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A Study of Short-Range MIMO Transmission Utilizing Polarization Multiplexing for the Simplification of Decoding 査読

Ken Hiraga, Kazumitsu Sakamoto, Kentaro Nishimori, Tomohiro Seki, Tadao Nakagawa, Kazuhiro Uehara

IEICE TRANSACTIONS ON COMMUNICATIONS E97B ( 2 ) 459 - 468 2014年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

One of the procedures for increasing the number of multi-input and multi-output (MIMO) branches without increasing the computational cost for MIMO detection or multiplexing is to exploit parallel transmissions by using polarization multiplexing. In this paper the effectiveness of using polarization multiplexing is confirmed under the existence of polarization rotation, which is inevitably present in short-range multi-input and multi-output (SR-MIMO) channels with planar array antennas. It is confirmed that 8 x 8 SR-MIMO transmission system with polarization multiplexing has 60 bit/s/Hz of channel capacity. This paper also shows a model for theoretical cross polarization discrimination (XPD) degradation, which is useful to calculate XPD degradations on diagonal paths.

DOI： 10.1587/transcom.E97.B.459

Theoretical and experimental analysis of spatial division using antenna directivities in short-range MIMO transmission 査読

M. Arai, T. Seki, K. Hiraga, T. Nakagawa, K. Uehara

ELECTRONICS LETTERS 50 ( 2 ) 65 - 66 2014年1月

An SD Method Utilizing Null Dependency on Transmission Distance Due to Two-Ray Fading 査読

Ken Hiraga, Kazumitsu Sakamoto, Maki Arai, Tomohiro Seki, Tadao Nakagawa, Kazuhiro Uehara

IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS 13 126 - 129 2014年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

A spatial division (SD) transmission method utilizing the characteristics of two-ray fading due to ground reflection with linear antenna arrays horizontal to the ground is proposed. Formulations of the optimum array arrangements as functions of the transmission distance and achievable channel capacity are clarified. For two- and three-element arrays, channel capacity is respectively doubled and tripled over that of free-space propagation. The proposed method provides increased capacity without the extra signal processing cost incurred when using conventional multiple-input-multiple-output (MIMO) transmission.

DOI： 10.1109/LAWP.2013.2297379

Performance Evaluation of Short-Range MIMO Using a Method for Controlling Phase Difference between Each Propagation Channel 査読

Kazumitsu Sakamoto, Ken Hiraga, Tomohiro Seki, Tadao Nakagawa, Kazuhiro Uehara

IEICE TRANSACTIONS ON COMMUNICATIONS E96B ( 10 ) 2513 - 2520 2013年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

A Simple decoding method for short-range MIMO (SR-MIMO) transmission can reduce the power consumption for MIMO decoding, but the distance between the transceivers requires millimeter-order accuracy in order to satisfy the required transmission quality: In this paper, we propose a phase difference control method between each propagation channel to alleviate the requirements for the transmission distance accuracy. In the proposed method, the phase difference between each propagation channel is controlled by changing the transmission (or received) power ratio of each element of sub-array antennas. In millimeter-wave broadband transmission simulation, we clarified that when sub-array antenna spacing is set to 6.6 mm and element spacing of sub-array antenna is set to 2.48 mm, the proposed method can extend the transmission distance range satisfying the required transmission quality, which is that bit error rate (BER) before error correction is less than 10(-2) from 9 similar to 29 mm to 0 similar to 50 mm in QPSK, from 15 similar to 19 mm to 0 similar to 30 mm in 16QAM, and from only 15 mm to 4 similar to 22 mm in 64QAM.

DOI： 10.1587/transcom.E96.B.2513

Effects of weight errors on capacity in simple decoding of short-range MIMO transmission 査読

Ken Hiraga, Kazumitsu Sakamoto, Tomohiro Seki, Tadao Nakagawa, Kazuhiro Uehara

IEICE Communications Express 2 ( 5 ) 193 - 199 2013年5月

An SDM Method Utilizing Height Pattern Due to Two-Ray Fading Characteristics 査読

Ken Hiraga, Kazumitsu Sakamoto, Maki Arai, Tomohiro Seki, Tadao Nakagawa, Kazuhiro Uehara

IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS 12 1622 - 1626 2013年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

A spatial division multiplexing (SDM) transmission method utilizing the characteristics of two-ray fading without relying on narrow beam of the antennas is introduced. This letter formulates the optimized array antenna arrangements and channel capacity as functions of the transmission distance and shows achievable channel capacity for two-and three-element antenna arrays. The letter also describes bandwidth dependency up to 15% bandwidth based on an assumed application to 60-GHz-band gigabit wireless systems. The proposed method provides increased capacity comparable to multiple-input-multiple-output (MIMO) transmission without the extra signal processing cost incurred when using conventional MIMO.

