The Computer Journal - current issue

Increasing Service Availability in a Wireless Home Network Environment

Lin, C.-Y., Wang, S.-C., Kuo, S.-Y., Chen, C.-Y. — Fri, 20 Nov 2009 08:02:32 PST

Service-oriented architecture (SOA) paradigm is an inspiring and evolving concept in the context of IT and business services. Recently, various networked embedded systems are penetrating into our life; the unique characteristics of these systems pose many technological challenges. Specifically, the capabilities to interoperate across home appliances and personal digital devices are critical in a smart home environment. As a consequence, the SOA paradigm is introduced as a basis to enhance the service interoperability. However, the service availability is another important concern. In this paper, we focus on augmenting the smart home environment with high service availability. First, we point out the potential problems by adopting the universal plug and play (UPnP) quality of service (QoS) architecture to deliver services with QoS requirements in wireless home networks. After that, we propose a local detour mechanism to tolerate link congestions and node/link failures. Furthermore, the proposed mechanism is based on standard UPnP actions, so that modifications to the existing UPnP QoS architecture are not required. Compared with content-adaptive and resource-adaptive-based approaches operated on fixed service routing paths, our work not only guarantees content quality, but also tolerates topology changes in wireless home networks.

SH-CRBAC: Integrating Attribute and Status Constraints into the RBAC Model in Smart Home Systems

Zou, D., Park, J. H., Kim, T.-H., Chen, X. — Fri, 20 Nov 2009 08:02:32 PST

The requirements for access control have been increased significantly in smart home systems. Many factors such as user ID, user location, service usage conditions and so on, regarded as authorization attributes, are important in making authorization decision in smart home systems. We investigate into the dynamic characteristics of the authorization in smart home systems and propose a new access-control model, SH-CRBAC, which aims to combine the advantages of attribute-based authorization mechanism and role-based access-control mechanism, and imposes attribute and status constraints on the RBAC model and enhances the generality and flexibility of authorization significantly in smart home systems. The status consistency of SH-CRBAC is analysed, and we also analyse the characteristics of SH-CRBAC through comparison with other popular existing authorization models in smart home systems.

Home Network Device Authentication: Device Authentication Framework and Device Certificate Profile

Lee, Y.-K., Lee, D. G., Han, J.-W., Kim, T.-H. — Fri, 20 Nov 2009 08:02:32 PST

As home devices have various functions and have improved computing power and networking ability, home device authentication has become increasingly important for improving the security of home network users. Moreover, device authentication supplies user convenience for the home network service user because it can replace the user authentication required for the used home network service. In addition, the safety of the home network can be strengthened if device authentication is considered in addition to the authentication and access control for the home network user. In this paper, we describe home device authentication, which is a basic and essential element of home network security. We propose a home device authentication framework, home device registration, method of issuing certificates and a home device certificate profile. Our home device certificate profile is based on the Internet X.509 certificate. In short, our device authentication concept can offer convenience and security to users of a home network service.

Near-Optimal Tracking for Residents' Comfort in Context-Aware Heterogeneous Smart Environments

Saxena, N., Roy, A., Shin, J. — Fri, 20 Nov 2009 08:02:32 PST

An information-theoretic, optimal framework is developed for tracking the residents in a context-aware heterogeneous smart environment. The framework envisions that each individual sensor system operates fairly independently and does not require public knowledge of individual topologies. The resident-tracking problem is formulated in terms of a new concept of weighted entropy. The framework is truly universal and provides an optimal, online learning and prediction of inhabitant's movement (location) profiles from the symbolic domain. The overall optimal tracking in heterogeneous smart homes is proved to be an NP-complete problem, and a greedy heuristic for near-optimal tracking is proposed. The concept of asymptotic equipartition property is also explored to predict the inhabitant's most likely path segments (comprising coverage areas of different sensor systems) with very good accuracy. Successful prediction helps in on-demand operations of automated indoor devices along the inhabitant's future paths and locations, thus providing the necessary comfort at a near-optimal cost. Simulation results on a typical smart home corroborate a high prediction success of ~91%, thereby providing sufficient resident-comfort (≥7 in the scale of 10) while reducing the daily energy consumption and manual operations to less than one-third of its original values.

GA-Based Keyword Selection for the Design of an Intelligent Web Document Search System

Chou, C.-H., Lee, C.-H., Chen, Y.-H. — Fri, 20 Nov 2009 08:02:32 PST

The main steps for designing an automatic document classification system include feature extraction and classification. In this article a method to improve feature extraction is proposed. In this method, genetic algorithm was applied to determine the threshold values of four criteria for extracting the representative keywords for each class. The purpose of these four threshold values is to extract as few representative keywords as possible. This keyword extraction method was combined with two classification algorithms, vector space model and support vector machine, for examining the performance of the proposed classification system under various extracting conditions.

