IEICE Transactions on Communications
Online ISSN : 1745-1345
Print ISSN : 0916-8516
Volume E95.B, Issue 3
Displaying 1-42 of 42 articles from this issue
Special Section on New/Next Generation Photonic Networking and Future Networks
  • Masayuki MURATA
    2012 Volume E95.B Issue 3 Pages 695
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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  • Hiroki IKEDA, Hidetoshi TAKESHITA, Satoru OKAMOTO
    Article type: INVITED PAPER
    2012 Volume E95.B Issue 3 Pages 696-705
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    The emergence of new services in the cloud computing era has made smooth service migration an important issue in access networks. However, different types of equipment are typically used for the different services due to differences in service requirements. This leads to an increase in not only capital expenditures but also operational expenditures. Here we propose using a service adaptive approach as a solution to this problem. We analyze the requirements of a future access network in terms of service, network, and node. We discuss available access network technologies including the passive optical network, single star network. Finally, we present a future service adaptive access/aggregation network and its architecture along with a programmable optical line terminal and optical network unit, discuss its benefit, and describe example services that it would support.
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  • Masahiko JINNO, Hidehiko TAKARA, Yoshiaki SONE, Kazushige YONENAGA, Ak ...
    Article type: INVITED PAPER
    2012 Volume E95.B Issue 3 Pages 706-713
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    This paper presents an elastic optical path network architecture as a novel networking framework to address the looming capacity crunch problem in internet protocol (IP) and optical networks. The basic idea is to introduce elasticity and adaptation into the optical domain to yield spectrally-efficient optical path accommodation, heightened network scalability through IP traffic offloading to the elastic optical layer, and enhanced survivability for serious disasters.
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  • Hiroaki HARAI
    Article type: INVITED PAPER
    2012 Volume E95.B Issue 3 Pages 714-722
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    This paper presents recent progress made in the development of an optical packet and circuit integrated network. From the viewpoint of end users, this is a single network that provides both high-speed, inexpensive services and deterministic-delay, low-data-loss services according to the users' usage scenario. From the viewpoint of network service providers, this network provides large switching capacity with low energy requirements, high flexibility, and efficient resource utilization with a simple control mechanism. The network we describe here will contribute to diversification of services, enhanced functional flexibility, and efficient energy consumption, which are included in the twelve design goals of Future Networks announced by ITU-T (International Telecommunication Union - Telecommunication Standardization Sector). We examine the waveband-based network architecture of the optical packet and circuit integrated network. Use of multi-wavelength optical packet increases the switch throughput while minimizing energy consumption. A rank accounting method provides a solution to the problem of inter-domain signaling for end-to-end lightpath establishment. Moving boundary control for packet and circuit services makes for efficient resource utilization. We also describe related advanced technologies such as waveband switching, elastic lightpaths, automatic locator numbering assignment, and biologically-inspired control of optical integrated network.
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  • Fumisato NARUSE, Yoshiyuki YAMADA, Hiroshi HASEGAWA, Ken-ichi SATO
    Article type: PAPER
    2012 Volume E95.B Issue 3 Pages 723-729
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    This paper presents a novel “virtual fiber” network service that exploits wavebands. This service provides virtual direct tunnels that directly convey wavelength paths to connect customer facilities. To improve the resource utilization efficiency of the service, a network design algorithm is developed that can allow intermediate path grooming at limited nodes and can determine the best node location. Numerical experiments demonstrate the effectiveness of the proposed service architecture.
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  • Kunitaka ASHIZAWA, Takehiro SATO, Kazumasa TOKUHASHI, Daisuke ISHII, S ...
    Article type: PAPER
    2012 Volume E95.B Issue 3 Pages 730-739
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    This paper proposes a scalable active optical access network using high-speed Plumbum Lanthanum Zirconate Titanate (PLZT) optical switch/splitter. The Active Optical Network, called ActiON, using PLZT switching technology has been presented to increase the number of subscribers and the maximum transmission distance, compared to the Passive Optical Network (PON). ActiON supports the multicast slot allocation realized by running the PLZT switch elements in the splitter mode, which forces the switch to behave as an optical splitter. However, the previous ActiON creates a tradeoff between the network scalability and the power loss experienced by the optical signal to each user. It does not use the optical power efficiently because the optical power is simply divided into 0.5 to 0.5 without considering transmission distance from OLT to each ONU. The proposed network adopts PLZT switch elements in the variable splitter mode, which controls the split ratio of the optical power considering the transmission distance from OLT to each ONU, in addition to PLZT switch elements in existing two modes, the switching mode and the splitter mode. The proposed network introduces the flexible multicast slot allocation according to the transmission distance from OLT to each user and the number of required users using three modes, while keeping the advantages of ActiON, which are to support scalable and secure access services. Numerical results show that the proposed network dramatically reduces the required number of slots and supports high bandwidth efficiency services and extends the coverage of access network, compared to the previous ActiON, and the required computation time for selecting multicast users is less than 30msec, which is acceptable for on-demand broadcast services.
