IEICE Transactions on Communications
Online ISSN : 1745-1345
Print ISSN : 0916-8516
Volume E98.B, Issue 12
Displaying 1-18 of 18 articles from this issue
Special Section of Position Papers Exploring Innovative Intelligence and Technologies in Communications, Part II
  • Shoji KASAHARA
    2015 Volume E98.B Issue 12 Pages 2369
    Published: December 01, 2015
    Released on J-STAGE: December 01, 2015
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  • Yuichi SAWAHARA, Yuya IKUTA, Yangjun ZHANG, Toshio ISHIZAKI, Ikuo AWAI
    Article type: PAPER
    2015 Volume E98.B Issue 12 Pages 2370-2375
    Published: December 01, 2015
    Released on J-STAGE: December 01, 2015
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    The authors propose “Disk-repeater” as a new structure alternative to the conventional resonator repeater. Disk-repeater has a simple structure comprised of just copper plates and wire, non-resonant structure. First, coupling coefficients are measured as functions of disk diameter and wire length to characterize the basic performance of Disk-repeater. It is explained by several experimental evidences that Disk-repeater and resonator are not magnetically coupled but electrically coupled. It is also shown that the transmission distance extends dramatically longer than that of conventional resonator repeater. Further, two-dimensional arrangement, where multiple disks are connected, shows very high efficiency and uniform transmission characteristic regardless of positions of receiving resonator. Disk-repeater gives possibility of unprecedented versatile application with the simple structure.
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  • Masanori ISHINO, Yuki KOIZUMI, Toru HASEGAWA
    Article type: PAPER
    2015 Volume E98.B Issue 12 Pages 2376-2381
    Published: December 01, 2015
    Released on J-STAGE: December 01, 2015
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    Internet of Things (IoT) devices, which have different characteristics in mobility and communication patterns from traditional mobile devices such as cellular phones, have come into existence as a new type of mobile devices. A strict mobility management scheme for providing highly mobile devices with seamless access is over-engineered for IoT devices' mobility management. We revisit current mobility management schemes for wireless mobile networks based on identifier/locator separation. In this paper, we focus on IoT communication patterns, and propose a new routing-based mobility scheme for them. Our scheme adopts routing information aggregation scheme using the Bloom Filter as a data structure to store routing information. We clarify the effectiveness of our scheme in IoT environments with a large number of IoT devices, and discuss its deployment issues.
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Regular Section
  • Shinichi KAWAGUCHI, Toshiaki YACHI
    Article type: PAPER
    Subject area: Energy in Electronics Communications
    2015 Volume E98.B Issue 12 Pages 2382-2388
    Published: December 01, 2015
    Released on J-STAGE: December 01, 2015
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    As the use of information technology is rapidly expanding, the power consumption of IT equipment is becoming an important social issue. As such, the power supply of IT equipment must provide various power saving measures through advanced features. A digitally controlled power supply is attractive for satisfying this requirement due to its flexibility and advanced management functionality. However, a digitally controlled power supply has issues with its transient response performance because the conversion time of the analog-digital converter and the time required for digital processing in the digital controller adversely affect the dynamic characteristics. The present paper introduces a new approach that can improve the transient response performance of the digital point-of-load (POL) power supplies of computer processors. The resulting power systems use feed-forward transient control, in addition to the general voltage regulation feedback control loop, to improve their dynamic characteristics. On the feed-forward control path, the processor workload information is supplied to the power supply controller from the processor. The power supply controller uses the workload information to predict the power load change and generates an auxiliary control to improve the transient response performance. As the processor workload information, the processor-integrated performance counter values are sent to the power supply controller via a hardware interface. The processor power consumption prediction equation is modeled using the moving average model, which uses performance counter values of several past steps. The prediction equation parameters are defined by multiple regression analysis using the measured CPU power consumption data and experimentally obtained performance counter information. The analysis reveals that the optimum parameters change with time during transient periods. The modeled equation well explains the processor power load change. The measured CPU power consumption profile is confirmed to be accurately replicated by the prediction for a period of 200ns. Using the power load change prediction model, circuit simulations of the feed-forward transient control are conducted. It is validated that the proposed approach improves power supply transient response under some practical server workloads.
