共查询到20条相似文献,搜索用时 31 毫秒
1.
Ultra wideband (UWB) systems are considered as the key wireless infrastructure platforms for efficient short-range communications.
In particular, the UWB based mobile computing systems are envisioned to be attractive solutions to various ad hoc networking
applications. However, due to UWB’s unique physical characteristics, the traditional resource management schemes for ad hoc
networks cannot be applied to UWB based systems directly. In this paper, we consider the bandwidth scheduling problem in a
UWB based hierarchical wireless ad hoc network, which is typically used in an enterprise-scale mobile computing environment.
Based on the mathematical analysis and the computer simulations, it is demonstrated that our proposed scheduling scheme exhibits
close-to-optimal performance governed by the proportional fairness (PF) constraint. Moreover, a novel self-organized clustering
method is designed to improve the system throughput while meeting the PF constraint. Simulation results suggest that the proposed
clustering method is effective under various system configurations.
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2.
Awareness systems have attracted significant research interest for their potential to support interpersonal relationships.
Investigations of awareness systems for the domestic environment have suggested that such systems can help individuals stay
in touch with dear friends or family and provide affective benefits to their users. Our research provides empirical evidence
to refine and substantiate such suggestions. We report our experience with designing and evaluating the ASTRA awareness system,
for connecting households and mobile family members. We introduce the concept of connectedness and its measurement through
the Affective Benefits and Costs of communication questionnaire (ABC-Q). We inform results that testify the benefits of sharing
experiences at the moment they happen without interrupting potential receivers. Finally, we document the role that lightweight,
picture-based communication can play in the range of communication media available.
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3.
In this paper, we present a new kind of mobile ad hoc application, which we call mobile profile based distributed grouping (MoPiDiG), which is a combination of mobile clustering and data clustering. In MoPiDiG, each mobile host is endowed with a user profile and, while the users move around, hosts with similar profiles are found and a robust mobile group is formed. The members of a group are able to cooperate with each other or attain a goal together. In this article, MoPiDiG is defined and compared with related approaches. Furthermore, a modular architecture and algorithms are presented to build arbitrary MoPiDiG applications. 相似文献
4.
A wireless sensor network (WSN) consists of a large number of small devices with computational power, wireless communication
and sensing capability. These networks have been developed for a wide range of applications, such as habitat monitoring, object
tracking, precision agriculture, building monitoring and military systems. Meanwhile, middleware systems have also been proposed
in to facilitate both the development of these applications and provide common application services. The development of middleware
for sensor networks, however, places new challenges on middleware developers due to the low availability of resources and
processing capacity of the sensor nodes. In this context, this paper presents the design and implementation of a middleware
for WSN named Mires. Mires incorporates characteristics of message-oriented middleware by allowing applications communicate
in a publish/subscribe way. In order to illustrate the proposed middleware, we have also developed an environment-monitoring
application and a data aggregation service.
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5.
In this paper, we present a new model for time-series forecasting using radial basis functions (RBFs) as a unit of artificial neural networks (ANNs), which allows the inclusion of exogenous information (EI) without additional pre-processing. We begin by summarizing the most well-known EI techniques used ad hoc, i.e., principal component analysis (PCA) and independent component analysis (ICA). We analyze the advantages and disadvantages of these techniques in time-series forecasting using Spanish bank and company stocks. Then, we describe a new hybrid model for time-series forecasting which combines ANNs with genetic algorithms (GAs). We also describe the possibilities when implementing the model on parallel processing systems. 相似文献
6.
We provide evidence of the feasibility and effectiveness of a middleware architecture for mobile devices (MoDs), which employs
dense distributions of small computerized entities for providing fault-tolerant location-aware services. We do so by describing
exemplary implementations based on radio frequency identification as an enabling technology. Firstly, we present prototypical
implementations of the hardware abstraction layer and of selected core middleware services. The latter enable a MoD to store
and retrieve data and position information in physical places in a fault-tolerant manner, and to identify places based on
a location abstraction which is robust against failure of individual tags. Secondly, we investigate the feasibility of some
higher-level services and applications by developing and evaluating prototypical systems for tracing and tracking, self-positioning,
and collaborative map-making.
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7.
We present an approach to connect multiple remote environments over web for natural interaction among people and objects.