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  • Xin WANG, Tithra CHAP, Sugang XU, Yoshiaki TANAKA
    Article type: PAPER
    2012 Volume E95.B Issue 3 Pages 740-751
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    Recently, the GMPLS controlled WSON has emerged as a promising optical transport network. In order to guarantee the optical signal transmission feature without deformation, the optoelectronic 3R regenerators still need to be sparsely placed in the network, termed as translucent networks. The growing size and complexity of the translucent network requires a transition of control plane to move from the traditional centralized model to a fully distributed architecture in the future. However, centrally designed routing, wavelength assignment, and 3R regenerator allocation approaches become unfeasible under the distributed paradigm due to the outdated and inconsistent network state information. A common solution is to accelerate the update frequency of network state, but the fundamental problem remains that the inaccurate state information is still inevitable. Furthermore, it adds a significant increase to the control traffic volume which adversely degrades the performance and scalability of the network control system. In order to mitigate the impact of having inaccurate state information on network performance in the distributed systems, a novel RWA approach is proposed in this paper, termed as routing and distributed wavelength assignment with top ranked probing wavelength set computation. In our proposal, the wavelength assignment is performed by signalling process with a set of carefully preselected probing wavelengths. This set is dynamically computed based on the resource utilization each time the network state is refreshed. The PCE module is adopted in WSON control plane to be responsible for the computation of RWA and 3R allocation. The performance of the proposed approach is studied by extensive simulations. The experiment results reveal that by employing the proposed scheme, without loss on the blocking performance the inaccuracy of the wavelength availability information can be well tolerated, and the set-up delay in lightpath provisioning can be kept at a low level.
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  • Kenichi SAKAMOTO, Yoshihiro ASHI, Akihiko TAKASE
    Article type: LETTER
    2012 Volume E95.B Issue 3 Pages 752-754
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    We propose a next-generation service-transport separated network architecture that uses packet technology. The transport network is responsible for the high speed and reliable bit transfer, and the service network is responsible for many types of network services. This separation makes it possible for the next-generation network to achieve both rapid bandwidth spreading and the speedy installation of new services. We also propose a next-generation transport network using the multi-protocol label switching transport profile (MPLS-TP) and optical networking technologies.
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Regular Section
  • Keiichi HIROSE, Tadatoshi BABASAKI
    Article type: INVITED SURVEY PAPER
    Subject area: Energy in Electronics Communications
    2012 Volume E95.B Issue 3 Pages 755-772
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
    JOURNAL FREE ACCESS
    To develop the advanced and rich life, and the also economy and social activity continuously, various types of energy are necessary. At the same time, to protect the global environment and to prevent the depletion of natural resources, the effective and moreover efficient use of energy is becoming important. Electric power is one of the most important forms of energy for our life and society. This paper describes topics and survey results of technical trends regarding the electric power supply systems which are playing a core role as the important infrastructure to support the emergence of information-oriented society. Specifically, the power supply systems that enhance high power quality and reliability (PQR) are important for the steady growth of information and communication services. The direct current (DC) power, which has been used for telecommunications power systems and information and communications technologies (ICT), enables existing utilities' grid and distributed energy resources to keep a balance between supply and demand of small-scaled power systems or microgirds. These techniques are expected to be part of smartgrid technologies and facilitate the installation of distributed generators in mission critical facilities.
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  • Minoru KATAYAMA, Hiroshi NAKADA, Hitoshi HAYASHI, Masashi SHIMIZU
    Article type: INVITED SURVEY PAPER
    Subject area: Sensing
    2012 Volume E95.B Issue 3 Pages 773-793
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    “Internet of Things” (IoT) requires information to be collected from “anything”, “anytime”, and “anywhere”. In order to achieve this, wireless devices are required that have (1) automatic data acquisition capability, (2) small size, (3) long life, and (4) long range communication capability. One way to meet these requirements is to adopt active Radio Frequency Identification (RFID) systems. Active RFID is more advantageous than passive RFID and enables higher data reading performance over longer distances. This paper surveys active RFID systems, the services they currently promise to provide, technical problems common to these services, and the direction in which research should head in the future. It also reports the results of EPCglobal (EPC: Electronic Product Code) pilot tests conducted on global logistics for tracking ocean/air container transportation using active RFID systems for which we developed several new types of active RFID tags. The test results confirm that our active RFID tags have sufficient capability and low power consumption to well support ocean/air transportation and logistics service.
