IEICE Transactions on Communications
Online ISSN : 1745-1345
Print ISSN : 0916-8516
Volume E91.B, Issue 11
Displaying 1-50 of 55 articles from this issue
Special Section on Emerging Technologies for Practical Ubiquitous and Sensor Networks
  • Masayoshi OHASHI
    2008 Volume E91.B Issue 11 Pages 3415
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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  • Takafumi FUJITA, Daisei UCHIDA, Yosuke FUJINO, Osamu KAGAMI, Kazuji WA ...
    Article type: PAPER
    2008 Volume E91.B Issue 11 Pages 3416-3425
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    This paper presents a wireless burst modulation/demodulation method for narrowband ubiquitous communication systems. This method especially suits those systems, whose traffic is especially dominated by short frame bursts. The proposed modulation method provides a preamble-less frame structure with training symbols, which improves both transmission efficiency and burst synchronization performance. Moreover, the proposed demodulation method achieves superior burst synchronization performance in low carrier-to-noise power ratio (CNR) environments by applying a synchronization method that includes symbol timing recovery, slot synchronization, carrier frequency correction and channel tracking. In addition, this paper presents the result of experiments on hardware prototypes of the proposed modulator and demodulator. The basic operation and practical performance of the proposed method is confirmed through testbed studies.
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  • Suguru DOKI, Hiraku OKADA, Kenichi MASE
    Article type: PAPER
    2008 Volume E91.B Issue 11 Pages 3426-3433
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    In a sensor network, a certain area or environment are observed by a lot of distributed sensor nodes and a sink collects data observed by sensor nodes. The observed data sequences that sensor nodes generate may have space- and/or time-dependent correlation. This correlation is regarded as redundant information and can be used for channel error correction by joint decoder using correlation. In this paper, we propose the joint decoding scheme using the time-dependent correlation consisting of the consecutive data sequences generated by a sensor node. We also propose a power control scheme using the time-dependent correlation for reduction in energy consumption. We evaluate the packet error rate and the energy consumption ratio, and clarify the effect of our proposed schemes.
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  • Junseok KIM, Younggoo KWON
    Article type: PAPER
    2008 Volume E91.B Issue 11 Pages 3434-3441
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    Maintaining the lowest possible transmission power in the wireless sensor networks (WSNs) is vulnerable to the interference fluctuations because of the bad signal-to-interference-plus-noise-ratio (SINR). The previous transmission power control (TPC) algorithms do not consider much for the interferences from other 2.4GHz devices, which can cause significant performance degradations in real world deployments. This paper proposes the interference-aware transmission power control (I-TPC) algorithm for WSNs. In the proposed algorithm, each node dynamically adjusts the transmission power and the received signal strength (RSS) target, hence the appropriate SINR is provided even when the wireless LAN (WLAN) interferences become strong. The experimental results show that the proposed algorithm outperforms the previous algorithms in terms of the energy and the packet reception ratio (PRR) performance in WLAN interference environments.
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  • Daisuke ANZAI, Shinsuke HARA
    Article type: PAPER
    2008 Volume E91.B Issue 11 Pages 3442-3449
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    The ability to estimate a target location is essential in many applications of wireless sensor networks. Received signal strength indicator (RSSI)-based maximum likelihood (ML) method in a wireless sensor network usually requires a pre-determined statistical model on the variation of RSSI in a sensing area and uses it as an ML function when estimating the location of a target in the sensing area. However, when estimating the location of a target, due to several reasons, we often measure the RSSIs which do not follow the statistical model, in other words, which are outlier on the statistical model. As the result, the effect of the outlier RSSI data worsens the estimation accuracy. If the wireless sensor network has a lot of sensor nodes, we can improve the estimation accuracy intentionally rejecting such outlier RSSIs. In this paper, we propose a simple outlier RSSI data rejection algorithm for an ML location estimation. The proposed algorithm iteratively eliminates the anchor nodes which measure outlier RSSIs. As compared with the location estimation methods with previously proposed outlier RSSI data rejection algorithms, our proposed method performs better with much less computational complexity.
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  • Uzair AHMAD, Brian J. D'AURIOL, Young-Koo LEE, Sungyoung LEE
    Article type: PAPER
    2008 Volume E91.B Issue 11 Pages 3450-3460
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    This paper presents a new methodology, Beacognition, for real-time discovery of the associations between a signal space and arbitrarily defined regions, termed as Semantically Meaningful Areas (SMAs), in the corresponding physical space. It lets the end users develop semantically meaningful location systems using standard 802.11 network beacons as they roam through their environment. The key idea is to discover the unique associations using a beacon popularity model. The popularity measurements are then used to localize the mobile devices. The beacon popularity is computed using an `election' algorithm and a new recognition model is presented to perform the localization task. We have implemented such a location system in a five story campus building. The comparative results show significant improvement in localization by achieving on average 83% SMA and 88% Floor recognition rate in less than one minute per SMA training time.
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  • Hidekata HONTANI, Yuya HIGUCHI
    Article type: PAPER
    2008 Volume E91.B Issue 11 Pages 3461-3468
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    In this article, we propose a vehicle positioning method that can estimate positions of cars even in areas where the GPS is not available. For the estimation, each car measures the relative distance to a car running in front, communicates the measurements with other cars, and uses the received measurements for estimating its position. In order to estimate the position even if the measurements are received with time-delay, we employed the time-delay tolerant Kalman filtering. For sharing the measurements, it is assumed that a car-to-car communication system is used. Then, the measurements sent from farther cars are received with larger time-delay. It follows that the accuracy of the estimates of farther cars become worse. Hence, the proposed method manages only the states of nearby cars to reduce computing effort. The authors simulated the proposed filtering method and found that the proposed method estimates the positions of nearby cars as accurate as the distributed Kalman filtering.
