Online ISSN
1751-8636
Print ISSN
1751-8628
IET Communications
Volume 5, Issue 17, 25 November 2011
Volumes & issues:
Volume 5, Issue 17
25 November 2011
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- Author(s): Jong Hyuk Park ; M. Denko ; P. Bellavista ; Y.-M. Huang
- Source: IET Communications, Volume 5, Issue 17, p. 2431 –2433
- DOI: 10.1049/iet-com.2011.0665
- Type: Article
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- Author(s): Y. Nam ; S. Rho ; S. Lee
- Source: IET Communications, Volume 5, Issue 17, p. 2434 –2442
- DOI: 10.1049/iet-com.2010.0936
- Type: Article
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The authors present an approach that extracts human activity patterns of daily living and represents spatiotemporal relations between activities intuitively. In general, customised services are provided based on activity patterns of users. This study focuses on extracting and determining activities that occur simultaneously. In order to determine simultaneous activities, the authors analysed the daily activities that are collected from device applications such as location sensors and electronics. In addition, a context model using the incremental statistical method is organised and temporal relations between the activities patterns are analysed. Furthermore, information visualisation of the spatiotemporal topology with duration and frequency is demonstrated. Also, the authors have experimented on a test-bed called the ubiquitous smart space and compared the accuracy of the incremental statistical method with that of the non-incremental method. - Author(s): S.M. Amiri ; P. Nasiopoulos ; V.C.M. Leung
- Source: IET Communications, Volume 5, Issue 17, p. 2443 –2450
- DOI: 10.1049/iet-com.2010.0952
- Type: Article
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The authors propose a new approach for network lifetime maximisation in visual wireless sensor networks (VWSN). The existence of redundant multiple sensing for some parts of the field results in additional computational complexity and requires more bandwidth and battery power in the nodes, hence reducing the network lifetime. In a VWSN, efficient node collaboration for data sensing and gathering is a key factor to determine network lifetime. The proposed approach provides a jointly optimised traffic routing and camera selection strategy to enhance the lifetime of the whole network. In this approach, different nodes can collaborate with each other to prevent unnecessary multiple sensing of different areas in the network, and at the same time collaborate in the routing of the generated traffics to the network sink. - Author(s): H. Hu ; D. Yang ; L. Fu ; H. Xiang ; C. Fu ; J. Sang ; C. Ye ; R. Li
- Source: IET Communications, Volume 5, Issue 17, p. 2451 –2460
- DOI: 10.1049/iet-com.2010.0615
- Type: Article
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The emerging technologies such as the Internet-of-Things, sensors, communication networks, have been or will be introduced to conventional domotics to provide a wide variety of smart home services to facilitate the household appliances or home cares and improve the lifestyles of people. Currently, smart home system are integrated with different features from product line and equipped with various sensors and actuators to meet the requirements of house occupants by specifying their customised user policies. However, the introduction of features and policies may result in undesired behaviours, and this effect is known as feature interactions. In this study, the authors proposed a Semantic Web-based policy interaction detection method with rules to model smart home services and policies with the aids of ontological analysis in the smart home domain, so as to construct a semantic context for inferring the interaction of policies. The authors focus their work on user policies interaction, which are detected by using the Semantic Web rule language in semantic context. The approach is successfully applied to the smart home system and is able to detect 90 interactions among 32 user policies by automated reasoning with tools support as Protégé and Jess. - Author(s): B.-G. Lee ; S.-J. Jung ; W.-Y. Chung
- Source: IET Communications, Volume 5, Issue 17, p. 2461 –2469
- DOI: 10.1049/iet-com.2010.0925
- Type: Article