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  • Kazumichi SATO, Keisuke ISHIBASHI, Tsuyoshi TOYONO, Haruhisa HASEGAWA, ...
    Article type: PAPER
    Subject area: Fundamental Theories for Communications
    2012 Volume E95.B Issue 3 Pages 794-802
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    Botnet threats, such as server attacks or sending of spam e-mail, have been increasing. Therefore, infected hosts must be found and their malicious activities mitigated. An effective method for finding infected hosts is to use a blacklist of domain names. When a bot receives attack commands from a Command and Control (C&C) server, it attempts to resolve domain names of C&C servers. We can thus detect infected hosts by finding these that send queries on black domain names. However, we cannot find all infected hosts because of the inaccuracy of blacklists. There are many black domain names, and the lifetimes of these domain names are short; therefore a blacklist cannot cover all black domain names. We thus present a method for finding unknown black domain names by using DNS query data and an existing blacklist of known black domain names. To achieve this, we focus on DNS queries sent by infected hosts. One bot sends several queries on black domain names due to C&C server redundancy. We use the co-occurrence relation of two different domain names to find unknown black domain names and extend the blacklist. If a domain name frequently co-occurs with a known black name, we assume that the domain name is also black. A cross-validation evaluation of the proposed method showed that 91.2% of domain names that are on the validation list scored in the top 1%.
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  • Yo-Han KO, Chang-Hwan PARK, Soon-Jik KWON, Yong-Soo CHO
    Article type: PAPER
    Subject area: Transmission Systems and Transmission Equipment for Communications
    2012 Volume E95.B Issue 3 Pages 803-809
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    In this paper, cell searching and direction-of-arrival (DoA) estimation methods are proposed for mobile relay stations with a uniform linear arrays in OFDM-based cellular systems. The proposed methods can improve the performance of cell searching and DoA estimation, even when there exist symbol timing offsets among the signals received from adjacent base stations and Doppler frequency shifts caused by the movement of the mobile relay station. The performances and computational complexities of the proposed cell searching and DoA estimation methods are evaluated by computer simulation under a mobile WiMAX environment.
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  • Ren SAKATA, Daisuke TAKEDA, Noritaka DEGUCHI, Tatsuma HIRANO, Takashi ...
    Article type: PAPER
    Subject area: Transmission Systems and Transmission Equipment for Communications
    2012 Volume E95.B Issue 3 Pages 810-818
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    Software Defined Radio (SDR) techniques are expected to be among the key technologies of heterogeneous cognitive radio networks for realizing efficient and convenient wireless communications by providing multiple radio services to users and decreasing development costs. In this paper, in order to evaluate the feasibility of SDR modems, we study the amount of computing throughput of a recent wireless system and determine a suitable modem architecture. Firstly, the functions for which SDR techniques provide significant benefits are clarified. Secondly, the computing throughputs are measured under the assumption that a dynamically reconfigurable processor, FlexSword™, is employed. Finally, based on a consideration of timing charts, we propose the architecture of an SDR-based modem with FlexSword. The possibility of implementing several wireless systems is also considered.
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  • Hiromi UEDA, Keita HAMASAKI, Takashi KURIYAMA, Toshinori TSUBOI, Hiroy ...
    Article type: PAPER
    Subject area: Fiber-Optic Transmission for Communications
    2012 Volume E95.B Issue 3 Pages 819-831
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    To realize economical optical burst signal receivers for the Optical Network Unit (ONU) of the Ethernet Optical Switched Access Network (E-OSAN), we previously implemented optical burst receivers with AC-coupling and DC-coupling using off-the-shelf components, and showed that the former offers better performance. This paper proposes a new optical burst signal receiver that uses the transfer function, Gn(s) =1-Hn(s), where Hn(s) denotes a Bessel filter transfer function of order n. We also present a method for designing the proposed receiver and clarify that it has better performance than the conventional AC-coupling one. We then present an LCR circuit synthesis of Gn(s), which is necessary to actually implement a burst receiver based on the proposal.
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  • Sumiko MIYATA, Katsunori YAMAOKA
    Article type: PAPER
    Subject area: Network System
    2012 Volume E95.B Issue 3 Pages 832-844
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    We have proposed a novel call admission control (CAC) for maximizing total user satisfaction in a heterogeneous traffic network and showed the effectiveness of our CAC by using an optimal threshold from numerical analysis [1]. In our previous CAC, when a new broadband flow arrives and the total accommodated bandwidth is more than or equal to the threshold, the arriving new broadband flow is rejected. In actual networks, however, users may agree to wait for a certain period until the broadband flow, such as video, begins to play. In this paper, when total accommodated bandwidth is more than or equal to the threshold, arriving broadband flows wait instead of being rejected. As a result, we can greatly improve total user satisfaction.
