50 resultados para 3G mobile communication


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With the seamless diffusion and acceptance of mobile phones into people's everyday life as trusted communication devices, businesses have begun exploring their potential as payment devices. In this paper, we report on the findings from a pioneering study conducted in Australia, which explored inhibitors and facilitators in the adoption of mobile phones as payment devices.

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Mobile computing has enabled users to seamlessly access databases even when they are on the move. However, in the absence of readily available high-quality communication, users are often forced to operate disconnected from the network. As a result, software applications have to be redesigned to take advantage of this environment while accommodating the new challenges posed by mobility. In particular, there is a need for replication and synchronization services in order to guarantee availability of data and functionality, (including updates) in disconnected mode. To this end we propose a scalable and highly available data replication and management service. The proposed replication technique is compared with a baseline replication technique and shown to exhibit high availability, fault tolerance and minimal access times of the data and services, which are very important in an environment with low-quality communication links.

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A simple distributed power control algorithm for communication systems with mobile users and unknown time-varying link gains is proposed. We prove that the proposed algorithm is exponentially converging. Furthermore, we show that the algorithm significantly outperforms the well-known Foschini and Miljanic algorithm in the case of quickly moving mobile users.

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Wireless sensor networks represent a new generation of real-time  embedded systems with significantly different communication constraints from the traditional networked systems. With their development, a new attack called a path-based DoS (PDoS) attack has appeared. In a PDoS attack, an adversary, either inside or outside the network, overwhelms sensor nodes by flooding a multi-hop endto- end communication path with either replayed packets or injected spurious packets. In this article, we propose a solution using mobile agents which can detect PDoS attacks easily.

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Wireless sensor networks represent a new generation of real-time embedded systems with significantly different communication constraints from the traditional networked systems. With their development, a new attack called a path-based DoS (PDoS) attack has appeared. In a PDoS attack, an adversary, either inside or outside the network, overwhelms sensor nodes by flooding a multi-hop end-to end communication path with either replayed packets or injected spurious packets. Detection and recovery from PDoS attacks have not been given much attention in the literature. In this article, we propose a solution using mobile agents which can detect PDoS attacks easily and efficiently and recover the compromised nodes.

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The current penetration of mobile phones in Australia is 92% and it records one of the world’s highest rates of ownership among children under 18. The paper reviews the literature on mobile phones and Australian children and examines the various discourses dominating the public debates; the systematic frames used in these discourses; and whose interests are served in the process. The frames discussed fall under the optimistic (gains); pessimistic (losses, costs or harms); pluralistic (technology per se is neutral but how it is used matters); historical development (skills learnt and the importance of using mobiles); futuristic predictions (promises and dangers for the future); current uses (connectivity, convergence and interactivity); and the techno-realist view (as a mixed blessing) views of technology. Taking the critical perspective and borrowing from Joshua Meyrowitz, the paper illustrates how mobile phones have eroded parental power over how, when, where and with whom their children communicate, surpassing adult supervision, intervention or knowledge, while at the same time, becoming a ‘digital leash’ for parents to re-establish their control an d an ‘umbilical cord’ for their off spring to remain connect! ed with parents, at all times.

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The authors present a novel and efficient multicast algorithm that aims to reduce delay and communication cost for the registration between mobile nodes and mobility agents and solicitation for foreign agent services based on the mobile IP. The protocol applies anycast group technology to support multicast transmissions for both mobile nodes and home/foreign agents. Mobile hosts use anycast tunnelling to connect to the nearest available home/foreign agent where an agent is able to forward the multicast messages by selecting an anycast route to a multicast router so as to reduce the end-to-end delay. The performance analysis and experiments demonstrated that the proposed algorithm is able to enhance the performance over existing remote subscription and bidirectional tunnelling approaches regardless of the locations of mobile nodes/hosts

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Recent advances m hardware technologies such as portable
computers and wireless communication networks have led to the emergence of mobile computing systems. Thus, availability and accessibility of the data and services become important issues of mobile computing systems. In this paper, we present a data replication and management scheme tailored for such environments In the proposed scheme data is replicated synchronously over stationary sites while for the mobile network, data is replicated asynchronously based on commonly visited sites for each user. The proposed scheme is compared with other techniques and is shown to require less communication cost for an operation as well as provide higher degree of data availability.

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Next generation networks (3G & beyond) will support real-time multimedia applications through traditional wide-area networking concepts as well as hot-spot (WLAN) and ad hoc networking concepts. In order to fulfill the vision of next generation networks a method of maintaining a real-time flow despite frequent topology changes and irregularity in user movement is required. Mobility prediction has been identified as having applications in the areas of link availability estimation and pro-active routing in ad hoc networks. In this work we present the mobility prediction based algorithm for route maintenance in mobile ad hoc networks. Simulation study of the algorithm proves it to offer significant benefits to dynamic source routing (DSR)

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A simple distributed power control algorithm for communication systems with mobile users and unknown timevarying link gains is proposed. We prove that the proposed algorithm is exponentially converging. Furthermore, we show that the algorithm significantly outperforms the well-known
Foschini and Miljanic algorithm in the case of quickly moving mobile users.

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Wireless sensor networks with mobile data collectors have been recently proposed for extending the sensor network lifetime. Powerful mobile collectors are deployed to patrol the network and approach the static sensors for collecting their data buffers using single hop communication. The route followed by the mobile collector is very crucial for the data collection operation performed in the network and highly impacts the data collection time. This paper presents a practically efficient algorithm for constructing the mobile collector route. The route is constructed dynamically during the network operational time regardless of the sensors data generation rates. The algorithm acts on minimizing the sleeping time and the number of sensors waiting for the arrival of the mobile collector. Simulation results demonstrate that the presented algorithm can effectively reduce the overall data collection time.

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Wireless sensor networks represent a new generation of real-time embedded systems with significantly different communication constraints from the traditional networked systems. With their development, a new attack called a path-based DoS (PDoS) attack has appeared. In a PDoS attack, an adversary, either inside or outside the network, overwhelms sensor nodes by flooding a multi-hop end-to-end communication path with either replayed packets or injected spurious packets. Detection and recovery from PDoS attacks have not been given much attention in the literature. In this article, we consider wireless sensor networks designed to collect and store data. In a path-based attack, both sensor nodes and the database containing collected data can be compromised. We propose a recovery method using mobile agents which can detect PDoS attacks easily and efficiently and recover the compromised nodes along with the database.

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This paper proposes a distributed control approach called local interactions with local coordinate systems (LILCS)to multirobot hunting tasks in unknown environments, where a team of mobile robots hunts a target called evader, which will actively try to escape with a safety strategy. This robust approach can cope with accumulative errors of wheels and imperfect communication networks. Computer simulations show the validity of the proposed approach.

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This research investigated the effect of dynamically repositioning the geographic location of a mobile base station within a sensor network in order to reduce energy consumption and increase network lifetime. Through simulation and experimental methodology, the proposed approach outperformed existing methods by extending network lifetime whilst reducing energy consumption.

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This thesis presents a novel approach for controlling a robotic swarm to generate a geometric pattern described by a given contour, and a suitable communication scheme which enables the robots to communicate with each other as an all-to-all network.