IEICE Transactions on Communications
Online ISSN : 1745-1345
Print ISSN : 0916-8516
Volume E94.B, Issue 10
Displaying 1-37 of 37 articles from this issue
Special Section on New Paradigm on Content Distribution and Sharing
  • Shigeo URUSHIDANI
    2011 Volume E94.B Issue 10 Pages 2705
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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  • Mohamed DIALLO, Serge FDIDA, Prométhée SPATHIS
    Article type: INVITED PAPER
    2011 Volume E94.B Issue 10 Pages 2706-2714
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
    JOURNAL FREE ACCESS
    In this paper, we are concerned about content-based networking (CBN) at extreme scales, characterized by a large number of widely spread consumers, heterogeneous consumer requirements, huge volume of publications, and the scarcity of end-to-end bandwidth. We extend CBN with a generic service model that allows consumers to express their interests in future publications including cached content, but also to quantify the maximum amount of information they are willing to consume. We take advantage of this knowledge to pace the dissemination process and therefore, enhance the service efficiency. Early evaluation results show gains of up to 80% compared to a baseline CBN model.
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  • Hideyuki SHIMONISHI, Shuji ISHII, Lei SUN, Yoshihiko KANAUMI
    Article type: INVITED PAPER
    2011 Volume E94.B Issue 10 Pages 2715-2722
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    We propose a flexible and scalable architecture for a network controller platform used for OpenFlow. The OpenFlow technology was proposed as a means for researchers, network service creators, and others to easily design, test, and virtually deploy their innovative ideas in a large network infrastructure, which will accelerate research activities on Future Internet architectures. The technology enables the independent evolution of the network control plane and the data plane. Rather than having programmability within each network node, the separated OpenFlow controller provides network control through pluggable software. Our proposed network controller architecture will enable researchers to use their own software to control their own virtual networks. Flexibility and scalability were achieved by designing the network controller as a modularized and distributed system on a cluster of servers. Testing showed that a group of servers can efficiently cooperate to serve as a scalable OpenFlow controller. Testing using the nationwide JGN2plus network demonstrated that high-definition video can be delivered through OpenFlow-based point-to-point and point-to-multipoint paths.
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  • Seungmin LEE, Dong-Il SEO
    Article type: PAPER
    2011 Volume E94.B Issue 10 Pages 2723-2731
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    Due to an increase in multimedia content and the acceleration of digital convergence, demand for next-generation IPTV service is rapidly growing. IPTV service seamlessly provides both real-time broadcasting and content sharing services on diverse terminals through complex networks. In this paper, a secure and scalable content sharing framework is proposed for next-generation IPTV service. The proposed framework has an advantage over conventional content protection techniques in producing scalable content with transcodable, adjustable, and perceptual security features. Moreover, it ensures end-to-end security over the entire service range based on a single security mechanism. The suitability of the proposed approach is demonstrated experimentally using a practical service scenario with real-world environments. The experiments show that the proposed approach can provide several different levels of content security, from a perceptual level to an almost unintelligible level, while keeping the additional time overhead low. Consequently, it is expected that use of this security technology alone can have a practical contribution in creating new business opportunities for IPTV services.
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  • Yohei OKAMOTO, Yosuke TANIGAWA, Hideki TODE
    Article type: PAPER
    2011 Volume E94.B Issue 10 Pages 2732-2740
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    Recently, video streaming services using P2P (Peer-to-Peer) have attracted attention to solve the problem of load concentration on servers and to reduce large latency. Many P2P streaming systems, like Coolstreaming, however, take a complicated approach to control playback timing severely. This leads to less churn resiliency and less adaptability to fluctuation of network traffic. Therefore, we focus on a simple and robust approach to realize “pseudo” streaming with high quality, which is based on BitTorrent. In the existing methods with the simple approach, peers download pieces just closer to playback timing to decrease the playback discontinuity. However, these methods do not consider the constitution of video structure in sophisticated manner. P2P streaming system must consider several important metrics for high-quality and fair distribution. Therefore, in this paper, we propose a new P2P video streaming system considering the cooperation of three important metrics; video structure, playback timing, and piece dispersion on network. In this system, users vary three piece selections to suit the delivery status. Specifically, users preferentially download pieces which affect the video quality, which are closer to playback timing, and which improve the delivery efficiency. Moreover, we show the effectiveness of the proposed method by computer simulation.