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  • Eunju HWANG, Kyung Jae KIM, Bong Dae CHOI
    Article type: PAPER
    Subject area: Network
    2012 Volume E95.B Issue 3 Pages 845-856
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    In IEEE 802.16e, power saving is one of the important issues for battery-powered mobile stations (MSs). We present a performance analysis of power saving class (PSC) of type I in IEEE 802.16e standard for voice over Internet protocol (VoIP) service with silence suppression in two-way communication. On-off pattern of a voice user in two-way communication is characterized by the modified Brady model, which includes short silence gaps less than 200ms and talkspurt periods shorter than 15ms, and so differs from the Brady model. Our analysis of PSC I follows the standard-based procedure for the deactivation of the sleep mode, where a uplink packet arrival during a mutual silence period wakes up the MS immediately while a downlink packet arrival waits to be served until the next listening window. We derive the delay distribution of the first downlink packet arriving during a mutual silence period, and find the dropping probability of downlink packets since a voice packet drops if it is not transmitted within maximum delay constraint. In addition, we calculate the average power consumption under the modified Brady model. Analysis and simulation results show that the sleep mode operation for the MS with VoIP service yields 32 ∼ 39% reduction in the power consumption of the MS. Finally we obtain the optimal initial/final-sleep windows that yield the minimum average power consumption while satisfying QoS constraints on the packet dropping probability and the maximum delay.
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  • Guangri JIN, Hiroshi FURUKAWA
    Article type: PAPER
    Subject area: Network
    2012 Volume E95.B Issue 3 Pages 857-865
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    Intermittent Periodic Transmission (IPT forwarding) has been proposed as an efficient packet relay method for wireless backhaul. In IPT forwarding, a source node sends packets to a destination node with a certain time interval (IPT duration) so that signal interference between relay nodes that send packets simultaneously are reduced and frequency reuse is realized which brings about an improvement of system throughput. However, optimum IPT duration setting for each node is a difficult problem which is not solved adequately yet. In this paper, we propose a new IPT duration setting protocol which employs some training packets to search for the optimum IPT duration for each node. A simulation and experiment show that the proposed method is not only very effective but also practical for wireless backhaul.
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  • Masao TANABE, Hirofumi AKAIKE, Masaki AIDA, Masayuki MURATA, Makoto IM ...
    Article type: PAPER
    Subject area: Internet
    2012 Volume E95.B Issue 3 Pages 866-875
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    As a result of the rapid development of the Internet in recent years, network security has become an urgent issue. Distributed denial of service (DDoS) attacks are one of the most serious security issues. In particular, 60 percent of the DDoS attacks found on the Internet are TCP attacks, including SYN flood attacks. In this paper, we propose adaptive timer-based countermeasures against SYN flood attacks. Our proposal utilizes the concept of soft-state protocols that are widely used for resource management on the Internet. In order to avoid deadlock, a server releases resources using a time-out mechanism without any explicit requests from its clients. If we change the value of the timer in accordance with the network conditions, we can add more flexibility to the soft-state protocols. The timer is used to manage the resources assigned to half-open connections in a TCP 3-way handshake mechanism, and its value is determined adaptively according to the network conditions. In addition, we report our simulation results to show the effectiveness of our approach.
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  • Shinichi AOZASA, Yoshitaka ENOMOTO, Hiroyuki OOHASHI, Yuji AZUMA
    Article type: PAPER
    Subject area: Network Management/Operation
    2012 Volume E95.B Issue 3 Pages 876-881
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    We realized single-mode hole-assisted optical fiber (HAF) cord whose fiber has a superior bending loss characteristic that complies with ITU-T Recommendation G. 657 for use in highly reliable optical fiber distribution facilities in central offices. The cord has an excellent anti-shock characteristic, and can be scanned by a conventional optical fiber cord identifier despite its very low bending loss. Experiments show that the single-mode HAF cord and its application to optical signal distribution in a central office can provide highly service reliability.
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  • Mitsuteru YOSHIDA, Kei SAKAGUCHI, Kiyomichi ARAKI
    Article type: PAPER
    Subject area: Wireless Communication Technologies
    2012 Volume E95.B Issue 3 Pages 882-888
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    In recent years, wireless communication technology has been studied intensively. In particular, MIMO which employs several transmit and receive antennas is a key technology for enhancing spectral efficiency. However, conventional MIMO architectures require some transceiver circuits for the sake of transmitting and receiving separate signals, which incurs the cost of one RF front-end per antenna. In addition to that, MIMO systems are assumed to be used in low spatial correlation environment between antennas. Since a short distance between each antenna causes high spatial correlation and coupling effect, it is difficult to miniaturize wireless terminals for mobile use. This paper shows a novel architecture which enables mobile terminals to be miniaturized and to work with a single RF front-end by means of adaptive analog beam-forming with parasitic antenna elements and antenna switching for spatial multiplexing. Furthermore, statistical analysis of the proposed architecture is also discussed in this paper.
