Showing papers in "International Journal of Pervasive Computing and Communications in 2008"

Adaptation in Context-Aware Pervasive Information Systems: The SECAS Project

Abstract: Purpose – The simple environment for context aware systems (SECAS) Project deals with the adaptation of applications to the context (user preferences and environment, terminal, etc.). The authors aim to develop a platform which makes the services, data and the user interface of applications adaptable to different context situations.Design/methodology/approach – Previous research has concentrated on how to capture context data and how to carry it to the application. The present work focuses on the impact of context on the application core. A case study in the medical field is also analysed.Findings – The paper illustrates a new definition of the context which separates the application data from the parameters of the context. This definition helps to establish a complete study on how to adapt applications on their three dimensions (services, content and presentation) to the context.Originality/value – The paper presents the SECAS platform, one that ensures the deployment of adaptive context‐aware applications.

Development and evaluation of a context‐driven, mobile tourist guide

Abstract: Purpose – The behavior of tourists strongly depends on the availability and quality of information. Too little information as well as too much can be disorienting and forces many tourists to join the majority visiting major sights. This causes a few crowded places in contrast to many which are under‐utilized. A Destination Management Organization has the goal to spread tourists more evenly, whereas the tourists would like to enjoy the destination to its full potential according to their personal interests. The paper aims to focus on the issues surrounding the creation of a mobile tourist guide.Design/methodology/approach – A field trial was conducted in the summer of 2005 to study the following questions as a precondition for the development: Is it possible to seed generic interest profiles in the mobile context that allow the accurate prediction of actual rankings? Are the interest profiles sufficiently diverse to base personalized tours on individual interest profiles instead of interest prototypes? How...

A context‐aware preference database system

Abstract: Purpose – A context‐aware system is a system that uses context to provide relevant information or services to its users. While there has been a variety of context middleware infrastructures and context‐aware applications, little work has been done on integrating context into database management systems. The purpose of this paper is to consider a preference database system that supports context‐aware queries, that is, queries whose results depend on the context at the time of their submission.Design/methodology/approach – The paper proposes using data cubes to store the dependencies between context‐dependent preferences and database relations and on‐line analytical processing techniques for processing context‐aware queries. This allows for the manipulation of the captured context data at various levels of abstraction, for instance, in the case of a context parameter representing location, preferences can be expressed, for example, at the level of a city, the level of a country or both. To improve query per...

FBSR: feedback‐based secure routing protocol for wireless sensor networks

Abstract: Purpose – Wireless sensor networks, due to their potentially wide application perspectives, may proliferate in future. Two major stumbling blocks are the dynamic variance of the network caused by both the capacity constraint of sensor nodes and uncertainties of wireless links, and secure routing in the special security sensitive environment. Therefore, adaptable and defendable routing mechanism is in urgent need for the deployment of sensor networks. This paper aims to propose a feedback‐based secure routing protocol (FBSR).Design/methodology/approach – Feedback from the neighboring nodes serves as the dynamic information of the current network, with which sensor nodes make forwarding decisions in a secure and energy aware manner. Feedback message is included in the MAC layer acknowledgement frame to avoid network congestion, and it is authenticated with the proposed Keyed One Way Hash Chain (Keyed‐OWHC) to avoid feedback fabrication. FBSR's resilience to node compromise is enhanced by statistic efforts a...

Energy‐proportional routing for lifetime extension of clustering‐based wireless sensor networks

Abstract: Purpose – The purpose of this paper is to propose an energy‐proportional routing (EPR) algorithm, which effectively extends the lifetimes of sensor networks.Design/methodology/approach – The algorithm makes no specific assumption on network topology and hence is suitable for improving sensor networks with clustering. To optimally utilize energy, light‐load units – nodes or clusters that conserve energy are ideal candidates as intermediate units for forwarding data from others. To balance the load, first, the proposed algorithm predicts energy consumption of each node in each round. Then the algorithm controls the energy consumption of each unit as close as possible to the threshold representing the energy utilization mean value among clusters. Finally the algorithm checks satisfaction of the energy constraints in terms of distances and predicted data amounts. The proposed algorithm performs routing by determining whether a cluster head or a node should either undertake forwarding tasks or transmit data to...

