Electronics and Communications in Japan (Part I: Communications)最新文献

{"title":"Transmit phase control to increase the minimum eigenvalue of the channel correlation matrix in the ETD system","authors":"R. Shimura, I. Sasase","doi":"10.1002/ECJA.20342","DOIUrl":"https://doi.org/10.1002/ECJA.20342","url":null,"abstract":"For conditions under which the channel conditions between the transmitting and receiving antennas are known on the transmitter side when TDD (Time Division Duplex) is used in the MIMO (Multi-Input Multi-Output) method, much attention has been devoted to E-SDM (Eigenbeam Space Division Multiplexing), in which the influence of CCI (Co-Channel Interference) is eliminated by making the different transmission signal sequences orthogonal in space by means of the eigenvectors of the channel matrix used as the transmission and reception weights. However, in such a system as E-SDM, in which eigenvectors of the channel matrix are used, more than two antennas are needed on the receiving side in order to perform eigenvalue decomposition of the channel matrix. In this paper, in order to realize a system using the eigenvectors as the transmission and reception weights even in a system with two transmitting antennas and one receiving antenna under TDD, the ETD (Eigenbeam Transmit Diversity) system is proposed. In this system, the concept of frequency diversity is applied, in which identical signals are transmitted on two subcarriers on one transmitting antenna, so that a MIMO system is virtually realized with subcarriers of the OFDM (Orthogonal Frequency Division Multiplexing) in place of receiving antennas in the row direction of the channel matrix. In the ETD system, the minimum eigenvalue of the channel matrix can be made larger by adaptively interchanging the signals among antennas and by transmission phase control. Hence, the BER characteristics of the signal sequence by which the minimum eigenvalue is multiplied can be improved. The characteristics are evaluated by computer simulations. It is shown that the proposed system is superior in terms of BER characteristics to the transmission diversity system in which transmission phase control is carried out among the antennas. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(7): 38–51, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20342","PeriodicalId":100405,"journal":{"name":"Electronics and Communications in Japan (Part I: Communications)","volume":"21 1","pages":"38-51"},"PeriodicalIF":0.0,"publicationDate":"2007-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86547464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A planar dipole antenna with wideband characteristics for UWB and wireless LAN","authors":"Atsushi Horita,&nbsp;Hisao Iwasaki","doi":"10.1002/ecja.20395","DOIUrl":"https://doi.org/10.1002/ecja.20395","url":null,"abstract":"<p>In recent years, attention has focused on UWB (Ultra Wideband), which is suitable for high-speed, large-capacity near-distance wireless communication systems. Since UWB uses the 3.1- to 10.6-GHz bands, research and development into antennas capable of obtaining wideband characteristics has become active. Research has also accelerated on antennas that can be shared with wireless LAN and other wireless communication systems. In this paper, we propose a wideband characteristics method that uses trapezoidal conductors for planar dipole antennas that satisfy the ultrawide bandwidths required for UWB, and for planar asymmetric dipole antennas that can be used for both IEEE802.11b/g, a wireless LAN in the 2.4-GHz band, and UWB. We performed analysis and measurement of impedance characteristics, and of directionality in each frequency band, and confirmed that the analysis results and measurement results virtually match. We also performed measurement to study group delay characteristics. We used the proposed method to achieve an antenna that is effective for both UWB and the 2.4-GHz-band wireless LAN, and showed the validity of the wideband characteristics method. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(12): 22–30, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20395</p>","PeriodicalId":100405,"journal":{"name":"Electronics and Communications in Japan (Part I: Communications)","volume":"90 12","pages":"22-30"},"PeriodicalIF":0.0,"publicationDate":"2007-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ecja.20395","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91857634","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"IP-HDTV multicast distribution system architecture with nonstop service availability","authors":"Teruyuki Hasegawa,&nbsp;Kazuhiro Kamimura,&nbsp;Haruo Hoshino,&nbsp;Shigehiro Ano,&nbsp;Toru Hasegawa","doi":"10.1002/ecja.20346","DOIUrl":"https://doi.org/10.1002/ecja.20346","url":null,"abstract":"<p>This paper proposes a new system architecture which achieves stable HDTV distribution service using ISP multicast networks. With the recent spread of broadband access networks including FFTH, the distribution of broadcasting contents using IP multicast is becoming indispensable in the