Special Section on Medical Information Communication Technology for Disaster Recovery and Human Health Care Support
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Kaikai CHI, Xiaohong JIANG, Yi-hua ZHU, Yanjun LI
Article type: PAPER
Subject area: Fundamental Theories for Communications
2012 Volume E95.B Issue 10 Pages
3103-3112
Published: October 01, 2012
Released on J-STAGE: October 01, 2012
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Recently, network coding has been applied to reliable multicast in wireless networks for packet loss recovery, resulting in significant bandwidth savings. In network-coding-based multicast schemes, once a receiver receives one packet from the source it sends an ACK to acknowledge packet receipt. Such acknowledgment mechanism has the following limitation: when an ACK from one receiver is lost, the source considers the corresponding packet to be lost at this receiver and then conducts unnecessary retransmission. Motivated by this basic observation, we first propose a block-based acknowledgment mechanism, where an ACK now acknowledges all previously received packets in the current block such that the later received ACKs can offset the loss of previous ACKs. To reduce the total amount of feedback overhead, we further propose a more simple feedback mechanism, in which the receivers only start to send acknowledgments from the last two packets (not from the first one as in the first mechanism) of the current block. The first mechanism has the potential to achieve better performance over the latter one in wireless networks with long deep fades (i.e., continuous packet losses) due to its continuous transmissions of ACKs, while the second one is more promising for wireless networks with only random packet losses due to its smaller amount of feedback. Both theoretical and simulation results demonstrate that, compared to the current acknowledgment mechanism in network-coding-based reliable multicast schemes, these two mechanisms can achieve much higher bandwidth efficiency.
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Won-Yong SHIN, Koji ISHIBASHI
Article type: PAPER
Subject area: Fundamental Theories for Communications
2012 Volume E95.B Issue 10 Pages
3113-3119
Published: October 01, 2012
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A one-dimensional ad hoc network with a single active source-destination pair is analyzed in terms of transport capacity, where each node uses multiple antennas. The analysis is based on using a multi-hop opportunistic routing transmission in the presence of fading. Specifically, the lower and upper bounds on the transport capacity are derived and their scaling law is analyzed as the node density,
λ, is assumed to be infinitely large. The lower and upper bounds are shown to have the same scaling (ln
λ)
1/α, where
α denotes the path-loss exponent. We also show that using multiple antennas at each node does not fundamentally change the scaling law.
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Saran TARNOI, Wuttipong KUMWILAISAK, Poompat SAENGUDOMLERT
Article type: PAPER
Subject area: Fundamental Theories for Communications
2012 Volume E95.B Issue 10 Pages
3120-3129
Published: October 01, 2012
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This paper presents novel analytical results on the successful decoding probability for random linear network coding in acyclic networks. The results consist of a tight lower bound on the successful decoding probability, its convergence, and its application in constructing a practical algorithm to identify the minimum field size for random linear network coding subject to a target on the successful decoding probability. From the two characterizations of random linear network coding, namely the set of local encoding kernels and the set of global encoding kernels, we first show that choosing randomly and uniformly the coefficients of the local encoding kernels results in uniform and independent coefficients for the global encoding kernels. The set of global encoding kernels for an arbitrary destination is thus a random matrix whose invertibility is equivalent to decodability. The lower bound on the successful decoding probability is then derived in terms of the probability that this random matrix is non-singular. The derived bound is a function of the field size and the dimension of global encoding kernels. The convergence rates of the bound over these two parameters are provided. Compared to the mathematical expression of the exact probability, the derived bound provides a more compact expression and is close to the exact value. As a benefit of the bound, we construct a practical algorithm to identify the minimum field size in order to achieve a target on the successful decoding probability. Simulation and numerical results verify the validity of the derived bound as well as its higher precision than previously established bounds.
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Hiroyuki ITO, Hiroshi HASEGAWA, Ken-ichi SATO
Article type: PAPER
Subject area: Energy in Electronics Communications
2012 Volume E95.B Issue 10 Pages
3130-3138
Published: October 01, 2012
Released on J-STAGE: October 01, 2012
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We investigate the possibility of reducing router power consumption through dynamic router performance control. The proposed algorithm employs a typical low pass filter and, therefore, is simple enough to implement in each related element in a router. Numerical experiments using several real Internet traffic data sets show the degree of reduction in power consumption that can be achieved by using the proposed dynamic performance control algorithm. Detailed analysis clarifies the relationships among various parameter values that include packet loss ratios and the degree of power savings. We also propose a simple method based on the leaky bucket model, which can instantaneously estimate the packet loss ratio. It is shown that this simple method yields a good approximation of the results obtained by exact packet-by-packet simulation. The simple method easily enables us to derive appropriate parameter values for the control algorithm for given traffic that may differ in different segments of the Internet.
