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Kobayashi K.,ATR Wave Engineering Laboratories | Oka T.,MItsubishi Electric | Nakamoto N.,MItsubishi Electric | Yano K.,Wave Systems | Ban H.,Wave Systems
30th AIAA International Communications Satellite System Conference (ICSSC), 2012 | Year: 2012

This paper proposes a novel transmission scheme that enhances the spectrum efficiency by exploiting multiple polarization planes. Unlike the conventional polarization usage that secures orthogonality, the proposed scheme transmits signals through more than 2 polarization planes and enhances spectrum efficiency in proportion to the number of the polarization planes. Degradation caused by cross polarization interference is restored by applying digital signal processing techniques. As a result of computer simulations, we have clarified that the proposed scheme improves required Eb/N0by about 1dB and 1.4dB without/with FEC, respectively, when three polarizations are simultaneously transmitted. © 2012 by the authors. Published by FGM Events LLC and distributed by AIAA with permission. All other rights reserved.


Hou Y.,ATR Wave Engineering Laboratories | Tsukamoto S.,ATR Wave Engineering Laboratories | Ariyoshi M.,ATR Wave Engineering Laboratories | Kobayashi K.,ATR Wave Engineering Laboratories | Okada M.,Nara Institute of Science and Technology
IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC | Year: 2015

Leaky coaxial cables (LCX) have been widely used as antennas to form linear service areas for radio communication systems. Such services of linear cells have been deployed inside tunnels, along railways, and so on. Usually, one LCX is utilized as one antenna. Therefore it requires more than one LCX to configure an multi-input multi-output (MIMO) system. In this paper, we propose a MIMO system using single LCX, which can be utilized as two antennas. When different RF transmit signals are fed to each end of the proposed cable, single LCX can work as two antennas. To confirm the feasibility of the proposed MIMO system, we conduct experiments to measure the characteristics of 2 × 2 MIMO channel using single LCX. The results confirm that our proposed 2×2 MIMO channel using single LCX can realize a good channel condition for MIMO transmission even within a highly correlated propagation condition. The proposed MIMO system using LCX will release the space requirement and reduce the cost of system for configuration of LCX MIMO system especially with large number of LCXs. It benefits the design and configuration of LCX-MIMO system for many scenarios of linear-cell. © 2014 IEEE.


Sonobe S.,ATR Wave Engineering Laboratories | Tsukamoto S.,ATR Wave Engineering Laboratories | Maeda T.,ATR Wave Engineering Laboratories | Yano K.,ATR Wave Engineering Laboratories | And 3 more authors.
2013 11th International Symposium and Workshops on Modeling and Optimization in Mobile, Ad Hoc and Wireless Networks, WiOpt 2013 | Year: 2013

We have developed an LTE-Advanced-based 8 x 8 multiuser MIMO experimental system with vector perturbation to overcome performance degradation of the MIMO technique under spatially correlated channel conditions, such as a line-of-sight (LoS) environment. This paper introduces our experimental system and shows results of outdoor/indoor experiments envisioning small-cell environments. Through experimental evaluation, it is confirmed that the throughput of the downlink transmission with vector perturbation reaches almost double that with MMSE spatial filtering. © 2013 IFIP.


Nakamoto N.,ATR Wave Engineering Laboratories | Ban H.,ATR Wave Engineering Laboratories | Kobayashi K.,ATR Wave Engineering Laboratories
IEEE Antennas and Propagation Society, AP-S International Symposium (Digest) | Year: 2012

We have been developing a 2.4 GHz point-to-multipoint wireless communication system suitable for use inside mechatronics ICT (Information and Communication Technology) equipment to replace wire harnesses inside equipment with wireless communication as a useful technique of weight reduction and simplification of system assembling [1]. One of the critical problems of such applications is that antennas are installed close to metallic components or in a narrow gap between metallic housings and thus suffer degradation of antenna performance due to effects of the ambient environment. Therefore, in order to maintain desired antenna performance inside equipment, we need to understand the dependence of antenna characteristics on the ambient environment inside equipment and design antennas with a consideration of it. © 2012 IEICE.