Focus of current communication and telepresence systems severely restrict user affordances in terms of movement, interaction,
peripheral vision, spatio-semantic integrity and even information flow. These systems allow information transfer rather than
experiential interaction. We propose Environment-to-Environment (E2E) as a new paradigm for communication which allows users
to interact in natural manner using text, audio, and video by connecting environments. Each Environment is instrumented using
as many different types of sensors as may be required to detect presence and activity of objects. This object position and
activity information is used by a scalable event-based multimodal information system called EventServer to share the appropriate
experiential information with other environments as well as to present incoming multimedia information on right displays and
speakers. This paper describes the design principles for E2E communication, discusses system architecture, and gives our experience
in implementing prototypes of such systems in telemedicine and office collaboration applications. We also discuss the research
challenges and a road-map for creating more sophisticated E2E applications in near future.
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8.
This paper describes a prototype system, ZoneIT, for selectively controlling the functionality of mobile devices, e.g. the
ringing of cellular telephones. ZoneIT exploits the fact that many such devices have short-range radio communication systems
(e.g. Bluetooth and ZigBee). It uses such radio systems to allow these devices to communicate with Base Stations to learn
what functionality is permissible in a particular zone. ZoneIT is secured by a process that enables mobile devices to authenticate
base stations, and so protect against denial of service attacks.
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9.
There is a fundamental difference between wireless and wired networks, since the latter employ point-to-point communication while the former use broadcast transmission as the communication primitive. In this paper, we describe an algorithm, called self-selection, which takes advantage of broadcast communication to efficiently implement the basic operation of selecting a node possessing some desired properties among all the neighbors of the requestor. Self-selection employs a prioritized transmission back-off delay scheme in which each node’s delay of transmitting a signal is dependent on the probability of the node’s ability to best perform a pertinent task, and in turn, enables the node to autonomously select itself for the task. We demonstrate the benefits of self-selection in two basic wireless ad hoc network communication algorithms: flooding and routing. By relating back-off delay to the signal strength of a received packet, we design an efficient variant of conventional flooding called Signal Strength Aware Flooding. By using distance-to-destination to derive back-off delay, we design a novel and fault-tolerant wireless ad hoc network routing protocol named Self-Selective Routing. 相似文献
10.
Increased network speeds coupled with new services delivered via the Internet have increased the demand for intelligence and
flexibility in network systems. This paper argues that both can be provided by new hardware platforms comprised of heterogeneous
multi-core systems with specialized communication support. We present and evaluate an experimental network service platform
that uses an emergent class of devices—network processors—as its communication support, coupled via a dedicated interconnect
to a host processor acting as a computational core. A software infrastructure spanning both enables the dynamic creation of
application-specific services on the network processor, mediated by middleware and controlled by kernel-level communication
support. Experimental evaluations use a Pentium IV-based computational core coupled with an IXP 2400 network processor. The
sample application services run on both include an image manipulation application and application-level multicasting.
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11.
Communication is in this paper seen as the foundation for purposeful human–human activity in dynamic environments. Coordination
is a central issue in large systems such as military organisations, enterprises, or rescue organisations, and communication
is needed in order to achieve coordination in such systems. This paper suggest a holistic approach to control, where control
in a large system is seen as an emergent product of human interaction, focusing on human–human communication from a technical,
organisational, temporal, and social perspective.
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12.
Computer-supported discursive learning (CSDL) systems for the support of asynchronous discursive learning need to fulfil specific
socio-technical conditions. To understand these conditions, we employed design experiments combining aspects of communication
theory, empirical findings, and continuous improvement of the investigated prototypes. Our theoretical perspective starts
with a context-oriented model of communication which is—as a result of the experiments—extended by including the role of a
third-party such as a facilitator. The theory-driven initial design requirements lead to the CSCL-prototype, KOLUMBUS, emphasizing
the role of annotations. In KOLUMBUS, annotations can be immediately embedded in their context of learning material. Practical
experience with the prototype in five cases reveals possibilities for implementing improvements and observing their impact.
On this basis, we provide guidelines for the design of CSDL systems that focus on the support of asynchronous discursive learning.
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13.
A novel routing protocol for wireless, mobile ad hoc networks is presented. This protocol incorporates features that enhance routing reliability, defined as the ability to provide almost 100% packet delivery rate. The protocol is based on a virtual structure, unrelated to the physical network topology, where mobile nodes are connected by virtual links and are responsible for keeping physical routes to their neighbors in the virtual structure. Routes between pairs of mobiles are set up by using information to translate virtual paths discovered in the virtual structure. Route discovery and maintenance phases of the protocol are based on unicast messages travelling across virtual paths, with sporadic use of flooding protocol. Most flooding is executed in the background using low priority messages. The routing protocol has been evaluated and compared with the Dynamic Source Routing protocol and with the Zone Routing Protocol by means of simulation. 相似文献
14.