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Takahiro OGAWA, Hiroshi HASEGAWA, Ken-ichi SATO
Article type: PAPER
Subject area: Fiber-Optic Transmission for Communications
2012 Volume E95.B Issue 10 Pages
3139-3148
Published: October 01, 2012
Released on J-STAGE: October 01, 2012
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We propose a novel dynamic hierarchical optical path network architecture that achieves efficient optical fast circuit switching. In order to complete wavelength path setup/teardown efficiently, the proposed network adaptively manages waveband paths and bundles of optical paths, which provide virtual mesh connectivity between node pairs for wavelength paths. Numerical experiments show that operational and facility costs are significantly reduced by employing the adaptive virtual waveband connections.
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Won-Kyeong SEO, Kang-Won LEE, Jae-In CHOI, You-Ze CHO
Article type: PAPER
Subject area: Network
2012 Volume E95.B Issue 10 Pages
3149-3157
Published: October 01, 2012
Released on J-STAGE: October 01, 2012
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PMIPv6 is the IETF standard for a network-based localized mobility management protocol. In PMIPv6, MNs are topologically anchored at an LMA, which forwards all data for registered MNs. However, since all data packets destined for MNs always traverse the MNs' LMA, the end-to-end packet delay is increased. Therefore, this paper proposes an RO scheme in single and multiple LMA environments. For efficient RO possibility detection, an IPv6 RO extension header and initial RO procedure are proposed. Plus, an effective post-handover RO procedure is presented, along with a packet forwarding scheme to avoid the race condition problem during an RO operation. A Performance evaluation confirms that the proposed scheme can significantly reduce the end-to-end delay, signaling overhead, and RO latency when compared with existing RO schemes.
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Dong Ho LEE, You-Ze CHO, Hoang-Anh PHAM, Jong Myung RHEE, Yeonseung RY ...
Article type: PAPER
Subject area: Network
2012 Volume E95.B Issue 10 Pages
3158-3167
Published: October 01, 2012
Released on J-STAGE: October 01, 2012
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In this paper, we present a new fault-tolerant, large-scale star network scheme called Scalable Autonomous Fault-tolerant Ethernet (SAFE). The primary goal of a SAFE scheme is to provide network scalability and autonomous fault detection and recovery. SAFE divides a large-scale, mission-critical network, such as the naval combatant network, into several subnets by limiting the number of nodes in each subnet. This network can be easily configured as a star network in order to meet fault recovery time requirements. For SAFE, we developed a novel mechanism for inter-subnet fault detection and recovery; a conventional Ethernet-based heartbeat mechanism is used in each subnet. Theoretical and experimental performance analyses of SAFE in terms of fail-over time were conducted under various network failure scenarios. The results validate our scheme.
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Chen-Hua SHIH, Jun-Li KUO, Cheng-Yuan HO, Yaw-Chung CHEN
Article type: PAPER
Subject area: Network
2012 Volume E95.B Issue 10 Pages
3168-3178
Published: October 01, 2012
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As we are moving toward next generation wireless networks, we are facing the integration of heterogeneous access networks. The main challenge is to provide mobile users moving freely across different radio access technologies with satisfactory quality of services for a variety of applications. Consequently, the seamless roaming over heterogeneous networks is an important concern. To minimize the disruption to the ongoing session when a mobile user is moving from one access network to another, we propose a framework that integrates IEEE 802.11 WLANs and IEEE 802.16WMANs based on the IEEE 802.21, so-called Media Independent Handover (MIH), to facilitate both homogeneous and heterogeneous handovers. Both numerical analysis and simulation results show that seamless roaming between WLAN and WMAN can be achieved and much better performance can be obtained compared with the IEEE 802.21 standard approach.
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ChengDong WU, Long CHENG, YunZhou ZHANG
Article type: PAPER
Subject area: Network
2012 Volume E95.B Issue 10 Pages
3179-3186
Published: October 01, 2012
Released on J-STAGE: October 01, 2012
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In this paper, two efficient redeployment strategies which are designed to balance the detection coverage rate and maintenance period are proposed. To develop these strategies, we first analyze the sensor detection coverage and energy consumption model. We then propose a network maintenance indicator that considers the coverage rate and residual energy in each node. We adopt the network maintenance indicator as the cost function. That is, the network maintenance is formulated as a cost optimization problem. Finally we propose COST_MAX_MIN and COST_MAX_AVG strategies to select the redeployed location of candidate nodes. Simulation results show that the COST_MAX_AVG prolong the repair period in comparison with the COST_MAX_MIN strategy.
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Omid ABEDI, Reza BERANGI
Article type: PAPER
Subject area: Network
2012 Volume E95.B Issue 10 Pages
3187-3196
Published: October 01, 2012
Released on J-STAGE: October 01, 2012
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In this paper, a
Spectrum-Aware Routing (
SAR) protocol for cognitive radio ad hoc networks, (
CRAHN), is proposed which is robust to primary user activity and node failures. The protocol allows nodes to collect spectrum information during a spectrum management interval followed by a transmission period. Cognitive users discover routes by joint channel and next hop selection (synchronization) in the transmission intervals. A restricted geographical routing approach is adopted to avoid performance degradation specially due to routing overhead. We also add spectrum mobility capabilities to routes in our proposed method to provide robustness to primary user activity.