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This study presents a novel approach to detect driver's drowsiness by applying two distinct methods in computer vision and image processing. The objective of this study is to combine both methods under one single profile instead of relied solely on a detection method to enhance the driver's drowsiness detection resolution. Therefore a non-intrusive drowsy-monitoring system is developed to alert the driver if driver falls into low arousal state. In physiological part, photoplethysmography (PPG) is analysed for its changes in signals waveform from awake to drowsy state. Meanwhile, eyes pattern or motion in image processing is addressed to detect driver fatigue. Genetic algorithm with template-matching approach is designed to detect eye region and estimate the drowsiness in different metric standard based on eyes behaviour. Moreover, PPG drowsy signals are integrated with eyes motion to derive the final probability model for delivering valid and reliable drowsiness detection system. Indeed, the proposed system provides high competitive edge over existing arbitrary drowsiness detection system where the driver's health and mental states can be monitored in real-time without constraints. - Author(s): J. Chung ; K.-H. Jung ; S.-Y. Jung ; S.-W. Kang ; J.-M. Gil
- Source: IET Communications, Volume 5, Issue 17, p. 2470 –2481
- DOI: 10.1049/iet-com.2010.0928
- Type: Article
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The extensive capability of sensors let sensors autonomously collect various information on smart objects and store them to the spatial database through the wireless sensor networks. Based on spatial database, location-dependent information services (LDISs) can supply the resources according to the user locations. In LDISs, nearest-neighbour queries which return the closest object around the query location is recognised as the key component for searching the easily accessible services in smart spaces. However, existing works only consider the Euclidean distance. Thus, they have limitations to provide user-centric services that require the consideration for not only the distance but also the status of smart objects. Motivated by the issues of nearest-neighbour queries, this study proposes the new type of query called specified nearest-neighbour (SNN). SNN query considers the status and the locations of smart objects. For the SNN, the authors suggest a novel signature-based R-tree (SR-tree) index structure that handles non-spatial information of objects efficiently. Further, the authors propose an SNN query processing technique. Finally, they evaluate the performance of the proposed algorithm in various circumstances. Performance results indicate that SNN algorithm with SR-tree outperforms the existing works in terms of computational cost and disk input/output (I/O). - Author(s): K.R. Vijayanagar and J. Kim
- Source: IET Communications, Volume 5, Issue 17, p. 2482 –2490
- DOI: 10.1049/iet-com.2010.0929
- Type: Article
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Smart spaces is a scenario that is ideal for the application of wireless communication technology to benefit non-expert users. A prime example of such an application would be low-cost and real-time video surveillance of hallways or video conferencing. Traditional solutions for these scenarios use state-of-the-art video codecs like H.264/AVC in order to achieve the low bitrate which is essential in wireless communication. On the flip side, such encoders are computationally complex and need expensive hardware to run on thus making them inefficient choices for being deployed in clusters. Recent research has resulted in distributed video coding (DVC) being proposed as a solution for applications that have limited battery resources and low hardware complexity, thus necessitating a low-complexity encoder. It is now a popular topic in the research community and the past years have seen several implementations. However, current DVC solutions use iteratively decodable channel codes like low-density parity check – accumulate (LDPCA) codes or Turbo codes that have large latencies. In order to make real-time communication possible, the proposed architecture makes efficient use of skip blocks to reduce the bitrate, eliminates the iterative decoding nature of the Wyner-Ziv (WZ) channel and uses a simple data-hiding-based compression algorithm. This drastically cuts down on the time complexity of the decoding procedure while still maintaining a rate–distortion performance better than that of H.264/AVC intra-coding and other current DVC solutions. - Author(s): K. Daabaj ; M. Dixon ; T. Koziniec ; K. Lee
- Source: IET Communications, Volume 5, Issue 17, p. 2491 –2500
- DOI: 10.1049/iet-com.2010.0932
- Type: Article