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  • Eui-Jik KIM, Sungkwan YOUM, Hyo-Hyun CHOI
    Article type: PAPER
    2008 Volume E91.B Issue 11 Pages 3469-3479
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    Many applications in wireless sensor networks (WSNs) require the energy efficiency and scalability. Although IEEE 802.15.4/Zigbee which is being considered as general technology for WSNs enables the low duty-cycling with time synchronization of all the nodes in network, it still suffer from its low scalability due to the beacon frame collision. Recently, various algorithms to resolve this problem are proposed. However, their manners to implement are somewhat ambiguous and the degradation of energy/communication efficiency is serious by the additional overhead. This paper describes an Energy-efficient BOP-based Beacon transmission Scheduling (EBBS) algorithm. EBBS is the centralized approach, in which a resource-sufficient node called as Topology Management Center (TMC) allocates the time slots to transmit a beacon frame to the nodes and manages the active/sleep schedules of them. We also propose EBBS with Adaptive BOPL (EBBS-AB), to adjust the duration to transmit beacon frames in every beacon interval, adaptively. Simulation results show that by using the proposed algorithm, the energy efficiency and the throughput of whole network can be significantly improved. EBBS-AB is also more effective for the network performance when the nodes are uniformly deployed on the sensor field rather than the case of random topologies.
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  • Takashi TAKEUCHI, Yu OTAKE, Masumi ICHIEN, Akihiro GION, Hiroshi KAWAG ...
    Article type: PAPER
    2008 Volume E91.B Issue 11 Pages 3480-3488
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    We propose Isochronous-MAC (I-MAC) using the Long-Wave Standard Time Code (so called “wave clock”), and introduce cross-layer design for a low-power wireless sensor node with I-MAC. I-MAC has a periodic wakeup time synchronized with the actual time, and thus we take the wave clock. However, a frequency of a crystal oscillator varies along with temperature, which incurs a time difference among nodes. We present a time correction algorithm to address this problem, and shorten the time difference. Thereby, the preamble length in I-MAC can be minimized, which saves communication power. For further power reduction, a low-power crystal oscillator is also proposed, as a physical-layer design. We implemented I-MAC on an off-the-shelf sensor node to estimate the power saving, and verified that the proposed cross-layer design reduces 81% of the total power, compared to Low Power Listening.
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  • Shintaro IZUMI, Takashi TAKEUCHI, Takashi MATSUDA, Hiroshi KAWAGUCHI, ...
    Article type: PAPER
    2008 Volume E91.B Issue 11 Pages 3489-3498
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    Broadcasting is an elementary operation in wireless multi-hop networks. Flooding is a simple broadcast protocol but it frequently causes serious redundancy, contention and collisions. Probability based methods are promising because they can reduce broadcast messages without additional hardware and control packets. In this paper, the counter-based scheme which is one of the probability based methods is focused on as a broadcast protocol, and the RAD (Random Assessment Delay) Extension is proposed to improve the original counter-based scheme. The RAD Extension can be implemented without additional hardware, so that the strength of the counter-based scheme can be preserved. In addition, we propose the additional algorithm called Hop Count Aware RAD Extension to establish shorter path from the source node. Simulation results show that both of the RAD Extension and the Hop Count Aware RAD Extension reduce the number of retransmitting nodes by about 10% compared with the original scheme. Furthermore, the Hop Count Aware RAD Extension can establish almost the same path length as the counter-based scheme.
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  • Haeyong KIM, Taekyoung KWON, Pyeongsoo MAH
    Article type: PAPER
    2008 Volume E91.B Issue 11 Pages 3499-3506
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    In wireless sensor networks, the sensor nodes collect data, which are routed to a sink node. Most of the existing proposals address the routing problem to maximize network lifetime in the case of a single sink node. In this paper, we extend this problem into the case of multiple sink nodes. To maximize network lifetime, we consider the two problems: (i) how to position multiple sink nodes in the area, and (ii) how to route traffic flows from sensor nodes to sink nodes. In this paper, the solutions to these problems are formulated into a Mixed Integer Linear Programming (MILP) model. However, it is computationally difficult to solve the MILP formulation as the size of sensor network grows because MILP is NP-hard. Thus, we propose a heuristic algorithm, which produces a solution in polynomial time. From our experiments, we found out that the proposed heuristic algorithm provides a near-optimal solution for maximizing network lifetime in dense sensor networks.
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  • Xiaohan LIU, Hideo MAKINO, Suguru KOBAYASHI, Yoshinobu MAEDA
    Article type: PAPER
    2008 Volume E91.B Issue 11 Pages 3507-3515
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    This article presents an indoor positioning and communication platform, using fluorescent lights. We set up a practical implementation of a VLC (Visible Light Communication) system in a University building. To finalize this work, it is important that we analyze the properties of the reception signal, especially the length of the data string that can be received at different walking speed. In this paper, we present a model and a series of formulae for analyzing the relationship between positioning signal availability and other important parameters, such as sensor angle, walking speed, data transmission rate, etc. We report a series of real-life experiments using VLC system and compare the results with those generated by the formula. The outcome is an improved design for determination of the reception area with more than 97% accurate signals, and an optimal transmission data length, and transmission rate.
