IEICE Transactions on Communications
Online ISSN : 1745-1345
Print ISSN : 0916-8516
Volume E94.B, Issue 3
Displaying 1-40 of 40 articles from this issue
Special Section on Information and Communication Technologies for Next-generation Mobile Multimedia Life
  • Eiji KAMIOKA
    2011 Volume E94.B Issue 3 Pages 617
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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  • Masugi INOUE, Masaaki OHNISHI, Chao PENG, Ruidong LI, Yasunori OWADA
    Article type: INVITED PAPER
    2011 Volume E94.B Issue 3 Pages 618-629
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    Wireless access networks of the future could provide a variety of context-aware services with the use of sensor information in order to solve regional social problems and improve the quality of residents' lives as a part of the regional infrastructure. NerveNet is a conceptual regional wireless access platform in which multiple service providers provide their own services with shared use of the network and sensors, enabling a range of context-aware services. The platform acts like a human nervous system. Densely located, interconnected access points with databases and data processing units will provide mobility to terminals without a location server and enable secure sensor data transport on a highly reliable, managed mesh network. This paper introduces the motivations, concept, architecture, system configuration, and preliminary performance results of NerveNet.
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  • Takeshi UMEZAWA, Kiyohide NAKAUCHI, Masugi INOUE, Takashi MATSUNAKA, T ...
    Article type: PAPER
    2011 Volume E94.B Issue 3 Pages 630-638
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    Despite the recent advances in personal communication devices and access network technology, users still face problems such as high device maintenance costs, complication of inter-device cooperation, illegal access to devices, and leakage of personal information. Consequently, it is difficult for users to construct a secure network with local as well as remote personal devices. We propose a User-driven Service Creation Platform (USCP), which enables users to construct a secure private network using a simple and intuitive approach that leverages the authentication mechanism in mobile phone networks. USCP separates signaling and data paths in a flat, virtual network topology. In this paper, we describe the basic design of USCP, the current implementation, and system evaluations.
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  • Satoshi UEMURA, Sumaru NIIDA, Hajime NAKAMURA
    Article type: PAPER
    2011 Volume E94.B Issue 3 Pages 639-648
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    Providing mobile services that ensure user satisfaction is one of the most crucial issues for telecommunication carriers and service providers. Traditionally, user satisfaction with the service, i.e., the Quality of Experience (QoE), has been assessed in a laboratory by using elaborate network systems and customized terminals. However, reliable QoE for a target mobile service in the context of actual use cannot be obtained by laboratory experiment, since QoE can be affected by a variety of factors such as environmental conditions and the mental state of the user. This paper proposes a novel Web script-based field evaluation method designed to ascertain user satisfaction with mobile services. The proposed method has the following practical advantages. Since experimental conditions, especially communication conditions, can be simulated with a Web script, such as FlashLite, a subjective assessment can be conducted anywhere using the mobile terminal of the participant. Thus, QoE for a target mobile service in the field can easily be obtained.
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  • Shigeaki TAGASHIRA, Yuhei KANEKIYO, Yutaka ARAKAWA, Teruaki KITASUKA, ...
    Article type: PAPER
    2011 Volume E94.B Issue 3 Pages 649-657
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    A critical problem with wireless LAN-based positioning systems is the degradation in position estimation accuracy due to complex variation in the strength of the received signal, which originates in the nature of the underlying wireless channel. Handling such variation effectively is essential for the creation of practical wireless LAN-based positioning systems. In this paper, we propose a collaborative mechanism for correcting position estimation errors. The main objective is to assist users in correcting estimation errors manually by providing access to a shared body of accumulated information on corrections made by many other users. In particular, the mechanism is designed to enable any group of users to collaboratively build upon this body of information. Finally, we evaluate the effectiveness of the proposed mechanism through experiments. The results confirm that the proposed mechanism can provide effective estimation error correction in a realistic environment.
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  • Masakatsu OGAWA, Takefumi HIRAGURI, Kentaro NISHIMORI, Naoki HONMA, Ka ...