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  • Hiroyuki URABAYASHI, Miki YAMAMOTO, Tomohiko YAGYU
    Article type: PAPER
    2011 Volume E94.B Issue 10 Pages 2741-2750
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    In research community of content distribution, a new communication paradigm of rendezvous-based abstraction which easily enables location-free content-oriented services, attracts great attention. ID/Locator separation architecture is originally proposed for resolving increase of routing table size in the current Internet but it has possibility of supporting this abstraction because host ID is clearly separated from its location. This feature of ID/Locator separation means an end host can be identified by ID independent of its network layer protocol. So, ID/Locator separation architecture enables communication with end host(s) operating different network-layer protocol, which might increase candidate paths between host pairs and improve content distribution path. In this paper, we evaluate this improvement of shortest path brought by inter-layer 3 networking. In inter-layer 3 networking, a shared node connecting different network layer plane plays an important role. We evaluate shortest path improvement with various shared node locations and show that strategic assignment of shared nodes brings large improvement. When multiple layer 3 networks are available for users, shortest path might be improved even only with multi-homing (without inter-layer 3 networking). We also evaluate shortest path improvement brought by multi-homing and inter-layer 3 networking for incremental deployment scenario of multi-homing. Our simulation results show that inter-layer 3 networking brings great improvement even with small number of users deploying multi-homing while only multi-homing itself brings small improvement.
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  • Jihoon LEE, Seungwoo JEON
    Article type: LETTER
    2011 Volume E94.B Issue 10 Pages 2751-2754
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    Rapid developments in mobile technology have transformed mobile phones into mobile multimedia devices. Due to these advancements, user created mobile content is on the increase, both in terms of quality and quantity. To keep pace with such movements, the new networking technology named content centric networking (CCN), which is optimized for content sharing, has appeared. However, it virtually ignores mobile devices. So, this letter proposes a smooth mobile content migration scheme for CCN to provide lower communication overhead and shorter download time.
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  • Choonhwa LEE, Eunsam KIM
    Article type: LETTER
    2011 Volume E94.B Issue 10 Pages 2755-2758
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    This paper presents a novel chunk selection strategy for peer-to-peer video streaming, called enr-first selection policy, which simultaneously considers both block rarity and playback deadline. The policy intends to boost overall network-wide streaming performance, while ensuring good playback continuity of individual peers. The efficacy of the proposed scheme is validated through our performance evaluation study that demonstrates a substantial gain.
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  • Duhwan JO, Sumi HELAL, Eunsam KIM, Wonjun LEE, Choonhwa LEE
    Article type: LETTER
    2011 Volume E94.B Issue 10 Pages 2759-2762
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    This paper presents novel hybrid push-pull protocols for peer-to-peer video streaming. Our approaches intend to reap the best of push- and pull-based schemes by adaptively switching back and forth between the two modes according to video chunk distributions. The efficacy of the proposed protocols is validated through an evaluation study that demonstrates substantial performance gains.
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Regular Section
  • Jirawat THAENTHONG, Steven GORDON
    Article type: PAPER
    Subject area: Network
    2011 Volume E94.B Issue 10 Pages 2763-2775
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    A MANEMO node is an IP-based mobile node that has interface attachments to both a mobile network, using Network Mobility (NEMO), and a Mobile Ad Hoc Network (MANET). While communicating with a correspondent node in the Internet, the MANEMO node should use the best possible path. Therefore as conditions change, a handover between NEMO and MANET is desirable. This paper describes the operation of a MANEMO handover when IEEE 802.11 is used. An analytical model illustrates that packet loss during a MANEMO handover may severely affect data and real-time applications. We therefore propose using buffering during the handover, by making use of the Power Save Mode in IEEE 802.11. In the proposed algorithm, a MANEMO node may rapidly switch between the two interfaces, eventually receiving packets delivered via the old network interface while initiating the Mobile IP/NEMO handover on the new interface. Performance results show that packet loss can be significantly reduced, with small and acceptable increases in signalling overhead and end-to-end delay.