DOI： 10.1109/LAWP.2013.2294454

Nonlinear modeling and analysis on concurrent amplification of dual-band gaussian signals 査読

Ikuma Ando, Gia Khanh Tran, Kiyomichi Araki, Takayuki Yamada, Takana Kaho, Yo Yamaguchi, Kazuhiro Uehara

IEICE Transactions on Electronics E96-C ( 10 ) 1254 - 1262 2013年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Institute of Electronics, Information and Communication, Engineers, IEICE

In the recently developed Flexible Wireless System (FWS), the same platform needs to deal with different wireless systems. This increases nonlinear distortion in its wideband power amplifier (PA) because the PA needs to concurrently amplify multi-band signals. By taking higher harmonics as well as inter- and cross-modulation distortion into consideration, we have developed a method to analytically evaluate the adjacent channel leakage power ratio (ACPR) and error vector magnitude (EVM) on the basis of the PA's nonlinear characteristics. We devise a novel method for modeling the PA amplifying dual-band signals. The method makes it possible to model it merely by performing a one-tone test, making use of the Volterra series expansion and the generalWiener model. We then use the Mehler formula to derive the closed-form expressions of the PA's output power spectral density (PSD), ACPR, and EVM. The derivations are based on the assumption that the transmitted signals are complex Gaussian distributed in orthogonal frequency division multiplexing (OFDM) transmission systems. We validate the method by comparing measurement and simulation results and confirm it can appropriately predict the ACPR and EVM performance of the nonlinear PA output with OFDM inputs. In short, the method enables correct modeling of a wideband PA that amplifies dualband signals merely by conducting a one-tone test. Copyright © 2013 The Institute of Electronics, Information and Communication Engineers.

DOI： 10.1587/transele.E96.C.1254

Study on short-range MIMO transmission using interference cancellation by antenna directivities 査読

Maki Arai, Tomohiro Seki, Ken Hiraga, Tadao Nakagawa, Kazuhiro Uehara

Asia-Pacific Microwave Conference Proceedings, APMC 395 - 397 2013年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

In this paper, a simple method for canceling interference by using antenna directivities is proposed for short-range transmission systems. For higher data transmission systems the millimeter-wave frequency bands are useful because of their wide bandwidths. Also, Multiple-Input Multiple-Output (MIMO) technology can be applied to these bands because the application enables channel capacity to be increased by using multiple antennas at the transmitter and receiver without expanding the frequency bandwidth. However, since MIMO transmission schemes are complicated we consider parallel transmission, a simple method for transmitting multiple data streams that is suitable for short-range MIMO transmission. We propose a simple method for canceling interference by using antenna directivities and improving channel capacity in parallel transmission. Numerical analysis shows that the method maximizes channel capacity at the optimal spacing Lopt = 2λ0. It is also found that the channel capacity of the method is 14 % higher than that of Eigenmode beamforming (EM-BF) for two transmission streams and 12 % higher for four streams. © 2013 IEEE.

DOI： 10.1109/APMC.2013.6695158

Signal Separation and Reconstruction Method for Simultaneously Received Multi-System Signals in Flexible Wireless System 査読

Takayuki Yamada, Doohwan Lee, Hiroyuki Shiba, Yo Yamaguchi, Kazunori Akabane, Kazuhiro Uehara

IEICE TRANSACTIONS ON COMMUNICATIONS E95B ( 4 ) 1085 - 1092 2012年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

We previously proposed a unified wireless system called "Flexible Wireless System". Comprising of flexible access points and a flexible signal processing unit, it collectively receives a wideband spectrum that includes multiple signals from various wireless systems. In cases of simultaneous multiple signal reception, however, reception performance degrades due to the interference among multiple signals. To address this problem, we propose a new signal separation and reconstruction method for spectrally overlapped signals. The method analyzes spectral information obtained by the short-time Fourier transform to extract amplitude and phase values at each center frequency of overlapped signals at a flexible signal processing unit. Using these values enables signals from received radio wave data to be separated and reconstructed for simultaneous multi-system reception. In this paper, the BER performance of the proposed method is evaluated using computer simulations. Also, the performance of the interference suppression is evaluated by analyzing the probability density distribution of the amplitude of the overlapped interference on a symbol of the received signal. Simulation results confirmed the effectiveness of the proposed method.