    Article type: PAPER
    2011 Volume E94.B Issue 3 Pages 658-666
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    This paper proposes a power saving control method for battery-powered portable wireless LAN (WLAN) access points (APs) in an overlapping basic service set (OBSS) environment. The IEEE802.11 standard does not support power saving control for APs. Some conventional power saving control methods for APs have been proposed that use the network allocation vector (NAV) to inhibit transmission at stations (STAs) while the AP is sleeping. However, since with these approaches the actual beacon interval in the OBSS environment may be extended due to the NAV as compared to the beacon interval which is set at the AP, the power consumption and delay may be increased as compared to a single BSS unaffected by interference from neighboring APs. To overcome this problem, this paper introduces a new action frame named power saving access point (PSAP) action frame which the AP uses to inform STAs within its BSS about the AP's sleep length. In addition, a function of the PSAP action frame is that STAs enter the sleep state after receiving the PSAP action frame. The proposed control method avoids the postponement of beacon transmission and reduces the power consumption in an OBSS environment, as compared to the conventional control method. Numerical analysis and computer simulation reveal that the newly proposed control method conserves power as compared to the conventional control method. The proposed control method achieves the minimum consumed power ratio at the AP, which is 44% as compared to the standard, when the beacon interval is 100ms and the sleep length is 60ms, even if the number of neighboring APs in an OBSS environment is increased.
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  • Kentaro NISHIMORI, Takefumi HIRAGURI, Masakatsu OGAWA, Naoki HONMA
    Article type: PAPER
    2011 Volume E94.B Issue 3 Pages 667-675
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    This paper proposes a new Ad-Hoc network system which comprises the multiple relay access points (APs) with multi channels. Ad-Hoc network systems are recently proposed and incorporated for the communication infrastructure, which relays wireless transmission among access points (APs) in wireless LAN (WLAN) system. System throughput is decreased due to hidden terminal problem when only a single channel is used for the Ad-Hoc network. In order to solve this problem, a new system with multi channels is proposed. However, even if the multi channels are employed, the co- and/or adjacent-channel interference occurs due to hidden terminal problem and multiple APs in a limited space, when considering a simultaneous transmit and reception at the relay AP. In this paper, we develop an Ad-Hoc network testbed which can reduce and avoid co- and/or adjacent-channel interference by using vertically arranged antenna configuration and distributed channel allocation scheme. Moreover, the effectiveness of our testbed is clarified by applying actual WLAN signals.
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  • Yo-Won JEONG, Kwang-Deok SEO, Kyu Ho PARK
    Article type: PAPER
    2011 Volume E94.B Issue 3 Pages 676-685
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    Joint source-channel coding (JSCC) is a method to jointly allocate the given total transmission bitrate to the source coding and channel coding to maximize the video quality at the receiving end. In this paper, we propose a practical model for efficiently determining a near-optimal code rate for JSCC in real-time video communications. The conventional code rate decision schemes using analytical source coding distortion model and channel-induced distortion model are usually complex, and typically employ the process of model parameter training which involves potentially high computational complexity and implementation cost. To avoid the complex modeling procedure, we introduce a very simple video quality model based on the playable bitrate which is defined as the total bit amount per unit time that is not affected by the channel loss during transmission including correctly recovered bits by the channel decoder. Because the video quality at the receiving end is clearly commensurate with the playable bitrate, we can easily determine the quality-oriented near-optimal code rate by finding the code rate that maximizes the playable bitrate at the sender side. The proposed playable bitrate model is very simple because it does not require the complex training procedure for obtaining model parameters, which is usually required in the conventional code rate decision method. It is shown by simulations that the proposed code rate decision scheme based on the playable bitrate model can efficiently determine the near-optimal code rate for JSCC in terms of high accuracy on the optimal code rate.
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  • Jangseong KIM, Taeshik SHON, Kwangjo KIM
    Article type: LETTER
    2011 Volume E94.B Issue 3 Pages 686-689
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    In this paper, we establish our child safety system model related to the addressing contradictory issue of wireless sensor networks caused by the mutual authentication and privacy protection of an end-user. Based on the system model, we propose the novel location-aware and privacy-preserving approach for providing child safety over wireless sensor networks. Although we illustrate our protocol over the sensor networks, the proposed protocol can be operated by various wireless networks (e.g., WiFi and UWB) which can support RSSI (Received Signal Strength Indication). Compared to a few previous works, the proposed approach can show the potential of enhancing accuracy with location information, preserve the privacy of an end-user, and provide the capability of controlling the child safety service to an end-user.