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  • Mathieu LENOBLE, Kenji ITO
    Article type: PAPER
    Subject area: Network
    2011 Volume E94.B Issue 10 Pages 2776-2784
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    In the decentralized-TDMA (D-TDMA) protocol, the terminals select a free slot based on the frame information (FI) which is a representation of the status of each slot in the network. The FI, however, constitutes a large portion of the packet, which seriously compromises the per-packet transport capacity of the D-TDMA protocol. We therefore propose an opportunistic header management scheme for increasing the number of payload bytes without adversely affecting the performance of the D-TDMA. Our proposal is based on every terminal being able to choose between two techniques for transmitting their data packets. The first, based on the FI redundancies, lets the terminals transmit only the relevant information. The second compresses the FI with a lossless data compressor, i.e. the Huffman algorithm. Computer simulations were conducted for an urban environment in which vehicles are moving. The simulation results show that the proposed technique significantly increases the throughput without degrading the quality of the D-TDMA protocol.
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  • Young-Keum SONG, Dongwoo KIM
    Article type: PAPER
    Subject area: Network
    2011 Volume E94.B Issue 10 Pages 2785-2795
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    In this paper, we present a distributed and interactive admission and power control protocol for spectrum underlay environments. The protocol enables distributed primary users (PUs) to estimate and adjust the level of tolerable interference as their transmitting powers evolve to a given signal-to-interference-plus-noise ratio (SINR) target. The protocol also guides the powers of distributed secondary users (SUs) to achieve their own targets while restricting the transmitting powers from SUs so as not to interfere with the PUs. This restriction of interference from SUs to PUs is an essential part of cognitive radio networks (CRNs) and is facilitated by sending a warning tone from PUs to SUs in the proposed protocol. The SUs that have frequently received the warning tones turn off their transmitters and so autonomously drop from the system. This paper proves that, under the proposed interactive protocol, every PU finally achieves its target if it is originally feasible without SUs and the transmit powers of remaining SUs converge to a fixed point. The proposed method protects PUs perfectly in the sense that all the PUs reach their targets after power control. Numerical investigation shows how safely PUs are protected and how well SUs are admitted as a function of protocol parameters, the frequency of warning tones, the number of SUs to be admitted and the number of active PUs.
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  • Sooyong LEE, Myungchul KIM, Sungwon KANG, Ben LEE, Kyunghee LEE, Soonu ...
    Article type: PAPER
    Subject area: Network
    2011 Volume E94.B Issue 10 Pages 2796-2804
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    Providing seamless QoS guarantees for multimedia services is one of the most critical requirements in the mobile Internet. However, the effects of host mobility make it difficult to provide such services. The next steps in signaling (NSIS) was proposed by the IETF as a new signaling protocol, but it fails to address some mobility issues. This paper proposes a new QoS NSIS signaling layer protocol (QoS NSLP) using a cross-layer design that supports mobility. Our approach is based on the advance discovery of a crossover node (CRN) located at the crossing point between a current and a new signaling path. The CRN then proactively reserves network resources along the new path that will be used after handoff. This proactive reservation significantly reduces the session reestablishment delay and resolves the related mobility issues in NSIS. Only a few amendments to the current NSIS protocol are needed to realize our approach. The experimental results and simulation study demonstrate that our approach considerably enhances the current NSIS in terms of QoS performance factors and network resource usage.
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  • Muhammad TARIQ, Martin MACUHA, Yong-Jin PARK, Takuro SATO
    Article type: PAPER
    Subject area: Network
    2011 Volume E94.B Issue 10 Pages 2805-2816
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    With Wireless Sensor Networks (WSNs) involving in diverse applications, the realistic analysis of energy consumption of a sensor node in an error-prone network environment is emerging as an elementary research issue. In this paper, we introduce a Distributed Communication Model (DCM) that can accurately determine the energy consumption through data communication from source to destination in error-prone network environments. The energy consumption is affected with the quality of link, which is characterized by symmetry, directivity, instability, and irregularity of the communication range of a sensor node. Due to weak communication links, significant packet loss occurs that affects the overall energy consumption. While other models unable to determine energy consumption due to lossy links in error-prone and unstable network environments, DCM can accurately estimate the energy consumption in such situations. We also perform comprehensive analysis of overheads caused by data propagation through multi-hop distributed networks. We validate DCM through both simulations and experiments using MICAz motes. Similarity of the results from energy consumption analysis with both simulations and experimentations shows that DCM is realistic, compared to other models in terms of accuracy and diversity of the environments.