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  • Taebok YOON, Jee-Hyong LEE
    Article type: PAPER
    2008 Volume E91.B Issue 11 Pages 3516-3523
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    Various types of data from environment are used to provide user-adaptive services. Among them, data of a user's past moving paths are useful to predict a moving user's next location and provide related services. This paper proposes a method to predict a moving user's location through analyzing his/her past moving paths. This method analyzes the user's moving path by using three elements of distance, time and direction of moving paths and Dynamic Time Warping (DTW), and selects the representative path, which is the one most similar to the current moving path in the past paths. The selected path can be used to provide service like space and time estimation.
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  • Muhammad Taqi RAZA, Zeeshan Hameed MIR, Ali Hammad AKBAR, Seung-Wha YO ...
    Article type: PAPER
    2008 Volume E91.B Issue 11 Pages 3524-3533
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    Target tracking is one of the key applications of Wireless Sensor Networks (WSNs) that forms basis for numerous other applications. The overall procedures of target tracking involve target detection, localization, and tracking. Because of the WSNs' resource constraints (especially energy), it is highly desired that target tracking should be done by involving as less number of sensor nodes as possible. Due to the uncertain behavior of the target and resulting mobility patterns, this goal becomes harder to achieve without predicting the future locations of the target. The presence of a prediction mechanism may allow the activation of only the relevant sensors along the future course, before actually the target reaches the future location. This prior activation contributes to increasing the overall sensor networks lifetime by letting non-relevant nodes sleep. In this paper, first, we introduce a Yaw rate aware sensor wAkeup Protocol (YAP) for the prediction of future target locations. Second, we present improvements on the YAP design through the incorporation of adaptability. The proposed schemes are distributive in nature, and select relevant sensors to determine the target track. The performance of YAP and A-YAP is also discussed on different mobility patterns, which confirms the efficacy of the algorithm.
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  • Jae-Hyun SEO, Yong-Hyuk KIM, Hwang-Bin RYOU, Si-Ho CHA, Minho JO
    Article type: PAPER
    2008 Volume E91.B Issue 11 Pages 3534-3543
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    An important objective of surveillance sensor networks is to effectively monitor the environment, and detect, localize, and classify targets of interest. The optimal sensor placement enables us to minimize manpower and time, to acquire accurate information on target situation and movement, and to rapidly change tactics in the dynamic field. Most of previous researches regarding the sensor deployment have been conducted without considering practical input factors. Thus in this paper, we apply more real-world input factors such as sensor capabilities, terrain features, target identification, and direction of target movements to the sensor placement problem. We propose a novel and efficient hybrid steady-state genetic algorithm giving low computational overhead as well as optimal sensor placement for enhancing surveillance capability to monitor and locate target vehicles. The proposed algorithm introduces new two-dimensional geographic crossover and mutation. By using a new simulator adopting the proposed genetic algorithm developed in this paper, we demonstrate successful applications to the wireless real-world surveillance sensor placement problem giving very high detection and classification rates, 97.5% and 87.4%, respectively.
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  • Youngsoo KIM, Sangbae JEONG, Daeyoung KIM
    Article type: PAPER
    2008 Volume E91.B Issue 11 Pages 3544-3551
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    In this paper, an efficient node-level target classification scheme in wireless sensor networks (WSNs) is proposed. It uses acoustic and seismic information, and its performance is verified by the classification accuracy of vehicles in a WSN. Because of the hard limitation in resources, parametric classifiers should be more preferable than non-parametric ones in WSN systems. As a parametric classifier, the Gaussian mixture model (GMM) algorithm not only shows good performances to classify targets in WSNs, but it also requires very few resources suitable to a sensor node. In addition, our sensor fusion method uses a decision tree, generated by the classification and regression tree (CART) algorithm, to improve the accuracy, so that the algorithm drives a considerable increase of the classification rate using less resources. Experimental results using a real dataset of WSN show that the proposed scheme shows a 94.10% classification rate and outperforms the k-nearest neighbors and the support vector machine.
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  • Sangjin KIM, Jihwan LIM, Jaehong HAN, Heekuck OH
    Article type: PAPER
    2008 Volume E91.B Issue 11 Pages 3552-3559
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    In an RFID search protocol, a reader uses a designated query instead of an unspecified query commonly used in RFID authentication protocols. Due to this fundamental difference, techniques used in RFID authentication protocols may not be suitable for RFID search protocols. Tan et al.'s protocol, however, is based on techniques used in previous works such as using random values. In this paper, we propose two RFID search protocols, one based on static ID and the other based on dynamic ID, both which does not require additional measures to satisfy security requirements of RFID protocols. We achieve this by using counters.
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  • Sung Ho JANG, Hi Sung CHOUN, Heung Seok CHAE, Jong Sik LEE
    Article type: PAPER
    2008 Volume E91.B Issue 11 Pages 3560-3568
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    RFID event filtering is an important issue of RFID data management. Tag read events from readers have some problems like unreliability, redundancy, and disordering of tag readings. Duplicated events lead to performance degradation of RFID systems with a flood of similar tag information. Therefore, this paper proposes a fuzzy logic-based quantized event filter. In order to reduce duplicated tag readings and solve disordering of tag readings, the filter applies a fuzzy logic system to control a filtering threshold by the change in circumstances of readers. Continuous tag readings are converted into discrete values for event generation by the filtering threshold. And, the filter generates as many events as the discrete values at a point of event generation time. Experimental results comparing the proposed filter with existing RFID event filters, such as the primitive event filter and the smoothing event filter, verify effectiveness and efficiency of the fuzzy logic-based quantized event filter.