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  • Chien-Sheng CHEN, Szu-Lin SU, Yih-Fang HUANG
    Article type: LETTER
    2011 Volume E94.B Issue 3 Pages 690-693
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    The objective of wireless location is to determine the mobile station (MS) location in a wireless cellular communications system. When signals are propagated through non-line-of-sight (NLOS) paths, the measurements at the base stations (BSs) contain large errors which result in poor detectability of an MS by the surrounding BSs. In those situations, it is necessary to integrate all available heterogeneous measurements to improve location accuracy. This paper presents hybrid methods that combine time of arrival (TOA) at three BSs and angle of arrival (AOA) information at the serving BS to obtain a location estimate for the MS. The proposed methods mitigate the NLOS effect by using the weighted sum of the intersections between three TOA circles and the AOA line without requiring the a priori knowledge of NLOS error statistics. Numerical results show that all positioning methods offer improved estimation accuracy over those which rely on the two circles and two lines. The proposed methods always achieve better location accuracy than the Taylor series algorithm (TSA) and the hybrid lines of position algorithm (HLOP) do, regardless of the NLOS error statistics.
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  • Kyungmin PARK, Chungha KOH, Kangjin YOON, Youngyong KIM
    Article type: LETTER
    2011 Volume E94.B Issue 3 Pages 694-697
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    In femto/macro cellular networks, the stability and fairness problems caused by the unplanned and random characteristic of femtocells must be solved. By applying queueing theory in IP based femto/macro cellular networks, we found the stability condition, and described two kinds of cell section policies of users. As a main contribution, we provided the adaptive channel distribution algorithm which minimizes the average packet sojourn time at transmitting systems and keeps the whole systems stable and fair among cells. Through experiments in various environments, we analyzed the influence of channel reuse factor, cell selection policies, and the number of femtocells on system performance.
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Regular Section
  • Takahiro MATSUDA, Taku NOGUCHI, Tetsuya TAKINE
    Article type: INVITED SURVEY PAPER
    Subject area: Fundamental Theories for Communications
    2011 Volume E94.B Issue 3 Pages 698-717
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    This survey summarizes the state-of-the-art research on network coding, mainly focusing on its applications to computer networking. Network coding generalizes traditional store-and-forward routing techniques by allowing intermediate nodes in networks to encode several received packets into a single coded packet before forwarding. Network coding was proposed in 2000, and since then, it has been studied extensively in the field of computer networking. In this survey, we first summarize linear network coding and provide a taxonomy of network coding research, i.e., the network coding design problem and network coding applications. Moreover, the latter is subdivided into throughput/capacity enhancement, robustness enhancement, network tomography, and security. We then discuss the fundamental characteristics of network coding and diverse applications of network coding in details, following the above taxonomy.
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  • Kazuhide NAKAJIMA, Tomoya SHIMIZU, Takashi MATSUI, Chisato FUKAI, Tosh ...
    Article type: PAPER
    Subject area: Optical Fiber for Communications
    2011 Volume E94.B Issue 3 Pages 718-724
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    The characteristics of hole-assisted fiber (HAF) are investigated both numerically and experimentally in terms of its applicability as a bending-loss insensitive fiber (BIF). We show that HAF with the desired mode-field diameter (MFD), bending-loss and cutoff wavelength characteristics can be roughly designed by taking a few specific structural parameters into consideration. We also show that an optical cord composed of adequately designed HAF realizes satisfactory transmission performance with respect to its multi-path interference (MPI) characteristics. These results reveal that a hole-assisted type BIF will be beneficial for realizing easy and economical installation and maintenance in future access networks.
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  • Miao ZHANG, Jiro HIROKAWA, Makoto ANDO
    Article type: PAPER
    Subject area: Antennas and Propagation
    2011 Volume E94.B Issue 3 Pages 725-734
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    A novel design technique for two-dimensional (2-D) waveguide slot arrays is proposed in this paper that combines a full-wave method of moments (MoM) analysis and an equivalent circuit with the explicit restraint of input matching. The admittance and slot spacing are determined first in an equivalent circuit to realize the desired distribution of power dissipation and phase, with the explicit restraint of input matching. Secondly by applying a full-wave MoM analysis to the finite 2-D array, slot parameters are iteratively determined to realize the active admittance designed above where slot mutual coupling and wall thickness are fully taken into account. The admittance, treated as the key parameter in the equivalent circuit corresponds to the power dissipation of the slots but not to the slot voltage, which is directly synthesized from the radiation pattern. The initial value of the power dissipation is assumed to be proportional to the square of the amplitude of the desired slot voltage. This assumption leads to a feedback procedure, because the resultant slot voltage distribution generally differs from the desired ones due to the effect of non-uniformity in the characteristic impedance on slot apertures. This slot voltage error is used to renew the initial distribution of power dissipation in the equivalent circuit. Generally, only one feedback cycle is needed. Two 24×27-element arrays with uniform and Taylor distributions were designed and fabricated at 25.3GHz. The measured overall reflections for both antennas were suppressed below -18dB over the 24.3-26.3GHz frequency range. High aperture efficiencies of 86.8% and 55.1% were realized for the antennas with uniform and Taylor distributions, the latter of which has very low sidelobes below -33dB in both the E- and H-planes.