Probabilistic self‐scheduling for coverage configuration in wireless ad‐hoc sensor networks

Abstract: Purpose – Sensing coverage is a critical issue in sensor network deployments. The paper aims to propose a novel scheme to maintain the sensing coverage in sensor networks, which is termed coverage‐aware self‐scheduling (CASS).Design/methodology/approach – The paper describes a generic unifying framework to incorporate different connectivity and coverage maintenance schemes. Simulations are carried out under the framework by integrating CASS with an existing connectivity maintenance scheme ‐ the low‐energy adaptive clustering hierarchy.Findings – Different from the existing work on coverage maintenance, CASS probabilistically schedules sensing activities according to the sensor's contribution to the sensing coverage of the whole sensor network. CASS reduces the number of active sensors to maintain certain coverage. Besides the sensing coverage, the connectivity of the network topologies is required for the purpose of communicating among sensors to collect sensing data. Simulation results show that CASS can...

A fuzzy service adaptation engine for context‐aware mobile computing middleware

Abstract: Purpose – Context‐aware mobile computing extends the horizons of the conventional computing model to a ubiquitous computing environment that serves users at anytime, anywhere To achieve this, mobile applications need to adapt their behaviors to the changing context The purpose of this paper is to present a generalized adaptive middleware infrastructure for context‐aware computingDesign/methodology/approach – Owing to the vague nature of context and uncertainty in context aggregation for making adaptation decisions, the paper proposes a fuzzy‐based service adaptation model (FSAM) to improve the generality and effectiveness of service adaptation using fuzzy theoryFindings – By the means of fuzzification of the context and measuring the fitness degree between the current context and the predefined optimal context, FSAM selects the most suitable policy to adopt for the most appropriate service The paper evaluates the middleware together with the FSAM inference engine by using a Campus Assistant applicati

SCAFOS: linking sensor data to context‐aware applications using abstract events

Abstract: Purpose – The event‐driven paradigm is appropriate for context aware, distributed applications, yet basic events may be too low level to be meaningful to users. The authors aim to argue that this bottom‐up approach is insufficient to handle very low‐level sensor data or to express all the queries users might wish to make.Design/methodology/approach – The authors propose an alternative model for querying and subscribing transparently to distributed state in a real‐time, ubiquitous, sensor‐driven environment such as is found in Sentient Computing.Findings – The framework consists of four components: a state‐based, temporal first‐order logic (TFOL) model that represents the concrete state of the world, as perceived by sensors; an expressive TFOL‐based language, the Abstract Event Specification Language (AESL) for creating abstract event definitions, subscriptions and queries; a higherorder service (Abstract Event Detection Service) that accepts a subscription containing an abstract event definition as an arg...

A weighted multilateration positioning method for wireless sensor networks

Abstract: Purpose – Localization problem is one of the most important research issues for wireless sensor networks (WSNs). The purpose of this paper is to present a two‐phase localization algorithm for WSNs.Design/methodology/approach – In the first phase, each sensor node obtains its initial position by DV‐hop method. In the second phase, each sensor node gathers the locations and distances to its neighbors, updates and exchanges these location information periodically and then operates the multilateration with different weight values.Findings – The simulation result shows that the average position error of the proposed two‐phase method is less than 20 per cent of the radio range, and the number of sensor nodes which can be located is larger than 70 per cent of total nodes for a network with low density.Originality/valve – The paper presents a weighted multilateration positioning methods for wireless sensor networks.

An efficient wireless network discovery scheme for heterogeneous access environments

Abstract: Purpose – Several new network types have emerged over the last couple of years. Many of these networks are being connected together to provide mobile users with the capability of staying always connected to the Internet which requires seamless transitions from one network to another without causing interruption to on‐going connections. To maintain connectivity during handoff, all the networks that are accessible to the mobile station need to be known. The paper aims to propose a novel energy‐efficient network discovery approach that enables fast discovery and selection of available access networks.Design/methodology/approach – The performance of the proposed approach over an actual network testbed consisting of heterogeneous networks (such as wireless local area, cellular) is evaluated.Findings – It was found that the approach yields between 12.4 and 19.1 per cent improvement in battery power consumption over other network discovery approaches.Originality/value – The paper proposes and implements a novel ...