ISP service menu. The important issues in the development of such a content distribution service are to provide high service availability and to construct a highly flexible distribution system that can handle various distribution formats. The authors have proposed a nonstop IP multicast technique without modification of router implementation intended for the ISP network, and also a packet transmission control procedure which works independently of the distribution format. A prototype was implemented and a video distribution experiment is performed on an IP multicast network corresponding to digital HDTV broadcasting by satellite. It is shown that nonstop service can be provided using the prototype system, compensating the loss of approximately 27,500 packets, accompanied by detection and recovering of network failure at the router. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(12): 73–85, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20346</p>","PeriodicalId":100405,"journal":{"name":"Electronics and Communications in Japan (Part I: Communications)","volume":"90 12","pages":"73-85"},"PeriodicalIF":0.0,"publicationDate":"2007-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ecja.20346","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91857628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An asynchronous messaging platform for context-aware service development","authors":"Taro Nakao,&nbsp;Kazutoshi Takano,&nbsp;Shigetoshi Yokoyama","doi":"10.1002/ecja.20403","DOIUrl":"https://doi.org/10.1002/ecja.20403","url":null,"abstract":"<p>The authors designed an asynchronous messaging platform to facilitate the development of context-aware services that are triggered by state judgment results (contexts) obtained by using multiple kinds of information from different generation sources in an environment where information providers, who actively disseminate information, and information holders, who provide information according to requests, persistently exist on a network. This platform also uses information that is obtained by using synchronous inquiries to calculate the activation triggers that are sought by the service providers in a distributed environment and provide these triggers to the application logic without destroying the asynchronous information generation order. In addition, the authors adapted this platform to a ubiquitous computing environment according to a design that takes into consideration large-scale distribution. They measured the basic performance of this platform and obtained measurement results showing that the platform can support a large-scale increase in the number of participating nodes and volume of circulating messages. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(12): 1– 12, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20403</p>","PeriodicalId":100405,"journal":{"name":"Electronics and Communications in Japan (Part I: Communications)","volume":"90 12","pages":"1-12"},"PeriodicalIF":0.0,"publicationDate":"2007-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ecja.20403","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91564571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"DS-SS modulated extremely weak power radio communications system synchronized by a GPS receiver PPS signal","authors":"Masashi Yoshida,&nbsp;Chunming Fan,&nbsp;Harumasa Hojo,&nbsp;Nobuaki Kubo,&nbsp;Akio Yasuda","doi":"10.1002/ecja.20379","DOIUrl":"https://doi.org/10.1002/ecja.20379","url":null,"abstract":"<p>With developments in the technology and greater adoption of satellite positioning systems such as GPS, there has been much research into location information systems and services and their practical applications. Extremely weak power radio communications systems are small-scale and low-power devices that do not require a license and are rarely used for communications purposes because they are able to communicate only over small distances compared to other communications media; however, if the distance over which they can be used for communication could be increased, then it would be easy to construct communications systems with them. To take advantage of this we propose an extremely weak power radio communications system based on the DS-SS scheme that synchronizes chips using the pulse-per-second (PPS) signal that is output by a GPS receiver. This system is continuously able to have access to location information due to the use of the GPS receiver and we anticipate that by using this it should be possible to increase the communications distances and communications quality. In recent years there has been an increase in the number of accidents in small-scale ships with low-end communications systems have capsized while at sea or drifted. Small-scale location information systems that can be used for marine distress situations such as capsizing or drifting have become increasingly sought after and communications systems that use such extremely weak power radio communications devices for marine location information systems have been proposed. In this paper we first give an overview of our proposed marine location information system and then describe the extremely weak power radio DS-SS communications system used to implement the system. Following this we perform simple communications experiments. The results of our experiments show that a communications distance of 80 m can be improved to 800 m. From the above results we show that in addition to the marine location information system created using the proposed method, a wide range of different applications are possible. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(12): 39–50, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20379</p>","PeriodicalId":100405,"journal":{"name":"Electronics and Communications in Japan (Part I: Communications)","volume":"90 12","pages":"39-50"},"PeriodicalIF":0.0,"publicationDate":"2007-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ecja.20379","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91857092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Location estimation using received signal power and maximum likelihood estimation in wireless sensor networks","authors":"Masahiro Takashima,&nbsp;Dapeng Zhao,&nbsp;Kentaro Yanagihara,&nbsp;Kiyoshi Fukui,&nbsp;Shigeru Fukunaga,&nbsp;Shinsuke Hara,&nbsp;Ken-Ichi Kitayama","doi":"10.1002/ecja.20359","DOIUrl":"https://doi.org/10.1002/ecja.20359","url":null,"abstract":"<p>This paper considers the sensor network based on IEEE 802.15.4, and proposes a method in which a probabilistic model of wireless propagation characteristics in a real environment is constructed, and the node position is estimated by maximum-likelihood estimation using the model. The performance of the proposed method is evaluated by simulation and position estimation experiments based on the probabilistic model obtained from the actual indoor measurement. It is shown that the proposed method is useful for indoor personnel location management. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(12): 62–72, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20359</p>","PeriodicalId":100405,"journal":{"name":"Electronics and Communications in Japan (Part I: Communications)","volume":"90 12","pages":"62-72"},"PeriodicalIF":0.0,"publicationDate":"2007-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ecja.20359","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91857627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interference suppression in FMICW radar with staggered pulse repetition interval","authors":"Takayuki Inaba","doi":"10.1002/ecja.20326","DOIUrl":"https://doi.org/10.1002/ecja.20326","url":null,"abstract":"<p>FMCW (frequency-modulated continuous wave) radar is a radar system which can achieve high resolution by relatively low signal processing load. The authors have reported on clutter suppression by FMICW (FM interrupted CW) radar, where the transmission/reception of FMCW radar in pulse waveform is switched in order to assure transmission/reception isolation and to suppress undesired waves from short distances. This paper proposes the FM staggered PRI system, in which the pulse repetition interval (PRI) is randomized for each pulse in order to suppress the interference when FMICW radars are congested within the search distance. The target-signal in the FM staggered PRI system is formulated. Conditions such as the average PRI and the possible range of staggering are derived from requirements such as the maximum search distance. The output <i>S/I</i> is statistically evaluated by computer simulation, with the average PRI, the pulse width, the number of interference waves, and the input <i>S/I</i> (signal-to-interference ratio) as variables. The effectiveness of the FM staggered PRI system is demonstrated. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(12): 86–100, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20326</p>","PeriodicalId":100405,"journal":{"name":"Electronics and Communications in Japan (Part I: Communications)","volume":"90 12","pages":"86-100"},"PeriodicalIF":0.0,"publicationDate":"2007-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ecja.20326","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91857630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"MMSE/EGC adaptive selection for nonuniformly aligned adaptive array antenna","authors":"Masayuki Takahashi,&nbsp;Takeo Fujii,&nbsp;Yukihiro Kamiya,&nbsp;Yasuo Suzuki","doi":"10.1002/ecja.20397","DOIUrl":"https://doi.org/10.1002/ecja.20397","url":null,"abstract":"<p>When an adaptive array antenna is used in cellular and other mobile communication base stations for the purpose of improving SINR, the array antenna itself sometimes falls into a fading valley, resulting in failure to obtain an adequate improvement effect. While this problem can be solved by increasing the aperture length of the array antenna, simply increasing the aperture length alone increases the number of antenna elements, so that a large-scale adaptive array antenna becomes required, leading to the problem of failure of the weighting to track changes in the environment during fast fading. In this paper, we try