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  • Jaewoon KIM, Sekwon KIM, Wonjin SUNG, Yoan SHIN
    Article type: LETTER
    2008 Volume E91.B Issue 11 Pages 3569-3573
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    We propose a selective detection scheme based on pulse repetition considering both BER (Bit Error Rate) performance and complexity in coherent UWB (Ultra Wide Band) systems. To take system complexity into account, the proposed scheme transmits the UWB signals by pulse repetition at the transmitter, like conventional PRC (Pulse Repetition Coding). However, to effectively improve BER performance of the system, the proposed scheme performs selective detection by estimating the SNR (Signal-to-Noise Ratio) of the received pulse-repeated signal at the UWB receiver.
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Regular Section
  • Daeseon CHOI, Younho LEE, Yongsu PARK, Seung-hun JIN, Hyunsoo YOON
    Article type: PAPER
    Subject area: Fundamental Theories for Communications
    2008 Volume E91.B Issue 11 Pages 3574-3583
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    This paper presents a fully self-organized key management scheme for mobile ad hoc networks. Unlike most previous schemes, there is no priori shared secret or no priori trust relationship in the proposed scheme; every node plays the same role and carries out the same function of key management. The proposed scheme consists of (1) Handshaking (HS) and (2) Certificate request/reply (CRR) procedures. In HS, a node acquires the public key of the approaching node via a secure side channel. In CRR, a node requests certificates of a remote node via a radio channel to the nodes that it has HSed. If the number of received valid certificates that contain the same public key exceeds a given threshold, the node accepts the remote node's public key as valid. Security is rigorously analyzed against various known attacks and network costs are intensively analyzed mathematically. Using this analysis, we provide parameter selection guideline to optimize performance and to maintain security for diverse cases. Simulation results show that every node acquires the public keys of all other nodes at least 5 times faster than in a previous scheme.
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  • Sunhun LEE, Kwangsue CHUNG
    Article type: PAPER
    Subject area: Network
    2008 Volume E91.B Issue 11 Pages 3584-3594
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    In video streaming applications over the Internet, TCP-friendly rate control schemes are useful for improving network stability and inter-protocol fairness. However, they do not always guarantee a smooth video streaming. To simultaneously satisfy both the network and user requirements, video streaming applications should be quality-adaptive. In this paper, we propose a new quality adaptation mechanism to adjust the quality of congestion-controlled video stream by controlling the frame rate. Based on the current network condition, it controls the frame rate of video stream and the sending rate in a TCP-friendly manner. Through a simulation, we prove that our adaptation mechanism appropriately adjusts the quality of video stream while improving network stability.
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  • Ki-Sik KONG
    Article type: PAPER
    Subject area: Network
    2008 Volume E91.B Issue 11 Pages 3595-3607
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    Although a lot of works for location management in wireless networks have been reported in the literature, most of the works have been focused on designing per-user-based strategies. This means that they can achieve the performance enhancement only for a certain class of mobile users with a specific range of CMR (call-to-mobility ratio). However, these per-user-based strategies can actually degrade the performance if a user's CMR changes significantly.Therefore, an efficient uniform location management strategy, which can be commonly applied to all mobile users regardless of their CMR, is proposed and analyzed in this paper. The motivation behind the proposed strategy is to exploit the concepts of the two well-known existing strategies: the location caching strategy and the local anchor strategy. That is, the location caching strategy exploits locality in a user's calling pattern, whereas the local anchor strategy exploits locality in a user's mobility pattern. By exploiting these characteristics of both strategies together with the profile management at the HLR (home location register), the proposed strategy can reduce the frequent access to the HLR, and thus effectively results in significant reduction in terms of the total location management cost. The analytical results also demonstrate that the proposed strategy can be uniformly applied to all mobile users, while always maintaining the performance gain over the IS-41 standard regardless of a user's CMR and the network traffic conditions.
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  • Yi WAN, Takuya ASAKA, Tatsuro TAKAHASHI
    Article type: PAPER
    Subject area: Network
    2008 Volume E91.B Issue 11 Pages 3608-3616
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    In P2P content distribution systems, there are many cases in which the content can be classified into hierarchically organized categories. In this paper, we propose a hybrid overlay network design suitable for such content called Pastry/NSHCC (Pastry for Non-Strictly Hierarchically Categorized Content). The semantic information of classification hierarchies of the content can be utilized regardless of whether they are in a strict tree structure or not. By doing so, the search scope can be restrained to any granularity, and the number of query messages also decreases while maintaining keyword searching availability. Through simulation, we showed that the proposed method provides better performance and lower overhead than unstructured overlays exploiting the same semantic information.
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  • Dong-Hoon YI, JongWon KIM
    Article type: PAPER
    Subject area: Network
    2008 Volume E91.B Issue 11 Pages 3617-3626
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    To guarantee the timely provisioning of QoS to real-time oriented multiparty and distributed computing applications (e.g., video conferencing and grid computing) that require the utilization of time and quantity-related resources, the resource should be reserved in advance. However, this new type of reservation (i.e., advance reservation) may collide with legacy (i.e., immediate) reservations that do not specify their session duration. In this paper, to suggest a balanced solution between sharing pools of resources and the managing of collisions between reservation calls, a revenue-based resource sharing scheme (focusing on the bandwidth) is proposed. The proposed scheme attempts to avoid possible collisions by employing a virtual profile of resources reserved in advance in an effort to achieve enhanced resource utilization. It is shown through NS-2 [22]-based network simulations that the proposed scheme can achieve balanced performance when compared with other schemes, including static resource partitioning and complete resource sharing.