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  • Ning LI, Yan GUO, Qi-Hui WU, Jin-Long WANG, Xue-Liang LIU
    Article type: PAPER
    Subject area: Antennas and Propagation
    2011 Volume E94.B Issue 3 Pages 735-741
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    A method based on covariance differencing for a uniform linear array is proposed to counter the problem of direction finding of narrowband signals under a colored noise environment. By assuming a Hermitian symmetric Toeplitz matrix for the unknown noise, the array covariance matrix is transformed into a centrohermitian matrix in an appropriate way allowing the noise component to be eliminated. The modified covariance differencing algorithm provides accurate direction of arrival (DOA) estimation when the incident signals are uncorrelated or just two of the signals are coherent. If there are more than two coherent signals, the presented method combined with spatial smoothing (SS) scheme can be used. Unlike the original method, the new approach dispenses the need to determine the true angles and the phantom angles. Simulation results demonstrate the effectiveness of presented algorithm.
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  • Yuji MATSUKI, Takuya SAKAMOTO, Toru SATO
    Article type: PAPER
    Subject area: Antennas and Propagation
    2011 Volume E94.B Issue 3 Pages 742-749
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    UWB (ultra wide-band) pulse radar is a promising candidate for surveillance systems. The fast SEABED (Shape Estimation Algorithm based on BST and Extraction of Directly scattered waves) imaging algorithm is deployed in the application of UWB pulse radar in fields that require real-time operations. However, since the SEABED algorithm uses signals received at multiple locations, this method either needs to scan antennas or to install many antennas. Such systems are inevitably costly and unrealistic for applications such as surveillance. To overcome this problem, a revised SEABED algorithm that estimates unknown target shape based on target motion using only a pair of fixed antennas was developed. However, the method cannot be used when the target moves arbitrarily because it assumes the target motion is parallel to the baseline of the pair of antennas. In this paper, we propose a new UWB radar imaging algorithm that is applicable even for targets with arbitrary motion. The proposed method introduces another antenna which is added to the pair of antennas used in the revised SEABED, and estimates unknown target motion based on the target surface using the three antennas. Next, the proposed method applies the SEABED imaging algorithm to the estimated motion and obtains the target image. Some numerical simulations establishes that the proposed method can accurately estimate the target shape even under severe conditions.
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  • Tatsunori OBARA, Kazuki TAKEDA, Kyesan LEE, Fumiyuki ADACHI
    Article type: PAPER
    Subject area: Wireless Communication Technologies
    2011 Volume E94.B Issue 3 Pages 750-757
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    Recently, overlap frequency-domain equalization (FDE) based on minimum mean square error (MMSE) criterion which requires no guard interval (GI) insertion was proposed for signal transmission using multi-code direct sequence code division multiple access (DS-CDMA) in a frequency-selective fading channel. Another promising equalization technique is time-domain sliding-window chip equalization (SWCE). In this paper, the bit error rate (BER) performances achievable with overlap FDE and SWCE are compared. It is shown that, by extending the fast Fourier transform (FFT) block size, overlap FDE can achieve almost the same BER performance as SWCE with much less computational complexity than SWCE.
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  • Gye-Tae GIL, Seong-Choon LEE, Dong-Hoi KIM
    Article type: PAPER
    Subject area: Wireless Communication Technologies
    2011 Volume E94.B Issue 3 Pages 758-764
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    This paper presents a novel dynamic subchannel allocation scheme that can improve the cell capacity by coordinating the intercell interference (ICI) in a cellular orthogonal frequency division multiple access (OFDMA) system. The proposed scheme mitigates the ICI by adopting the virtual cell concept and improves the frequency reuse factor through subchannel reuse among different virtual cells. In particular, each virtual cell is assigned a primary and a secondary subchannel group, and each sector base station (BSs) allocates the subchannel resulting in the least ICI in probability out of the candidate subchannels to the mobile stations, dynamically searching from its primary group and then secondary group. In addition, an optional use of pico-cell overlay at the intersection of the virtual cells is also proposed to enhance the fairness of the proposed scheme with the BS-MS distance. Through computer simulation, it is shown that the proposed scheme has the advantages of improved cell capacity and fairness compared to the conventional schemes.
