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

{"title":"A decoding method for Tornado-type codes utilizing error packets","authors":"Ryohei Yamato,&nbsp;Daisuke Umehara,&nbsp;Yoshiteru Morihiro,&nbsp;Taku Noguchi,&nbsp;Makoto Kawai","doi":"10.1002/ecja.20361","DOIUrl":"https://doi.org/10.1002/ecja.20361","url":null,"abstract":"<p>Satellite communications is suitable for multicast communications which can achieve one-to-many delivery because it can broadcast to multiple receiving stations over a wide area. However, packet retransmission is inefficient for satellite communications because of its large delay and bit error rate. In order to avoid packet retransmission, FEC (forward error correction) exploiting error correcting codes have been put to practical use in satellite multicasting. Tornado-type codes are well known as a kind of error correcting codes suitable for multicasting. Tornado-type codes are encoded and decoded in packets. As a result, they are effective for combatting packet losses by buffer overflow or congestion control. Furthermore, their coding and decoding have low time complexity. On the other hand, the bit errors in the packet are processed as a packet loss in decoding because the Tornado-type codes are decoded packet-wise. In this paper, we propose an effective decoding method for bit errors in the packets for Tornado-type codes. We show by computer simulation that the proposed method is effective in bit error environments. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(10): 57– 66, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20361</p>","PeriodicalId":100405,"journal":{"name":"Electronics and Communications in Japan (Part I: Communications)","volume":"90 10","pages":"57-66"},"PeriodicalIF":0.0,"publicationDate":"2007-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ecja.20361","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91862573","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":"Proposed high-efficiency packet forwarding method under multihome environment","authors":"Hiroshi Shiota,&nbsp;Akihiro Otaka,&nbsp;Takashi Nakashima,&nbsp;Yasuyuki Okumura","doi":"10.1002/ecja.20368","DOIUrl":"https://doi.org/10.1002/ecja.20368","url":null,"abstract":"<p>In the past few years, communication among clients, such as IP video telephony and file sharing, that is peer-to-peer (P2P) communication, has increased. P2P communication is often considered to be communication over relatively short geographic distances as in local communication. However, in P2P communication, the communication partner is not limited to belonging to the same Internet Service Provider (ISP) as oneself and communication may be routed over long paths known as routing through an Internet exchange (IX) even when geographically close. However, the problem becomes inefficient transmission. To solve this problem, we herein propose a multinetwork access method using multiple networks, implement efficient packet forwarding, and study the reduction in IX or ISP network traffic when this method is applied to an access network. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(10): 36– 46, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20368</p>","PeriodicalId":100405,"journal":{"name":"Electronics and Communications in Japan (Part I: Communications)","volume":"90 10","pages":"36-46"},"PeriodicalIF":0.0,"publicationDate":"2007-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ecja.20368","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91565246","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":"Replica distribution of data associated with location on wireless ad hoc networks","authors":"Gen Tsuchida,&nbsp;Tomoyuki Okino,&nbsp;Masahiro Tamori,&nbsp;Takashi Watanabe,&nbsp;Tadanori Mizuno,&nbsp;Susumu Ishihara","doi":"10.1002/ecja.20320","DOIUrl":"https://doi.org/10.1002/ecja.20320","url":null,"abstract":"<p>In mobile ad hoc networks, due to the change of topology caused by the movement of hosts and the change of radio link status, it is difficult for mobile hosts to retain accessibility to data on other hosts. To solve such a problem, replica distribution methods which distribute replicas of data items to other mobile hosts and maintain them have been proposed. In this paper, we propose and evaluate a method to enhance the accessibility to data items that are associated with locations and requested by Geocast from hosts. This method is based on flooding of replicas of data items, and it uses the locations of mobile hosts and the associated locations of data items for controlling the range of the replications and the redundancy of the replicas. Furthermore, to keep the accessibility to such data high, replicas are dynamically relocated after the movement of hosts. We confirmed the effectiveness of the proposed method by detailed simulations including multiple data request models. Simulation results showed that the proposed method achieves high accessibility to location-dependent data especially when the storage size is small. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(10): 67– 80, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20320</p>","PeriodicalId":100405,"journal":{"name":"Electronics and Communications in Japan (Part I: Communications)","volume":"90 10","pages":"67-80"},"PeriodicalIF":0.0,"publicationDate":"2007-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ecja.20320","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91862572","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":"New weighting method to synthesize a zero sidelobe correlation filter for burst signals","authors":"Mitsuyoshi Shinonaga,&nbsp;Junichiro Suzuki,&nbsp;Shinichi Yajima,&nbsp;Shinkichi Nishimoto","doi":"10.1002/ecja.20373","DOIUrl":"https://doi.org/10.1002/ecja.20373","url":null,"abstract":"<p>The detection of received radar signals uses Doppler filtering as the correlation process on the received echoes for many transmitted pulses in addition to the pulse compression process which is the correlation process in the range direction. Normal radar echoes become blips widened in the azimuth direction, but the Doppler filtering process is not the optimum process from the perspective of improving the signal-to-noise ratio. Furthermore, compression of the spread in the azimuth direction of the signal is demanded in order to detect the azimuth. In this paper, we show that the azimuth beam width compression process can be implemented by filtering which satisfies the maximum SNR based on the zero sidelobe constraint condition applied to pulse compression. In addition, we theoretically explain the weighting matrix derived by this design method and use simulations to compare with the pulse compression process of the characteristics of a zero sidelobe correlation function. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(10): 25– 35, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20373</p>","PeriodicalId":100405,"journal":{"name":"Electronics and Communications in Japan (Part I: Communications)","volume":"90 10","pages":"25-35"},"PeriodicalIF":0.0,"publicationDate":"2007-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ecja.20373","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91862568","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":"Transmission performance of WDM/OFDM hybrid systems over optical fibers","authors":"Kenichiro Tanaka,&nbsp;Seiji Norimatsu","doi":"10.1002/ecja.20387","DOIUrl":"https://doi.org/10.1002/ecja.20387","url":null,"abstract":"<p>Orthogonal frequency division multiplexing (OFDM) can achieve high utilization efficiency. In this paper, the authors combine OFDM with wavelength division multiplexing (WDM) to investigate the optical fiber transmission characteristics of a WDM/OFDM hybrid system that can easily achieve high utilization efficiency even when the number of channels is high. They used intensity modulation (IM), differential binary phase-shift keying (DBPSK), and differential quadrature phase-shift keying (DQPSK) as modulation methods to show transmission characteristics related to multi-repeater and nonrepeater systems. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(10): 14– 24, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20387</p>","PeriodicalId":100405,"journal":{"name":"Electronics and Communications in Japan (Part I: Communications)","volume":"90 10","pages":"14-24"},"PeriodicalIF":0.0,"publicationDate":"2007-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ecja.20387","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91862569","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 routing protocol for mobile terminals in an ad hoc network with established network","authors":"Masashi Yoshida,&nbsp;Tetsuya Miki","doi":"10.1002/ecja.20363","DOIUrl":"https://doi.org/10.1002/ecja.20363","url":null,"abstract":"<p>The expansion of a communication area and the provision of services to wide districts can be expected if ad hoc networks are connected to established networks. In this environment, two types of routes exist between mobile stations that compose ad hoc networks: routes using wireless links only and routes via base station and the established networks. However, most routing protocols decide a route simply by the minimum hop counts between mobile stations without taking the differences of communication performance between the established network and ad hoc networks into account. This paper presents a new routing protocol that uses simple formulas to decide which route is effective, a route using wireless links only, or a route via the established networks. The formulas are derived from the results of simulation on the communication performance of some routes that uses IEEE802.11b as wireless links and Ethernet of 100 Mb/s as wired links. The performance of our proposed routing protocol, which is realized as an extension of ad hoc on-demand distance vector (AODV), is evaluated by simulation. The results show that the proposed routing protocol is effective especially under a high data rate situation compared with AODV. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(10): 47– 56, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20363</p>","PeriodicalId":100405,"journal":{"name":"Electronics and Communications in Japan (Part I: Communications)","volume":"90 10","pages":"47-56"},"PeriodicalIF":0.0,"publicationDate":"2007-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ecja.20363","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91863336","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":"New antenna weighting method for adaptable beamwidth with zero sidelobe constraints","authors":"Junichiro Suzuki,&nbsp;Yasuharu Masuda,&nbsp;Mitsuyoshi Shinonaga,&nbsp;Shinkichi Nishimoto","doi":"10.1002/ecja.20370","DOIUrl":"10.1002/ecja.20370","url":null,"abstract":"<p>For sidelobe suppression design of antennas, weighting with window functions has been traditionally used. The antenna gain is degraded if a low sidelobe level is sought, so that expansion of the antenna beamwidth is inevitable. Also, there have been discussions of using the convergent calculation in the derivation of a window function that realizes desired characteristics such as sidelobe-free conditions, but it has not been clear whether the theoretically maximum antenna gain is realized. This paper presents a method of analytical derivation of a weight vector satisfying the maximum achievable antenna gain while the desired beamwidth is obtained under the null sidelobe constraint for the sidelobe region output. In addition, we demonstrate the effectiveness of the method by simulation examples. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(9): 35–44, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20370</p>","PeriodicalId":100405,"journal":{"name":"Electronics and Communications in Japan (Part I: Communications)","volume":"90 9","pages":"35-44"},"PeriodicalIF":0.0,"publicationDate":"2007-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ecja.20370","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75827871","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":"Multilevel coding for low-density parity-check codes","authors":"Wataru Matsumoto,&nbsp;Weigang Xu,&nbsp;Hideki Imai","doi":"10.1002/ecja.20173","DOIUrl":"10.1002/ecja.20173","url":null,"abstract":"<p>In recent years attention has turned to LDPC codes, which show performance approaching communication path capacity. In the past, application of LDPC codes has mainly been BPSK-based proposals. In this paper, we propose a new design method for multilevel coding that uses LDPC codes as element codes. First, we focus on the possibility of freedom of design for LDPC codes in regards to any desired encoding rate, optimize a degree profile using Gaussian Approximation, and use the actual BER characteristics shown in LDPC codes of finite length formed by this degree file to find the differential <i>SNR</i>_<i>norm</i> up to the Shannon limit of SNR values at the time of some specific BER. With the <i>SNR</i>_<i>norm</i> for the encoding rate at several points, we calculate an <i>SNR</i>_<i>norm</i> approximation formula for a continuous, wide-range encoding rate, and use this approximation formula to propose a method for designing multivalue coded modulation based on multilevel coding. In addition, we demonstrate the results of a simulation of this proposed method using irregular EG-LDPC codes, and demonstrate that this method is effective for restricting deterioration of performance in actual usage. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(8): 57–68, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20173 Copyright © 2004 Wiley Periodicals, Inc.Copyright © 2007 Wiley Periodicals, Inc.</p>","PeriodicalId":100405,"journal":{"name":"Electronics and Communications in Japan (Part I: Communications)","volume":"90 8","pages":"57-68"},"PeriodicalIF":0.0,"publicationDate":"2007-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ecja.20173","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84559928","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 method of decreasing cross-polarization in dual-polarized patch antennas","authors":"Kengo Nishimoto,&nbsp;Toru Fukasawa,&nbsp;Masataka Ohtsuka,&nbsp;Shigeru Makino,&nbsp;Yonehiko Sunahara","doi":"10.1002/ecja.20393","DOIUrl":"10.1002/ecja.20393","url":null,"abstract":"<p>In this paper, we propose a method for decreasing cross-polarization in the tilt plane by optimizing the dielectric substrates of dual-polarized patch antennas. At the same time, we clarify the limit values for the cross-polarization level. First, we use a cavity model of the patch antenna to find cross-polarization dielectric characteristics in the tilt plane. We learn from this that the direction of cross-polarization increase or decrease in relation to the dielectric is reversed during horizontal polarized excitation and vertical polarized excitation. Therefore, if the cross-polarization level during horizontal polarized excitation and vertical polarized excitation is the same dielectric, the lowest cross-polarization level can be obtained in conditions where both horizontal polarization and vertical polarization are decreasing cross-polarization. Next, we investigate the case where parasitic elements are mounted on the patch antenna, and use the FDTD method and test to show that our method is valid. In addition, if the patch is positioned perpendicularly to the horizontal plane, we show that the optimum dielectric remains virtually unchanged in the tilt plane up to about 15^° from the horizontal plane. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(8): 1–9, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20393 Copyright © 2004 Wiley Periodicals, Inc.Copyright © 2007 Wiley Periodicals, Inc.</p>","PeriodicalId":100405,"journal":{"name":"Electronics and Communications in Japan (Part I: Communications)","volume":"90 8","pages":"1-9"},"PeriodicalIF":0.0,"publicationDate":"2007-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ecja.20393","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86847573","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":"Automatic selection of Web services based on attributes and ratings","authors":"Shingo Ata,&nbsp;Hisae Matsunaga,&nbsp;Ikuo Oka,&nbsp;Chikato Fujiwara","doi":"10.1002/ecja.20284","DOIUrl":"10.1002/ecja.20284","url":null,"abstract":"<p>Web services are a unified framework that enables the exchange of information among distributed applications using existing World Wide Web communications technologies. Web services offer the benefit of simplifying the sharing of information among different applications that are operated via remote terminals. However, when multiple services exist that provide the same functionality, a mechanism for automatically selecting the most appropriate service from those on offer is necessary. Unfortunately, the majority of automatic selection mechanisms are designed to use a fixed set of indicators as the selection criteria and are therefore unable to adapt to the diverse demands of users. In this paper we propose a new mechanism for automatically performing such service selection that integrates a wide range of different indicators. Specifically, we assign attributes to each of the services that can be used as evaluation criteria; we then gather these attributes at the user's client. We can compute a rating for each service on the basis of the attributes that have been collected and select the service that is assigned the highest rating. In this paper we introduce the concept of an attribute database (an <i>attribute repository</i>) and define a new communications protocol to enable the registration and searching of attributes in order to deal with variation in the attributes used by different services. In addition, using a simulation of a distributed applications environment, we perform evaluations and demonstrate that the proposed selection mechanism is able to reduce execution times as compared to a random selection mechanism. We also implement the proposed mechanism in an experimental environment and show that it can be used in practice for automatically selecting services on the basis of attribute values. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(8): 40–49, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20284 Copyright © 2004 Wiley Periodicals, Inc.Copyright © 2007 Wiley Periodicals, Inc.</p>","PeriodicalId":100405,"journal":{"name":"Electronics and Communications in Japan (Part I: Communications)","volume":"90 8","pages":"40-49"},"PeriodicalIF":0.0,"publicationDate":"2007-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ecja.20284","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82683371","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}