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  • Ahmad Kamil ABDUL HAMID, Yoshihiro KAWAHARA, Tohru ASAMI
    Article type: PAPER
    Subject area: Network Management/Operation
    2011 Volume E94.B Issue 10 Pages 2817-2827
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    In this paper, we propose an SNMP-aware web cache design that has two main objectives: (1) to avoid overload of network devices by SNMP requests, and (2) guaranteeing the monitoring time granularity of SNMP Object Identifiers (OID) for a large scale network such as the Internet. To meet these objectives, a cache is built into an RESTful active proxy, called Tambourine, which is the gateway for accessing management information through the Internet. Tambourine changes the landscape of traditional SNMP monitoring by allowing the Internet users to monitor closed-domain network devices through translating requests in HTTP into SNMP. However, the typical web cache algorithm can not be used in Tambourine due to two main reasons: (1) SNMP is not a cache-aware protocol and therefore can not provide Tambourine with the caching rules that need to be applied, and (2) the cache in Tambourine needs to accommodate two SNMP monitoring patterns: periodic and on-demand polling. In order for efficient periodic polling, SNMP traffic is reduced by a multi-TTL cache and user (or Manager)-side aggregation. For efficient on-demand polling, four-state transition is used to categorize OIDs into dynamic and static objects, each of which is allocated an optimum TTL. To provide users with a proper time stamp, the cache time stamp is included in the response to the users' request. Our experiments show that our cache design gives the staleness of 0 and a bounded number of SNMP requests even when the number of users' requests goes to infinity.
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  • Xianglan JIN, Dong-Sup JIN, Jong-Seon NO, Dong-Joon SHIN
    Article type: PAPER
    Subject area: Wireless Communication Technologies
    2011 Volume E94.B Issue 10 Pages 2828-2836
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    The probability of making mistakes on the decoded signals at the relay has been used for the maximum-likelihood (ML) decision at the receiver in the decode-and-forward (DF) relay network. It is well known that deriving the probability is relatively easy for the uncoded single-antenna transmission with M-pulse amplitude modulation (PAM). However, in the multiplexing multiple-input multiple-output (MIMO) transmission, the multi-dimensional decision region is getting too complicated to derive the probability. In this paper, a high-performance near-ML decoder is devised by applying a well-known pairwise error probability (PEP) of two paired-signals at the relay in the MIMO DF relay network. It also proves that the near-ML decoder can achieve the maximum diversity of MSMD+MR min(MS,MD), where MS, MR, andMD are the number of antennas at the source, relay, and destination, respectively. The simulation results show that 1) the near-ML decoder achieves the diversity we derived and 2) the bit error probability of the near-ML decoder is almost the same as that of the ML decoder.
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  • Yuyuan CHANG, Kiyomichi ARAKI
    Article type: PAPER
    Subject area: Wireless Communication Technologies
    2011 Volume E94.B Issue 10 Pages 2837-2846
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    In multiple-input multiple-output (MIMO) systems, the multiuser MIMO (MU-MIMO) systems have the potential to provide higher channel capacity owing to multiuser and spatial diversity. Block diagonalization (BD) is one of the techniques to realize MU-MIMO systems, where multiuser interference can be completely cancelled and therefore several users can be supported simultaneously. When the number of multiantenna users is larger than the number of simultaneously receiving users, it is necessary to select the users that maximize the system capacity. However, computation complexity becomes prohibitive, especially when the number of multiantenna users is large. Thus simplified user scheduling algorithms are necessary for reducing the complexity of computation. This paper proposes a simplified capacity-based user scheduling algorithm, based on analysis of the capacity-based user selection criterion. We find a new criterion that is simplified by using the properties of Gram-Schmidt orthogonalization (GSO). In simulation results, the proposed algorithm provides higher sum rate capacity than the conventional simplified norm-based algorithm; and when signal-to-noise power ratio (SNR) is high, it provides performance similar to that of the conventional simplified capacity-based algorithm, which still requires high complexity. Fairness of the users is also taken into account. With the proportionally fair (PF) criterion, the proposed algorithm provides better performance (sum rate capacity or fairness of the users) than the conventional algorithms. Simulation results also shows that the proposed algorithm has lower complexity of computation than the conventional algorithms.