Exploring GSM data in pervasive environments

Abstract: Purpose – A cell phone that behaves in a manner reflective of the current context has been a goal for the pervasive and ubiquitous research communities for a long time. This paper aims to demonstrate how two aspects of context – location and activity – can be inferred using GSM data present on standard cell phones.Design/methodology/approach – A background knowledge of GSM networks is provided, followed by an assessment of the stability of signal strength levels in order to establish their usefulness in inferring aspects of context. A qualitative location system using GSM signals is presented and how to infer the current activity of the cell phone carrier is demonstrated.Findings – The paper shows that by using the patterns of signal strength fluctuations and changes to the current serving cell and monitored neighbouring cells it is possible to distinguish between various states of movement such as walking, driving a car and remaining stationary.Originality/value – The paper focuses on the practical aspec...

A scenario‐based approach for direct interruptability prediction on wearable devices

Abstract: Purpose – People are subjected to a multitude of interruptions. In order to manage these interruptions it is imperative to predict a person's interruptability – his/her current readiness or inclination to be interrupted. This paper aims to introduce the approach of direct interruptability inference from sensor streams (accelerometer and audio data) in a ubiquitous computing setup and to show that it provides highly accurate and robust predictions.Design/methodology/approach – The authors argue that scenarios are central for evaluating the performance of ubiquitous computing devices (and interruptability predicting devices in particular) and prove this on the setup employed, which was based on that of Kern and Schiele.Findings – The paper demonstrates that scenarios provide the foundation for avoiding misleading results, and provide the basis for a stratified scenario‐based learning model, which greatly speeds up the training of such devices.Practical implications – The direct prediction seems to be compet...

A cross‐layer design for heterogeneous routing in wireless mesh networks

Abstract: Purpose – Wireless mesh networks (WMNs) are regarded as a milestone in developing next‐generation wireless networks. The multi‐hop architecture of WMN makes it very attractive. However, interoperability is an inherent problem for deploying a large‐scale WMN, which may consist of various types of wireless networks. There are two intuitive approaches to solving the interoperability problem: the dual‐stack/multi‐stack approach and the naive layer‐2 broadcast approach. While the former incurs high cost in all devices, the latter creates broadcast storm in the whole network. This paper aims to propose a cross‐layer heterogeneous routing protocol for solving this problem without the adverse effects of the intuitive approaches.Design/methodology/approach – A conceptual discussion and approach are employed.Findings – The simulation results validate the efficiency of the proposed protocol.Originality/value – The paper provides details of a method for routing selection in WMNs.

A hybrid power‐saving protocol by dual‐channel and dual‐transmission‐range clustering for IEEE 802.11‐based MANETs

Abstract: Purpose – There are two types of medium access control (MAC) layer power‐saving (PS) protocols for IEEE 802.11‐based mobile ad hoc networks: synchronous and asynchronous ones. This paper seeks to propose a hybrid PS protocol to take advantages of both types of protocols.Design/methodology/approach – The protocol utilizes the concept of dual‐channel and dual‐transmission‐range clustering. It divides all the hosts into clusters. Each cluster has a head and all the heads are organized as a virtual backbone to help route data. The protocol also utilizes the cluster head dismissal mechanism to avoid the ever‐increasing of cluster heads and to adapt to topology changing.Findings – Simulation results demonstrate that the proposed protocol is more power‐efficient and more scalable than related protocols.Originality/value – The proposed protocol is applicable to MANETs composed of hosts with single IEEE 802‐11 network interface card.

ASDF: an object oriented service discovery framework for wireless sensor networks

Abstract: Purpose – The purpose of this paper is to present a new service discovery protocol (SDP) suitable for wireless sensor networks (WSN). The constraints imposed by ultra low‐cost sensor and actuators devices (basic components of a WSN) are taken into account to minimize the overall footprint.Design/methodology/approach – It is based on the lightweight WSN communication model used by picoObjects, a tiny implementation of the distributed object concept and the same design criteria are followed, aiming at minimal overhead for devices and communication protocols. In spite of its simplicity it is powerful enough to deploy a valuable set of services.Findings – This approach provides a remote interface that client applications can use without knowing where the service is implemented (platform and location independence).Research limitations/implications – The future work is mainly focused on integrating third party services using different SDPs, making possible the real deployment of large heterogeneous pervasive en...