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  • Feng LU, Chen LIU, Hua-An ZHAO
    Article type: PAPER
    Subject area: Wireless Communication Technologies
    2012 Volume E95.B Issue 3 Pages 889-897
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    This paper considers the power allocation (PA) problem for three-node decode-and-forward (DF) relay communication systems, where the aggregate transmit power constraint is imposed on the source and the relay and the optimization target is to maximize the system's instantaneous information rate. Since the relay is equipped with multiple antennas, the receiver and transmitter beamforming strategies are generally adopted. In this paper, we start by proposing a closed-form solution for the frequency-flat (FF) fading environment, then give a bisection algorithm with low complexity to obtain an optimal solution for the frequency-selective (FS) fading scenario. Finally, simulations validate the proposed methods.
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  • Kilhwan KIM, Yunho JUNG, Seongjoo LEE, Jaeseok KIM
    Article type: PAPER
    Subject area: Wireless Communication Technologies
    2012 Volume E95.B Issue 3 Pages 898-912
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    This paper proposes an efficient list extension algorithm for soft-output multiple-input-multiple-output (soft-MIMO) detection. This algorithm extends the list of candidate vectors based on the vector selected by initial detection, in order to solve the empty-set problem, while reducing the number of additional vectors. The additional vectors are obtained from multiple detection orders, from which high-quality soft-output can be generated. Furthermore, a method to reduce the complexity of the determination of the multiple detection orders is described. From simulation results for a 4×4 system with 16- and 64-quadrature amplitude modulations (QAM) and rate 1/2 and 5/6 duo-binary convolutional turbo code (CTC), the soft-MIMO detection to which the proposed list extension was applied showed a performance degradation of less than 0.5dB at bit error rate (BER) of 10-5, compared to that of the soft-output maximum-likelihood detection (soft-MLD) for all code rate and modulation pairs, while the complexity of the proposed list extension was approximately 38% and 17% of that of an existing algorithm with similar performance in a 4×4 system using 16- and 64-QAM, respectively.
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  • Rui LIU, Lv DING, Xi Qi GAO
    Article type: PAPER
    Subject area: Wireless Communication Technologies
    2012 Volume E95.B Issue 3 Pages 913-923
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    In this paper, we investigate two improved turbo receivers for the Long Term Evolution (LTE) uplink in the presence of transmitter (Tx) in-phase and quadrature-phase imbalance (IQI) with parameters known at eNodeB. For multiuser multiple-input multiple-output (MU-MIMO) single-carrier frequency division multiple access (SC-FDMA) systems, we derive a optimal joint linear minimum mean square error (MMSE) turbo multiuser detector (MUD) based on the mirror symmetry clusters. For the single use SC-FDMA system with Tx IQI, we derive an optimal widely linear MMSE (WLMMSE) turbo equalizer. Both receivers are implemented in the discrete frequency domain and only slightly increase the computational complexity compared to the conventional turbo receivers. Monte Carlo simulations show that the proposed receivers significantly outperform the conventional turbo receivers. The simulation results are then confirmed by the extrinsic information transfer (EXIT) chart analysis.
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  • Tetsuya UCHIUMI, Tatsunori OBARA, Kazuki TAKEDA, Fumiyuki ADACHI
    Article type: PAPER
    Subject area: Wireless Communication Technologies
    2012 Volume E95.B Issue 3 Pages 924-932
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    In the conventional iterative superimposed pilot-assisted channel estimation (SI-PACE), simple averaging of the instantaneous channel estimates obtained by using the pilot over several single-carrier (SC) blocks (called the frame in this paper) is taken in order to reduce the interference from data symbols. Therefore, the conventional SI-PACE has low tracking ability against fading time variations. To solve the tracking problem, Wiener filtering (WF)-based averaging can be used instead of simple averaging. However, WF incurs high computational complexity. Furthermore, the estimation error of the fading autocorrelation function significantly degrades the channel estimation accuracy. In order to improve the channel estimation accuracy while keeping the computational complexity low, a new iterative SI-PACE using sliding WF (called iterative SWFSI-PACE) is proposed. The channel estimation is done by sliding a WF having a shorter filter size than the measurement interval. The bit error rate (BER) and throughput performances of SC-FDE using iterative SWFSI-PACE are investigated by computer simulation to show that the proposed scheme achieves good BER and throughput performances while keeping the computational complexity low irrespective of the fading rate (or maximum Doppler frequency).