SAR protocol performance is investigated through simulations of different scenarios and is compared with the most similar work,
CAODV protocol. The results indicate that
SAR can achieve significant reduction in control overhead as well as improved throughput.
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Jingjing SHI, Daisuke ANZAI, Jianqing WANG
Article type: PAPER
Subject area: Antennas and Propagation
2012 Volume E95.B Issue 10 Pages
3197-3205
Published: October 01, 2012
Released on J-STAGE: October 01, 2012
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This paper aims at channel modeling and bit error rate (BER) performance improvement with diversity reception for in-body to on-body ultra wideband (UWB) communication for capsule endoscope application. The channel characteristics are firstly extracted from 3.4 to 4.8GHz by using finite difference time domain (FDTD) simulations incorporated with an anatomical human body model, and then a two-path impulse response channel model is proposed. Based on the two-path channel model, a spatial diversity reception technique is applied to improve the communication performance. Since the received signal power at each receiver location follows a lognormal distribution after summing the two path components, we investigate two methods to approximate the lognormal sum distribution in the combined diversity channel. As a result, the method matching a short Gauss-Hermite approximation of the moment generating function (MGF) of the lognormal sum with that of a lognormal distribution exhibits high accuracy and flexibility. With the derived probability density function (PDF) for the combined diversity signals, the average BER performances for impulse-radio (IR) UWB with non-coherent detection are investigated to clarify the diversity effect by both theoretical analysis and computer simulation. The results realize an improvement around 10dB on Eb/No at BER of 10
-3 for two-branch diversity reception.
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Toshio IHARA, Kenji SEKI
Article type: PAPER
Subject area: Antennas and Propagation
2012 Volume E95.B Issue 10 Pages
3206-3214
Published: October 01, 2012
Released on J-STAGE: October 01, 2012
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This paper proposes an asymptotic method for calculating the received intensity of multi-path millimeter waves transmitted over an undulating surface. This method is a generalization of the asymptotic method that the authors previously derived, based on a quartic phase function approximation, from the physical optics integral expression of the received intensity. The applicability of the previous method is limited to ratios of transmission distance (
D) to surface undulation wavelength (
λs) of roughly less than 2. This is because the method is based on a quartic phase function approximation. In this paper, this limitation is resolved through this method's generalization, which is achieved by incorporating a technique for calculating the diffraction integral with a higher-degree phase function by using the steepest descent technique with a procedure for systematically identifying the active saddles of the phase function. Numerical examples demonstrate that the proposed asymptotic method can attain calculation accuracy comparable with the physical optics method, even in the case of large
D/
λs values.
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Marie-Christine GOSSELIN, Sven KÜHN, Andreas CHRIST, Marcel ZEFFE ...
Article type: PAPER
Subject area: Electromagnetic Compatibility (EMC)
2012 Volume E95.B Issue 10 Pages
3215-3224
Published: October 01, 2012
Released on J-STAGE: October 01, 2012
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The exposure of children to mobile phones has been a concern for years, but so far the conclusions with respect to compliance with safety standards are based only on simulations. Regulators have requested that these conclusions be supported by experimental evidence. The objectives of this study are 1) to test if the hypothesis that the specific anthropomorphic mannequin (SAM) used in standardized compliance testing is also conservative for homogeneous child head models and 2) to validate the numerical prediction of the peak spatial SAR (psSAR) in child head phantoms. To achieve these objectives, head phantoms of 3- and 8-year-old children were developed and manufactured. The results confirm that SAM is also conservative for child head phantoms, and that the agreement between numerical and experimental values are within the combined uncertainty of 0.9dB, provided that the actual peak spatial SAR (psSAR) is determined. The results also demonstrate that the currently suggested numerical SAR averaging procedures may underestimate the actual psSAR by more than 1.3dB and that the currently defined limits in terms of the average of a cubic mass are impractical for non-ambiguous evaluations, i.e., for achieving inter-laboratory repeatability.
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Takenori YASUZUMI, Nayuta KAMIYA, Ryosuke SUGA, Osamu HASHIMOTO, Yukin ...