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  • Kohei WATABE, Hiroyuki OHSAKI
    Article type: PAPER
    Subject area: Network
    2015 Volume E98.B Issue 12 Pages 2389-2399
    Published: December 01, 2015
    Released on J-STAGE: December 01, 2015
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    DTNs (Delay/Disruption-Tolerant Networks) composed of mobile nodes in low node-density environments have attracted considerable attention in recent years. In this paper, we propose a CD-BCAST (Contact Duration BroadCAST) mechanism that can reduce the number of message forwardings while maintaining short message delivery delays in DTNs composed of mobile nodes. The key idea behind CD-BCAST is to increase the probability of simultaneous forwarding by intentionally delaying message forwarding based on the contact duration distribution measured by each node. Through simulations, we show that CD-BCAST needs substantially less message forwardings than conventional mechanisms and it does not require parameter tuning under varieties of communication ranges and node densities.
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  • Chi Trung NGO, Hoon OH
    Article type: PAPER
    Subject area: Network
    2015 Volume E98.B Issue 12 Pages 2400-2418
    Published: December 01, 2015
    Released on J-STAGE: December 01, 2015
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    The tree-based routing approach has been known as an efficient method for node mobility management and data packet transmission between two long-distance parties; however, its parameter adjustment must balance control overhead against the convergence speed of topology information according to node mobility. Meanwhile, location-based routing works more efficiently when the distance between the source and destination is relatively short. Therefore, this paper proposes a roadside unit (RSU) based hybrid routing protocol, called RSU-HRP that combines the strengths of both protocols while offsetting their weaknesses. In RSU-HRP, the tree construction is modified to take into account the link and route quality to construct a robust and reliable tree against high node mobility, and an optimized broadcast algorithm is developed to reduce control overhead induced by the advertisement message periodically sent from a roadside unit. In addition, the two routing methods are selectively used based on the computed distance in hops between a source and a destination. Simulation results show that RSU-HRP far outperforms TrafRoute in terms of packet delivery ratio, end-to-end delay, and control overhead in both Vehicle-to-Infrastructure and Vehicle-to-Vehicle communication models.
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  • Nagao OGINO, Yuto NAKAMURA, Shigehiro ANO
    Article type: PAPER
    Subject area: Network
    2015 Volume E98.B Issue 12 Pages 2419-2430
    Published: December 01, 2015
    Released on J-STAGE: December 01, 2015
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    A threshold secret sharing scheme can realize reliable delivery of important content using redundant routes through a network. Furthermore, multicast delivery of threshold secret shared content can achieve efficient resource utilization thanks to the application of multicast and network coding techniques to multiple pieces of the content. Nevertheless, a tradeoff exists between reliability and efficiency if multicast content delivery uses network coding. This paper proposes a flexible multicast delivery scheme for threshold secret shared content that can control the tradeoff between reliability and efficiency. The proposed scheme classifies all the pieces obtained from the original content into multiple groups, and each group is subjected to network coding independently. An optimization procedure is proposed for the multicast delivery scheme, which involves two different heuristic delivery route computation methods applicable to large-scale networks. Evaluation results show that the optimized multicast delivery scheme adopting an appropriate grouping method and classifying the pieces into a suitable number of groups can minimize the required link bandwidth while satisfying a specified content loss probability requirement.
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  • Yu NAKAYAMA, Ken-Ichi SUZUKI, Jun TERADA, Akihiro OTAKA
    Article type: PAPER
    Subject area: Network
    2015 Volume E98.B Issue 12 Pages 2431-2438
    Published: December 01, 2015
    Released on J-STAGE: December 01, 2015
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    Ring aggregation networks are widely employed for metro access networks. A layer-2 ring with Ethernet Ring Protection is a popular topology for carrier services. Since frames are forwarded along ring nodes, a fairness scheme is required to achieve throughput fairness. Although per-node fairness algorithms have been developed for the Resilient Packet Ring, the per-node fairness is insufficient if there is bias in a flow distribution. To achieve per-flow fairness, N Rate N+1 Color Marking (NRN+1CM) was proposed. However, NRN+1CM can achieve fairness in case there are sufficient numbers of available bits on a frame header. It cannot be employed if the frame header cannot be overwritten. Therefore, the application range of NRN+1CM is limited. This paper proposes a Signaling based Discard with Flags (SDF) scheme for per-flow fairness. The objective of SDF is to eliminate the drawback of NRN+1CM. The key idea is to attach a flag to frames according to the input rate and to discard them selectively based on the flags and a dropping threshold. The flag is removed before the frame is transmitted to another node. The dropping threshold is cyclically updated by signaling between ring nodes and a master node. The SDF performance was confirmed by employing a theoretical analysis and computer simulations. The performance of SDF was comparable to that of NRN+1CM. It was verified that SDF can achieve per-flow throughput fairness without using a frame header in ring aggregation networks.