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  • Masafumi HASHIMOTO, Go HASEGAWA, Masayuki MURATA
    Article type: PAPER
    Subject area: Terrestrial Wireless Communication/Broadcasting Technologies
    2011 Volume E94.B Issue 3 Pages 765-776
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    Per-flow unfairness of TCP throughput in the IEEE 802.11 wireless LAN (WLAN) environment has been reported in past literature. A number of researchers have proposed various methods for alleviating the unfairness; most require modification of MAC protocols or queue management mechanisms in access points. However, the MAC protocols of access points are generally implemented at hardware level, so changing these protocols is costly. As the first contribution of this paper, we propose a transport-layer solution for alleviating unfairness among TCP flows, requiring a small modification to TCP congestion control mechanisms only on WLAN stations. In the past literature on fairness issues in the Internet flows, the performance of the proposed solutions for alleviating the unfairness has been evaluated separately from the network bandwidth utilization, meaning that they did not consider the trade-off relationships between fairness and bandwidth utilization. Therefore, as the second contribution of this paper, we introduce a novel performance metric for evaluating trade-off relationships between per-flow fairness and bandwidth utilization at the network bottleneck. We confirm the fundamental characteristics of the proposed method through simulation experiments and evaluate the performance of the proposed method through experiments in real WLAN environments. We show that the proposed method can achieve better a trade-off between fairness and bandwidth utilization, regardless of vendor implementations of wireless access points and wireless interface cards.
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  • Ryosuke FUJIWARA, Kenichi MIZUGAKI, Goichi ONO, Tatsuo NAKAGAWA, Takay ...
    Article type: PAPER
    Subject area: Sensing
    2011 Volume E94.B Issue 3 Pages 777-785
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    In this work, an ultra-wideband impulse radio (UWB-IR) transceiver with accurate time-of-arrival (TOA) estimation for a ranging/positioning system was developed for wireless sensor network applications. The system uses an impulse radio characterized by a low duty cycle and direct-sequence spreading, which enable very precise ranging and good receiver sensitivity. An algorithm enabling the TOA of the first-path signal to be measured accurately in a multi-path environment with simple, low-power and low cost implementations was proposed. UWB chips with CMOS 0.18-µm technology and UWB transceiver modules performed that the accuracy of the proposed ranging system is 18.5cm in a closed space.
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  • Toyoshi SHIMOMAI, Kentaro ADACHI, Toshiaki KOZU
    Article type: PAPER
    Subject area: Sensing
    2011 Volume E94.B Issue 3 Pages 786-792
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    Wide-band noise modulation is added to the adaptive scan technique for spaceborne rain radar. The performance of this technique is studied by simulation using one month of TRMM (Tropical Rainfall Measuring Mission) Precipitation Radar (PR) data from the viewpoints of improving the sensitivity and reducing power consumption. The results show that the adaptive scan technique with wide-band noise modulation uses about 25% less energy than the conventional scanning technique. The adaptive scan using wide-band noise modulation is more effective than that using a normal pulse for localized rainy areas. Surface data as well as rainfall data can be obtained by using the adaptive scan using wide-band noise modulation.
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  • Zhixing YANG, Qiuliang XIE, Kewu PENG, Zhaocheng WANG
    Article type: LETTER
    Subject area: Fundamental Theories for Communications
    2011 Volume E94.B Issue 3 Pages 793-795
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    A method to construct bit-interleaved coded modulation with iterative demapping and decoding (BICM-ID) is developed that approaches the Shannon limit very closely at high spectrum efficiency, where amplitude-phase shift keying (APSK) constellations are designed and chosen. For 1/2-rate 64APSK, the Es/N0 threshold derived through extrinsic information transfer (EXIT) charts is less than 0.55dB away from the Shannon limit of the continuous-input additive white Gaussian noise (AWGN) channel, and exceeds the theoretical limit constrained by standard 64QAM-input.