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  • Kasim ÖZTOPRAK, Gözde Bozdagi AKAR
    Article type: PAPER
    Subject area: Network
    2008 Volume E91.B Issue 11 Pages 3627-3638
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    In this paper, we propose a fault tolerant hybrid p2p-CDN video streaming arhitecture to overcome the problems caused by peer behavior in peer-to-peer (P2P) video streaming systems. Although there are several studies modeling and analytically investigating peer behaviors in P2P video streaming systems, they do not come up with a solution to guarantee the required Quality of the Services (QoS). Therefore, in this study a hybrid geographical location-time and interest based clustering algorithm is proposed to improve the success ratio and reduce the delivery time of required content. A Hybrid Fault Tolerant Video Streaming System (HFTS) over P2P networks conforming the required QoS and Fault Tolerance is also offered. The simulations indicate that the required QoS can be achieved in streaming video applications using the proposed hybrid approach.
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  • Pavel POUPYREV, Peter DAVIS, Hiroyuki MORIKAWA
    Article type: PAPER
    Subject area: Network
    2008 Volume E91.B Issue 11 Pages 3639-3647
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    This paper proposes a MAC protocol for presence information discovery in ubiquitous networks. The proposed protocol is designed for proactive discovery in which wireless devices periodically broadcast packets containing presence information. The protocol is based on Framed Aloha. The objective of the protocol is to assure the discovery time of single-hop neighbors considering wireless collisions and also power consumption. In this paper, we show that the proposed protocol is able to assure specified discovery time in distributed networks with random topology.
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  • Jung-Hwan KIM, Kee-Bum KIM, Sajjad Hussain CHAUHDARY, Wencheng YANG, M ...
    Article type: PAPER
    Subject area: Network
    2008 Volume E91.B Issue 11 Pages 3648-3656
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    The proliferation of research on target detection and tracking in wireless sensor networks has kindled development of monitoring continuous objects such as fires and hazardous bio-chemical material diffusion. In this paper, we propose an energy-efficient algorithm that monitors a moving event region by selecting only a subset of nodes near object boundaries. The paper also shows that we can effectively reduce report message size. It is verified with performance analysis and simulation results that total average report message size as well as the number of nodes which transmit the report messages to the sink can be greatly reduced, especially when the density of nodes over the network field is high.
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  • Bo-Chao CHENG, Huan CHEN, Ryh-Yuh TSENG
    Article type: PAPER
    Subject area: Network
    2008 Volume E91.B Issue 11 Pages 3657-3666
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    Much recent research concentrates on designing an Intrusion Detection System (IDS) to detect the misbehaviors of the malicious node in MANET with ad-hoc and mobility natures. However, without rapid and appropriate IDS response mechanisms performing follow-up management services, even the best IDS cannot achieve the desired primary goal of the incident response. A competent containment strategy is needed to limit the extent of an attack in the Incident Response Life Cycle. Inspired by the T-cell mechanisms in the human immune system, we propose an efficient MANET IDS response protocol (T-SecAODV) that can rapidly and accurately disseminate alerts of the malicious node attacks to other nodes so as to modify their AODV routing tables to isolate the malicious nodes. Simulations are conducted by the network simulator (Qualnet), and the experiment results indicate that T-SecAODV is able to spread alerts steadily while greatly reduce faulty rumors under simultaneous multiple malicious node attacks.
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  • Satoshi UEMURA, Norihiro FUKUMOTO, Hideaki YAMADA, Hajime NAKAMURA
    Article type: PAPER
    Subject area: Network Management/ Operation
    2008 Volume E91.B Issue 11 Pages 3667-3676
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    A feature of services provided in a Next Generation Network (NGN) is that the end-to-end quality is guaranteed. This is quite a challenging issue, given the considerable fluctuation in network conditions within a Fixed Mobile Convergence (FMC) network. Therefore, a novel approach, whereby a network node and a mobile terminal such as a cellular phone cooperate with each other to control service quality is essential. In order to achieve such cooperation, the mobile terminal needs to become more intelligent so it can estimate the service quality, including the user's perceptual quality, and notify the measurement result to the network node. Subsequently, the network node implements some kind of service control function, such as a resource and admission control function, based on the notification from the mobile terminal. In this paper, the role of the mobile terminal in such collaborative system is focused on. As a part of a QoS/QoE measurement system, we describe an objective speech quality assessment with payload discrimination of lost packets to measure the user's perceptual quality of VoIP. The proposed assessment is so simple that it can be implemented on a cellular phone. We therefore did this as part of the QoS/QoE measurement system. By using the implemented system, we can measure the user's perceptual quality of VoIP as well as the network QoS metrics, in terms of criteria such as packet loss rate, jitter and burstiness in real time.
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  • Yoshitaka SHIMIZU, Fusao NUNO, Kazuji WATANABE
    Article type: PAPER
    Subject area: Wireless Communication Technologies
    2008 Volume E91.B Issue 11 Pages 3677-3687
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    Wide area ubiquitous wireless networks, which consist of access points (APs) connected to the fixed network and a great many wireless terminals (WTs), can offer a wide range of applications everywhere. In order to enhance network performance, we need to collect different kinds of data from as many WTs as possible; each AP must be capable of accommodating more than 103 WTs. This requirement can be achieved by employing DSA, a typical centralized media access control scheme, since it has high resource utilization efficiency. In this paper, we propose a novel DSA scheme that employs three new techniques to enhance throughput performance; (1) considering that most terminals tend to send data periodically, it employs both polling-based schemes, i.e. request-polling and data-polling, and a random access scheme. (2) In order to enhance bandwidth utilization effectiveness by polling, the polling timing is decided according to the data generation timing. (3) The AP decides the polled data size according to the latest distribution of data size and polls the WT for the data directly. If the data-polling size can not be determined with confidence, the AP uses request-polling instead of data-polling. Simulations verify that the proposed scheme offers better transmission performance than the existing schemes.
