルレコーディングシステムによる測位誤差解析に関する検討
土屋潤三; 小佐古昂; 高崎和之; 唐沢好男; 小松覚; GPSトータルレコーディングシステムによる測位誤差解析に関する検討; 信学総大
Oral presentation, Japanese, 2009信学総大
Mar. 2009 - ETP Modeling for OFDM transmission with SIMO-MRC under multipath fading where delay profile exceeds guard interval
A.R. Bajracharya; Q.A. Vu; 唐沢好男
Oral presentation, English, 2009信学総大
Mar. 2009 - 高速フェージングチャネルに耐性を有する４アンテナSTBC伝送方式
S. Susmita; 佐々木進; 唐沢好男
Oral presentation, Japanese, 2009信学総大
Mar. 2009 - 電波反射箱を用いたMIMOキーホール伝搬実験
柏崎大輔; 篠沢政宏; 谷口哲樹; 唐沢好男
Oral presentation, Japanese, 2009信学総大
Mar. 2009 - トータルレコーディング技術に基づく地上デジタル放送マルチパス波の到来方向・遅延時間高分解能測定法
竹本淳; 高橋宏和; 唐沢好男
Oral presentation, Japanese, 信学技報
Jan. 2009 - MIMO端末評価のための電波環境構築法に関する考察
唐沢好男; 清水昌彦
Oral presentation, Japanese, 信学技報
Jan. 2009 - Maximal Ratio Combining Subband Adaptive Arrey with Reduced Signal
T. Taniguchi; Ramli Nordin Bin; Y. Karasawa
Oral presentation, English, 信学技報
Nov. 2008 - マルチパスリッチ環境を実現する電波反射箱[II]
佐々木克守; 大島一郎; 唐沢好男
Oral presentation, Japanese, 信学技報
Sep. 2008 - 電波吸収シートを用いた環境制御型電波反射箱
佐々木克守; 大島一郎; 唐沢好男
Oral presentation, English, 信学ソ大
Sep. 2008 - トータルレコーダを用いた地上デジタル放送波のマルチパス遅延時間測定法
高橋宏和; 竹本淳; 谷口哲樹; 唐沢好男
Oral presentation, Japanese, 信学ソ大
Sep. 2008 - 電流方式を用いた人体伝送における電極面積の影響
高崎和之; 原和輝; 唐沢好男
Oral presentation, Japanese, 信学ソ大
Sep. 2008 - ITS車車間通信の伝搬モデル構築とその関連技術
唐沢好男; Napitupulu; J.T.J
Oral presentation, Japanese, 日本学術会議 URSI-F委員会 第525回
Jun. 2008 - 自律分散制御システムの同期確立問題：搦手からのアプローチ～ITS車車間通信への地デジ信号利用を例として～
唐沢好男
Invited oral presentation, Japanese, IEICE
May 2008 - Statistical Analysis of Double Fading MIMO Channels Including LOS Environments
谷口哲樹; 唐沢好男; 鶴田誠
Oral presentation, English, 信学技報
May 2008 - Statistical Distribution of Eigenvalues in MIMO Channels
T. Taniguchi; S. Sha; Y. Karasawa
Invited oral presentation, English, The first European Conference on Antennas and Propagation, The first European Conference on Antennas and Propagation, Nice, France, International conference
2006 - Inovative antennas and propagation studies for MIMO syste ms(Keynote speech)
Y. Karasawa
Invited oral presentation, English, Int. Symp. Antennas Propagat. (ISAP2006), Int. Symp. Antennas Propagat. (ISAP2006), Singapore, International conference
2006 - MIMO multidimensional propagation channel modeling
Y. Karasawa