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  • Suguru OKUYAMA, Kazuki TAKEDA, Fumiyuki ADACHI
    Article type: PAPER
    Subject area: Wireless Communication Technologies
    2011 Volume E94.B Issue 10 Pages 2847-2856
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    Broadband single-carrier frequency division multiple access (SC-FDMA) uplink using frequency-domain square-root Nyquist filtering is considered. The peak-to-average power ratio (PAPR) of filtered SC signals can be reduced by increasing the filter roll-off factor α. Furthermore, an additional frequency diversity gain can be obtained by making use of the excess bandwidth introduced by the transmit root Nyquist filtering. However, if the carrier-frequency separation is kept the same as in the case of α = 0, the adjacent users' signal spectra overlap with the desired users' spectrum and the multiuser interference (MUI) is produced. In this paper, we propose two frequency-domain iterative MUI cancellation schemes which can achieve the frequency diversity gain through spectrum combining. The achievable bit error rate (BER) and throughput performances are evaluated by computer simulation.
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  • Xin LIU, Jin-long WANG, Qihui WU, Yang YANG
    Article type: PAPER
    Subject area: Wireless Communication Technologies
    2011 Volume E94.B Issue 10 Pages 2857-2867
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    We investigate the problem of joint frequency and power allocation in wireless mesh networks, using a self-pricing game based solution. In traditional pricing game models, the price factor is determined from the global information of the network, which causes heavy communication overhead. To overcome this problem, we propose a self-pricing game model, in which the price factor is determined by the distributed access points processing their individual information; moreover, it is implemented in an autonomous and distributed fashion. The existence and the efficiency of Nash equilibrium (NE) of the proposed game are studied. It is shown that the proposed game based solution achieves near cooperative network throughput while it reduces the communication overhead significantly. Also, a forcing convergence algorithm is proposed to counter the vibration of channel selection. Simulation results verify the effectiveness and robustness of the proposed scheme.
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  • Won-Yong SHIN, Koji ISHIBASHI
    Article type: LETTER
    Subject area: Fundamental Theories for Communications
    2011 Volume E94.B Issue 10 Pages 2868-2871
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    The concept of regional diversity-multiplexing tradeoff (DMT) is introduced by extending the asymptotic outage probability expression for multiple-input multiple-output (MIMO) channels. It is shown that for both Rayleigh and Rician MIMO channels, the regional diversity gain is a linear function of the regional multiplexing gain and that the original DMT curve can be obtained from the set of regional DMT lines. As a result, vital information for capturing both finite and infinite signal-to-noise ratio characteristics in terms of DMT is provided.
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  • Wenyu LUO, Liang JIN, Yingsong LI
    Article type: LETTER
    Subject area: Fundamental Theories for Communications
    2011 Volume E94.B Issue 10 Pages 2872-2876
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    Recently, Li and Xia proposed a physical-layer security design to guarantee a low probability of interception (LPI) for asynchronous cooperative systems without relying on upper-layer data encryption. The proposed scheme utilizes diagonal unitary codes to perform different encoding in the frequency domain over subcarriers within each OFDM block to randomize the transmitted signals. To build on their idea, in this letter, a subcarrier-reference (SR) transmission scheme is proposed with deliberate signal randomization to achieve LPI in multiuser MISO-OFDMA systems. For each user, one of the allocated subcarriers is chosen by the transmitter to send reference signals, and others are chosen to send the user's information symbols. By some deliberate signal randomization, the eavesdropper cannot detect the transmitted symbols, while the authorized users can operate the system successfully without knowledge of the channels by subcarrier-reference demodulation. Extensive simulations are conducted to demonstrate the scheme's effectiveness.
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  • Shin KANEKO, Sang-Yuep KIM, Noriki MIKI, Hideaki KIMURA, Hisaya HADAMA ...