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  • Jang Sub KIM, Ho Jin SHIN, Dong Ryeol SHIN
    Article type: PAPER
    Subject area: Terrestrial Radio Communications
    2008 Volume E91.B Issue 11 Pages 3688-3694
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    In this paper, a new methodology to estimate the number of competing stations in an IEEE 802.11 network, is proposed. Due to the nonlinear nature of the measurement model, an iterative nonlinear filtering algorithm, called the Scaled Unscented Filter (SUF), is employed. The SUF can provide a superior alternative to nonlinear filtering than the conventional Extended Kalman Filter (EKF), since it avoids errors associated with linearization. This approach demonstrates both high accuracy in addition to prompt reactivity to changes in the network occupancy status. In particular, the proposed algorithm shows superior performance in non saturated conditions when compared to the EKF. Numerical results demonstrate that the proposed algorithm provides a more viable method for estimation of the number of competing stations in an IEEE 802.11 network, than estimators based on the EKF.
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  • Takuya SAKAMOTO, Toru SATO
    Article type: PAPER
    Subject area: Sensing
    2008 Volume E91.B Issue 11 Pages 3695-3703
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    UWB (Ultra Wide-Band) pulse radar is a promising candidate for surveillance systems designed to prevent crimes and terror-related activities. The high-speed SEABED (Shape Estimation Algorithm based on BST and Extraction of Directly scattered waves) imaging algorithm, is used in the application of UWB pulse radar in fields that require realtime operations. The SEABED algorithm assumes that omni-directional antennas are scanned to observe the scattered electric field in each location. However, for surveillance systems, antenna scanning is impractical because it restricts the setting places of the devices. In this paper, movement of a body is used to replace antenna scanning. The instantaneous velocity of any given motion is an unknown variable that changes as a function of time. A pair of antennas is used to analyze delay time to estimate the unknown motion. We propose a new algorithm to estimate the shape of a human body using data obtained from a human body passing stationary antennas.
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  • Satoshi SUGAHARA, Kouhei YAMADA, Tetsuya KAWASHIMA, Masaharu EDO, Tosh ...
    Article type: PAPER
    Subject area: Energy in Electronics Communications
    2008 Volume E91.B Issue 11 Pages 3704-3711
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    In this paper, the characteristics of a micro DC-DC converter for portable electronic equipments are described. In the converter, an inductor, switching devices and control integrated circuits (ICs) were integrated. The external size of the converter module was 3.0mm × 3.0mm × 1.0mm. And the converter had a high efficiency of 83% at the input voltage of 7.2V and the output voltage of 1.5V. The miniaturization of the converter was achieved by developing a small inductor of the size of 3.0mm × 3.0mm × 0.525mm. High efficiency was achieved by adopting 0.6µm CMOS process for ICs and switching devices, using N channel MOSFET for a high side power switch, and controlling a dead time adaptively. The efficiency characteristics of the converter were analyzed experimentally and theoretically. And the losses of the converter were theoretically analyzed.
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  • Guo-Wei LU, Kazi Sarwar ABEDIN, Tetsuya MIYAZAKI
    Article type: LETTER
    Subject area: Fiber-Optic Transmission for Communications
    2008 Volume E91.B Issue 11 Pages 3712-3714
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    We propose and experimentally demonstrate an all-optical broadband wavelength conversion scheme with simultaneous power amplification based on a pump-modulated fiber optic parametric amplifier (FOPA). All-optical tunable wavelength conversion from one to two wavelengths was achieved with ≥ 13dB extinction ratio and < 2.7-dB power penalty, accompanied by a high (≥ 37dB) and flat (∼ 3dB variation) FOPA gain spectrum over 47nm.
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  • Seil JEON, Namhi KANG, Younghan KIM, Wonsik YOON
    Article type: LETTER
    Subject area: Internet
    2008 Volume E91.B Issue 11 Pages 3715-3718
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    Packet delivery in Proxy Mobile IPv6 (PMIPv6) relies on an anchor node called LMA. All packets sent by a source node reach a receiver node via LMA, even though the two nodes attach to the same MAG. In some scenarios, PMIPv6 results in high delivery latency and processing costs due to this unnecessary detour. To address this issue, several PMIPv6 route optimization schemes have been proposed. However, high signaling costs and excessive delays remain when handover is performed. For this reason, we propose an enhanced PMIPv6 route optimization (EPRO) scheme. In addition, we analyze the performance of the EPRO. Analytical results indicate that the EPRO outperforms previous schemes in terms of signaling overhead and handover latency.