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  • Bin SONG, Hao QIN, Mingming YANG, Lifeng GU
    Article type: LETTER
    Subject area: Fundamental Theories for Communications
    2011 Volume E94.B Issue 3 Pages 796-797
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    A new selective retransmission method for HARQ (Hybrid Automatic Repeat reQuest) systems is proposed. This method can avoid the blindness of symbols retransmission by the transformation of lostmap matrix and simulation results show that the proposed method can reduce the number of retransmissions effectively.
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  • Tae Won BAN, Bang Chul JUNG
    Article type: LETTER
    Subject area: Transmission Systems and Transmission Equipment for Communications
    2011 Volume E94.B Issue 3 Pages 798-801
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    A novel adaptive cyclic prefix (CP) transmission scheme is proposed for the uplink of orthogonal frequency division multiple access (OFDMA) systems to reduce the power consumption of mobile stations (MSs). In the proposed scheme, an MS adaptively changes its CP length in each frame, while the guard interval is maintained at a fixed duration to avoid frame synchronization problem and the interference problem with frames of other users. Using the proposed scheme, MSs can save power by not transmitting signal during the time difference between the guard interval and the duration of the adaptive CP. We numerically analyze the performance of the proposed scheme in terms of achievable capacity, the amount of power saving, and the feedback overhead of CP values. The result shows that the proposed scheme can reduce MS power consumption by about 20% with a small amount of additional feedback overhead.
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  • Ryuji HAYASHI, Masanori HAMAMURA
    Article type: LETTER
    Subject area: Transmission Systems and Transmission Equipment for Communications
    2011 Volume E94.B Issue 3 Pages 802-805
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    A new type of modulation called continuous-phase parallel-combinatory high-compaction multicarrier modulation (CPPC/HC-MCM) is proposed. CPPC/HC-MCM employs the technique of continuous-phase modulation (CPM) and avoids the formation of amplitude gaps between two successive signals to enhance the spectral efficiency of conventional PC/HC-MCM. Results of simulations show that CPPC/HC-MCM is spectrally efficient and achieves a smaller bit error rate than conventional (unmodulated) PC/HC-MCM at a common spectral efficiency even if the peak-to-average power ratio is considered.
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  • Man FENG, Lenan WU, Jiajia DING, Chenhao QI
    Article type: LETTER
    Subject area: Transmission Systems and Transmission Equipment for Communications
    2011 Volume E94.B Issue 3 Pages 806-809
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    The extended binary phase shift keying (EBPSK) transmission system with ultra narrow bandwidth has excellent BER performance, which raises many doubts with the researchers. Therefore, on the premise of the existence of a special filter that can transform the modulated phase information into amplitude information, the theoretical BER formula of EBPSK system in Additive White Gaussian Noise (AWGN) channel has been deduced. This paper gives the theoretical values of the parameters in the above BER formula and discusses the effects of parameters on BER firstly. Then the paper shows that the special impacting filter satisfies the above assumption, therefore, in the frame of binary detection theory, the excellent performance of high-efficiency EBPSK system can be explained and the correction of the theoretical BER formula can be validated.
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  • Sungwook KIM
    Article type: LETTER
    Subject area: Network
    2011 Volume E94.B Issue 3 Pages 810-812
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    Bandwidth is an extremely valuable and scarce resource in multimedia networks. Therefore, efficient bandwidth management is necessary in order to provide high Quality of Service (QoS) to users. In this paper, a new QoS-aware bandwidth allocation algorithm is proposed for the efficient use of available bandwidth. By using the multi-objective optimization technique and Talmud allocation rule, the bandwidth is adaptively controlled to maximize network efficiency while ensuring QoS provisioning. In addition, we adopt the online feedback strategy to dynamically respond to current network conditions. With a simulation study, we demonstrate that the proposed algorithm can adaptively approximate an optimized solution under widely diverse traffic load intensities.
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  • Masashi YOSHIDA, Koichi YAGISHITA, Yusuke DOHI, Kumiko KOBAYASHI, Yuta ...
    Article type: LETTER
    Subject area: Network
    2011 Volume E94.B Issue 3 Pages 813-817
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    Distributed hash tables (DHTs) enable companies or campuses to use voice over IP (VoIP) systems in private networks at low cost. However, DHTs incur latency stretch caused by a topology mismatch between the application layer and the physical layer. Reducing this latency stretch is critical when implementing real-time applications that use DHTs, such as VoIP systems. This letter proposes a new method for reducing the latency stretch by creating node IDs, which form structured overlays that consider node proximity. Simulation results show that the proposed method is superior to Chord in terms of the distance between nodes, look-up path length, network burden, and look-up latency.