Article type: PAPER
Subject area: Electromagnetic Compatibility (EMC)
2012 Volume E95.B Issue 10 Pages
3225-3231
Published: October 01, 2012
Released on J-STAGE: October 01, 2012
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This paper presents a compact metal plate lens antenna for evaluating a wave absorber placed on ceiling of the ETC gate. The focal distance of the lens was derived to be 129cm by the geometrical optics procedure. By arranging the lens in front of a horn antenna, the gain and beamwidth characteristics were improved from 18dBi to 26dBi and from 22 degrees to 7 degrees, respectively. Then the antenna characteristics were evaluated when the distance between the antenna and the lens was changed in order to miniaturize the lens antenna. As the result, the changes in beamwidth were held to within 1dB when the lens came close to the horn antenna. Scattering, phase and electric field intensity of electromagnetic wave were evaluated to clarify the foundation of the given characteristics. It was found that the field intensity for the miniaturized lens antenna is stronger than that for GO designed one though the phase uniformity is worse. The distance between the horn antenna and lens can be reduced to 80cm. The absorption characteristics for the arranged absorbers which have different absorptions were measured, and it was shown that the proposed method was suitable for specifying the deteriorated absorber in the ETC system.
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Satoshi DENNO, Jun IMAMURA, Masahiro MORIKURA
Article type: PAPER
Subject area: Wireless Communication Technologies
2012 Volume E95.B Issue 10 Pages
3232-3241
Published: October 01, 2012
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This paper proposes a virtual layered successive detector with adaptive transmit signal phase rotation for quadrature amplitude modulation (QAM) that enables high speed communication even in downlinks of wireless communication systems. It is shown that the detection performance is degraded when the eigenvalue of a virtual channel becomes close to the power of the additive white Gaussian noise (AWGN). Therefore, adaptive transmit signal phase rotation is introduced for the detector to improve the transmission performance. For the transmit phase rotation, three techniques to search the rotation angles are proposed, which can reduce the feedback information from the receiver to the transmitter. Among the three proposed techniques, the technique called “iterative variable step step search” is shown to achieve the best performance. Actually, it is confirmed by computer simulation that the variable step search makes the detector attain about 17dB of a gain at the bit error rate (BER) of 10
-5 in 4×2 multiple-input-multiple-output (MIMO) systems.
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Hiroshi KUBO, Masatsugu HIGASHINAKA, Akihiro OKAZAKI
Article type: PAPER
Subject area: Wireless Communication Technologies
2012 Volume E95.B Issue 10 Pages
3242-3251
Published: October 01, 2012
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This paper proposes non-coherent multiple-input multi-ple-output (MIMO) communication systems employing per transmit antenna differential mapping (PADM), which generates an independent differentially encoded sequence for each of the multiple transmit antennas by means of space-time coding and mapping. At a receiver, the proposed PADM employs adaptive maximum-likelihood detection (MLD). The features of PADM are as follows: 1) it has excellent tracking performance for fast time-varying fading channels, because it can detect transmitted data without needing channel state information (CSI); 2) it can be applied not only to transmit diversity (TD) but also to spatial multiplexing (SM). In this paper, we analyze the adaptive MLD based on pseudo matrix inversion and derive its metric for data detection. In order to satisfy requirements on multiple transmitted sequences for the adaptive MLD, this paper proposes a mapping rule for PADM. Next, this paper describes a receiver structure based on per-survivor processing (PSP), which can drastically reduce the complexity of adaptive MLD. Finally, computer simulations confirm that the proposed non-coherent MIMO communication systems employing PADM have excellent tracking capability for TD and SM on fast time-varying fading channels.
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Dongjae LEE
Article type: PAPER
Subject area: Terrestrial Wireless Communication/Broadcasting Technologies
2012 Volume E95.B Issue 10 Pages
3252-3260
Published: October 01, 2012
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This paper addresses conjugate-gradient (CG) based pilot-assisted channel estimation and equalization in doubly selective channels for orthogonal frequency division multiplexing (OFDM) block transmissions. With the help of the discrete prolate spheroidal sequence, which shows flat mean-square error (MSE) curves for the reconstructed channels in the presence of Doppler frequency mismatch, a basis expansion model for a parsimonious channel representation over multiple OFDM blocks is developed, a system equation for the least square channel estimation under widely used pilot lattices, where the pilot symbols are irregularly placed in the subcarrier domain, is formulated by introducing carving matrices, and the standard CG method is applied to the system. Relying on the CG method again, the linear minimum mean-square error channel equalization is pursued without performing any matrix inversion, while elevating the convergence speed of the iterative algorithm with a simple preconditioner. Finally, we validate our schemes with numerical experiments on the integrated services digital broadcasting-terrestrial system in doubly-selective channels and determine the normalized MSE and uncoded bit error rate.