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  • Norharyati BINTI HARUM, Tomoaki OHTSUKI, Masao NAKAGAWA
    Article type: PAPER
    Subject area: Wireless Communication Technologies
    2012 Volume E95.B Issue 3 Pages 933-942
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    Joint transmission (JT) in time-division-duplex code-division multiple-access (TDD-CDMA) systems can provide a low peak-to-average power ratio (PAPR) for single paths, but causing a high PAPR in multipath environments. To avoid the high PAPR, we propose a new approach to JT technique by selecting certain paths instead of all paths used in JT processing so that PAPR becomes lower. The path selection proposal involves two methods; path selection by taking certain paths from all paths and by taking paths having path gains above a certain threshold value. To enhance the effectiveness of the proposed techniques, we evaluate a combination of the proposed technique with the clipping technique. We evaluate both PAPR and bit error rate (BER) performance for the proposed techniques and its combination with the clipping technique. We compare the results of the proposed techniques with conventional JT technique and the combination techniques with clipping technique. From the results of computer simulation, we show that the proposed path selection techniques perform low PAPR and good BER performance compared to the conventional JT processing. We also show that the combination of proposed path selection technique and clipping performs low PAPR performance without severe BER degradation compared to the conventional clipping technique.
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  • Sungho JEON, Junghyun KIM, Jaekwon LEE, Young-Woo SUH, Jong-Soo SEO
    Article type: PAPER
    Subject area: Wireless Communication Technologies
    2012 Volume E95.B Issue 3 Pages 943-949
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    In this paper, we propose a power amplifier linearization technique combined with iterative noise cancelation. This method alleviates the effect of added noises which prevents the predistorter (PD) from estimating the exact characteristics of the power amplifier (PA). To iteratively cancel the noise added in the feedback signal, the output signal of the power amplifier without noise is reconstructed by applying the inverse characteristics of the PD to the predistorted signals. The noise can be revealed by subtracting the reconstructed signals from the feedback signals. Simulation results based on the mean-square error (MSE) and power spectral density (PSD) criteria are presented to evaluate PD performance. The results show that the iterative noise cancelation significantly enhances the MSE performance, which leads to an improvement of the out-of-band power suppression. The performance of the proposed technique is verified by computer simulation and hardware test results.
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  • Minseok KIM, Kimtho PO, Jun-ichi TAKADA
    Article type: PAPER
    Subject area: Terrestrial Wireless Communication/Broadcasting Technologies
    2012 Volume E95.B Issue 3 Pages 950-960
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    Spectrum sensing, a key technical challenge in cognitive radios (CR) technology, is a technique that enables the spectrum of licensed systems to be accessed without causing undue interference. It is well known that cyclostationarity detectors have great advantages over energy detectors in terms of the robustness to noise uncertainty that significantly degrades the performance as well as the capability to distinguish the signal of interest from the other interferences and noise. The generalized likelihood ratio test (GLRT) is a recognized sensing technique that utilizes the inherent cyclostationarity of the signal and has been intensively studied. However, no comprehensive evaluation on its performance enhancement has been published to date. Moreover high computational complexity is still a significant problem for its realization. This paper proposes a maximum ratio combining multi-cyclic detector which uses multiple cyclic frequencies for performance enhancement with reduced computational complexity. An orthogonal frequency-division multiplexing (OFDM) signal based on the ISDB-T (integrated services digital broadcasting terrestrial), a Japanese digital television broadcasting standard, was used in the evaluation assuming this as a primary system in WRAN (wireless regional area network) applications like IEEE 802.22.
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  • Kyung-Hoon WON, Jun-Hee JANG, Hyung-Jin CHOI
    Article type: PAPER
    Subject area: Sensing
    2012 Volume E95.B Issue 3 Pages 961-971
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    In 3GPP (3-rd Generation Partnership Project) LTE (Long Term Evolution) system, the use of PRS (Positioning Reference Signal) for OTDOA (Observed Time Difference of Arrival) based positioning method has been agreed. However, PRSs can be overlapped at the receiver side in synchronous network because the frequency shift pattern of PRS is decided by cell ID (Identity). Moreover, in asynchronous network, the loss of orthogonality between received PRSs generates continuous interferences. Even though autonomous muting can be applied to solve the interference problems in synchronous and asynchronous networks, the muting scheme degrades the overall positioning efficiency and requires additional network complexity. Therefore, in this paper, we propose novel OTDOA based positioning methods at the receiver side to improve positioning efficiency: cancellation method of serving PRS for synchronous network, TDORS (Time Domain Orthogonal Reference Signal) generation and useful CIR (Channel Impulse Response) selection methods for asynchronous network. We verified that the proposed methods can achieve an accurate estimation and stable operation without PRS muting.