Data rate estimation algorithm for IEEE 802.11e HCCA scheduler

Abstract: Purpose – As the real‐time applications used in today's wireless network grow, some schemes are required to provide better quality of services. From the evaluation of referenced scheduling scheme provided in IEEE 802.11e standard document, we know that it does not perform well on traffic which is not strictly constant‐bit‐rate (CBR). Therefore, it is necessary to design a more flexible scheme to dynamically adjust the estimation of transmission opportunity allocated to QoS‐enhanced stations with different characteristics of applications. This paper aims to present a data rate estimation algorithm for the scheduler of the IEEE 802.11e hybrid coordination function controlled channel access.Design/methodology/approach – The performance of the algorithm is evaluated through Network Simulator ‐2.Findings – With the proposed algorithm, the QoS access point can provide guaranteed parameters such as delay and throughput for both the real‐time variable‐bit‐rate and CBR traffics.Originality/valve – The paper presen...

Component‐based ad hoc systems for ubiquitous computing

Abstract: Purpose – The problems with poor performance and quality of ubiquitous applications due to limited computing resources are addressed.Design/methodology/approach – The concept of ad hoc systems is introduced based on the idea that a resource‐limited device may cooperate with computers around to complete a complex task. Subsequently, the adaptive software framework, FRAME, may be improved to realize ad hoc systems.Findings – It is possible to apply the adaptive software framework to the challenges of ad hoc systems, including a lot of user intervention and unstable computing environments.Research limitations/implications – The present study provides a starting‐point for further research in exploring and utilizing ubiquitous resources to achieve a better user experience.Practical implications – The component‐based architecture provides a flexible development approach of ubiquitous applications from the software engineering perspective.Originality/value – Our analysis and experimental results show that the co...

Hierarchical data gathering schemes in wireless sensor networks

Abstract: Purpose – This paper aims to balance the total energy consumption and the transmission delay for data gathering application in wireless sensor networks.Design/methodology/approach – This paper adopts a hierarchical grid structure to reduce the total energy consumption, and utilizes a tree architecture to decrease the transmission delay.Findings – In the results, the proposed method performs better, in terms of the number of rounds and the energy × delay cost, than other data gathering protocols with different network sizes and node densities. Moreover, the proposed method also provides good coverage preservation in different environments.Research limitations/implications – In this paper, sensor nodes are assumed to be uniformly distributed, homogenous, energy‐constrained. Each sensor node also has ability to adjust its transmission power. For practice, the proposed method needs location information of sensor nodes and the radio interference between sensor nodes during data transmissions should be consider...

Logical Coordinate Assignment for Geographic Routing in Wireless Sensor Networks

Abstract: Purpose – The purpose of this paper is to propose a distributed protocol to build a logical coordinate system based on the hop counts of each node to four selected landmarks, and the real location information is not needed.Design/methodology/approach – The designed protocol uses the sink node as one of the landmarks and then selects three other sensor nodes near the corners of the sensor network as landmarks.Findings – The simulation results show that the proposed protocol has the superior performance in packet delivery ratio, average hop counts among nodes, and communication overhead to previous works.Originality/value – This paper presents a distributed protocol to build a logical coordinate system based on hop counts to landmarks.

A simple dynamic clustering approach to achieve energy efficiency for wireless sensor networks

Abstract: Purpose – Recent wireless communication and electronics technology has enabled the development of low‐cost, low‐power, and multi‐functional sensor nodes. However, the fact that sensor nodes are severely energy‐constrained has been an issue and many energy‐efficient routing protocols have been proposed to resolve it. Cluster‐based routing protocol is one of them. To achieve longer lifetime, some cluster‐based routing protocols use information on GPS‐based location of each sensor node. However, because of high cost, not all sensor nodes can be GPS‐enabled. The purpose of this paper is to propose a simple dynamic clustering approach to achieve energy efficiency for wireless sensor networks (WSN).Design/methodology/approach – Instead of using location information of each sensor node, this approach utilizes information of remaining energy of each sensor node and changes in the number of cluster head nodes dependent on the number of sensor nodes alive. Performance results are presented and compared with some re...