Invited oral presentation, English, 2006 Asia-Pasific Microwave Conference (APMC2006), 2006 Asia-Pasific Microwave Conference (APMC2006), Yokohama, International conference
2006 - MIMO Propagation Channel Modeling
Y. Karasawa
Invited oral presentation, English, XXVIIIth General Assembly of International Union of Radio Science (URSI-GA05), XXVIIIth General Assembly of International Union of Radio Science (URSI-GA05), New Delhi, International conference
2005 - Training Courses for Antennas and Propagation Designers in IEICE Japan
Y. Karasawa; M. Ando
Invited oral presentation, English, XXVIIIth General Assembly of International Union of Radio Science (URSI-GA05), XXVIIIth General Assembly of International Union of Radio Science (URSI-GA05), New Delhi, International conference
2005 - MIMO Propagation Channel Modeling
Y. Karasawa
Invited oral presentation, English, URSI-F Open Symp, URSI-F Open Symp, Cairns, International conference
2004 - マルチパスフェージングの空間相関特性を考慮したMIMOチャンネルの固有値分布特性
付鑑宇; 谷口哲樹; 唐沢好男
Oral presentation, Japanese, 電波研連F分科会, 第469回
Nov. 2002 - MIMOの情報伝送能力に関する電波伝搬的視点からの考察
唐沢好男
Oral presentation, Japanese, 電子情報通信学会, 信学技報
Oct. 2002 - 2つの矩形導波路から構成される方向性結合器の解析
冨田正治; 唐沢好男
Oral presentation, Japanese, 電磁界理論研究会
Oct. 2002 - MIMO: 電波伝搬的視点からその実力を読む
唐沢好男
Oral presentation, Japanese, 電気通信学会東京支部シンポジウム「新世代移動通信を担うワイヤレス伝送技術」 （招待発表）
Oct. 2002 - Subband Adaptive Array for DS-CDMA Mobile Radio
X.N.Tran; T.Omata; T.Taniguchi; Y.Karasawa
Oral presentation, English, シンポジウム, 2002年電子情報通信学会ソサイエティ大会
Sep. 2002 - 大都市における降雨強度特性の長期的傾向
齊藤研次; 西村安由; 小野健一; 唐沢好男
Oral presentation, Japanese, 2002年電子情報通信学会ソサイエティ大会
Sep. 2002 - IQ分割バンドパスサンプリングを用いるアダプティブアレーアンテナの実験的検討
佐々木信也; 谷口哲樹; 唐沢好男
Oral presentation, Japanese, 2002年電子情報通信学会ソサイエティ大会
Sep. 2002 - マルチパス環境におけるMIMO最大比合成特性
付鑑宇; 唐沢好男
Oral presentation, Japanese, 2002年電子情報通信学会ソサイエティ大会
Sep. 2002 - MIMO構成によるOFDM伝送システムの検討
Xa Nguyen; 谷口哲樹; 唐沢好男
Oral presentation, Japanese, 2002年電子情報通信学会ソサイエティ大会
Sep. 2002 - OFDMドップラースプレッド補正に用いるビームスペースアダプティブアレーの最大比合成の最適化
Pubudu Sampath Wijesena; 唐沢好男
Oral presentation, Japanese, 2002年電子情報通信学会ソサイエティ大会
Sep. 2002 - キャリアレス無線伝送方式
北川淳一; 谷口哲樹; 唐沢好男
Oral presentation, Japanese, 2002年電子情報通信学会ソサイエティ大会
Sep. 2002 - MIMO高性能ワイヤレス情報伝送のための伝搬チャネルモデル
唐沢好男
Oral presentation, Japanese, シンポジウム（招待発表）, 2002年電子情報通信学会ソサイエティ大会