    Article type: LETTER
    Subject area: Fiber-Optic Transmission for Communications
    2011 Volume E94.B Issue 10 Pages 2877-2880
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    We propose frequency-domain optical code-division- multiplexing (CDM) employing quadrature-amplitude-modulation (QAM) using two of multi-level (M-ary) data generated based on electrical-domain spatial code spreading. Its spectral efficiency is enhanced compared to the conventional scheme with amplitude-shift-keying (ASK) using only one of M-ary data. Although it demands the recovery of amplitude and optical phase information, the practicality of the receiver is retained with self-homodyne detection using a phase-shift-keying (PSK) pilot light. Performance is theoretically evaluated and the optimal parameters are derived. Finally, the feasibility of the proposed technique is experimentally confirmed.
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  • Zheng HUANG, Kentaro KOBAYASHI, Masaaki KATAYAMA, Takaya YAMAZATO
    Article type: LETTER
    Subject area: Network
    2011 Volume E94.B Issue 10 Pages 2881-2885
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    This letter investigates the cluster lifetime of single-hop wireless sensor networks with cooperative Multi-Input Single-Output (MISO) scheme. The energy consumptions of both intra-cluster and out-cluster communications are considered. Moreover, uniform and linear data aggregations are discussed. It is found the optimal transmission scheme varies with the distance from the cluster to the base station. More interestingly and novelly, the effect of cluster size on the cluster lifetime has been clarified.
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  • Hiroyuki HATANO, Kazuya SUGIYAMA, Tomoharu MIZUTANI, Yoshihiko KUWAHAR ...
    Article type: LETTER
    Subject area: Network
    2011 Volume E94.B Issue 10 Pages 2886-2890
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    We consider how to accurately estimate the position of targets that exist in closed areas such as a room. In the past, arranging the sensors in a straight line would trigger large position estimation errors in the same direction of the straight line. However, this arrangement is useful because of easy setting, wirings, and space limitations. In this paper, we show a novel algorithm which can reduce the error using signals from reflection objects such as walls. The algorithm uses ellipse relations among sensors, targets and reflection points. Using ellipse relations, the algorithm estimates the positions of the reflection points which are assumed to be the locations of the virtual sensors. So in spite of the straight sensor arranging, the sensors are virtually distributed such as surrounding the targets. In this paper, we show the algorithm and error reduction performances as determined from computer simulations.
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  • Ken HIRAGA, Tomohiro SEKI, Kentaro NISHIMORI, Kenjiro NISHIKAWA, Ichih ...
    Article type: LETTER
    Subject area: Antennas and Propagation
    2011 Volume E94.B Issue 10 Pages 2891-2895
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    Short-range multiple-input and multiple-output (SR-MIMO) has attracted much attention, because the technique makes it possible to raise channel capacity to several hundred Gbit/s by utilizing the millimeter-wave band (e.g., 60GHz band). Although the opposed transceiving antennas are assumed to be accurately positioned in previous studies regarding SR-MIMO, a very important issue is to evaluate the performance degradation due to displacement between MIMO transceivers. In SR-MIMO over the millimeter-wave band, any displacement is perceived as significant because the wavelength is small. This paper evaluates the influence on SR-MIMO transmission performance over millimeter-wave caused by displacement between the transmitting and receiving antennas. The channel capacity is found to degrade by 5% when the horizontal displacement is 1mm and by 2.7% when the rotational displacement is 10 degrees. In addition, comparing performances obtained with a number of antenna array arrangements clarifies that a square pattern arrangement is suitable for short-range wireless transmission.
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  • Shengliang PENG, Xi YANG, Shuli SHU, Pengcheng ZHU, Xiuying CAO
    Article type: LETTER
    Subject area: Wireless Communication Technologies
    2011 Volume E94.B Issue 10 Pages 2896-2899
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    This paper proposes an adaptive sequential cooperative energy detection scheme for primary user detection in cognitive radio to minimize the detection time while guaranteeing the desired detection accuracy. Simulation results are provided to show the effectiveness of the proposed scheme.
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  • Lifeng HE, Fang YANG, Zhaocheng WANG
    Article type: LETTER
    Subject area: Wireless Communication Technologies
    2011 Volume E94.B Issue 10 Pages 2900-2902
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    In this letter, a novel physical layer signaling transmission scheme is proposed, where the signaling information is conveyed by a pair of training sequences located in the odd and even subcarriers of an orthogonal frequency division multiplexing (OFDM) training symbol. At the receiver side, only a single correlator is required to detect the signaling information. Computer simulations verify the proposed signaling could outperform the S1 signaling and achieve similar robustness as the S2 signaling of the DVB-T2 standard.