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Kenta UMEBAYASHI, Hironori TSUCHIYA, Yasuo SUZUKI
Article type: PAPER
Subject area: Terrestrial Wireless Communication/Broadcasting Technologies
2012 Volume E95.B Issue 10 Pages
3261-3269
Published: October 01, 2012
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This paper investigates the use of cooperative spectrum sensing (CSS) to detect primary user (PU) signals during spectrum sharing between the PU and the secondary user (SU). In particular, we employ a variant of CSS (which achieves space diversity), called weighted gain combining CSS (W-CSS), which has the potential to achieve increased diversity gain and enhance detection performance. In a typical W-CSS system, the SU needs to obtain the PU signal power information in order to set the proper weight value. However, as it is hard for the SU to ascertain whether the PU is present or absent, this is difficult to obtain. To address this problem, a PU signal power estimation algorithm is introduced. In addition, we also analyze the statistics of the estimator and derive the detection probability of the W-CSS when the PU signal power estimation algorithm is applied. The analysis and related simulation results reveal that the detection probability of the proposed W-CSS under time-variant Rayleigh fading asymptotically approaches the detection probability in an additive white Gaussian noise channel as the number of antennas is increased. This also follows results from our Monte Carlo simulations, showing that multiple antenna elements could suppress the effect of Rayleigh fading. In short, the accuracy of the estimation algorithm is affected by channel variation (especially in the case of fast Rayleigh fading). Hence, to address this problem, we employ multiple antenna elements with a square-law combining energy detector in the W-CSS.
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Junjie WU, Jianyu YANG, Yulin HUANG, Haiguang YANG, Lingjiang KONG
Article type: PAPER
Subject area: Sensing
2012 Volume E95.B Issue 10 Pages
3270-3278
Published: October 01, 2012
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Bistatic synthetic aperture radar (BSAR) with one fixed station (OF-BSAR) can be used in wide area surveillance, ground moving target indication etc. This paper analyzes the spatial variance of OF-BSAR. Analytical expressions of the spatial invariance region in the data space are given. Using these results, we can determine the spatial invariance region in the data set and the imaging area. After that, we give a data blocking scheme for raw data focusing. Numerical simulation verifies the results of this paper.
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Shouhei KIDERA, Hiroyuki YAMADA, Tetsuo KIRIMOTO
Article type: PAPER
Subject area: Sensing
2012 Volume E95.B Issue 10 Pages
3279-3289
Published: October 01, 2012
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Three-dimensional (3-D) reconstruction techniques employed by airborne radars are essential for object recognition in scenarios where optically vision is blurry, and are required for the monitoring of disasters and coast-guard patrols. There have been reports on 3-D reconstruction methods that exploit the layover appearing in inverse synthetic aperture radar (ISAR) imagery, which are suitable for the recognition of artificial targets such as buildings, aircraft or ships. However, existing methods assume only a point target or the aggregate of point targets, and most require the tracking of the multiple points over sequential ISAR images. In the case of a solid object with a continuous boundary, such as a wire or polyhedral structure, the positioning accuracy of such methods is severely degraded owing to scattering centers continuously shifting on the target surface with changes in the rotation angle. To overcome this difficulty, this paper extends the original Range Points Migration (RPM) method to the ISAR observation model, where a double mono-static model with two transmitting and receiving antennas is introduced to suppress cross-range ambiguity. The results of numerical simulation and experimental validation demonstrate that the extended RPM method has a distinct advantage for accurate 3-D imaging, even for non-point targets.
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Jie LI, Gang WEI
Article type: LETTER
Subject area: Fundamental Theories for Communications
2012 Volume E95.B Issue 10 Pages
3290-3293
Published: October 01, 2012
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A wideband beamformer with mainlobe control is proposed. To make the beamformer robust against pointing errors, inequality rather than equality constraints are used to restrict the mainlobe response, thus more degrees of freedom are saved. The constraints involved are nonconvex, therefore are linearly approximated so that the beamformer can be obtained by iterating a second-order cone program. Moreover, the response variance element is introduced to achieve a frequency invariant beamwidth. The effectiveness of the technique is demonstrated by numerical examples.
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Makoto YAMADA, Masaharu UNO, Hirotaka ONO
Article type: LETTER
Subject area: Fiber-Optic Transmission for Communications
2012 Volume E95.B Issue 10 Pages
3294-3297
Published: October 01, 2012
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We propose a new configuration for a parallel fiber amplifier that can amplify both the C- and L-bands simultaneously by employing bundled Er
3+-doped fiber (EDF). The bundled EDF is a candidate amplification medium for multi-core optical fiber amplifiers. Our parallel fiber amplifier is another application of the multi-core amplification medium. The amplifier achieves almost the same signal gain of 20dB for both the C- and L-bands by using a bundled EDF, which is realized by bundling seven identical single-core EDFs.
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Junghwan KIM, Minkyu PARK, Sangchul HAN, Jinsoo KIM
Article type: LETTER
Subject area: Network System
2012 Volume E95.B Issue 10 Pages
3298-3301
Published: October 01, 2012
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Prefix caching improves the performance of IP lookup by exploiting spatial and temporal locality of IP references. However, it cannot cache non-leaf prefixes, so several prefix expansion schemes have been proposed to handle those prefixes. Such schemes have some drawbacks to incur modification of routing table or severe miss penalty. We propose an efficient prefix expansion scheme which achieves good performance without additional burden to lookup scheme. In the proposed scheme a non-leaf prefix is expanded to the length of the longest immediate descendant prefix when it is cached. Evaluation result shows our scheme achieves very low miss ratio even though it does not increase the size of routing table and cache miss penalty.