Sep. 2002 - MIMOチャネルの電波伝搬モデルに関する考察
唐沢好男
Oral presentation, Japanese, URSI-F分科会 第465回会合
Jun. 2002 - FDD方式DS-CDMA移動通信の送信アダプティブアレー［Ⅱ］
P.H.Hoang; 唐沢好男
Oral presentation, Japanese, 信学技報
May 2002 - 遅延の広がりがガードインターバルを超えるマルチパス環境におけるOFDM 伝送特性の等価伝送路モデルによる解析［Ⅱ］－指数関数型遅延プロファィルのマルチパス環境における統計的推定－
唐沢好男; 下条則之
Oral presentation, Japanese, 信学技報
May 2002 - OFDM伝送時のドップラスプレッドに耐性を有する移動受信用ビームスペースアダプティブアレー
Pubudu S. Wijesena; 唐沢好男
Oral presentation, Japanese, 信学技報
Apr. 2002 - IQ分割バンドパスサンプリングを用いるアダプティブアレーアンテナ
佐々木信也; 谷口哲樹; 唐沢好男
Oral presentation, Japanese, 信学技報
Apr. 2002 - 遅延の広がりがガードインターバルを超えるマルチパス環境におけるOFDM伝送特性の等価伝送路モデルによる解析
下条則之; 唐沢好男
Oral presentation, Japanese, 信学技報
Apr. 2002 - Performance Analysis and Evaluation of Subband Adaptive Array using Data Transmission with Cyclic Prefix under Multipath Fading Environment
T.Taniguchi; X.N.Tran; Y.Karasawa
Oral presentation, English, 信学会無線通信システム研究会
Apr. 2002 - 遅延の広がりがガードインターバルを超えるマルチパス環境におけるOFDM伝送特性の等価伝送路モデルを用いた解析
下条 則之; 唐沢好男
Oral presentation, Japanese, 電波研連F分科会、第462回
Mar. 2002 - サイクリック・プリフィックスの付加によるデータ伝送方式を用いたサブバンドアダプティブアレーの最適ウェイトベクトル解析
Xuan Nam TRAN; T.Taniguchi; Y.Karasawa
Oral presentation, Japanese, 2002年電子情報通信学会総合大会, B-1-123
Mar. 2002 - IQバンドパスサンプリングを用いるアダプティブアレーアンテナ（Ⅱ）
佐々木信也; 谷口哲樹; 唐沢好男
Oral presentation, Japanese, 2002年電子情報通信学会総合大会, B-1-124
Mar. 2002 - 遅延の広がりがガードインターバルを超えるマルチパス環境におけるOFDM伝送特性の等価伝送路モデルを用いた解析
下条則之; 唐沢好男
Oral presentation, Japanese, 2002年電子情報通信学会総合大会, B-5-167
Mar. 2002 - MIMO構成における最大比合成ダイバーシチとOFDMの最適伝送について
唐沢好男; 谷口哲樹; 張 毅民
Oral presentation, Japanese, 信学技報、A・P2001-196
Jan. 2002 - Analysis of indoor radio propagation and wideband digital transmission characteristics based on the equivalent transmission-path model with ray tracing
Y. Karasawa; N. Gejoh
Invited oral presentation, English, APMC2001, Taipei, Dec. 4-7,2001. (to be presented), (invited), International conference
Dec. 2001 - FDD方式DS-CDMA移動通信の送信アダプティブアレー
ファン フィ ホアン; 唐沢好男
Oral presentation, Japanese, 信学技報、A・P2001-147, SANE2001-93
Nov. 2001 - 時空間通信路モデリング（招待発表）
唐沢好男
Oral presentation, Japanese, 情報理論とその応用学会、SITA Workshop
Nov. 2001 - 時空間通信路モデリング（招待発表）
唐沢好男
Invited oral presentation, Japanese, 情報理論とその応用学会、SITA Workshop
Nov. 2001 - サイクリック・プリフィックスの付加によるデータ伝送方式を用いたサブバンドアダプティブアレーの特性改善に関する理論解析