LooM: An anonymity quantification method in pervasive computing environments

Abstract: Purpose – The paper's aim is to present a novel anonymity quantification method, LooM (loosely managed privacy protection method) for achieving privacy protection in pervasive computing environments. Design/methodology/approach – The main feature is that the method quantitatively controls anonymity by a single value (disclosure threshold value) using a classification algorithm of the decision tree. The value is not affected by the set size of users or the distribution of users' private information. The effectiveness of this method is confirmed by simulation using sample databases of attribute‐value pairs. Proposes a model of privacy information disclosure that achieves a balance between users' privacy protection requirements and service providers' disclosure requirements and applies web questionnaire survey data to this model. Findings – LooM can be applicable to a variety of pervasive computing and communication services handling a huge amount of data containing privacy information. Originality/value – The paper proposes a model of privacy information disclosure that achieves a balance between users' privacy protection requirements and service providers' disclosure requirements.

An OSA service capability server for mobile services

Abstract: Purpose – This paper aims to propose an open service access (OSA) service capability server (SCS) architecture that supports the network capabilities to the Application Server (AS).Design/methodology/approach – Based on this architecture, the service capability feature (SCF) provides the OSA Application programming interface functions by implementing the SCF service logic module and callback module. The SCF uses the XML communication module to interact with service capability (SC), which is the bearer to realize services by implementing the SC service logic module. The SC service logic interacts with mobile core network through the session initiation protocol (SIP)‐based session control module and the SIP Callback module.Findings – The push to talk over cellular service is used to illustrate how the proposed OSA SCS interacts with the AS and the mobile core network elements.Practical implications – In the design, when implementing a new service (i.e. to create a new SCS), one only needs to create the Call...

JRC: jitter‐based rate control scheme for wired‐wireless hybrid network

Abstract: Purpose – Emerging real‐time multimedia services over IP have penetrated into the daily lives of normal people with the advent of advanced broadband communications and innovated interconnection technologies. To protect shared Internet from unfairness and further congestion collapse, rate control plays a crucial role for many multimedia services such as streaming applications. Streaming applications such as video on demand (VoD) or voice over IP (VoIP) services face some critical problems such as insufficient bandwidth and improper performance of transmission protocols. Besides, the new generation networks are anticipated to integrate all heterogeneous wired and wireless networks and offer seamless customized multimedia services anywhere, anytime. However, wireless networks usually with low and variable bandwidth, and non‐congestion related loss do bring the challenge to the existing transport protocol, such as TCP, TFRC etc.Design/methodology/approach – The paper uses simulations and compares other method...

HoNeY: leveraging the MHP to provide HOme NEtwork interoperabilitY

Abstract: Purpose – Home networks enable, potentially, an increased level of integration among appliances present in the house, enabling an ubiquitous control of devices and simplifying man/machine interactions. This paper aims to present the home network interoperability (HoNeY) platform.Design/methodology/approach – Home networks and their challenges are analyzed, then the technology that constitutes the base for the present implementation is briefly revised. The HoNeY platform is presented, in terms of its architecture, implementation, and constraints.Findings – The HoNeY platform is an multimedia home platform (MHP)‐based, low‐complex, cost‐effective architecture for automatic discovery, configuration, and dynamic access to distributed services in home environments.Originality/value – This paper describes HoNeY, a mechanism of service discovery and code mobility designed for interoperability of devices connected to home networks, compatible with the MHP standard.

Adaptive attenuation factor model for localization in wireless sensor networks

Abstract: Purpose – The accuracy of sensor location estimation influences directly the quality and reliability of services provided by a wireless sensor network (WSN). However, current localization methods may require additional hardware, like global positioning system (GPS), or suffer from inaccuracy like detecting radio signals. It is not proper to add extra hardware in tiny sensors, so the aim is to improve the accuracy of localization algorithms.Design/methodology/approach – The original signal propagation‐based localization algorithm adopts a static attenuation factor model and cannot adjust its modeling parameters in accordance with the local environment. In this paper an adaptive localization algorithm for WSNs that can dynamically adjust ranging function to calculate the distance between two sensors is presented. By adjusting the ranging function dynamically, the location of a sensor node can be estimated more accurately.Findings – The NCTUNs simulator is used to verify the accuracy and analyze the performa...