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Smart space (SS) communication has rapidly emerged as an exciting new paradigm that includes ubiquitous, grid and pervasive computing to provide intelligence, insight and vision for the emerging world of intelligent environments, products, services and human interaction. Dependable networking of a SS environment can be ensured through reliable routing, efficient selection of error-free links, rapid recovery from broken links and the avoidance of congested gateways. Since link failure and packet loss are inevitable in SS wireless sensor networks (WSNs), the authors have developed an efficient scheme to achieve a reliable data collection for SSs composed of low capacity wireless sensor nodes. WSNs must tolerate a certain lack of reliability without a significant effect on packet delivery performance, data aggregation accuracy or energy consumption. An effective hybrid scheme is presented that adaptively reduces control traffic with a metric that measures the reception success ratio of representative data packets. Based on this approach, the proposed routing scheme can achieve reduced energy consumption while ensuring minimal packet loss in environments featuring high link failure rates. The performance of the proposed routing scheme is experimentally investigated using both simulations and a test bed of TelosB motes. It is shown to be more robust and energy efficient than the network layer provided by TinyOS2.x. The results show that the scheme is able to maintain better than 95% connectivity in an interference-prone medium while achieving a 35% energy saving. - Author(s): L. Li and K. Choi
- Source: IET Communications, Volume 5, Issue 17, p. 2501 –2508
- DOI: 10.1049/iet-com.2010.0933
- Type: Article
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Power consumption is the most important issue in circuit design nowadays, and clock gating is the most widely used technique to reduce the dynamic power at register transfer level. The traditional clock gating style using an XOR gate to generate a gated clock was proposed but has not been well studied. It can be extended to multiple flip-flops easily but the power performance is not optimal. In this study, the authors propose a fine-grained activity-driven optimised bus-specific-clock-gating for ultra-low-power smart spaces applications, which can selectively choose qualified flip-flops to be gated based on their output switching activities to optimise the power. This technique has been experimented on ISCAS’89 benchmark circuits, and average power can be reduced by 19.21%. - Author(s): G. Wu ; J. Ren ; L. Yao ; Z. Xu
- Source: IET Communications, Volume 5, Issue 17, p. 2509 –2517
- DOI: 10.1049/iet-com.2010.0862
- Type: Article
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As an important part of the smart space, body sensor networks (BSNs) provide continuous health monitoring and automation assistance for smart environment residents. A high degree of security and reliability for BSN is extremely required. An adaptive and flexible intrusion-tolerant scheme for BSN, namely ITFBS, is proposed. ITFBS dynamically detects intrusions according to the collected intrusion-related information, and it can provide an adaptive intrusion-tolerant strategy with passive replication by utilising two-step threshold-based intrusion detection and replicas classification. The correctness and effectiveness of ITFBS is theoretically proved, and the experimental results show that ITFBS can effectively tolerate intrusions with low power consumption and high adaptability. - Author(s): R. Rios and J. Lopez
- Source: IET Communications, Volume 5, Issue 17, p. 2518 –2532
- DOI: 10.1049/iet-com.2010.0825
- Type: Article
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Extensive work has been done on the protection of wireless sensor networks (WSNs) from the hardware to the application layer. However, only recently, the privacy preservation problem has drawn the attention of the research community because of its challenging nature. This problem is exacerbated in the domain of WSNs owing to the extreme resource limitation of sensor nodes. In this study the authors focus on the location privacy problem in WSNs, which allows an adversary to determine the location of nodes of interest to him. The authors provide a taxonomy of solutions based on the power of the adversary and the main techniques proposed by the various solutions. In addition, the authors describe and analyse the advantages and disadvantages of different approaches. Finally, they discuss some open challenges and future directions of research.