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  • Sangchoon KIM
    Article type: LETTER
    Subject area: Wireless Communication Technologies
    2011 Volume E94.B Issue 10 Pages 2903-2907
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    In this letter, a prerake combining scheme for signal detection in ultra-wideband (UWB) multiple input single output (MISO) systems with a hybrid pulse amplitude and position modulation (PAPM) is analytically examined. For a UWB MISO system, the analytical BER performance of a prerake combining scheme with PAPM is presented in a log-normal multipath fading channel. The analytical BERs are observed to match well the simulated results for the set of parameters chosen. The prerake diversity combining UWB systems, which can significantly reduce the complexity of the receiver side compared to the rake diversity systems, improve the error performance as the number of transmit antennas increases.
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  • Changeui SHIN, Hyunsung GO, Seungwon CHOI
    Article type: LETTER
    Subject area: Wireless Communication Technologies
    2011 Volume E94.B Issue 10 Pages 2908-2911
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    This letter presents a novel user scheduling algorithm that provides a maximum sum-rate based on zero-forcing beamforming (ZFBF) in multiple-input multiple-output (MIMO) systems. The proposed technique determines primary user pairs in which the sum-rate exceeds a predetermined threshold. To determine the threshold, we define the maximum-sum-rate criterion (MSRC) derived from the extreme value theory (EVT). Applying the MSRC in ZFBF-based user scheduling, we find that the performance of the proposed method is comparable to that of the exhaustive searching scheme which has a greater computational load. Through computer simulations, we show that the proposed method outperforms the very well-known correlation-based method, semi-orthogonal user selection (SUS), yielding a sum rate that is about 0.57bps/Hz higher when the transmit SNR is 10dB with perfect CSI at BS and the numbers of users and transmit antennas in a cell are 100 and 4, respectively.
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  • Kaibin ZHANG, Liuguo YIN, Jianhua LU
    Article type: LETTER
    Subject area: Wireless Communication Technologies
    2011 Volume E94.B Issue 10 Pages 2912-2915
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    Adaptive network coded cooperation (ANCC) scheme may have excellent performance for data transmission from a large collection of terminals to a common destination in wireless networks. However, the random relay selection strategy for ANCC protocol may generate the distributed low-density parity-check (LDPC) codes with many short cycles which may cause error floor and performance degradation. In this paper, an optimized relay selection strategy for ANCC is proposed. Before data communication, by exploiting low-cost information interaction between the destination and terminals, the proposed method generates good assembles of distributed LDPC codes and its storage requirement reduces dramatically. Simulation results demonstrate that the proposed relay selection protocol significantly outperforms the random relay selection strategy.
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  • Sung Kwon HONG, Jong-Moon CHUNG
    Article type: LETTER
    Subject area: Wireless Communication Technologies
    2011 Volume E94.B Issue 10 Pages 2916-2919
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    In this letter, two new network coding (NC) diversity enhancement schemes are introduced for wireless relay systems. Conventional diversity enhancement approaches for relay systems suffer from error propagation at each relay and exhibit second order diversity performance. In the proposed schemes, when a relay experiences a decoding failure, the relay makes a request to have the source transmit the NC frames to the destination in its time slot. Due to this operation, the proposed schemes prevent error propagation and achieve near third order diversity performance. The proposed schemes are compared to conventional schemes based on the derived mathematical error bounds and simulation performance, both of which demonstrate the superiority of the proposed schemes.
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  • Fuh-Hsin HWANG, Tsui-Tsai LIN
    Article type: LETTER
    Subject area: Wireless Communication Technologies
    2011 Volume E94.B Issue 10 Pages 2920-2924
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    We present a simple constellation precoding technique for a coherent MIMO transmission scheme. Significant coding/diversity gains can be achieved with or without full channel state information. It is shown that the proposed scheme outperforms the conventional space-time block codes in the presence of continuous fading.