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  • YanBing LIU, Tao WU, XingPing XIAN
    Article type: LETTER
    Subject area: Network
    2011 Volume E94.B Issue 3 Pages 818-822
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    It has been shown that power control is an efficient approach to achieve the quality of service (QoS) requirement in wireless networks. In this letter, we present a utility function that denotes the QoS and energy efficiency of each wireless terminal. We propose a framework of power control based on the game theory for the QoS of wireless mesh networks (WMNs). In this framework, all players do their best to maximize their own utility. Furthermore, we present a Nash Equilibrium (NE) point of the power control game. We prove that the equilibrium is inefficient, and we propose a distributed power control algorithm that improves the total utility with respect to the NE point. Finally, the proposed framework is evaluated by a numerical experiment, the results of which show the rationality of our system model and the efficiency of our power control algorithm.
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  • Song XIAO, Ji LU, Ning CAI
    Article type: LETTER
    Subject area: Network
    2011 Volume E94.B Issue 3 Pages 823-826
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    Network Coding (NC) can improve the information transmission efficiency and throughput of data networks. Random Linear Network Coding (RLNC) is a special form of NC scheme that is easy to be implemented. However, quantifying the performance gain of RLNC over conventional Store and Forward (S/F)-based routing system, especially for wireless network, remains an important open issue. To solve this problem, in this paper, based on abstract layer network architecture, we build a dynamic random network model with Poisson distribution describing the nodes joining the network randomly for tree-based single-source multicast in MANET. We then examine its performance by applying conventional Store and Forward with FEC (S/F-FEC) and RLNC methods respectively, and derive the analytical function expressions of average packet loss rate, successful decoding ratio and throughput with respect to the link failure probability. An experiment shows that these expressions have relatively high precision in describing the performance of RLNC. It can be used to design the practical network coding algorithm for multi-hop multicast with tree-based topology in MANET and provide a research tool for the performance analysis of RLNC.
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  • Yong Suk PARK, Kyu Yeol LEE, Ca Van PHAN, Hyo Hyun CHOI, Jeong Geun KI ...
    Article type: LETTER
    Subject area: Network
    2011 Volume E94.B Issue 3 Pages 827-830
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    We propose a geographic forwarding protocol for wireless sensor networks (WSNs). Our proposed protocol, named Landmark-based Location-Aware Routing (LLAR), intelligently combines greedy forwarding and a hole detouring technique utilizing landmark information. Compared to existing approaches, our proposal utilizes the feedback message from the sink node for discovery of the optimal path. Simulations show that our proposed scheme can eliminate a significant number of overhead messages compared to its counterparts, thereby further achieving higher energy efficiency.
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  • Jhih-Chung CHANG, Jui-Chung HUNG, Ann-Chen CHANG
    Article type: LETTER
    Subject area: Antennas and Propagation
    2011 Volume E94.B Issue 3 Pages 831-833
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    The letter deals with direction-of-arrival (DOA) estimation under nonuniform white noise and moderately small signal-to-noise ratios. The proposed approach first uses signal subspace projection for received data vectors, which form an efficient iterative quadratic maximum-likelihood (IQML) approach to achieve fast convergence and high resolution capabilities. In conjunction with a signal subspace selection technique, a more exact signal subspace can be obtained for reducing the nonuniform noise effect. The performance improvement achieved by applying the proposal to the classic IQML method is confirmed by computer simulations.
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  • Sheng LEI, Xin ZHANG, Cong XIONG, Dacheng YANG
    Article type: LETTER
    Subject area: Wireless Communication Technologies
    2011 Volume E94.B Issue 3 Pages 834-837
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    We create an efficient statistical pruning (SP) algorithm for fixed-complexity sphere decoder (FSD) by utilizing partial decision feedback detection (i.e., SP-FSD). Simulation results show that SP-FSD not only attains the near-optimal performance, but also achieves much lower complexity than the original FSD and its two lately-developed variants: the simplified FSD (SFSD) and the statistical threshold-based FSD (ST-FSD).
