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Mobile Data Management, 2002. Proceedings. Third International Conference on

Date 11-11 Jan. 2002

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  • Proceedings Third International Conference on Mobile Data Management MDM 2002

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    The following topics are dealt with: mobile data management; mobile and disconnected operation; e-commerce; data allocation and replication; moving objects; and location management and awareness. View full abstract»

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  • Author index

    Page(s): 175
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    Freely Available from IEEE
  • A strategy for efficient access of multiple data items in mobile environments

    Page(s): 71 - 78
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    Many approaches have been proposed to schedule data items for broadcasting in a mobile environment. However, the issues of accessing multiple data items on the broadcast channel are less discussed. In this paper, an efficient strategy for accessing multiple data items in mobile environments is proposed. Two issues are investigated in this paper, that is, deciding the content of the broadcast channel based on the queries from the clients, and scheduling the data items to be broadcast. Experiments are performed to compare our proposed methods for deciding the content and to show that our data scheduling methods can reduce the average access time without considerable increase on processing time. View full abstract»

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  • Design of compiler for mobile environment and its formalization using evolving algebra

    Page(s): 159 - 160
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    A challenging area of ubiquitous wireless computing is the provision of system software for mobile programmers. We propose a software architecture for a compiler in a mobile environment. The solution does not require lower level details of the wireless communication, protocols and hardware platform of mobile computers. The design takes into consideration the resource constraints of the mobile host. In our architecture, we break down the compiler into two major independent modules, one kept at the mobile host keeping in view frequent intervention of the mobile programmer and the other kept at the static host to generate codes suitable for different configurations of the mobile host. The paper describes formalization of the compiler using evolving algebra at various abstraction levels. View full abstract»

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  • A reconfigurable stream orchestration framework for mobile users

    Page(s): 35 - 42
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    We present a framework for supporting multi-device stream orchestration for mobile users. As computing power becomes cheaper and larger numbers of devices become networked, we believe that users will have access to multiple devices in their neighborhood. Such a multi-device environment presents a significantly powerful environment for mobile users compared to thin wireless clients. Our architecture enables a mobile user to treat these disparate devices as a virtually integrated entity, enabling the user to experience rich communication sessions. The framework automatically detects devices in a user's neighborhood, understands their capabilities, transparently transforms content and routes a session to multiple devices based on their capabilities. We describe the problem space, our architecture and implementation experience. View full abstract»

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  • Disseminating data in unreliable wireless environment

    Page(s): 157 - 158
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    In this paper, we reexamine the issue of selective tuning using the flexible indexing scheme by T. Imielinski et al. (1994) in the context of unreliable wireless channels. We propose a mechanism that can be applied to uniform and nonuniform broadcast to enable a client using the scheme to recover from errors. View full abstract»

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  • Building Internet marketplaces on the basis of mobile agents for parallel processing

    Page(s): 53 - 60
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    In this paper, we propose a framework of Internet marketplaces on the basis of mobile agent. It not only simulates real commercial activities by consumers, agents and merchants, but also provides an environment for parallel processing. The latter is particularly important as more shops (sites) can be searched in real time to provide consumers with better choices. The conducted experiments show that, in comparison with several serial mobile agent models, parallel mobile agent model can improve the performance significantly. View full abstract»

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  • Adaptable consistency control mechanism for a mobility enabled file system

    Page(s): 27 - 34
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    Most existing distributed file systems (DFS) implement a single consistency model to maintain one-copy equivalence. The functionality of that consistency model is based on a balance between environmental constraints and the targeted level of consistency. Such systems efficiently maintain consistency while the environmental capabilities remain constant, for example, presuming uninterrupted connectivity. However when these characteristics change, the inflexible nature of a single consistency model results in its inability, to maintain an expected balance between consistency and constraints. GLOMAR is a DFS middleware layer that allows application developers to map their specific consistency models to environmental constraints. As a result, multiple consistency models can be created, with each scoped for a particular application and environmental scenario. The paper outlines important aspects of GLOMAR, detailing its implementation and outlining a consistency model implementation based on Web services and the SOAP protocol. View full abstract»

