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

{"title":"Specification execution model for detecting feature interactions","authors":"Masayuki Shimokura,&nbsp;Sachiko Kawada,&nbsp;Shizuko Kawauchi,&nbsp;Tadashi Ohta","doi":"10.1002/ecja.20349","DOIUrl":"10.1002/ecja.20349","url":null,"abstract":"<p>While independent provision of service results in normal operation, operation in tandem with other services causes defective operation to occur. These defects are called ‘feature interactions.’ Our investigation of the international benchmark for detection of feature interactions revealed that feature interactions not occurring in real systems (called ‘lsquo;seeming interactions’) were being detected. Analysis of the cause showed that a conventional state transition model was being used unchanged for the service specification execution model. Seeming interactions are an important issue for increasing the man-hours used to solve feature interactions. In this paper, we propose a trigger point model that clarifies the service specification trigger point as the specification execution model. Through use of this model, we were able to eliminate as seeming interactions about 60% of the feature interactions listed in the international benchmark, confirming the validity of the proposed model. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(4): 23–34, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20349</p>","PeriodicalId":100405,"journal":{"name":"Electronics and Communications in Japan (Part I: Communications)","volume":"90 4","pages":"23-34"},"PeriodicalIF":0.0,"publicationDate":"2006-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ecja.20349","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79255203","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":"Steady-state characteristics on a single-phase buck rectifier with improved input-current waveform","authors":"Shin-Ichi Motegi,&nbsp;Akeshi Maeda","doi":"10.1002/ecja.20330","DOIUrl":"10.1002/ecja.20330","url":null,"abstract":"<p>A single-phase buck rectifier applying pulse width modulation (PWM) creates a large amount of low-order harmonics flow out in the input current. A high-inductance inductor must be used to reduce the pulsations of the DC inductor current and to produce a sinusoidal input current. To address this, the authors propose a single-phase buck rectifier with improved input current waveform by adding a switch for back flow of the DC inductor current to the conventional structural elements. In this paper, the main circuit configuration and operating theory of the proposed rectifier are explained, and its effectiveness is confirmed through experimental results and simulations. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(4): 56–65, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20330</p>","PeriodicalId":100405,"journal":{"name":"Electronics and Communications in Japan (Part I: Communications)","volume":"90 4","pages":"56-65"},"PeriodicalIF":0.0,"publicationDate":"2006-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ecja.20330","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74360103","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":"Access point selection strategy in IEEE802.11E WLAN networks toward load balancing","authors":"Shojiro Takeuchi,&nbsp;Kaoru Sezaki,&nbsp;Yasuhiko Yasuda","doi":"10.1002/ecja.20347","DOIUrl":"10.1002/ecja.20347","url":null,"abstract":"<p>IEEE802.11 WLAN (Wireless LAN) has been widely used in enterprises and public spaces such as airports. In these large WLAN networks, RRM (Radio Resource Management) is necessary for efficient use of radio resources, and also load balancing among APs (Access Point) has to be taken into account. Since, in IEEE802.11, STA (Station) has the right to select an AP with which it will associate, the AP selection mechanism implemented in STA is important for load balancing. This paper proposes an association mechanism called HRFA (High-Rate First Association) in order to achieve load balancing and efficient use of radio resources. Furthermore, IEEE802.11e was developed by Task Group E of the IEEE802.11 working group and specified a MAC protocol to provide QoS in the MAC layer and to support real-time traffic over WLAN. In order for WLAN to be more widely used, the functionalities of IEEE802.11e must be provided in WLAN devices. Our proposed HRFA can be applied to WLANs compliant with IEEE802.11e. Since the HRFA can be implemented without any modifications in the IEEE802.11 and IEEE802.11e standards, it is useful from the implementation-cost and compatibility point of views. Simulation results show that HRFA can efficiently utilize radio resources and can also achieve load balancing in IEEE802.11e WLAN networks. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(4): 35–45, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20347</p>","PeriodicalId":100405,"journal":{"name":"Electronics and Communications in Japan (Part I: Communications)","volume":"90 4","pages":"35-45"},"PeriodicalIF":0.0,"publicationDate":"2006-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ecja.20347","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76735641","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":"Scheduling algorithm for fairness improvement among subscribers in multihop wireless networks","authors":"Haruki Izumikawa,&nbsp;Keizo Sugiyama,&nbsp;Shuichi Matsumoto","doi":"10.1002/ecja.20364","DOIUrl":"10.1002/ecja.20364","url":null,"abstract":"<p>Recently, attention has focused on multihop wireless networks capable of expanding the communication area by employing wireless relays between nodes and access points. However, the problem in a multihop wireless network is differences arise in the throughput caused by the number of hops from the base station connected to wired networks. In this paper, we propose a scheduling algorithm which solves this problem. In this proposal, the uplink packets and downlink packets are queued separately, and the uplink packets are classified into packets originated within the node and forwarded packets from adjacent wireless nodes and queued. When the node transmits a packet, the fairness among the nodes is improved by scheduling based on the source identifiers of the queued packets. The results of a performance evaluation using a network simulator verified a maximum tenfold improvement in the fairness among the subscribers compared to typical schemes. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(4): 11–22, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20364</p>","PeriodicalId":100405,"journal":{"name":"Electronics and Communications in Japan (Part I: Communications)","volume":"90 4","pages":"11-22"},"PeriodicalIF":0.0,"publicationDate":"2006-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ecja.20364","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89029403","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":"Residual capacity estimation of stationary lithium-ion secondary battery based on its discharge voltage characteristics","authors":"Toshio Matsushima","doi":"10.1002/ecja.20355","DOIUrl":"10.1002/ecja.20355","url":null,"abstract":"<p>The relationship between the residual capacity and the discharge voltage of a lithium-ion secondary battery having sufficient capacity to be used as a backup power supply in telecommunication applications is described. From results of high-temperature accelerated deterioration tests conducted on lithium-ion secondary cells, a drop in not only the capacity but also the discharge duration and the discharge voltage was observed, and a fixed relationship was found between the drop in discharge voltage and the residual capacity. This relationship was confirmed not only for single cells, but also for a multicell battery composed of 14 cells which was periodically discharged while being maintained at a floating charge. The possibility of estimating the residual capacity of lithium-ion secondary cells and batteries from a voltage measurement obtained in constant-current discharging was confirmed. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(3): 1–8, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20355</p>","PeriodicalId":100405,"journal":{"name":"Electronics and Communications in Japan (Part I: Communications)","volume":"90 3","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2006-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ecja.20355","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80809892","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":"Storage space saving and error avoidance of passive delay variation measurement employing a hash-based technique for IP networks","authors":"Satoru Ohta","doi":"10.1002/ecja.20328","DOIUrl":"10.1002/ecja.20328","url":null,"abstract":"<p>Delay variation of packets is a significant performance measure in IP networks. Both active and passive measurements can evaluate delay variation. Among these, passive measurement is more advantageous because it can monitor the performance experienced by users without disturbing network load. Meanwhile, a shortcoming of using passive measurement is an extremely large storage space required to record packets and timestamps. This problem is solved by feeding a portion of each packet to a hash function as its input and recording the output to identify the packet. Since the data length of the hash function output is very short, such an approach effectively decreases the storage space. However, this approach still needs a considerably large storage space to record time-stamps. Additionally, the collisions among hash output values may bring unacceptable measurement errors. This paper proposes a method to decrease the storage space required to record timestamps for hash-based delay variation measurement. This decrease is achieved by a variable length coding of timestamps. The paper also presents methods to avoid measurement errors brought by hash value collisions. Through experiments, it is shown that the proposed techniques correctly measure delay variation as well as effectively reduce the storage space. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(3): 21–32, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20328</p>","PeriodicalId":100405,"journal":{"name":"Electronics and Communications in Japan (Part I: Communications)","volume":"90 3","pages":"21-32"},"PeriodicalIF":0.0,"publicationDate":"2006-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ecja.20328","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89025794","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":"Estimating scale of peer-to-peer file sharing applications using multilayer partial measurement","authors":"Satoshi Kamei,&nbsp;Masato Uchida,&nbsp;Tatsuya Mori,&nbsp;Yutaka Takahashi","doi":"10.1002/ecja.20318","DOIUrl":"10.1002/ecja.20318","url":null,"abstract":"<p>Autonomous distributed systems comprising an overlay network on the Internet are proliferating as a new technology responsible for the next-generation Web. Due to the properties of such a large-scale system, it is difficult to measure the characteristics of the entire system without modifying the internal protocol of the applications. In this paper, by using a measurement method applicable to P2P applications and measured results obtained by applying this measurement method in part, a general-purpose method for estimating the size and behavior of the entire P2P network is proposed. Further, the present method is applied to a real P2P network and its effectiveness is presented by a specific example. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(3): 54–63, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20318</p>","PeriodicalId":100405,"journal":{"name":"Electronics and Communications in Japan (Part I: Communications)","volume":"90 3","pages":"54-63"},"PeriodicalIF":0.0,"publicationDate":"2006-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ecja.20318","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77692549","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":"Traffic characteristics of Go-Back-N ARQ scheme with selective repeat in intra-block and with limited retransmissions","authors":"Shumji Fujii,&nbsp;Toyohisa Kaneko,&nbsp;Yukuo Hayashida","doi":"10.1002/ecja.20311","DOIUrl":"10.1002/ecja.20311","url":null,"abstract":"<p>Based on highly reliable data transmission, we previously proposed a Go-Back-N ARQ scheme with selective repeat in intra-block, where the receiver returns the acknowledge signal in the unit of a block composed of multiple frames, with the aim of reducing the network traffic and the objective of effectively processing the frames. This paper considers the traffic characteristics when the number of block retransmissions in a Go-Back-N ARQ scheme with selective repeat in intra-block is limited. In this scheme, blocks composed of multiple frames which contain information with some correlation as in images are transmitted. If the retransmission of a block reaches the preset limit, the receiver accepts that block even if erroneous frames are included, and the errors are processed as noise or distortion. Therefore, an upper bound can be set for the time elapsed from the start to the end of the block transmission. We theoretically analyze the system considered and derive the throughput, the average transmission delay of a block, and the average transmission delay with the condition of the number of transmissions. The traffic characteristics are investigated from numerical examples using analytical results. We show that the throughput performance and average transmission delay performance are improved by limiting the number of retransmissions. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(3): 64–73, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20311</p>","PeriodicalId":100405,"journal":{"name":"Electronics and Communications in Japan (Part I: Communications)","volume":"90 3","pages":"64-73"},"PeriodicalIF":0.0,"publicationDate":"2006-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ecja.20311","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82129093","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 feeding method for small helical antennas","authors":"Nozomu Hasebe","doi":"10.1002/ecja.20324","DOIUrl":"10.1002/ecja.20324","url":null,"abstract":"<p>A feeding method is proposed for small helical antennas with diameters of about 1/80 to 1/20 wavelength. The present feeding method consists of excitation of a helix with a total length of about 1/4 wavelength and with its lower edge grounded by an open-ended center conductor oriented coaxially to the helix. In this paper, it is shown that matching with a 50-Ω feed system can be accomplished even when the helical diameter is varied in the same feeding method. The gain and the bandwidth characteristics of the ground plane versus diameter are discussed. As an example, a gain of −7.2 dB_<i>d</i> (with respect to the dipole antenna) on the ground plane is obtained when the helical diameter is 1/46 wavelength and the height is 1/56 wavelength. Like the monopole antenna, the main radiation pattern is omnidirectional vertical polarization in the horizontal plane and figure-eight in the vertical plane. When this antenna is installed on a transmitter case, the gain is about −4 dB_<i>d</i>. When installed on the transmitter case, the antenna radiates the orthogonal polarization component. The null of the main radiation pattern in the zenith direction can be compensated by this polarization. The radiation characteristics of the antenna are numerically calculated by the method of moments and are verified experimentally. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(3): 33–41, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20324</p>","PeriodicalId":100405,"journal":{"name":"Electronics and Communications in Japan (Part I: Communications)","volume":"90 3","pages":"33-41"},"PeriodicalIF":0.0,"publicationDate":"2006-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ecja.20324","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87630646","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":"Stochastic node placement improving fault tolerance in wireless sensor networks","authors":"Mika Ishizuka,&nbsp;Masaki Aida","doi":"10.1002/ecja.20319","DOIUrl":"10.1002/ecja.20319","url":null,"abstract":"<p>One of the most important issues in wireless sensor networks is to develop the technology for improved fault tolerance, since sensor nodes are prone to failure (for mechanical reasons, for example) and have limited energy storage. The strategy for determining the positions in which sensor nodes are placed is very important, because it affects the likelihood that a target will be within the sensing range of a node, and that there will be a communication path from that node back to the base station. We have considered that when many sensor nodes are to be placed in a wide area, an effective approach is stochastic node placement, whereby sensors may be scattered in a controlled manner, such that their approximate positions are characterized by a probability density function. Then, as the first step of our research, we have proposed stochastic node placements in which the degrees of the nodes follow a power-law distribution (“power-law placement”). Through simulation studies, we have shown that power-law placement, with well-tuned parameters, shows a higher tolerance against random failures and failure through battery exhaustion than general stochastic node placement. However, this can be difficult to implement. As the second step of our research, this paper proposes an alternative method of stochastic node placement that has as high a fault tolerance as power-law placement and can be achieved with a reasonable degree of complexity. To this end, we first investigate the requirements necessary for other types of stochastic node placement to exhibit as high a fault tolerance as power-law placement. Next, we propose ways of achieving stochastic node placement that meets these requirements. Our proposal has theoretical basis that any stochastic node placement can be achieved by scattering sensor nodes many times from the air in a number of appropriately controlled operations. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(3): 42–53, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20319</p>","PeriodicalId":100405,"journal":{"name":"Electronics and Communications in Japan (Part I: Communications)","volume":"90 3","pages":"42-53"},"PeriodicalIF":0.0,"publicationDate":"2006-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/ecja.20319","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80686201","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}