An Improved RFID-Based Locating Algorithm by Eliminating Diversity of Active Tags for Indoor Environment

Zhang, T., Chen, Z., Ouyang, Y., Hao, J., Xiong, Z. — Fri, 20 Nov 2009 08:02:32 PST

The location awareness is a crucial foundation for perceptions of the surroundings in the smart environment. Radio frequency identification (RFID), as one of the most promising technologies, plays a more important role in the indoor location awareness. This paper surveys current RFID-based locating research and discusses the problem that is brought by the tag's diversity derived from different manufacturer types and different used-time of built-in battery. We present the algorithm named RFDiffFreeLoc to improve the location precision by eliminating the dissimilarity among tags. In the stimulation experiments, we analyze the impact of noise on performance and contrast our algorithm with the existing LANDMARC algorithm. The simulation performances show that our algorithm is feasible via two metrics: the mean error and cumulative error distribution. The results indicate that RFDiffFreeLoc significantly increases the locating accuracy: when the space between the reference tags is 1 m, the mean error drops 0.076–0.344 m according to various noise conditions. Furthermore, a prototype system named RFHome is deployed for validating the algorithm in the actual home environment. The practical experimental results demonstrate that our algorithm is more effective than previous LANDMARC algorithm.

Multi-Agent Group Programming Based On Co-evolution

Wenjun, L., Tianjiang, W., Fang, L. — Fri, 20 Nov 2009 08:02:32 PST

As an effective means of multi-agent problem solving, autonomous individual programming and interaction that are essential need, are limited in their ability to accommodate the interests of others, and therefore, may unnecessarily constrain the solving ability and negotiability of an agent, particularly in a distributed cooperative environments founded on private and uncertain information. In this paper, a multi-agent group programming model is presented, where each agent executes local programming by evolutionary search. Based on co-evolution idea, agents resolve conflicts and revise their own search direction to optimize local and social objectives in an interactive process by means of clustering and group choice. Finally, the paper presents simulation results that illustrate the operational effectiveness of our agent group programming model.

Ambient Ecologies in Smart Homes

Goumopoulos, C., Kameas, A. — Fri, 20 Nov 2009 08:02:32 PST

An important characteristic of ubiquitous computing (UbiComp) environments is the integration of information, communication and sensing technologies into our everyday objects, giving rise to a new proactive computing model in homes. A smart home uses networked sensors, devices and appliances to build an intelligent environment in which many activities in the home are automated and where devices and services seamlessly cooperate to support domestic tasks. Programming and maintaining such an infrastructure is challenging because suitable abstractions are currently missing. In this work we have attempted to define ambient ecologies as a metaphor for modeling UbiComp applications, specify design patterns and programming principles and develop infrastructure to provide a paradigm of application engineering and tools to support ambient ecology designers, developers and end-users. We describe our model and the middleware architecture and present the engineering of applications in a smart home environment.

Optimizing Access Point Allocation Using Genetic Algorithmic Approach for Smart Home Environments

Lee, J.-H., Han, B.-J., Lim, H.-J., Kim, Y.-D., Saxena, N., Chung, T.-M. — Fri, 20 Nov 2009 08:02:32 PST

In recent years, high-bandwidth and low-cost wireless technologies have emerged as a competitive element, enabling the smart home environment. On the other hand, with the increasing demands for various services, the current access point allocation schemes give rise to significant challenges for a stable connection service, bandwidth and load distribution. In this paper, we present an optimal access point allocation scheme based on genetic algorithm that attempts to optimize multiple parameters, such as bandwidth, and load-balancing requirements. The proposed allocation scheme provides a set of approximately efficient solutions, which allows a wireless user to choose an access point based on its capacity and load balancing, not only regarding its signaling strength or service set identifier. The simulation results are provided to demonstrate the impact of the proposed optimization procedure on overall system performance in terms of connection distribution, load balancing and call dropping probability.

Joint Routing and Rate Control Scheme for Multi-Stream High-Definition Video Transmission over Wireless Home Networks

Zhou, L., Zheng, B., Wei, A., Geller, B., Cui, J. — Fri, 20 Nov 2009 08:02:32 PST

The support for multiple high-definition video streams in wireless home networks requires appropriate routing and rate control measures, ascertaining the reasonable links for transmitting each stream and the rate of the video to be delivered over the chosen links. In this paper, we invest the combination of the routing and rate control in a united convex optimization formulation and propose a distributed joint solution based on cross-layer design. We first develop a distortion model which captures both the impact of encoder quantization and packet loss due to network congestion on the overall video quality. Then, the optimal joint rate control and routing scheme is realized by adapting its rate to the time-varying traffic and minimizing the overall network congestion. Furthermore, simulation results are provided, which demonstrate the effectiveness of our proposed joint routing and rate control scheme in the context of wireless home networks.