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  • Dynamic mobile IP and Nice-TCP for improving TCP/IP performance

    Page(s): 163 - 164
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (243 KB) |  | HTML iconHTML  

    Mobile IP is an Internet protocol designed to support host mobility. It provides the host the ability to stay connected to the Internet regardless of its location. This paper presents a modified Mobile IP protocol, (Dynamic Mobile (IP-DM-IP)). DM-IP eliminates triangular routing, which exists in current Mobile IP and it can be easily implemented in the existing wireless infrastructure. In DM-IP the packets can be sent directly from the communicating host to the mobile node bypassing the "home agent". We also present a TCP protocol (Nice TCP (N-TCP)), which considers the packet losses due to mobility and wireless errors. The congestion control criteria are modified so that by default the TCP does not need to invoke congestion control algorithm if a packet is dropped. We show that N-TCP also works for Mobile ad hoc networks. View full abstract»

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  • Broadcast transaction scheduling in mobile computing environments

    Page(s): 161 - 162
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    Most of the recent studies on broadcast based data dissemination approach have an implicit assumption that the server is able to broadcast consistent data to the mobile clients. However, this assumption may not be valid unless there is a special algorithm to handle broadcasting data in a consistent and timely manner. In this work, we address a number of issues related to this problem. An efficient algorithm called the read-write set test is adopted to read the entire database, which causes little interference with the update transactions at the server. For broadcast transaction scheduling, an algorithm based on a mixed strategy is proposed to handle the case of flat broadcast disks. Using these two algorithms together with some fine tuning, the objectives of reading entire database consistently with minimum impact to the system, broadcasting fresh data, and meeting the periodicity requirement can be met. View full abstract»

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  • Index and data allocation on multiple broadcast channels considering data access frequencies

    Page(s): 87 - 93
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    In a wireless environment, the bandwidth of the channels and the energy of the portable devices are limited. Data broadcast has become an excellent method for efficient data dissemination. In this paper the problem for generating a broadcast program of a set of data items with the associated access frequencies on multiple channels is explored. In our approach, we consider allocating index information and data items on multiple broadcast channels by extending the distributed indexing approach. Moreover global data replication and local data allocation are performed to improve the average access time of all data items. Simulation is performed to compare the performance of our approach with an existing approach. The result of the experiments shows that our approach outperforms the existing approach. View full abstract»

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  • Allocation of shared data based on mobile user movement

    Page(s): 105 - 112
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    In this paper we devise data allocation algorithms that can utilize the knowledge of user moving patterns for proper allocation of shared data in a mobile computing system. By employing the data allocation algorithms devised, the occurrences of costly remote accesses can be minimized and the performance of a mobile computing system is thus improved The data allocation algorithms for shared data, which are able to achieve local optimization and global optimization, are developed. Local optimization refers to the optimization that the likelihood of local data access by an individual mobile user is maximized whereas global optimization refers to the optimization that the likelihood of local data access by all mobile users is maximized By exploring the corresponding features, we devise algorithm SD-local and algorithm SD-global to achieve local optimization and global optimization, respectively. The simulation results show that the knowledge obtained from the user moving patterns is very important in devising effective data allocation algorithms which can lead to prominent performance improvement in a mobile computing system. View full abstract»

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  • Semantic data access in an asymmetric mobile environment

    Page(s): 94 - 101
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    The mobile environment is inherently asymmetric. To utilize the downstream bandwidth effectively, hot data items should be disseminated over the broadcast channel to the mobile clients. To equip clients with the ability to identify the nature of the broadcast and to determine the answerability of their queries, semantic descriptions are associated with information units in the broadcast, organized into data chunks. Based on the nature of data items received over the broadcast, clients can initiate appropriate requests to make up for the remaining items over the back channels in an on-demand basis. We investigation into several semantic-based algorithms to organize data chunks and compare their performance with traditional data item-based organization in the asymmetric environment. View full abstract»

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  • UCS-Router: a policy engine for enforcing message routing rules in a universal communication system