Editorial: Smart Space Technological Developments
Extracting and visualising human activity patterns of daily living in a smart home environment
Collaborative routing and camera selection for visual wireless sensor networks
Semantic Web-based policy interaction detection method with rules in smart home for detecting interactions among user policies
Real-time physiological and vision monitoring of vehicle driver for non-intrusive drowsiness detection
Nearest-neighbour query processing with non-spatial predicates for service allocation in smart space environment
Real-time low-bitrate multimedia communication for smart spaces and wireless sensor networks
Reliable routing for low-power smart space communications
Activity-driven optimised bus-specific-clock-gating for ultra-low-power smart space applications
ITFBS: adaptive intrusion-tolerant scheme for body sensor networks in smart space applications
Analysis of location privacy solutions in wireless sensor networks
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- Author(s): K. Zheng ; Y. Wang ; C. Lin ; X. Shen ; J. Wang
- Source: IET Communications, Volume 5, Issue 17, p. 2533 –2541
- DOI: 10.1049/iet-com.2011.0134
- Type: Article
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Femtocell technology has gained widespread attention recently due to its advantages, such as infrastructure cost reduction, improved service coverage and high data throughput in indoor environments. As femtocell networks are customer-deployed without proper network planning, their interference environment tends to be much more complicated than traditional cellular networks. The authors present the framework of channel allocation in orthogonal frequency-division multiplexing access (OFDMA) femtocell network with the graphical approaches. A novel graph-based interference coordination scheme is proposed to maximise the system throughput while ensuring proportional rate fairness among femtocells. The scheme explicitly uses the received signal-to-interference-plus-noise-ratio to generate the interference graph of OFDMA femtocell networks, so as to guarantee the acceptable inter-cell interference for all the links. First, all the femtocells are partitioned into different groups by applying a greedy graph colouring algorithm to maximise the sum throughput of each group. The femtocells in the same group share the assigned subchannels while those in different groups are allocated to orthogonal subchannels. Then, an optimisation problem is formulated to determine the number of subchannels assigned to each group. Further, an approximation method is proposed to solve the optimisation problem. Simulation results are conducted to demonstrate the effectiveness of the proposed scheme in terms of throughput and fairness index. - Author(s): S.-J. Yoon ; S.-H. Lee ; Y.-B. Ko
- Source: IET Communications, Volume 5, Issue 17, p. 2542 –2550
- DOI: 10.1049/iet-com.2010.1042
- Type: Article
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Geocasting is an efficient mechanism for disseminating messages towards a specific geographical region. Since its packet forwarding is based on the location information of nodes, it does not require any periodic or on-demand path updates. Especially, geocasting is suitable for several applications in tactical ad hoc networks such as alarms for chemical and missile attacks, guerrilla detection or a local weathercast. However, traditional geocast protocols proposed for pure mobile ad hoc networks are inadequate to meet high demands of reliability in military applications. In this study, the authors propose even more efficient and reliable dual-path geocasting protocol which utilises two independent paths and novel acknowledgement mechanisms to improve the chances of successful message delivery. The authors investigate how to locate this dual path to achieve the best performance by means of destination points. The authors’ comprehensive simulation study using ns-2 shows that the proposed scheme results in high delivery ratio with low packet overhead and latency. - Author(s): J.I.-Z. Chen
- Source: IET Communications, Volume 5, Issue 17, p. 2551 –2557
- DOI: 10.1049/iet-com.2010.0344
- Type: Article
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The carrier frequency offset (CFO) is one of the critical parameters for degrading the overall performance of radio systems modulated with a scheme of multiple carriers. The evaluation of system performance for a multi-carrier coded-division multiple-access (MC-CDMA) radio system with CFO effect mentioned previously is investigated in this study. Apart from the aforementioned parameter, the other important parameter referred to as fading branch correlation (FBC) occurring in the propagating channel is rarely applied in the study of MC-CDMA systems’ performance. For the sake of simplicity, subcarriers are typically considered independently. However, the randomisation incurred in generating CFO and FBC should be simultaneously considered to calculate the overall performance. The focus of this work is an aggregate investigation to determine which parameter, that is, CFO or FBC, primarily dominates the performance of an MC-CDMA system. Assume that applying the same quantity of CFO (ɛ) and FBC (λ) in serving the simulation, that is, both values of CFO and FBC are assumed and assigned in the interval of (0.4, 1.0). Moreover, several novel formulas include both CFO and FBC parameters and many three-dimensional curves are presented and illustrated in this article. - Author(s): X. Zhang ; Z. Ding ; M. Peng ; W. Wang ; K.K. Leung ; H.-H. Chen
- Source: IET Communications, Volume 5, Issue 17, p. 2558 –2568
- DOI: 10.1049/iet-com.2010.1045
- Type: Article