DOI： 10.1587/transcom.E95.B.1085

Effectiveness of Short-Range MIMO Using Dual-Polarized Antenna 査読

Ken Hiraga, Tomohiro Seki, Kentaro Nishimori, Kazuhiro Uehara

IEICE TRANSACTIONS ON COMMUNICATIONS E95B ( 1 ) 87 - 96 2012年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

Short-range Multiple-Input-Multiple-Output (SR-MIMO) transmission is an effective technique for achieving high-speed and short-range wireless communication. With this technique, however, the optimum aperture size of array antennas grows when the transmission distance is increased. Thus, antenna miniaturization is an important issue in SR-MIMO. In this paper, we clarify the effectiveness of using dual-polarized planar antennas as a means of miniaturizing SR-MIMO array antennas by measurements and analysis of MIMO transmission characteristics. We found that even in SR-MIMO transmission, the use of dual-polarized transmission enables higher channel capacity. Dual-polarized antennas can reduce by two thirds the array area that is needed to obtain the same channel capacity. For a transmission distance of two wavelengths, the use of a dual-polarized antenna improved the channel capacity by 26 bit/s/Hz while maintaining the same number of transmitters and receivers and the same antenna aperture size. Moreover, dual-polarized SR-MIMO has a further benefit when zero-forcing (ZF) reception without transmit beamforming is adopted, i.e., it effectively simplifies hardware configuration because it can reduce spatial correlation even in narrow element spacing. In this work, we confirmed that the application of dual-polarization to SR-MIMO is an effective way to both increase channel capacity and enhance transceiver simplification.

DOI： 10.1587/transcom.E95.B.87

Analyses of Antenna Displacement in Short-Range MIMO Transmission over Millimeter-Wave 査読

Ken Hiraga, Tomohiro Seki, Kentaro Nishimori, Kenjiro Nishikawa, Ichihiko Toyoda, Kazuhiro Uehara

IEICE TRANSACTIONS ON COMMUNICATIONS E94B ( 10 ) 2891 - 2895 2011年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

Short-range multiple-input and multiple-output (SR-MIMO) has attracted much attention, because the technique makes it possible to raise channel capacity to several hundred Gbit/s by utilizing the millimeter-wave band (e.g., 60 GHz band). Although the opposed transceiving antennas are assumed to be accurately positioned in previous studies regarding SR-MIMO, a very important issue is to evaluate the performance degradation due to displacement between MIMO transceivers. In SR-MIMO over the millimeter-wave band, any displacement is perceived as significant because the wavelength is small. This paper evaluates the influence on SR-MIMO transmission performance over millimeter-wave caused by displacement between the transmitting and receiving antennas. The channel capacity is found to degrade by 5% when the horizontal displacement is 1 mm and by 2.7% when the rotational displacement is 10 degrees. In addition, comparing performances obtained with a number of antenna array arrangements clarifies that a square pattern arrangement is suitable for short-range wireless transmission.

DOI： 10.1587/transcom.E94.B.2891

A Low-Noise, High-Gain Quasi-Millimeter-Wave Receiver MMIC with a Very High Degree of Integration Using 3D-MMIC Technology 査読

Takana Kaho, Yo Yamaguchi, Kazuhiro Uehara, Kiyomichi Araki

IEICE TRANSACTIONS ON ELECTRONICS E94C ( 10 ) 1548 - 1556 2011年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

We present a highly integrated quasi-millimeter-wave receiver MMIC that integrates 22 circuits in a 3 x 2.3 mm area using three-dimensional MMIC (3D-MMIC) technology. The MMIC achieves low noise (3 dB) and high gain (41 dB) at 26 GHz by using an on-chip image reject filter. It integrates a multiply-by-eight (X8) local oscillator (LO) chain with the IF frequency of the 2.4 GHz band and can use low-cost voltage-controlled oscillators (VCO5) and demodulators in a 2-3 GHz frequency band. Multilayer inductors contribute to the miniaturization especially in a 2-12 GHz frequency band. Furthermore, it achieves a high dynamic range by using two step attenuators with a new built-in inverter using an N-channel depression field-effect transistor (FET). The power consumption of the MMIC is only 450 mW.