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  • Gen LI, Ying WANG, Tong WU, Ping ZHANG
    Article type: LETTER
    Subject area: Wireless Communication Technologies
    2011 Volume E94.B Issue 3 Pages 838-840
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    This letter addresses linear processing issues for the downlink of closed-loop multi-user non-regenerative MIMO-relay systems with arbitrary number of antennas at each node. First three precoding design schemes at BS are presented. Then given the fixed BS linear processing matrix, we propose a joint iterative linear processing scheme for the relay station and mobile stations, aiming to minimize the total mean squared error (MSE). Finally Simulation results are provided to show the performance gain of joint linear processing at the multi-antenna nodes.
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  • Ann-Chen CHANG, Jhih-Chung CHANG
    Article type: LETTER
    Subject area: Wireless Communication Technologies
    2011 Volume E94.B Issue 3 Pages 841-843
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    This letter deals with eigenspace-based (ESB) beamforming based on the decision-directed (DD) correction with robust capability. It has been shown that the output of the ESB beamformer includes the desired signal and noise under small pointing errors. In conjugation with DD and soft decision decoding scheme, the proposed approach can be used to form a robust DD-ESB beamformer without any specific training sequence. Computer simulations are provided to illustrate the effectiveness of the proposed beamformer.
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  • Peng LAN, Ju LIU, Fenggang SUN, Peng XUE
    Article type: LETTER
    Subject area: Wireless Communication Technologies
    2011 Volume E94.B Issue 3 Pages 844-847
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    Notification from Editors

    “Iterative Transmit/Receive Antenna Selection in MIMO Systems Based on Channel Capacity Analysis” by Peng LAN, Ju LIU, Fenggang SUN and Peng XUE, IEICE Transactions on Communications, vol.E94-B, no.3, pp.844-847, March 2011.

    This manuscript was canceled on August 6, 2013 because it was found to be a duplicate submission.
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  • Jun ZOU, Ming DING, Hanwen LUO
    Article type: LETTER
    Subject area: Wireless Communication Technologies
    2011 Volume E94.B Issue 3 Pages 848-851
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    This letter proposes a robust joint linear precoding scheme based on the minimum mean squared error (MMSE) criterion for amplify-and-forward (AF) multiple-input multiple-output (MIMO) relay broadcast systems with limited feedback, where only the quantized channel direction information (CDI) of the forward channel is available for the base station (BS) and the relay station (RS). The proposed scheme employs an iterative algorithm which alternately optimizes the BS and RS precoders to jointly minimize the expected MSE conditioned on the quantized CDI.
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  • Linglong DAI, Jintao WANG, Zhaocheng WANG, Jun WANG
    Article type: LETTER
    Subject area: Wireless Communication Technologies
    2011 Volume E94.B Issue 3 Pages 852-855
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    To realize transmit diversity for the time domain synchronous OFDM (TDS-OFDM) system, this letter proposes the space-time-frequency orthogonal training sequence and the corresponding flexible channel estimation methods. Simulation results indicate that an significant performance improvement could be achieved for low-density parity-check code (LDPC) coded TDS-OFDM system over multi-path fading channels.
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  • Soobum CHO, Sang Kyu PARK
    Article type: LETTER
    Subject area: Wireless Communication Technologies
    2011 Volume E94.B Issue 3 Pages 856-859
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    Tone reservation (TR) is an efficient peak-to-average power ratio (PAPR) reduction scheme that adds peak reduction tones (PRTs) to the orthogonal frequency division multiplexing (OFDM) signal. However, enormous numbers of iterations are needed to find the optimal PRT set, which makes the TR scheme quite complex. In this letter, we propose a modified TR scheme that considerably reduces the computational complexity of the optimization process for the PRT set compared with the conventional TR scheme.
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  • Jin-soo KIM, Jae-Gon KIM, Kwang-deok SEO
    Article type: LETTER
    Subject area: Multimedia Systems for Communications
    2011 Volume E94.B Issue 3 Pages 860-862
    Published: March 01, 2011
    Released on J-STAGE: March 01, 2011
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    We propose an efficient selective block encoding scheme with motion information feedback in distributed video coding (DVC). The proposed scheme estimates the spatial and temporal matching costs for each block in the side information (SI) and for the blocks with high matching costs, the motion information is provided to the encoder side to selectively encode the motion-compensated frame difference signal. Experimental results show that the proposed scheme outperforms the recently developed DVC algorithms.
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