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Network coding can deliver multiple data streams simultaneously and make full use of broadcast nature of wireless channels. The authors propose two diversity-enabled network-coding (NC) schemes to optimise wireless uplink scheduling. The existing scheduling protocols normally have to allow the users with relatively low channel gains to transmit, and it can maintain fairness but reduce congregated throughput. The main idea of the proposed scheme is to always schedule users with the best channel condition, while the use of NC encourages the scheduled users to help others which have not been served previously. Delay and capacity performance for different network coded scheduling schemes are analysed. Round-robin and pure opportunistic scheduling are evaluated for performance comparison. In order to show the effectiveness of the proposed schemes, NC schedulers are applied to a time division duplexing code division multiple access wireless cellular networks. System-level simulation was carried out based on the third generation partnership project specifications. Per-sector average throughput and cumulative distribution function of user average throughput are adopted as the performance metrics. Analytical and simulation results show that the proposed NC schedulers can achieve a better tradeoff between fairness and throughput than those without NC. - Author(s): Y. Liu ; Z. Tan ; K.S. Kwak
- Source: IET Communications, Volume 5, Issue 17, p. 2569 –2577
- DOI: 10.1049/iet-com.2010.1101
- Type: Article
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This study deals with signal transmission and reception over a fast-fading wireless environment. Conventional methods usually consider the rapid change of channel to be harmful, which may decrease the performance of existing systems. There are also methods proposed to make use of the cause of degradation in existing systems – Doppler spread – to provide additional diversity, at the cost of folds increased complexity. In this study, the authors focus on exploiting the array gains provided by the fast-fading wireless channel multipath array gain (MAG) and Doppler array gain (DAG). The conceptions of MAG and DAG are straightforward extensions of the conception of array gain in multi-antenna systems. For methods which exploit multipath and Doppler diversities, complex signal processing is required at the receiver side, leading to a great increase in complexity. The MAG and DAG can be easily obtained using simple transmit waveform design. Therefore, no extra computational load is required. Both analytical and simulation results show that, with the same computational complexity, the proposed methods can significantly outperform the conventional ones. - Author(s): Z. Xu ; L. Wang ; K.S. Kwak ; G. Chen
- Source: IET Communications, Volume 5, Issue 17, p. 2578 –2585
- DOI: 10.1049/iet-com.2010.0828
- Type: Article
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Designing a non-ideal delay line (DL) with phase distortion in a transmitted-reference ultra-wideband system with an autocorrelation receiver is a great technical challenge. Differing from the currently empirical design method of DL, a semi-analytic approach is proposed through Gaussian approximation of the expression for conditional bit error rate (BER), based on investigation on the degradation of average BER caused by a group delay ripple range (GDRR) over independent Nakagami-m fading channels. This GDRR-based design method can directly evaluate its effects on the system performance and determine the acceptable phase distortion level to trade-off the BER performance and system complexity. - Author(s): H. Li and S. Xie
- Source: IET Communications, Volume 5, Issue 17, p. 2586 –2593
- DOI: 10.1049/iet-com.2010.1016
- Type: Article
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This study addresses the joint robust linear transceiver design problems for a downlink multi-user multiple-input multiple-output (MIMO) antenna system in the presence of imperfect channel state information (CSI). The uncertainty in the channel is characteried by a norm-bounded region, and two robust optimal design problems are considered. One is aimed at minimising the total transmitter power subject to users' mean square error (MSE) constraints in the presence of channel uncertainty, the other is to minimise the worst-case sum-mean square error (sum-MSE) under power constraints for all admissible uncertainties. For these two problems, the authors propose two iterative algorithms based on second-order cone programming (SOCP) formulations, which can be efficiently solved and have less computational complexity than their semi-definite programming (SDP) counterparts. Simulation results also illustrate that the proposed robust design approaches can significantly reduce the computational complexity while achieving almost the same performance as the robust SDP methods.
Graph-based interference coordination scheme in orthogonal frequency-division multiplexing access femtocell networks
Dual-path-based reliable geocasting for tactical ad hoc networks
Random characteristics of carrier frequency offset and a joint fading branch correlation in an asynchronous multi-carrier coded-division multiple-access system
Performance of network-coding-assisted scheduling schemes and their applications in uplink time division duplexing code division multiple access systems
Exploiting multipath and Doppler array gains in fast-fading wireless channel
Designing delay lines based on group delay ripple range for transmitted-reference ultra-wideband systems
Robust linear transceivers for downlink multi-user multiple-input multiple-output systems using second-order cone programming optimisation
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