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  • Jeehoon LEE, Minjoong RIM, Kiseon KIM
    Article type: PAPER
    Subject area: Network
    2015 Volume E98.B Issue 12 Pages 2439-2445
    Published: December 01, 2015
    Released on J-STAGE: December 01, 2015
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    An incremental relaying protocol is a promising scheme for preventing the inefficient use of resources in half-duplex cooperative relay networks. In particular, the incremental selection amplify-and-forward (ISAF) relaying scheme is a well-designed protocol under the condition that the source-to-destination (SD) link is static during the two transmission phases. However, from a practical viewpoint, the SD link is not static but varies with time, and thus the ISAF relaying scheme may not work well in the field. In this work, we first show that the outage performance of the ISAF relaying scheme may decrease when the SD link is not static during the two transmission phases. We then propose a modified version of the ISAF relaying scheme which overcomes such a limitation of the ISAF relaying scheme under time-varying environments. Finally, numerical and simulation results are provided to support our findings.
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  • Qing YANG, Jiancheng LI, Hongyi WANG
    Article type: PAPER
    Subject area: Network
    2015 Volume E98.B Issue 12 Pages 2446-2453
    Published: December 01, 2015
    Released on J-STAGE: December 01, 2015
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    In many radio frequency identification (RFID) applications, the reader identifies the tags in its scope repeatedly. For these applications, many algorithms, such as an adaptive binary splitting algorithm (ABS), a single resolution blocking ABS (SRB), a pair resolution blocking ABS (PRB) and a dynamic blocking ABS (DBA) have been proposed. All these algorithms require the staying tags to reply with their IDs to be recognized by the reader. However, the IDs of the staying tags are stored in the reader in the last identification round. The reader can verify the existence of these tags when identifying them. Thus, we propose an anti-collision algorithm with short reply for RFID tag identification (ACSR). In ACSR, each staying tag emits a short reply to indicate its continued existence. Therefore, the data amount transmitted by staying tags is reduced significantly. The identification rate of ACSR is analyzed in this paper. Finally, simulation and analysis results show that ACSR greatly outperforms ABS, SRB and DBA in terms of the identification rate and average amount of data transmitted by a tag.
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  • Tomomi AOKI, Yasuhiko TANABE
    Article type: PAPER
    Subject area: Antennas and Propagation
    2015 Volume E98.B Issue 12 Pages 2454-2462
    Published: December 01, 2015
    Released on J-STAGE: December 01, 2015
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    This paper proposes a novel direction-of-arrival (DOA) estimation method that can reduce performance degradation due to angular spread. Some algorithms previously proposed for such estimation make assumptions about the distributions of amplitude and phase for incident waves because most DOA estimation algorithms are sensitive to angular spread. However, when the assumptions are inaccurate, these algorithms perform poorly as compared with algorithms without countermeasures against angular spread. In this paper, we propose a method for selecting an appropriate DOA estimation algorithm according to the channel vector of each source signal as estimated by independent component analysis. Computer simulations show that the proposed method can robustly estimate DOA in environments with angular spread.
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  • Lingsheng YANG, Jianping FANG, Tao LI
    Article type: PAPER
    Subject area: Antennas and Propagation
    2015 Volume E98.B Issue 12 Pages 2463-2469
    Published: December 01, 2015
    Released on J-STAGE: December 01, 2015
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    A compact dual-band MIMO (Multiple-Input-Multiple-Output) antenna system for LTE33 band, LTE 2300 and ISM 2.4GHz applications is presented. The whole system consists of four identical folded 3-D IFAs (inverted F antenna) mounted on nonmetallic cuboids. By using the radiation pattern diversity of the antenna elements, higher than 15dB isolation among the antenna elements and low correlation coefficient (CC<0.3) are achieved without any specially designed decoupling structures. Its gain and radiation pattern are elucidated.