DOI： 10.1587/transele.E94.C.1548

Combined Nyquist and Compressed Sampling Method for Radio Wave Data Compression of a Heterogeneous Network System 査読

Doohwan Lee, Takayuki Yamada, Hiroyuki Shiba, Yo Yamaguchi, Kazuhiro Uehara

IEICE TRANSACTIONS ON COMMUNICATIONS E93B ( 12 ) 3238 - 3247 2010年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

To satisfy the requirement of a unified platform which can flexibly deal with various wireless radio systems we proposed and implemented a heterogeneous network system composed of distributed flexible access points and a protocol free signal processing unit Distributed flexible access points are remote RF devices which perform the reception of multiple types of radio wave data and transfer the received data to the protocol free signal processing unit through wired access network The protocol free signal processing unit performs multiple types of signal analysis by software To realize a highly flexible and efficient radio wave data reception and transfer we employ the recently developed compressed sensing technology Moreover we propose a combined Nyquist and corn pressed sampling method for the decoding signals to be sampled at the Nyquist rate and for the sensing signals to be sampled at the compressed rate For this purpose the decoding signals and the sensing signals are converted into the intermediate band frequency (IF) and mixed In the IF band the decoding signals are set at lower center frequencies than those of the sensing signals The down converted signals are sampled at the rate of four times of the whole bandwidth of the decoding signals plus two times of the whole bandwidth of the sensing signals The purpose of above setting is to simultaneously conduct Nyquist rate and compressed rate sampling in a single ADC Then all of odd (or even) samples are preserved and some of even (or odd) samples are randomly discarded This method reduces the data transfer burden in dealing with the sensing signals while guarantee ing the realization of Nyquist rate decoding performance Simulation and experiment results validate the efficiency of the proposed method

DOI： 10.1587/transcom.E93.B.3238

An Analysis of Multi-Layer Inductors for Miniaturizing of GaAs MMIC 査読

Yo Yamaguchi, Takana Kaho, Motoharu Sasaki, Kenjiro Nishikawa, Tomohiro Seki, Tadao Nakagawa, Kazuhiro Uehara, Kiyomichi Araki

IEICE TRANSACTIONS ON ELECTRONICS E93C ( 7 ) 1119 - 1125 2010年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

Newly developed multi-layer inductors on GaAs three-dimensional MMICs are presented. We analyzed single-, double-, triple-, and quadruple-layer stacked-type inductors in what may be the first report on inductors on a GaAs MMIC with three or more layers. The performance of single- and multi-layer inductors was measured and calculated by electromagnetic field simulation. The multi-layer inductors produce 2-11 times higher inductance than that of conventional inductors on 2D-MMICs although they are the same size. This means that the proposed multi-layer inductors have smaller areas with the same inductances than those of conventional inductors. We also conducted the first-ever investigation of how performance factors such as parasitic capacitance, Q-factor, and self-resonant frequency are degraded in multi-layer inductors vis-a-vis those of conventional inductors. A microwave amplifier using multi-layer inductors was demonstrated and found to reduce circuit size by 20%.

DOI： 10.1587/transele.E93.C.1119

A Very Low Spurious X-Band Frequency Quadrupler with Very High Integration Using 3D-MMIC Technology 査読

Yo Yamaguchi, Takana Kaho, Kazuhiro Uehara

IEICE TRANSACTIONS ON ELECTRONICS E91C ( 11 ) 1744 - 1750 2008年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

A highly integrated frequency quadrupler MMIC that uses three-dimensional MMIC (3D-MMIC) technology is presented. It consists of four driver amplifiers, two doublers, and a 2-band elimination filter. These seven circuits are integrated in only a 2.36 mm(2) area. The filter sufficiently suppresses spurious output components. The third and fifth harmonic components, which are the spurious components nearest to the desired component, are well suppressed. The desired/undesired ratio is about 40 dB. The driver amplifiers make the quadrupler output a constant power of the desired multiplied signal under low input power. The MMIC supplies +5 dBm of the fourth harmonic component in the input power range from -10 dBm to +5 dBm. The power dissipation of the MMIC is only 160 mW.