チャン スアン ナム; 谷口哲樹; 唐沢好男
Oral presentation, Japanese, 信学技報、A・P2001-148, SANE2001-94
Nov. 2001 - Performance analysis of subband adaptive array in multipath fading environment
T. N. Xuan; T. Taniguch; Y. Karasawa
Oral presentation, English, TECHNICAL REPORT OF IEICA
Oct. 2001 - 矩形導波路に対する方向性結合器の解析
冨田正治; 唐沢好男
Oral presentation, Japanese, 2001年電子情報通信学会ソサイエティ大会, C-1-11
Sep. 2001 - FDD方式CDMA移動通信の送信アダプティブアレー
Hoang Pham Huy; 唐沢好男
Oral presentation, Japanese, 2001年電子情報通信学会ソサイエティ大会, B-5-70
Sep. 2001 - 電波吸収天井板による屋内ディジタル伝送特性改善に関する等価伝送路モデルによる解析
下条則之; 唐沢好男
Oral presentation, Japanese, 2001年電子情報通信学会ソサイエティ大会, B-5-160
Sep. 2001 - ビームスペースアレーアンテナによるOFDM移動受信時のドップラースプレッド補正
ウィジェセーナプブドゥ; 唐沢好男
Oral presentation, Japanese, 2001年電子情報通信学会ソサイエティ大会, B-5-96
Sep. 2001 - マルチパス環境における直交周波数分割多元接続方式(OFDMA)のスループット特性
付 鑑宇; 唐沢好男
Oral presentation, Japanese, 2001年電子情報通信学会ソサイエティ大会, B-5-111
Sep. 2001 - IQ分割バンドパスサンプリング信号を用いるアダプティブアレーアンテナ
佐々木信也; 谷口哲樹; 唐沢好男
Oral presentation, Japanese, 2001年電子情報通信学会ソサイエティ大会, B-1-146
Sep. 2001 - MUSICアルゴリズムを用いた衛星通信のための近接波源の位置推定
プラシットナコンラット; 谷口哲樹; 唐沢好男
Oral presentation, Japanese, 2001年電子情報通信学会ソサイエティ大会, B-1-31
Sep. 2001 - Adaptive Downlink Beamforming for FDD in DS-CDMA Mobile Radio
Huy-Hong Pham; Yoshio Karasawa
Oral presentation, English, 電波研連F分科会, 第457回, 2001.9.14
Sep. 2001 - 突発的に発生する強い干渉波に耐性を有するソフトウェアアンテナ-アレーアンテナ相関行列第2固有値のパワーインバージョン特性を利用した-
畑中芳隆; 唐沢好男
Oral presentation, Japanese, TECHNICAL REPORT OF IEICE
Aug. 2001 - 屋内電波吸収壁によるマルチパス抑圧効果とディジタル伝送特性改善に関する等価伝送路モデルによる解析
下条則之; 唐沢好男
Oral presentation, Japanese, TECHNICAL REPORT OF IEICE
Aug. 2001 - 屋内電波吸収壁によるマルチパス抑圧効果とディジタル伝送特性改善に関する等価伝送路モデルによる解析
下条則之; 唐沢好男
Oral presentation, Japanese, 電波研連F分科会, 第455回, 2001.6.22
Jun. 2001 - マルチパス環境における直交周波数分割多元接続方式(OFDMA)のスループット特性に関する基礎的検討
付鑑宇; 唐沢好男
Oral presentation, Japanese, TECHNICAL REPORT OF IEICE
Jun. 2001 - マルチパス環境における直交周波数分割多元接続方式(OFDMA)のスループット特性に関する基礎的検討
付鑑宇; 唐沢好男
Oral presentation, Japanese, 信学技報、CS2001-46、RCS2001-53
Jun. 2001 - サイクリックプレフィックスを付加した拡散符号を用いるスペクトル拡散通信とサブバンド信号処理アダプティブアレーによるインプリシット2D-RAKE
小俣貴紀; 唐沢好男
Oral presentation, Japanese, TECHNICAL REPORT OF IEICE
May 2001 - サイクリックプレフィックスを付加した拡散符号を用いるスペクトル拡散通信とサブバンド信号処理アダプティブアレーによるインプリシット2D-RAKE
小俣貴紀; 唐沢好男
Oral presentation, Japanese, 信学技報A・P2001-15、SAT2001-2
May 2001