Design and Implementation of the DLNA Family Intercom System for Smart Homes

Lai, C.-F., Huang, H.-C., Huang, Y.-M., Chao, H.-C. — Fri, 20 Nov 2009 08:02:32 PST

In a traditional intercom system that only allows place-to-place communication in a house, it is necessary to dial the extension number of a specific family member, or dial each extension number individually via the intercom broadcasting, in order to reach the desired person. Additional master stations controlled the intercom system are required, and it is load to maintain the stations for general users. In order to solve these problems, we propose the digital living network alliance (DLNA) compatible family intercom system (DFIS): the architecture to support user mobility. This architecture makes it possible to quickly reach a family member without the knowledge of the extension number that caters to a fixed location. In other words, it will be not necessary to dial the extension number of the location of the desired person. We introduce call control and phone handling under the subject of DFIS architecture and demonstrate that the proposed DLNA family intercom device and DLNA family intercom adaptor can work well.

An Efficient Lossless Compression Algorithm for Tiny Nodes of Monitoring Wireless Sensor Networks

Marcelloni, F., Vecchio, M. — Fri, 20 Nov 2009 08:02:32 PST

Energy is a primary constraint in the design and deployment of wireless sensor networks (WSNs), since sensor nodes are typically powered by batteries with a limited capacity. Energy efficiency is generally achieved by reducing radio communication, for instance, limiting transmission/reception of data. Data compression can be a valuable tool in this direction. The limited resources available in a sensor node demand, however, the development of specifically designed compression algorithms. In this paper, we propose a simple lossless entropy compression (LEC) algorithm which can be implemented in a few lines of code, requires very low computational power, compresses data on the fly and uses a very small dictionary whose size is determined by the resolution of the analog-to-digital converter. We have evaluated the effectiveness of LEC by compressing four temperature and relative humidity data sets collected by real WSNs, and solar radiation, seismic and ECG data sets. We have obtained compression ratios up to 70.81% and 62.08% for temperature and relative humidity data sets, respectively, and of the order of 70% for the other data sets. Then, we have shown that LEC outperforms two specifically designed compression algorithms for WSNs. Finally, we have compared LEC with gzip, bzip2, rar, classical Huffman and arithmetic encodings.

Effective and Efficient Event Dissemination for RFID Applications

Jin, B., Zhao, X., Long, Z., Qi, F., Yu, S. — Fri, 20 Nov 2009 08:02:32 PST

The adoption of radio frequency identification (RFID) tags and devices facilitates the observation and monitoring of event patterns, while highly temporal restrained RFID data further make events complicated. Although the existing Pub/Sub systems can help distributed applications monitor and disseminate interesting events, they are unable to express RFID-related events directly. Extending a system for new RFID requirements not only needs a lot of work, but also provides no performance guarantees. It is, therefore, necessary to design and implement an effective and efficient Pub/Sub system in order to capture and disseminate RFID-related events. This paper presents a composite subscription specification for RFID-related application scenarios. It enables the subscription of predicates for RFID code as well as various complex events. Moreover, this paper proposes the algorithms for RFID-code subscription matching and complex events detection which have been implemented in our Pub/Sub system, OncePubSub. Also, experiments were conducted to quantify the performance and overhead of the above algorithms. Performance evaluation results indicate that OncePubSub is more efficient than SIENA- and JESS-based systems.

B2B Services: Worksheet-Driven Development of Modeling Artifacts and Code

Huemer, C., Liegl, P., Schuster, R., Zapletal, M. — Fri, 20 Nov 2009 08:02:32 PST

In the development process of a B2B system, it is crucial that the business experts are able to express and evaluate agreements and commitments between the partners, and that the software engineers get all necessary information to bind the private process interfaces to the public ones. UN/CEFACT's modeling methodology (UMM) is a Unified Modeling Language (UML) profile for developing B2B processes. The formalisms introduced by UMM's stereotypes facilitate the communication with the software engineers. However, business experts—who usually have a very limited understanding of UML—prefer expressing their thoughts and evaluating the results by plain text descriptions. In this paper, we describe an approach that presents an equivalent of the UMM stereotypes and tagged values in text-based templates called worksheets. This strong alignment allows an integration into a UMM modeling tool and ensures consistency. We show how a specially designed XML-based worksheet definition language allows customization to special needs of certain business domains. Furthermore, we demonstrate how information kept in worksheets may be used for the semi-automatic generation of pattern-based UMM artifacts which are later transformed to web service definition language and business process execution language code.