DOI： 10.1093/ietele/e91-c.11.1744

Performance evaluation of an autonomous adaptive base station that supports multiple wireless network systems 査読

Kazunori Akabane, Hiroyuki Shiba, Munehiro Matsui, Kazuhiro Uehara

IEICE TRANSACTIONS ON COMMUNICATIONS E91B ( 1 ) 22 - 28 2008年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

Various wireless systems are being developed to meet users' needs, and the rapid increase in frequency demand that accompanies the increasing popularity of wireless services means that more effective use of frequency resources is urgently needed. However, existing base stations are making no effort to use frequency resources effectively, and cooperation among wireless system base stations is needed to use frequency resources more effectively. Base stations can cooperate more efficiently if they are able to use multiple channels of many wireless systems simultaneously. We propose an autonomous adaptive base station (AABS) that can switch among various wireless systems the way software defined radio (SDR) base stations do. AABS can autonomously select and use the most suitable wireless system on the basis of user traffic and its hardware resources. Moreover, frequency resources are used effectively because AABS prevents unnecessary radio wave transmission when the number of users in the wireless systems decreases. AABS is also suitable for "multi-link communication" because it can use multiple channels of multiple wireless systems simultaneously. We developed AABS prototype and evaluated its performance. Our experimental and computer simulation results show the performance of AABS and its efficiency.

DOI： 10.1093/ietcom/e9l-b.1.22

A miniaturized in-phase power divider with a DC block function 査読

Hitoshi Hayashi, Tadao Nakagawa, Kazuhiro Uehara, Yoshihiro Takigawa

IEICE TRANSACTIONS ON ELECTRONICS E90C ( 10 ) 2022 - 2029 2007年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

This paper describes a miniaturized in-phase power divider with a DC block function. We first propose three types of miniaturized in-phase power dividers composed of two distributed transmission lines, a resistor, and three capacitors to function as a DC block. Then, we use a simulation to compare the dividers. The simulation results show that. by properly selecting circuit configuration, we both achieve broadband frequency characteristics and miniaturize circuitry as compared to the conventional Wilkinson power divider with two DC block capacitors. Finally, an experimental UHF power divider fabricated to test the design concept is presented. Over the frequency range from 0.44 to 0.66 GHz, the experimental power divider exhibits power splits of -3.2 +/- 0.2 dB, return losses greater than 20 dB. and isolation between output ports greater than 20 dB.

DOI： 10.1093/ietele/e90-c.10.2022

Miniaturized broadbland lumped-element in-phase power dividers 査読

Hitoshi Hayashi, Tadao Nakagawa, Kazuhiro Uehara, Yoshihiro Takigawa

IEICE TRANSACTIONS ON ELECTRONICS E90C ( 6 ) 1222 - 1227 2007年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

This paper describes miniaturized broadband lumped-element in-phase power dividers. We first propose two types of miniaturized broadband lumped-element in-phase power dividers composed of two inductors, a resistor, and two capacitors. Next, we use a simulation to compare these dividers with conventional power dividers. The simulation results reveal that the proposed lumped-element in-phase power dividers can help miniaturize circuits (by decreasing inductances by about 30%, reducing the number of necessary capacitors by half, and decreasing necessary capacitances by about 30% as compared to conventional lumped-element dividers) and attain broadband frequency characteristics (by increasing normalized operating frequency bandwidths (f/fo) by about 80% as compared to conventional lumped-element dividers).

DOI： 10.1093/ietele/e90-c.6.1222

An active terminal circuit and its application to a distributed amplifier 査読

Hitoshi Hayashi, Munenari Kawashima, Tadao Nakagawa, Kazuhiro Uehara, Yoshihiro Takigawa

IEICE TRANSACTIONS ON ELECTRONICS E90C ( 6 ) 1203 - 1208 2007年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

This paper describes a broadband active terminal circuit and its application to a distributed amplifier. In this study, we first analyzed and compared three types of active terminal circuits using representative circuit configurations, namely, an active terminal circuit with a common-emitter BJT, an active terminal circuit with a Darlington BJT pair, and an active terminal circuit with cascode-connected BJTs. The simulation results showed that the active terminal circuit with cascode-connected BJTs kept the matching condition up to high frequency. After the simulation, we fabricated a distributed amplifier that used an active terminal circuit with cascode-connected BJTs. The RF amplifier achieved a flat gain of 9.7 +/- 1.0 dB over a range of 3-15 GHz.

DOI： 10.1093/ietele/e90-c.6.1203

Trends in broadband wireless communication systems and software defined radios 招待査読

Kazuhiro Uehara

Interdisciplinary Information Sciences Journal 12 ( 2 ) 163 - 172 2006年9月

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