to solve the first issue by making the element spacing nonuniformly aligned, reducing the number of elements. For the second issue, the weighting is divided into two layers, resolving the problem through both use of MMSE to eliminate interference and use of EGC for diversity combining. In a slow fading environment, however, favorable characteristics can be obtained when the entire weighting is controlled by MMSE. In this paper, we estimate the fading speed by the amount of envelope fluctuation in the desired signal after elimination of interference by the initial layer MMSE, and propose during slow fading the use of MMSE batch control, and during fast fading a control that incorporates both MMSE and EGC diversity combining. Finally, we use a computer simulation to evaluate the validity. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(12): 13–21, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20397</p>","PeriodicalId":100405,"journal":{"name":"Electronics and Communications in Japan (Part I: Communications)","volume":"90 12","pages":"13-21"},"PeriodicalIF":0.0,"publicationDate":"2007-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ecja.20397","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91858470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Control of heating pattern for interstitial microwave hyperthermia by a coaxial-dipole antenna—aiming at treatment of brain tumor","authors":"Satoru Kikuchi,&nbsp;Kazuyuki Saito,&nbsp;Masaharu Takahashi,&nbsp;Koichi Ito","doi":"10.1002/ecja.20390","DOIUrl":"https://doi.org/10.1002/ecja.20390","url":null,"abstract":"<p>Interstitial microwave hyperthermia is one of the modalities for cancer treatment that insert a thin microwave antenna into the affected part to selectively heat only the tumor. The authors are investigating this technique with an aim of clinical applications of this medical treatment for brain tumors. In the clinical treatment of brain tumors, it is more critical that “only the tumor parts be heated” than for the treatment of other tissues. Therefore, an antenna that can generate a localized heating pattern on the tumor is required. Although the heating pattern can be controlled here in the longitudinal direction of the antenna by using multiple antennas to form an array applicator, control of the heating pattern in the axial direction is relatively difficult. In this paper, to enable the heating pattern to be controlled in the axial direction, the authors introduced a coaxial-dipole antenna and improved its structure. In addition, they assumed that it was actually applied in the medical treatment of brain tumors and used a numerical calculation model that included a tumor created from MR images to verify the effectiveness of the improved coaxial-dipole antenna according to numerical calculations. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(12): 31–38, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20390</p>","PeriodicalId":100405,"journal":{"name":"Electronics and Communications in Japan (Part I: Communications)","volume":"90 12","pages":"31-38"},"PeriodicalIF":0.0,"publicationDate":"2007-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ecja.20390","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91857625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Passive remote sensing of the Earth's plasmasphere using Whistler mode waves","authors":"Yoshitaka Goto,&nbsp;Yuichi Sakai,&nbsp;Yoshiya Kasahara,&nbsp;Toru Sato","doi":"10.1002/ecja.20377","DOIUrl":"https://doi.org/10.1002/ecja.20377","url":null,"abstract":"<p>As the uses of artificial satellites diversify, investigation of the propagation characteristics of electric waves surrounding the Earth has become an important task. These electric waves are strongly influenced by plasma, a propagation medium, but although on the one hand investigation of plasma in the ionosphere is proceeding with various different methods being used, current investigations into the density profile of plasma in the plasmasphere is not progressing since it is hampered by the fact that satellites produce only single point observations. In this paper we develop a method for estimating the density profile of the global electrical field of the plasmasphere from natural VLF band electromagnetic wave frequency spectra and propagation vector direction information observed by satellite by solving an ill-posed inverse problem. We confirm the uniqueness of the solution by performing a brute force search using a dictionary and investigate the applicability of our method to actual data by using pseudo-observation data. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(12): 51–61, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20377</p>","PeriodicalId":100405,"journal":{"name":"Electronics and Communications in Japan (Part I: Communications)","volume":"90 12","pages":"51-61"},"PeriodicalIF":0.0,"publicationDate":"2007-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ecja.20377","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91857626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}