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Kou KIKUTA, Daisuke ISHII, Satoru OKAMOTO, Naoaki YAMANAKA
Article type: LETTER
Subject area: Network System
2012 Volume E95.B Issue 10 Pages
3302-3306
Published: October 01, 2012
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We report the first successful experiment on Point-to-Multipoint (P2MP) VLAN path establishment on the overlay-model-based GMPLS-controlled wide area Ethernet. To support the overlay model, P2MP VLAN path signaling with egress output port indication is proposed and implemented. It is confirmed that our extended RSVP-TE software can correctly establish P2MP VLAN paths in the overlay-model network.
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Laihyuk PARK, Jeongseok YU, Chan-Gun LEE, Sungrae CHO
Article type: LETTER
Subject area: Network
2012 Volume E95.B Issue 10 Pages
3307-3311
Published: October 01, 2012
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Directional antennas provide numerous benefits, such as higher gains, increased transmission range, and lower interferences. In this paper, we propose a reliable broadcast protocol for directional antenna referred to as beam table-based reliable broadcast for directional antennas (BTRB). The BTRB employs (1) ACK-based scheme to provide full reliability; (2) spatio-temporal ACK combination to resolve the problems of ACK implosion and transmission delay; and (3) beam table caching to represent spatial relationship among destination nodes in the broadcast group. Performance evaluation has shown that the proposed BTRB shows full reliability and outperforms existing reliable broadcast schemes with respect to transmission delay by about 55%.
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Changxiao ZHAO, Huagang XIONG
Article type: LETTER
Subject area: Network
2012 Volume E95.B Issue 10 Pages
3312-3315
Published: October 01, 2012
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In this letter, we propose a channel-aware scheduling algorithm to support real-time applications in wireless multimedia sensor networks. Multimedia streams are sensitive to real-time delivery but can tolerate some packet loss. Therefore, this specific application is modelled as an (m,k)-firm stream. To satisfy the real-time requirements, a scheduling scheme that provides packet partitioning and real-time delivery is proposed. Packet partitioning combines static assignment and dynamic adjustment while considering the channel state. The scheme is designed to minimize the number of mandatory packets delivered in a bad channel state to avoid dynamic failure. In addition, automatic repeat request technology is introduced to enhance the reliability of real-time delivery. Simulations and analyses show that the proposed scheme has a good ability to withstand a bad channel status.
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Chen-Hua SHIH, Jun-Li KUO, Yaw-Chung CHEN
Article type: LETTER
Subject area: Network
2012 Volume E95.B Issue 10 Pages
3316-3319
Published: October 01, 2012
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Establishing peer-to-peer (P2P) live streaming for mobile ad hoc network (MANET) requires an efficient scheme to deliver the real-time data in the infrastructure-less disaster environment. However, P2P membership management is difficult in the dynamic mobility and resource limited MANET. In this paper, we present a cross-layer design for P2P-MANET which integrates P2P DHT-based routing protocol and IPv6 routing protocol. Therefore, the proposed scheme can manage and recover the P2P overlay as well as selecting efficient routing path to multicast video streaming. The simulation results demonstrate that the proposed scheme performs relatively better than the layered approach or the off-the-shelf design in terms of the playback continuity and signaling overhead.
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Yoo-Cheol NA, Sang-Won MIN, Bok-Ki KIM
Article type: LETTER
Subject area: Internet
2012 Volume E95.B Issue 10 Pages
3320-3323
Published: October 01, 2012
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In this letter, we propose a novel binding scheme for network mobility support in PMIPv6 networks where new network-layer messages are suggested to solve the duplicate tunneling problem. Also our proposed scheme is designed to reduce handover latency and signaling overhead for network-based mobility management. To evaluate the performance of our method, we verify the operation of the proposed scheme with the network simulator,
ns-2, and accomplished the simulation to show its superior performance. The simulation results show that our proposed scheme works more efficiently than the scheme defined by the IETF NETLMM WG in terms of packet loss, handover latency, and average packet throughput.
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Masatoshi TSUJI
Article type: LETTER
Subject area: Antennas and Propagation
2012 Volume E95.B Issue 10 Pages
3324-3327
Published: October 01, 2012
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This paper proposes an easy-to-design, theory-consistent compact feeding circuit, with a single input and four outputs, being comprised of two hybrid circuits that are capable of switching a beam in three directions. The circuits that determine the phase differences between the antennas are present on the same single layer, and thus there is no effect of vias and the design agrees well with the underlying theory. In addition, the vertically and horizontally symmetrical circuit pattern contributes to a substantial reduction in design time. The circuit is designed for use in the ISM band and its properties are evaluated using an RF circuit simulator. A prototype is fabricated and evaluated. The results of the simulation and measurement agree well with the theoretical values. The dimensions of the feeding circuit are 75(H) × 55(W) × 3.0(T)mm.