    Page(s): 8 - 15
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    UCS-Router (E. Bertino et al.) is a policy engine developed for message dispatching in a Universal Communication System. A user of the system has a unique identifier, named Universal Communication Identifier (UCI), independent from the actual communication devices the user owns. It is a task of the UCS-Router to properly route messages or phone calls arriving at the UCI to the proper user devices. The routing process is performed according to policies the user specifies on the type of message, on the device capabilities and states, on the sender characteristics, and on the message sending time. We present a declarative policy language developed for UCS-Router. Users of UCS-Router can use this language for specifying message filtering and routing policies. Moreover, we present issues that can arise in the evaluation process of the policies. Such issues are primarily due to the high expressiveness of the language and to the possibility to handle a great variety of message media format. Finally, we present how the UCS-Router addresses such issues. View full abstract»

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  • Replica allocation in ad hoc networks with periodic data update

    Page(s): 79 - 86
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    Recent advances in computer and wireless communication technologies have led to an increasing interest in ad hoc networks which are temporarily constructed by only mobile hosts. In ad hoc networks, since mobile hosts move freely, disconnections occur frequently, and this causes frequent network division. Consequently, data accessibility in ad hoc networks is lower than that in the conventional fixed networks. Assuming an environment where each data item is periodically updated, we propose three replica allocation methods to improve data accessibility by replicating data items on mobile hosts. In these three methods, we take into account the access frequency from mobile hosts to each data item, the status of the network connection, and the time remaining until each item is updated next. We also show the results of simulation experiments regarding the performance evaluation of our proposed methods. View full abstract»

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  • iQueue: a pervasive data composition framework

    Page(s): 146 - 153
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    There will soon be a huge number of data sources accessible to applications across the Internet. These include Web services, personal devices such as cellular phones and cars, and sensors measuring physical phenomena. New classes of data-composition applications can exploit this data. However, the data is diverse, voluminous, and often rapidly changing. The sources of data can be mobile, distributed, and failure-prone. Without system support, applications that use this kind of data are difficult to write. The iQueue data composition framework provides system support for data composition, thereby making the task of writing applications easier. View full abstract»

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  • User behavior analysis of location aware search engine

    Page(s): 139 - 145
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    The rapid growth of Internet access from mobile users has emphasised the importance of location specific information on the Web. A unique Web service called Mobile Info Search (MIS) from NTT Laboratories gathers information and provides location aware search facilities. We performed association rule mining and sequence pattern mining against an access log which was accumulated at the MIS site in order to get insight into the behavior of mobile users regarding spatial information on the Web. Details of the Web log mining process and the rules we derived are reported in this paper. View full abstract»

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  • Indexing the current positions of moving objects using the lazy update R-tree

    Page(s): 113 - 120
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    With the rapid advances of wireless communications and positioning techniques, tracking the positions of moving objects is becoming increasingly feasible and necessary. Traditional spatial index structures are not suitable for storing these positions because of numerous update operations. To reduce the number of update operations, many existing approaches use a linear function to describe the movements of objects. In many real applications, however, the movements of objects are too complicated to be represented as a simple linear function. In this case, such approaches based on a linear function cannot reduce update cost efficiently. In this paper we propose a novel R-tree based indexing technique called LUR-tree. This technique updates the structure of the index only when an object moves out of the corresponding MBR (minimum bounding rectangle). If a new position of an object is in the MBR, it changes only the position of the object in the leaf node. It can update the position of the object quickly and reduce update cost greatly. Since it is based on the R-tree, the LUR-tree also uses the same algorithms to process various types of queries as the R-tree. We present the experimental results which show that our technique outperforms other techniques. View full abstract»

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  • BlueLocator: enabling enterprise location-based services

    Page(s): 167 - 168
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    BlueLocator, a framework enabling enterprise location-based services as well as an enterprise user locating and tracking system, is introduced in this paper. Privacy control in LBS is discussed and a report-to-chain based access control list assignment policy is shown as an example of how a privacy related rule can be used for applications. View full abstract»