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  • Takuya SAKAMOTO, Yuji MATSUKI, Toru SATO
    Article type: PAPER
    Subject area: Sensing
    2012 Volume E95.B Issue 3 Pages 972-979
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    Ultra wideband (UWB) radar is considered a promising technology to complement existing camera-based surveillance systems because, unlike cameras, it provides excellent range resolution. Many of the UWB radar imaging algorithms are based on large-scale antenna arrays that are not necessarily practical because of their complexity and high cost. To resolve this issue, we previously developed a two-dimensional radar imaging algorithm that estimates unknown target shapes and motion using only three antennas. In this paper, we extend this method to obtain three-dimensional images by estimating three-dimensional motions from the outputs of five antennas. Numerical simulations confirm that the proposed method can estimate accurately the target shape under various conditions.
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  • Xinyi ZHONG, Youyun XU, Mo LI
    Article type: LETTER
    Subject area: Fundamental Theories for Communications
    2012 Volume E95.B Issue 3 Pages 980-982
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    We use network coding based on coded cooperation for the Two-Way Relay channel, where two nodes communicate with each other assisted by a third, relay node. We consider the time-division two-way relay channel without power control, which means the two users and the relay use the same transmission power. Using the proposed network coding approach, channel codes are used at both users and network coding is used at the relay. It is shown via simulation that the proposed scheme provides substantial coding gain in fading channels.
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  • ShuKai HU, Chao CHEN, Rong SUN, XinMei WANG
    Article type: LETTER
    Subject area: Fundamental Theories for Communications
    2012 Volume E95.B Issue 3 Pages 983-986
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    Quasi-cyclic (QC) low-density parity-check (LDPC) codes have several appealing properties regarding decoding, storage requirements and encoding aspects. In this paper, we focus on the QC LDPC codes over GF(q) whose parity-check matrices have fixed column weight j=2. By investigating two subgraphs in the Tanner graphs of the corresponding base matrices, we derive two upper bounds on the minimum Hamming distance for this class of codes. In addition, a method is proposed to construct QC LDPC codes over GF(q), which have good Hamming distance distributions. Simulations show that our designed codes have good performance.
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  • Seung-Yeon KIM, Sang-Sik AHN, Seungwan RYU, Choong-Ho CHO, Hyong-Woo L ...
    Article type: LETTER
    Subject area: Transmission Systems and Transmission Equipment for Communications
    2012 Volume E95.B Issue 3 Pages 987-990
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    In this letter, we propose and analyze a cooperative transmission scheme (CTS) that uses transmission timing control for LTE enterprise femtocells. In our scheme, the user equipment (UE) can receive the desired signal from an adjacent ƒBS as well as its serving femtocell BS (ƒBS). Thus, UE achieves an improved signal to interference ratio (SIR) due to the synchronization of the two signals. Analysis and simulation results show that the proposed scheme can reduce the outage probability for enterprise femtocells compared to the conventional system. In particular, a significant performance improvement can be achieved for UEs located at cell edges.
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  • Yuhua XU, Qihui WU, Jinlong WANG, Neng MIN, Alagan ANPALAGAN
    Article type: LETTER
    Subject area: Network
    2012 Volume E95.B Issue 3 Pages 991-994
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    This letter investigates the problem of distributed channel selection in cognitive radio ad hoc networks (CRAHNs) with heterogeneous spectrum opportunities. Firstly, we formulate this problem as a local congestion game, which is proved to be an exact potential game. Then, we propose a spatial best response dynamic (SBRD) to rapidly achieve Nash equilibrium via local information exchange. Moreover, the potential function of the game reflects the network collision level and can be used to achieve higher throughput.
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  • InKwan YU, Richard NEWMAN
    Article type: LETTER
    Subject area: Network
    2012 Volume E95.B Issue 3 Pages 995-998
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    When a graph can be decomposed into components of well-connected subgraphs, it is possible to speed up random walks by taking advantage of topology of the graph. In this paper, a modified Metropolis random walk scheme is introduced and conditions are given when it performs better than the original Metropolis algorithm.
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  • Xujie LI, Weiwei XIA, Qiong YANG, Lianfeng SHEN
    Article type: LETTER
    Subject area: Network
    2012 Volume E95.B Issue 3 Pages 999-1002
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    This letter presents an analytical study of outage probability of a 3G/Ad Hoc cooperative network. The considered cooperative network can improve the signal quality so as to decrease the outage probability. Meanwhile, it imposes additional interference on other ongoing users. But on the whole, our analytical study and simulation results show that the cooperative network can still effectively overcome outage event and decrease the average outage probability.