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Hyengcheul CHOI, Kyung-Young JUNG, Hyeongdong KIM
Article type: LETTER
Subject area: Antennas and Propagation
2012 Volume E95.B Issue 10 Pages
3328-3331
Published: October 01, 2012
Released on J-STAGE: October 01, 2012
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Ground antennas are suitable for use in mobile electronic devices due to their compactness. These ground antennas incorporate two capacitors for controlling the resonance frequency and a shorting loop for impedance matching. In this work, we compare the performance of a ground antenna with that of a meandered inverted-F antenna (IFA). It is numerically and experimentally shown that a ground antenna can yield simultaneous improvements in both the antenna size and radiation efficiency when compared to the meandered IFA. The bandwidth of the ground antenna for a voltage standing wave ratio (VSWR) of 3: 1 is 240MHz from 2350MHz to 2590MHz, while the minimum total antenna efficiency is 62% within the 2.4GHz ISM band.
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Shunsuke YOSHIMURA, Hiroshi HIRAYAMA, Nobuyoshi KIKUMA, Kunio SAKAKIBA ...
Article type: LETTER
Subject area: Antennas and Propagation
2012 Volume E95.B Issue 10 Pages
3332-3336
Published: October 01, 2012
Released on J-STAGE: October 01, 2012
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A novel method for automatically creating an optimum direction-of-arrival (DOA) estimation algorithm for a given radio environment using a genetic algorithm (GA) is proposed. DOA estimation algorithms are generally described by parameters and operators. The performance of a DOA estimation algorithm is evaluated using root mean square error (RMSE) through computer simulations. A GA searches for the combination of parameters and operators that gives the lowest RMSE. Because a GA can treat only bit strings, Polish notation is used to convert bit strings into a DOA estimation algorithm. A computer simulation showed that the proposed method can create a new angle spectrum function. The created angle spectrum function has higher resolution than the Capon method.
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Ho-Kyung SON, Jong-Ho KIM, Che-Young KIM
Article type: LETTER
Subject area: Electromagnetic Compatibility (EMC)
2012 Volume E95.B Issue 10 Pages
3337-3340
Published: October 01, 2012
Released on J-STAGE: October 01, 2012
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In this letter, the amount of interference and an analytic methodology from a combination of Korea's LTE system and Japan's digital terrestrial TV broadcasting system using the 700MHz frequency band are established when considering a practical deployment of both systems. We performed Monte-Carlo simulations on the throughput loss to evaluate how much interference radiating from Japan's DTV is imposed on the Korean LTE system. The results of the established methodology can be used as a guideline for allowing the deployed LTE system to avoid an unacceptable amount of interference.
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Dac-Binh HA, Vo Nguyen Quoc BAO, Nguyen-Son VO
Article type: LETTER
Subject area: Wireless Communication Technologies
2012 Volume E95.B Issue 10 Pages
3341-3344
Published: October 01, 2012
Released on J-STAGE: October 01, 2012
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We derive a closed-form expression for the outage probability (OP), which is an important performance metric used to measure the probability that the target error rate performance of wireless systems exceeds a specified value, of multiple-input multiple-output (MIMO) amplify-and-forward (AF) relaying systems with best antenna selection under independent, but not necessarily identical distributed Nakagami-
m fading. To gain further insights on the performance, the asymptotic approximation for OP, which reveals the diversity gain, is presented. We show that the diversity gain is solely determined by the fading severity parameters and increases with number of antennas at all nodes.
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Jiamin LI, Dongming WANG, Pengcheng ZHU, Lan TANG, Xiaohu YOU
Article type: LETTER
Subject area: Wireless Communication Technologies
2012 Volume E95.B Issue 10 Pages
3345-3348
Published: October 01, 2012
Released on J-STAGE: October 01, 2012
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All points on the Pareto boundary can be obtained by solving the weighted sum rate maximization problem for some weighted coefficients. Unfortunately, the problem is non-convex and difficult to solve without performing an exhaustive search. In this paper, we propose an optimal distributed beamforming strategy for the two-user multiple-input single-output (MISO) interference channel (IC). Through minimizing the interference signal power leaked to the other receiver for fixed useful signal power received at the intended receiver, the original non-convex optimization problem can be converted into a family of convex optimization problems, each which can be solved in distributed manner with only local channel state information at each transmitter. After some conversion, we derive the closed-form solutions to all Pareto optimal points based on a game-theoretic viewpoint which indicates that linear combinations of the maximum-ratio transmit (MRT) and zero-forcing (ZF) beamforming strategies can achieve any point on the Pareto boundary of the rate region for the two-user MISO interference channel, and the only computation involved is to solve a basic quadratic equation. Finally, the result is validated via numerical simulations.