P2P (Peer-to-Peer) overlay is a promising distributed computing and communication paradigm that allows for a group of participants
to share information and coordinate their resources. Dissemination of information among end users can also be greatly facilitated
by the publish/subscribe model. In this paper, we employ the publish/subscribe model in a P2P mobile tactical networking environment.
Considering the particular requirements for mobile tactical networks, we investigate the problem of subscriber mobility management
and propose a novel proactive handoff approach for improved system responsiveness and reliability. A comprehensive performance
evaluation of the proposed mechanism is presented. The obtained results demonstrate significant performance benefits of the
proposed scheme.
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15.
Research on peer-to-peer (P2P) networks has attracted much attention recently. A key factor is their ability to handle dynamics
in the system in a distributed fashion, including ad hoc and dynamic join and departure of the peers and dynamic changes in
the underlying network environment. As more and more innovating P2P applications appear, the need to support intuitive communication
and synchronization among the peers in the P2P system becomes imperative. In this paper, we discuss how to build a tuple space
on top of P2P systems and use on-line games as a target application. A simple API is supported for accessing the data stored
in the tuple space and communicating between the peers. Through experiments and a demonstration game, we show that our system
can facilitate the development of network games in a fully distributed environment.
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16.
The European Union co-funded COMUNICAR (communication multimedia unit inside car) project designed and developed an integrated multimedia human–machine interface (HMI) able to manage a wide variety of driver information systems (from entertainment to safety). COMUNICAR proposed an innovative information provision paradigm, in which the on-vehicle HMI is able to tailor the delivery of the information in real time according to the actual driving context and the drivers workload. COMUNICAR adopted a user-centred design process involving an iterative development based on extensive user tests since the early phases of the project. This approach was particularly useful to define and improve the layout of the user interface and specify the rules that decide the scheduling and the modalities of the delivery of the information messages to the driver. This paper introduces the COMUNICAR concept and the user-centred flow of design. Then, a concrete case of user-test driven, iterative improvement of a systems functionality is presented. We also briefly describe two software tools that we have designed to enhance the development process in a user-centred perspective. Finally, the future evolution of the concept of smart and safe information scheduling is sketched and discussed. 相似文献
17.
Quantitative usability requirements are a critical but challenging, and hence an often neglected aspect of a usability engineering process. A case study is described where quantitative usability requirements played a key role in the development of a new user interface of a mobile phone. Within the practical constraints of the project, existing methods for determining usability requirements and evaluating the extent to which these are met, could not be applied as such, therefore tailored methods had to be developed. These methods and their applications are discussed. 相似文献
18.
We present a study of using camera-phones and visual-tags to access mobile services. Firstly, a user-experience study is described in which participants were both observed learning to interact with a prototype mobile service and interviewed
about their experiences. Secondly, a pointing-device task is presented in which quantitative data was gathered regarding the speed and accuracy with which participants aimed and clicked
on visual-tags using camera-phones. We found that participants’ attitudes to visual-tag-based applications were broadly positive,
although they had several important reservations about camera-phone technology more generally. Data from our pointing-device
task demonstrated that novice users were able to aim and click on visual-tags quickly (well under 3 s per pointing-device
trial on average) and accurately (almost all meeting our defined speed/accuracy tradeoff of 6% error-rate). Based on our findings,
design lessons for camera-phone and visual-tag applications are presented.
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19.
We introduce a system for sensing complex social systems with data collected from 100 mobile phones over the course of 9 months.
We demonstrate the ability to use standard Bluetooth-enabled mobile telephones to measure information access and use in different
contexts, recognize social patterns in daily user activity, infer relationships, identify socially significant locations,
and model organizational rhythms.
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20.
Tracking location is challenging due to the numerous constraints of practical systems including, but not limited to global
cost, device volume and weight, scalability and accuracy; these constraints are typically more severe for systems that should
be wearable and used indoors. We investigate the use of wearable solar cells to track changing light conditions (a concept
that we named LuxTrace) as a source of user displacement and activity data. We evaluate constraints of this approach and present
results from an experimental validation of displacement and activity estimation. The results indicate that a distance estimation
accuracy of 21 cm (80% quantile) can be achieved. A simple method to combine LuxTrace with complementary absolute location
estimation methods is also presented. We apply carpet-like distributed RFID tags to demonstrate online learning of new lighting
environments.
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