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  • Su Min JANG, Choon Seo PARK, Jae Soo YOO
    Article type: LETTER
    Subject area: Network
    2012 Volume E95.B Issue 3 Pages 1003-1006
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    Skyline queries on sensor networks have attracted much attention from the database research community due to their wide applications related to multi-criteria decision making. The existing methods use filters that are based on the data locality of sensor nodes and routing paths. However, they have two serious problems: i) unnecessary data transmission is still to frequent. ii) the processing cost of a continuous skyline query on high-dimensional data is very high. In this paper, we propose a new method that uses competitive mechanisms for processing continuous skyline queries. The proposed method dramatically reduces the data transmissions of sensors and quickly processes a continuous skyline query on high-dimensional data. An extensive performance study verifies the merits of our new method.
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  • Haifeng SUN, Guangchun LUO, Hao CHEN
    Article type: LETTER
    Subject area: Network
    2012 Volume E95.B Issue 3 Pages 1007-1010
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    We propose a Junction-Based Traffic Aware Routing (JTAR) protocol for Vehicular Ad Hoc Networks (VANETs) in sparse urban environments. A traffic aware optimum junction selection solution is adopted in packet-forwarding, and a metric named critical-segment is defined in recovery strategy. Simulation results show that JTAR can efficiently increase the packet delivery ratio and reduce the delivery delay.
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  • Jeongseo PARK, Jinsoo CHO, Taekeun PARK
    Article type: LETTER
    Subject area: Internet
    2012 Volume E95.B Issue 3 Pages 1011-1014
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    In this letter, we investigate the performance impact of disjoint multiple paths on SCTP in the connected MANET under emergency situations. Disjoint multiple paths allow multi-homing of SCTP to be fully utilized in MANETs, but it may cause inappropriate SACK handling. Through simulations, we evaluate the impact in terms of throughput and energy efficiency.
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  • Do-Hoon KIM, Kyu-Min KANG, Chungyong LEE
    Article type: LETTER
    Subject area: Wireless Communication Technologies
    2012 Volume E95.B Issue 3 Pages 1015-1018
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    We present a carrier and sampling frequency offset estimation and compensation scheme for a multi-band orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband (UWB) modem. We first perform initial carrier frequency offset (CFO) estimation and compensation during the preamble period, and then conduct the estimation and compensation of the residual CFO and sampling frequency offset (SFO) during the payload period. The proposed design scheme reduces the logic gate count of the frequency offset compensation block by about 10%, while it gives almost the same performance at the packet error rate (PER) of 10-4 in the CM1 channel. The frequency offset estimation and compensation block is implemented using 90nm CMOS technology and tested.
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  • Vo Nguyen Quoc BAO, Trung Quang DUONG
    Article type: LETTER
    Subject area: Wireless Communication Technologies
    2012 Volume E95.B Issue 3 Pages 1019-1022
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    In this letter, we consider a cognitive radio based multihop network under the spectrum sharing underlay paradigm. By taking into account the interference constraints, we present an exact closed-form expression for outage probability, which is valid for the whole signal-to-noise ratio regime. In addition, some numerical examples of interest that study the effect of the number of hops and/or the interferer threshold on primary users are illustrated and discussed. Numerical results show that multihop systems still offer a considerable gain as compared to direct transmission under the same limit of interference.
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  • Hui DENG, Xiaoming TAO, Ning GE, Jianhua LU
    Article type: LETTER
    Subject area: Wireless Communication Technologies
    2012 Volume E95.B Issue 3 Pages 1023-1026
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    This letter studies cellular controlled short-range communication in OFDMA networks. The network needs to decide when to allow direct communication between a closely located device-to-device (D2D) pair instead of conveying data from one device to the other via the base station and when not to, in addition to subchannel and power allocation. Our goal is to maximize the total network throughput while guaranteeing the rate requirements of all users. For that purpose, we formulate an optimization problem subject to subchannel and power constraints. A scheme which combines a joint mode selection and subchannel allocation algorithm based on equal power allocation with a power reallocation scheme is proposed. Simulation results show that our proposed scheme can improve the network throughput and outage probability compared with other schemes.
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  • Wei LIU, Yuan HU, Xingqun ZHAN
    Article type: LETTER
    Subject area: Navigation, Guidance and Control Systems
    2012 Volume E95.B Issue 3 Pages 1027-1030
    Published: March 01, 2012
    Released on J-STAGE: March 01, 2012
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    With the development of COMPASS system, finding suitable and efficient multiplexing solutions have become important for the system signal design. In this paper, based on the alternative BOC (AltBOC) modulation technique, the multiplexing scheme for COMPASS Phase II B1 signals is proposed. Then, to combine all COMPASS Phase III (CP III) B1 components into a composite signal with constant envelope, the generalized majority voting (GMV) technique is employed based on the characteristics of CP III B1 signals. The proposed multiplexing schemes also provide potential opportunities for GNSS modernization and construction, such as GPS, Galileo, etc.
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