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  • Younchan JUNG, J. William ATWOOD, Hans-Jürgen ZEPERNICK
    Article type: LETTER
    Subject area: Internet
    2008 Volume E91.B Issue 11 Pages 3719-3721
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    The basic playout scheme (BAS) is designed not to take into account network impairment information during silence periods. We propose a jitter-robust playout mechanism (RST), which uses silence description (SID) packets. The lateness loss percentages are compared between the BAS and the RST algorithms. We report that the accuracy of the playout schedule calculation in the BAS is getting worse as the previous silence interval increases and our proposed RST algorithm is more effective in removing high jitter than the BAS. Under high jitter Internet conditions, the accuracy of the estimates and therefore the resulting of VoIP playout quality can be significantly improved by using the SID packets in the playout schedule recalculation.
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  • Lan TANG, Pengcheng ZHU, Xiaohu YOU, Yan WANG
    Article type: LETTER
    Subject area: Wireless Communication Technologies
    2008 Volume E91.B Issue 11 Pages 3722-3726
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    We consider a time-division multiple access (TDMA) transmission scheme in MIMO broadcast channels. To cope with the fairness issue in heterogeneous networks with slow fading, an opportunistic scheduling algorithm based on the channel eigen-direction is investigated. In the system with sparse users, the mismatch between a random beamforming vector and the principle eigenvector of the channel incurs a throughput penalty. To reduce such a throughput loss, a multiple random beams selection (MRBS) scheme exploiting chordal distances is proposed. Two feedback schemes (unquantized or quantized chordal distances) are considered. The closed-form throughput expressions of the proposed schemes are derived.
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  • Xiaorong JING, Zhengzhong ZHOU, Tianqi ZHANG
    Article type: LETTER
    Subject area: Wireless Communication Technologies
    2008 Volume E91.B Issue 11 Pages 3727-3731
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    We propose a feasible V-BLAST detector based on modified Householder QRD (M-H-QRD) over spatially correlated fading channel, which can almost match the performance of the V-BLAST algorithm with much lower complexity and better numerical stability. Compared to the sorted QRD (S-QRD) detector, the proposed detector requires a smaller minimum word-length to reach the same value of error floor for fixed-point (FP) numerical precision despite no significant performance difference for floating-point machine precision. All these advantages make it attractive when implemented using FP arithmetic.
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  • Junyang SHEN, Gang XIE, Siyang LIU, Lingkang ZENG, Jinchun GAO, Yuanan ...
    Article type: LETTER
    Subject area: Wireless Communication Technologies
    2008 Volume E91.B Issue 11 Pages 3732-3735
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    Amidst conflicting views about whether soft cooperative energy detection scheme (SCEDS) outperforms hard cooperative energy detection scheme (HCEDS) greatly in cognitive radio, we establish the bridge that mathematically connects SCEDS and HCEDS by closed approximations. Through this bridge, it is demonstrate that, if the number of detectors of HCEDS is 1.6 times as that of SCEDS, they have nearly the same performance which is confirmed by numerical simulations, enabling a quantitative evaluation of the relation between them and a resolution of the conflicting views.
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  • Luu Quoc TIN, Hyung-Yun KONG
    Article type: LETTER
    Subject area: Wireless Communication Technologies
    2008 Volume E91.B Issue 11 Pages 3736-3739
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    In incremental relaying, the destination uses a checking system and requires a retransmission from the relay in case an error happens. After receiving the signal from the relay, the destination combines the signals from the source and the relay and performs detection. However, the combined signal is actually worse because of the erroneous signal from the source. Our scheme eliminates the detrimental signal from the source and uses only the fresh signal from the relay, resulting in a large performance improvement and reduced complexity. The symbol error rate (SER) and its upper bound are established to analyze the power allocation strategy. Simulations verify the rightness of the theoretic studies, and many benefits of cooperative ARQ schemes are revealed.
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  • Zhimeng ZHONG, Shihua ZHU, Gangming LV
    Article type: LETTER
    Subject area: Wireless Communication Technologies
    2008 Volume E91.B Issue 11 Pages 3740-3744
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    In this letter, we analyze the pairwise error probability (PEP) behaviour of distributed space-time code (DSTC) with amplify-and-forward relaying over Nakagami-m multipath channels. An upper bound of PEP for DSTC is derived. From our analysis, it is seen that of the paths from the source to relays and from relays to the destination, those with smaller diversity order result in an overall system performance bottleneck. Numerical examples are provided to corroborate our theoretical analysis.
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  • Xiaoming SHE, Jingxiu LIU, Lan CHEN, Hidekazu TAOKA, Kenichi HIGUCHI
    Article type: LETTER
    Subject area: Wireless Communication Technologies
    2008 Volume E91.B Issue 11 Pages 3745-3748
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    Transmit beamforming can exploit the spatial diversity afforded by multiple-input multiple-output (MIMO) systems with low complexity. To apply this technique in more practical systems with the constraint of limited feedback, codebook based beamforming and vector quantization technique have been considered in various papers. On the other hand, multi-user scheduling is able to achieve another form of diversity arising from the independence of fading for different users, however, has not been fully taken into account in existing codebook based beamforming schemes. In this letter, a multi-codebook based beamforming and scheduling scheme is proposed, which exploits both spatial diversity and multi-user diversity by switching the codebook for different resource blocks. Meanwhile, the multi-codebook design issue is addressed, the corresponding theoretical analysis is provided, and the performance gain of proposed scheme is simulated. Furthermore, the impacts of related parameters on the performance gain are also investigated.