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  • Satoshi ISHIHARA, Teruo ONISHI, Akimasa HIRATA
    Article type: PAPER
    Subject area: Electromagnetic Compatibility (EMC)
    2015 Volume E98.B Issue 12 Pages 2470-2476
    Published: December 01, 2015
    Released on J-STAGE: December 01, 2015
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    A method for measuring the magnetic field strength for human exposure assessment closer than 20cm to wireless power transfer (WPT) systems for information household appliances is investigated based on numerical simulations and measurements at 100kHz and 6.78MHz. Four types of magnetic sources are considered: a simple 1-turn coil and three types of coils simulating actual WPT systems. A magnetic sensor whose cross sectional area is 100cm2 as prescribed in International Electrotechnical Commission 62233 is used. Simulation results show that the magnetic field strength detected by the magnetic sensor is affected by its placement angle. The maximum coefficient of variation (CV) is 27.2% when the magnetic source and the sensor are in contact. The reason for this deviation is attributable to the localization of the magnetic field distribution around the magnetic source. The coupling effect between the magnetic source and the sensor is negligible. Therefore, the sensor placement angle is an essential factor in magnetic field measurements. The CV due to the sensor placement angle is reduced from 21% to 4% if the area of the sensor coil is reduced from 100 to 0.75cm2 at 6.78MHz. However, the sensitivity of the sensor coil is decreased by 42.5dB. If measurement uncertainty that considers the deviation in the magnetic field strength due to the sensor placement angle is large, the measured magnetic field strength should be corrected by the uncertainty. If the magnetic field distribution around the magnetic source is known, conservative exposure assessments can be achieved by placing the magnetic sensor in locations at which the spatial averaged magnetic field strengths perpendicular to the magnetic sensor coils become maximum.
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  • Cheng JI, Daisuke ANZAI, Jianqing WANG, Ikuko MORI, Osamu FUJIWARA
    Article type: PAPER
    Subject area: Electromagnetic Compatibility (EMC)
    2015 Volume E98.B Issue 12 Pages 2477-2484
    Published: December 01, 2015
    Released on J-STAGE: December 01, 2015
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    We conduct, in accordance with IEC 61000-4-2, an electrostatic discharge (ESD) test for a small size battery-operated control circuit board in a myoelectric artificial hand system to investigate the influence of the induced noises by indirect ESDs from an ESD generator to a horizontal coupling plane (HCP) and a vertical coupling plane (VCP). A photo-coupler is set between the small size control board and a motor control circuit to suppress noise in the pulse width modulation (PWM) signals. Two types of ESD noise are observed at the output pins of PWM signals. One type is the ESD noise itself (called Type A) and the other one is the ESD noise superimposed over the PWM pulses (Type B). No matter which polarity the charge voltages of the ESD generator have, both types can be observed and the Type A is dominant in the output pulses. Moreover, the ESD interference in the HCP case is found to be stronger than that in the VCP case usually. In the PWM signals observed at the photo-coupler output, on the other hand, Type A noises tend to increase for positive polarity and decrease for negative polarity, while Type B noises tend to increase at -8kV test level in the HCP case. These results suggest that the photo-coupler does not work well for ESD noise suppression. One of the reasons has been demonstrated to be due to the driving capability of the photo-coupler, and other one is due to the presence of a parasitic capacitance between the input and output of the photo-coupler. The parasitic capacitance can yield a capacitive coupling so that high-frequency ESD noises pass through the photo-coupler.
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  • Pham Ngoc SON, Hyung Yun KONG
    Article type: PAPER
    Subject area: Wireless Communication Technologies
    2015 Volume E98.B Issue 12 Pages 2485-2495
    Published: December 01, 2015
    Released on J-STAGE: December 01, 2015
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    In this paper, we analyze a cooperative communication network with multi energy-harvesting and decode-and-forward relays in which the best relay is selected based on criteria such as Maximizing First-Hop Signal to Noise Ratios (SNRs) (MFHS protocol), Maximizing Second-Hop SNRs (MSHS protocol), and Maximizing End-to-End SNRs (MEES protocol). In these protocols, the relays apply power-splitting receivers to harvest energy from radio frequency signals emitted from a source. Thus, each received SNR in the second hop is a function of a direct relay-destination gain and an indirect source-relay gain. The system performance of the proposed protocols is evaluated via exact outage probability analyses and Monte Carlo simulations. For further comparisons, an energy-harvesting decode-and-forward scheme with randomly relay selection (RRS protocol) and an energy-harvesting amplify-and-forward scheme (BAF protocol) are investigated and discussed. The simulation results show that 1) the MEES protocol outperforms the MFHS and MSHS protocols, and the MFHS protocol is more efficient than the MSHS protocol in the low SNR regions; 2) the proposed protocols achieve the best performance at the specific optimal power splitting ratios for which the MEES protocol has a balanced ratio for energy harvesting and decoding capacity; and 3) the theoretical analyses agree well with the simulation results.