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  • Bei LIU, Ling QIU, Jie XU
    Article type: LETTER
    Subject area: Wireless Communication Technologies
    2011 Volume E94.B Issue 10 Pages 2925-2928
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    In cellular networks, maximizing the energy efficiency (EE) while satisfying certain QoS requirements is challenging. In this article, we utilize effective capacity (EC) theory as an effective means of meeting these challenges. Based on EC and taking a realistic base station (BS) power consumption model into account, we develop a novel energy efficiency (EE) metric: effective energy efficiency (EEE), to represent the delivered service bit per energy consumption at the upper layer with QoS constraints. Maximizing the EEE problem with EC constraints is addressed and then an optimal power control scheme is proposed to solve it. After that, the EEE and EC tradeoff is discussed and the effects of diverse QoS parameters on EEE are investigated through simulations, which provides insights into the quality of service (QoS) provision, and helps the system power consumption optimization.
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  • Jangkyu YUN, Mahnsuk YOON, Byunghwa LEE, Kijun HAN
    Article type: LETTER
    Subject area: Terrestrial Wireless Communication/Broadcasting Technologies
    2011 Volume E94.B Issue 10 Pages 2929-2932
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    Handoff is a critical issue for stations in IEEE 802.11-based wireless networks. In order to provide Voice-over IP (VoIP) and real-time streaming applications to stations, a handoff mechanism is needed that can reduce latency and provide seamless communication. However, the IEEE802.11 handoff scheme is not appropriate to supply their quality of service (QoS), because it is based on a full-scanning approach. Full-scanning spends too much time searching for access points (APs). Therefore, various pre-scan handoff protocols such as SyncScan and DeuceScan have been proposed. They scan to find nearby APs before the station loses contact with its current AP, but the pre-scanning overhead is considerable. Our handoff mechanism reduces the delay and overhead associated with the link layer handoff by periodically scanning the channel groups.
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  • Woongsoo NA, Sungrae CHO
    Article type: LETTER
    Subject area: Terrestrial Wireless Communication/Broadcasting Technologies
    2011 Volume E94.B Issue 10 Pages 2933-2936
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    Dynamic spectrum access (DSA) has drawn immediate attention recently since it can opportunistically exploit any spectrum holes and thus improve bandwidth utilization. From the perspective of medium access control (MAC) design, the QoS requirement of SU is one of the design issues in DSA network. In this paper, we propose a new admission control scheme referred to as log-based dynamic spectrum access admission control (DSAC) aiming at (1) protection of the primary users and (2) QoS prioritization for the existing secondary users. The DSAC algorithm protects the PU by limiting SUs' access using PU's arrival log or statistics. Furthermore, the DSAC reserves a channel for previously admitted SU to reduce frequent service disruption of the SU. Reservation of channels is carried out without assuming any specific arrival process, and thus the DSAC would be practical for general user arrival patterns unlike the existing admission control techniques. Performance evaluation has shown that the proposed DSAC outperforms existing admission control schemes with respect to the PU blocking rate, SU communication stability, and SU aggregate throughput by about 13%, 26%, and 20%, respectively.
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  • Sang Gyu LEE, Sung Woong RA, Song Jae LEE
    Article type: LETTER
    Subject area: Satellite Communications
    2011 Volume E94.B Issue 10 Pages 2937-2940
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    Aassuming that the depolarization-induced noise generated in the dual-polarized channel is AWGN and spreads uniformly over the whole channel, we derive an effective XPD formula that can be used to estimate the depolarization effects for both partially and completely overlapped channels.
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  • Hae-Yong YANG, Kyung-Hoon LEE, Sung-Jea KO
    Article type: LETTER
    Subject area: Multimedia Systems for Communications
    2011 Volume E94.B Issue 10 Pages 2941-2944
    Published: October 01, 2011
    Released on J-STAGE: October 01, 2011
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    We present an improvement to the existing steganography-based bandwidth extension scheme. Enhanced WB (wideband) speech quality is achieved by embedding multiple highband spectral gains into a G.711 bitstream. The number of spectral gains is selected by optimizing the quantity of the embedding data with respect to the quality of the extended WB speech. Compared to the existing method, the proposed scheme improves the WB PESQ (Perceptual Evaluation of Speech Quality) score by 0.334 with negligible degradation of the embedded narrowband speech.
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