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  • Dispatching multiple mobile agents in parallel for visiting e-shops

    Page(s): 61 - 68
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    The mobile agent approach is suitable for deploying large-scale parallel processing over distributed hosts. However, if the number of mobile agents is very large and the dispatch is processed in a serial way, it can become a bottleneck that impacts the efficiency as a whole. In this paper, we first briefly present a mobile agent based framework for Internet marketplaces enabling parallel processing. Then we present and discuss several hierarchical dispatch models where the dispatch of multiple mobile agents can be processed in parallel over different hosts. In the best case, the time complexity for dispatching n mobile agents is O(log2n). Discussions of these models are taken on the basis of theoretical analysis and experiments. View full abstract»

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  • Research challenges in location-enabled m-services

    Page(s): 3 - 7
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    Rapid, sustained advances in key computing hardware technologies combine to enable a new class of computing services that aim to meet the needs of mobile users. These ubiquitous and intelligent services adapt to each user's particular preferences and current circumstances, i.e., they are personalized. The services exploit data available front multiple sources, including data on past interactions with users, data accessible via the Internet, and data obtained from sensors. The user's geographical location is particularly central to these services. We outline some of the research challenges that aim to meet the computing of such services. In particular, focus is on update and query processing in the context of georeferenced data, where certain challenges related to the data representation, indexing and precomputation are described. View full abstract»

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  • MobileIQ: a framework for mobile information access

    Page(s): 43 - 50
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    We address issues related to mobility, personalization and asynchronous operation to support efficient access to the World Wide Web across weakly connected or low bandwidth wireless links. WWW provides a large globally, distributed computing and information access infrastructure. With the large amount of accessible information came the problem of information overload, making the process of finding content of interest a difficult issue. This is further exacerbated in mobile environments because of the well known resource constraints. We have developed MobileIQ, a distributed system and service infrastructure that can offer personalized mobile information access in a wireless network environment. MobileIQ addresses challenges unique to a mobile environment such as mobility management and disconnection management, in addition to issues common to all environments: content personalization, bandwidth utilization, download latencies, and user privacy. We also demonstrate how this architecture may be used to provide location-based services to users of the MobileIQ system. View full abstract»

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  • An approach to disconnected operation in an object-oriented database

    Page(s): 19 - 26
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    With the advent of mobile computers, new challenges arise for software designers. The paper focuses on disconnected operation: making mobile computers work well on shared data whether the network is available or not. Initially the shared data is cached on the mobile computer. Modifications and additions to this cached data will be reconciled with the shared data when the mobile computer is reconnected to the network. Conflict resolution will be used to reconcile conflicting changes. We examine these issues by adding support for disconnected operation to Thor an object-oriented database. View full abstract»

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  • Location aggregation from multiple sources

    Page(s): 131 - 138
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    Tracking the location of people, computers, vehicles, and other mobile objects and performing computation on such location data are quickly gaining interest. The idea of location-based services has captured the imagination of application developers, wireless service providers, and content providers alike. However, the location of people, the most interesting mobile object, is tricky to determine because we don't track persons but rather the devices they carry or the transportation they use. That a person may be associated with numerous tracking devices simultaneously, but perhaps intermittently, makes location tracking challenging. We describe a methodology for aggregating location data from multiple sources associated with a single mobile object. We describe our existing location service infrastructure and illustrate scenarios where location aggregation is desirable and indeed required. Our experimentation in location-based services uses location data from wireless PDAs, vehicle tracking devices, and mobile and stationary computers. View full abstract»

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  • Query processing for moving objects with space-time grid storage model

    Page(s): 121 - 128
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    With the growing popularity of mobile computing devices and wireless communications, managing dynamically changing information about moving objects is becoming feasible. In this paper we implement a system that manages such information and propose an efficient range query algorithm with a filtering step which efficiently determines if a polyline corresponding to the trajectory of a moving object intersects with a given range. We study the performance of the system, which shows that despite the filtering step, for moderately large ranges, the range query algorithm we propose outperforms the algorithm without filtering. View full abstract»

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