Miura A.,ATR Wave Engineering Laboratories | Ohira M.,ATR Wave Engineering Laboratories | Kitazawa S.,ATR Wave Engineering Laboratories | Ueba M.,ATR Wave Engineering Laboratories
IEICE Transactions on Communications | Year: 2010

This paper proposes a new switched-beam eight-sector antenna for multi-gigabit wireless LAN in the 60-GHz band. Our antenna system introduces access-point (AP) and user-terminal (UT) antennas having the same sec θ pattern in the elevation plane so that the received signal power at the receiver is kept constant, independent of the position of the UT. For this system, an eight-sector antenna, a single-pole eight-throw (SP8T) switch, and a beam control unit are integrated as the switched-beam eight-sector antenna. The specifications of the antenna are wide bandwidth (≥3 GHz), high-gain (≥13 dBi at θ=66°), and wide coverage area in both azimuth (0° ≤ φ ≤ 180°) and elevation planes (0? ≤ θ ≤ 66°). The antenna beam is steered within the specified response time (which is short) by the Media Access Control (MAC). In our antenna, both high gain for a wide elevation angle and wide bandwidth are obtained by using the proposed closely spaced waveguide slot array antenna, which is used as each sector of the eight-sector antenna. The SP8T switch with the beam control unit enables 180° beam scan in the azimuth plane. In a component evaluation, the eight-sector antenna achieves a 10-dB return loss bandwidth of 8 GHz with more than 40-dB port-to-port isolation. Radiation characteristics of the eight-sector antenna indicate that it covers 82% of the entire coverage area at the center frequency and that the coverage rate in the operating frequency band is from 78% to 88%. The performance of the SP8T switch and the beam control unit is verified by measuring the insertion loss at all eight ports and the switching response time. In the antenna system evaluation, measurement by using two prototype antennas as the AP and the UT antennas in the usage condition indicates that the measured received signal power meets the specified constant power for the specified wide elevation angle range, independent of the position of the UT. These experimental results verify the effectiveness of our proposed antenna for multi-gigabit WLAN. Copyright © 2010 The Institute of Electronics, Information and Communication Engineers.


Kitazawa S.,ATR Wave Engineering Laboratories | Ban H.,ATR Wave Engineering Laboratories | Kobayashi K.,ATR Wave Engineering Laboratories
2012 IEEE MTT-S International Microwave Workshop Series on Innovative Wireless Power Transmission: Technologies, Systems, and Applications, IMWS-IWPT 2012 - Proceedings | Year: 2012

This paper presents a feasibility study of energy harvesting from ambient radio frequency (RF) sources. A preliminary assessment of the ambient RF energy was carried out by calculation of power spectrum density and measurement of received power in a common suburban area. The results showed that the median value of received power obtained -25dBm from 800 MHz band mobile telephone base station (BS) was averagely 13dB stronger than that from Digital TV broadcasting. A prototype multi-stage RF-DC conversion circuit was designed and tested. Experimental results showed that a 1.0 F electric double layer capacitor can be charged up to 320 mV in 3900 minutes at common suburban area. We confirm that the possibility of energy harvesting from ambient RF sources in suburban area, and clarify the problems in devices for the future energy harvesting systems. © 2012 IEEE.


Ohira M.,ATR Wave Engineering Laboratories | Miura A.,Japan National Institute of Information and Communications Technology | Ueba M.,ATR Wave Engineering Laboratories
IEEE Transactions on Antennas and Propagation | Year: 2010