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  • Shiori YOSHIOKA, Yosuke TANIGAWA, Hideki TODE
    Article type: PAPER
    Subject area: Wireless Communication Technologies
    2015 Volume E98.B Issue 12 Pages 2496-2507
    Published: December 01, 2015
    Released on J-STAGE: December 01, 2015
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    This paper deals with the inefficient channel utilization of wireless LANs that use rate adaptation. Recently, wireless LANs are being utilized in various environments. However, inefficient channel utilization is still a serious problem. The effective solutions include to decrease the frequency of packet loss and to transmit packets at a higher rate. While the backoff algorithm in IEEE 802.11 avoids only the packet loss caused by collision, other previous works tackle the packet loss caused by channel fading by means of transmission at a lower rate. This approach is called rate adaptation and a simple rate adaptation scheme is widely diffused in commercial 802.11 wireless LAN devices. However, utilizing lower transmission rate degrades transmission efficiency because the channel is occupied for a longer time. In this paper, decreasing transmission rate is avoided with novel transmission scheduling. Specifically, the proposed scheduling interrupts packet transmission to receiver stations under fading channel condition until the condition improves. Instead, other packets to other stations are transmitted in advance. To implement this proposed scheduling, only access points (APs) need to be modified. Hence, legacy wireless stations can benefit from higher communication bandwidth simply by introducing the modified APs. Moreover, although wireless stations must also be modified, an extended RTS/CTS handshake is also proposed to quickly detect the improvement of channel condition and to minimize the wasted time even if fading loss occurs. Here, wireless stations must also be modified to adopt the extended RTS/CTS handshake but further bandwidth increase is achievable. Evaluation results demonstrate that network throughput is improved without degrading the throughput fairness among receiver stations and packet transfer delay of interrupted stations.
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  • Azril HANIZ, Gia Khanh TRAN, Ryosuke IWATA, Kei SAKAGUCHI, Jun-ichi TA ...
    Article type: PAPER
    Subject area: Sensing
    2015 Volume E98.B Issue 12 Pages 2508-2519
    Published: December 01, 2015
    Released on J-STAGE: December 01, 2015
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    Conventional localization techniques such as triangulation and multilateration are not reliable in non-line-of-sight (NLOS) environments such as dense urban areas. Although fingerprint-based localization techniques have been proposed to solve this problem, we may face difficulties because we do not know the parameters of the illegal radio when creating the fingerprint database. This paper proposes a novel technique to localize illegal radios in an urban environment by interpolating the channel impulse responses stored as fingerprints in a database. The proposed interpolation technique consists of interpolation in the bandwidth (delay), frequency and spatial domains. A localization algorithm that minimizes the squared error criterion is employed in this paper, and the proposed technique is evaluated through Monte Carlo simulations using location fingerprints obtained from ray-tracing simulations. Results show that utilizing an interpolated fingerprint database is advantageous in such scenarios.
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  • Shouhei OHNO, Shouhei KIDERA, Tetsuo KIRIMOTO
    Article type: PAPER
    Subject area: Sensing
    2015 Volume E98.B Issue 12 Pages 2520-2527
    Published: December 01, 2015
    Released on J-STAGE: December 01, 2015
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    Satellite-borne or aircraft-borne synthetic aperture radar (SAR) is useful for high resolution imaging analysis for terrain surface monitoring or surveillance, particularly in optically harsh environments. For surveillance application, there are various approaches for automatic target recognition (ATR) of SAR images aiming at monitoring unidentified ships or aircraft. In addition, various types of analyses for full polarimetric data have been developed recently because it can provide significant information to identify structure of targets, such as vegetation, urban, sea surface areas. ATR generally consists of two processes, one is target feature extraction including target area determination, and the other is classification. In this paper, we propose novel methods for these two processes that suit full polarimetric exploitation. As the target area extraction method, we introduce a peak signal-to noise ratio (PSNR) based synthesis with full polarimetric SAR images. As the classification method, the circular polarization basis conversion is adopted to improve the robustness especially to variation of target rotation angles. Experiments on a 1/100 scale model of X-band SAR, demonstrate that our proposed method significantly improves the accuracy of target area extraction and classification, even in noisy or target rotating situations.
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