An improved efficient performance design with multiple channels and bandwidth allocation strategy for mobile ad hoc networks

Abstract: Purpose – In this paper, the design of multiple channels to achieve the goal of a high‐performance medium access control (MAC) protocol is to be proposed to solve the problem of wasting bandwidth resources due to waiting for the backoff time.Design/methodology/approach – In the MAC design of this paper, a control channel and a data channel are used to improve bandwidth utilization. When the control channel waits for the backoff time, the data channel may transfer data. As a result, bandwidth utilization can be improved. In order to have better bandwidth utilization in multiple channels, the authors also propose a bandwidth allocation strategy for control channels and data channels. According to the strategy, the control and data signals can be smoothly transmitted without blocking or waiting, thereby not wasting bandwidth resources. Finally, the authors propose multiple control sub‐channels and data sub‐channels to further reduce the backoff time penalty and make more communication pairs work in a transmi...

A speech and character combined recognition engine for mobile devices

Abstract: Purpose – The purpose of this paper is to describe a speech and character combined recognition engine (SCCRE) developed for working on personal digital assistants (PDAs) or on mobile devices. Also, the architecture of a distributed recognition system for providing a more convenient user interface is discussed.Design/methodology/approach – In SCCRE, feature extraction for speech and for character is carried out separately, but the recognition is performed in an engine. The client recognition engine essentially employs a continuous hidden Markov model (CHMM) structure and this CHMM structure consists of variable parameter topology in order to minimize the number of model parameters and to reduce recognition time. This model also adopts the proposed successive state and mixture splitting (SSMS) method for generating context independent model. SSMS optimizes the number of mixtures through splitting in mixture domain and the number of states through splitting in time domain.Findings – The recognition results s...

A model for context‐aware applications

Abstract: Purpose – Context correctness and fault handling are very important to the quality of service in context‐aware applications. However, they are often ignored by researchers and application developers. This paper aims to present a model for context‐aware applications.Design/methodology/approach – This paper proposes a transaction model for context‐aware applications, in order to provide a uniform infrastructure for service quality management.Findings – The paper finds that, in this model, context‐aware applications are organized as a number of logic units and each unit may have a compensation module, which will be executed when errors or exceptions occur during the execution of those applications in order to minimize the bad infection. This model supports nested scopes and the number of levels of subtransactions is unlimited.Practical implications – The paper also presents an implementation of this transaction model, which is specialized for context‐aware use.Originality/value – This paper utilized a novel ...

Scalable and adaptive context delivery mechanism for context‐aware computing

Abstract: Purpose – Presence of innumerable sensors, complex deduction of contexts from sensor data, and reusability of contextual information impose the requirement of middleware for context aware computing. Smart applications, hosted in myriad devices (e.g. PDA, mobile, PCs), acquire different contexts from the middleware and act intelligently based on the available contexts in a context‐aware computing environment. As the system grows larger, scalable delivery of contexts from the middleware to numerous context‐aware applications will be inevitable. However, pure unicast based or pure broadcast‐based dissemination cannot provide high scalability as well as low‐average latency. The purpose of this paper is to present a scalable context delivery mechanism for the middlewares to facilitate the development of larger context‐aware computing systems.Design/methodology/approach – The proposed scheme is based on hybrid data dissemination technique where the most frequently requested data (e.g. HOT contexts) are delivere...

A visual framework for deploying and managing context‐aware services

Abstract: Purpose – The purpose of this paper is to present a component framework for building visual interfaces for pervasive computing systems.Design/methodology/approach – The proposed framework enables end‐users to build visual interfaces for their systems by using document‐editing manner.Findings – The building and operating visual interfaces are useful for managing pervasive computing systems.Research limitations/implications – The framework is designed based on Java but programming language‐independent version is needed.Practical implications – A component framework was implemented for building visual interfaces for pervasive computing.Originality/value – A framework for visual interfaces for pervasive computing is unique.