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  • Hyounkuk KIM, Hyuncheol PARK
    Article type: LETTER
    Subject area: Wireless Communication Technologies
    2008 Volume E91.B Issue 11 Pages 3749-3752
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    This letter introduces an efficient near-maximum likelihood (ML) detector for a coded double space-time transmit diversity-orthogonal frequency division multiplexing (DSTTD-OFDM) system. The proposed near-ML detector constructs a candidate vector set through a relaxed minimization method. It reduces computational loads from $\mathcal{O}(2|\mathcal{A}|^{2})$ to $\mathcal{O}(|\mathcal{A}|^{2})$, where $|\mathcal{A}|$ is the modulation order. Numerical results indicate that the proposed near-ML detector provides both almost ML performance and considerable complexity savings.
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  • Wen-Long CHIN, Sau-Gee CHEN
    Article type: LETTER
    Subject area: Wireless Communication Technologies
    2008 Volume E91.B Issue 11 Pages 3753-3756
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    In OFDM receivers, an accurate signal-to-noise ratio (SNR) estimation is desirable for all sorts of operations involved in high-performance baseband demodulation. In this work, conventional SNR estimation techniques are investigated. Next, a blind SNR estimation scheme for the phase-shift keying (PSK) signals based on the coherence function is proposed. The proposed method is non-data-aided (NDA) and hence bandwidth-efficient. Simulations confirm that the proposed method has the best performance from moderate to high SNRs both in AWGN and dispersive channels; however, the proposed method has worse performance when SNRs are low.
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  • Fang YANG, Kewu PENG, Jian SONG, Zhixing YANG
    Article type: LETTER
    Subject area: Wireless Communication Technologies
    2008 Volume E91.B Issue 11 Pages 3757-3759
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    A simple transmit diversity scheme based on cyclic-shift pseudo noise (PN) sequences for the time domain synchronous orthogonal frequency division multiplexing (TDS-OFDM) system is proposed and the corresponding channel estimation algorithms are also investigated. Simulation results are presented to verify the effectiveness of the proposed method.
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  • Bao Quoc VO NGUYEN, Hyung Yun KONG
    Article type: LETTER
    Subject area: Wireless Communication Technologies
    2008 Volume E91.B Issue 11 Pages 3760-3763
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    This paper provides a closed form expression for calculating the bit error rate of the decode-and-forward relay protocol that uses equal-gain combining (EGC) at the destination with an arbitrary number of relays. We have shown that EGC technique for decode-and-forward relay scheme offers remarkable diversity advantage over direct transmission. In addition, we also study the impact of combining techniques on the performance of the system by comparing a system that uses EGC to one that uses maximum ratio combining (MRC) & selection combining (SC). Simulations are performed to confirm our theoretical analysis.
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  • Chengyu LIN, Wenjun ZHANG, Feng YANG, Youyun XU
    Article type: LETTER
    Subject area: Wireless Communication Technologies
    2008 Volume E91.B Issue 11 Pages 3764-3767
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    To improve the performance of the optimal pilot sequences over multiple OFDM symbols in fast time-varying channels, this letter proposes a novel channel estimation method using virtual pilot tones in multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems. Assuming that the superimposed virtual pilot tones at the data locations over the specific sub-carriers are transmitted from all transmit antennas, the corresponding virtual received pilot signals at the same locations are obtained from the neighboring real received pilot signals over the same sub-carriers by Wiener filter. Based on the least squares (LS) channel estimation, the channel parameters can be obtained from the combination of the virtual and real received pilot signals over one OFDM symbol. Simulation results show that the proposed channel estimation method greatly outperforms the previous method for the optimal pilot sequences over multiple OFDM symbols in fast time-varying channels, as well as approaches the method for the comb-type optimal pilot sequences in performance.
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  • Gabriel PORTO VILLARDI, Giuseppe THADEU FREITAS DE ABREU, Ryuji KOHNO
    Article type: LETTER
    Subject area: Terrestrial Radio Communications
    2008 Volume E91.B Issue 11 Pages 3768-3774
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    The application of Cumulative Decision Feedback (DF) technique for energy/complexity constrained Wireless Sensor Networks (WSN) is considered. Theoretical bit error probability and average rate of a BPSK modulated DF are derived together with PHY-MAC layers' energy efficiency model for DF and Forward Error Correction (FEC) techniques. Moreover, an empirical optimization, which in turn relies upon a low complexity SNR estimation method also derived in this letter, is applied to the DF technique in order to obtain maximum energy efficiency.
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  • Youngju DO, Seungbeom LEE, Sin-Chong PARK
    Article type: LETTER
    Subject area: Terrestrial Radio Communications
    2008 Volume E91.B Issue 11 Pages 3775-3778
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    In this paper, we design and implement a multi-protocol 13.56MHz reader in software. In order to satisfy the timing constraint, three level optimizations called compile level, syntax level, and architectural level optimizations are applied. The execution time of optimized code is reduced by 85%, so that it satisfies timing requirement of a 60MHz speed EISC processor. In addition, the binary code size is minimized to 211KBytes which can be loaded on a 256KB size memory.
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  • Akira TANAKA, Susumu YOSHIDA
    Article type: LETTER
    Subject area: Terrestrial Radio Communications
    2008 Volume E91.B Issue 11 Pages 3779-3783
    Published: November 01, 2008
    Released on J-STAGE: November 28, 2008
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    A QoS support technique for easily minimizing delay in multihop wireless networks is proposed. Using a priority queue operation that reduces delays overall, the proposed technique, Reduced Congestion Queuing (RCQ), solves problems peculiar to multihops. By adding RCQ to a multihop system, base station or access point density and cost can be more effectively curtailed than by simply applying multihops to a cellular network or wireless LAN because RCQ expands the multihop service area. Due to its simplicity, the proposed technique can be used in a wide range of applications, including VoIP.
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