A new wideband waveguide slot array is proposed for covering a wide elevation-angle range with a planar sector antenna of a multigigabit wireless LAN in the 60-GHz band. The requirement of millimeter-wave sector antennas is to realize both wide bandwidth of 11.2% and wide elevation-angle coverage with a required gain of over 10 dBi. To satisfy both the required gain and bandwidth, the important structural features of the proposed antenna are that multiple slot elements are successively arranged at an interval of the length less than one quarter guide wavelengths and that the slot length increases from the shorted waveguide end to the feed end. The operational principle of the slot array is based on multisection quarter-wavelength reflection cancellation, so the slot array can achieve the required bandwidth. Furthermore, this antenna produces a unidirectional radiation pattern by using the radiators and the reflectors, resulting in the required gain over a wide elevation-angle range. In the design, the structural parameters of the slot array are selected to meet the requirements for 60-GHz-band sector antenna. The developed substrate-integrated- waveguide (SIW) slot array achieves both the 10 dB return-loss bandwidth of 15% and the specified gain in 8896% of the one-sector coverage range of 5966 GHz. The effectiveness of the proposed slot array for a sector antenna is verified by the good agreement between the simulated and measured results. © 2010 IEEE.


Kamoda H.,ATR Wave Engineering Laboratories | Hanazawa M.,ATR Wave Engineering Laboratories | Kitazawa S.,ATR Wave Engineering Laboratories | Ban H.,ATR Wave Engineering Laboratories | Kobayashi K.,ATR Wave Engineering Laboratories
European Microwave Week 2013, EuMW 2013 - Conference Proceedings; EuMC 2013: 43rd European Microwave Conference | Year: 2013

A 3×3 rectenna array for ambient RF energy harvesting was studied in terms of antenna element spacing and antenna type. The antenna types considered were a half-wavelength dipole and a loop antenna. To take into account the mutual coupling between antenna elements, the active element patterns for all the elements were calculated. Then, the patterns were used to estimate the combined DC power using non-linear RF-to-DC conversion efficiency. As a result, the obtainable DC power was highly dependent on the receiving angle even when using an omni-directional dipole due to the mutual coupling. The largest DC power was obtained in the array broadside directions when the element spacing was 0.7 or 0.8 wavelengths for both dipole and loop antennas. However, in the scenario considered, to maintain a DC power of 5 dBμW or more from arbitrary receiving directions, the dipole element with the element spacing of 0.8 wavelengths or more was preferable. © 2013 European Microwave Association.


Kamoda H.,ATR Wave Engineering Laboratories | Ano S.,ATR Wave Engineering Laboratories | Kitazawa S.,ATR Wave Engineering Laboratories | Kukutsu N.,ATR Wave Engineering Laboratories | Kumagai T.,ATR Wave Engineering Laboratories
ISAP 2014 - 2014 International Symposium on Antennas and Propagation, Conference Proceedings | Year: 2015

With the aim of achieving a wireless harness system in an automobile engine compartment (EC), radio propagation channels from 1.5 to 8 GHz in ECs were characterized with numerous measurements. Because there are many metal objects in EC, the channel's frequency-distance interdependence was taken into account in the characterization. As a result, the path loss exponents for distance were found to be about 1 and 3 below and above 450 mm, respectively. The exponent for frequency was 0.5 to 1. The delay spread increased as distance increased at a rate of about 3 ns/m. It also exhibited a decreasing trend with increasing frequency at the far distance. © 2014 Institute of Antenna Engineers of Taiwan.


Hatamoto H.,Oki Electric Industry Co. | Ano S.,ATR Wave Engineering Laboratories | Kikuchi N.,Oki Electric Industry Co. | Shimizu S.,Oki Electric Industry Co.
IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC | Year: 2013

In this paper, transmission performance for wireless harness systems is evaluated using propagation models which include pathloss and power delay profile in an automobile engine compartment. In the wireless harness system in vehicles, it is assumed that an electronic control unit has a wireless access point (AP) and each sensor has a wireless station terminal (ST). First, pathloss and power delay profile models are analyzed using measured propagation data of the scattering parameter in the Toyota Prius's engine room which size is 0.9 × 1.2 × 0.6 m on condition that the vehicle's engine is turned off. Second, performance results of channel capacity and throughput, where on-off keying based signals are transmitted between the AP and each ST, are evaluated using analyzed propagation models. Simulation results confirm that high channel capacity and throughput performance are satisfied when transmit power is less than 0 dBm in 2-3 GHz on condition that positions of AP's antennas are fixed, positions of STs are uniformly set in the engine space, and wireless channels are quasi-static. © 2013 IEEE.

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