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Hua JIANG, Kanglian ZHAO, Yang LI, Sidan DU
Article type: LETTER
Subject area: Wireless Communication Technologies
2012 Volume E95.B Issue 10 Pages
3349-3352
Published: October 01, 2012
Released on J-STAGE: October 01, 2012
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In this letter we design a new family of space-time block codes (STBC) for multi-input multi-output (MIMO) systems. The complex orthogonal STBC achieves full diversity and full transmission rate with fast maximum-likelihood decoding when only two transmit antennas are employed. By combining the Alamouti STBC and the multidimensional signal constellation rotation based on the cyclotomic number field, we construct cyclotomic orthogonal space-time block codes (COSTBCs) which can achieve full diversity and full rate for multiple transmit antennas. Theoretical analysis and simulation results demonstrate excellent performance of the proposed codes, while the decoding complexity is further reduced.
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Akindele Segun AFOLABI, Erdenebileg MUNKHBAT, Yumi TAKAKI, Chikara OHT ...
Article type: LETTER
Subject area: Wireless Communication Technologies
2012 Volume E95.B Issue 10 Pages
3353-3357
Published: October 01, 2012
Released on J-STAGE: October 01, 2012
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Orthogonal Frequency Division Multiple Access (OFD-MA) is a leading air interface candidate for future generation cellular networks. However, if deployed in a multi-user multi-tier cellular system, it is important to fairly share radio resources such as transmission power and sub-carriers among co-tier and cross-tier users. This paper focuses on a mathematical formulation of cell inner-zone/outer-zone radio resource partitioning variables and considers the case of an FFR-based macrocell underlaid with femtocell. By applying an exhaustive search procedure on the developed formulation, we determine the optimal radio resource partitioning parameter values from the perspectives of macrocell user fairness and femtocell throughput maximization.
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Liang LI, Ling QIU, Guo WEI
Article type: LETTER
Subject area: Terrestrial Wireless Communication/Broadcasting Technologies
2012 Volume E95.B Issue 10 Pages
3358-3361
Published: October 01, 2012
Released on J-STAGE: October 01, 2012
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In this letter we propose a practical sensing-based opportunistic spectrum sharing scheme for cognitive radio (CR) downlink MIMO systems. Multi-antennas are exploited at the secondary transmitter to opportunistically access the primary spectrum and effectively achieve a balance between secondary throughput maximization and mitigation of interference probably caused to primary radio link. We first introduce a brief secondary frame structure, in which a sensing phase is exploited to estimate the
effective interference channel. According to the sensing result and taking the interference caused by the primary link into account, we propose an enhanced
signal-to-leakage-and-noise ratio (SLNR)-based precoding scheme for the secondary transmitter. Compared to conventional schemes where perfect knowledge of the channels over which the CR transmitter interferes with the primary receiver (PR) is assumed, our proposed scheme shows its superiority and simulation results validate this.
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Jaemin JEUNG, Seungmyeong JEONG, JaeSung LIM
Article type: LETTER
Subject area: Terrestrial Wireless Communication/Broadcasting Technologies
2012 Volume E95.B Issue 10 Pages
3362-3364
Published: October 01, 2012
Released on J-STAGE: October 01, 2012
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We propose a deception mechanism to combat a compromised station in IEEE 802.11 channel hopping systems. A compromised station can follow the hopping channels and continuously attack them, since it recognizes the channel-hopping sequence. The key concept of the deception mechanism is that an access point notifies a new hopping seed but not to the jammer, while a deception station deceives the jammer. Simulations show that the proposed scheme increases network throughput compared to conventional channel hopping schemes when they are under compromised station attacks.
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Sunyoung LEE, Kae Won CHOI, Seong-Lyun KIM
Article type: LETTER
Subject area: Terrestrial Wireless Communication/Broadcasting Technologies
2012 Volume E95.B Issue 10 Pages
3365-3369
Published: October 01, 2012
Released on J-STAGE: October 01, 2012
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In this letter, we focus on detecting a random primary user (PU) network for cognitive radio systems in a cooperative manner by using maximum likelihood (ML) detection. Different from traditional PU network models, the random PU network model in this letter considers the randomness in the PU network topology, and so is better suited for describing the infrastructure-less PU network such as an ad hoc network. Since the joint pdf required for the ML detection is hard to obtain in a closed form, we derive approximate ones from the Gaussian approximation. The performance of the proposed algorithm is comparable to the optimal one.
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Hiroyasu OBATA, Kenji ISHIDA, Chisa TAKANO, Junichi FUNASAKA, Masaaki ...
Article type: LETTER
Subject area: Satellite Communications
2012 Volume E95.B Issue 10 Pages
3370-3373
Published: October 01, 2012
Released on J-STAGE: October 01, 2012
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Some researchers have started using the high-speed communication satellite WINDS to evaluate TCP congestion control methods. However, they do not aim to maximize TCP throughput when WINDS is paired with a Large Earth Station (LET). This paper evaluates the typical TCP performance of satellite links over a network composed of LET and WINDS in order to break the TCP throughput record for satellite links.
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