A new approach for efficiently achieving high availability in mobile computing

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.

Consumer loyalty versus propensity to switch between providers in mature IT markets (the case of mobile phone market)

The example of the youth mobile phone market is used for pilot empirical testing of a model of consumers’ decision making, based on common features of consumer behaviour in mature markets of information and high technology products. Firstly, we discuss the key properties of mature high technology markets which affect market behaviour and strategies. These properties include: established customer and provider bases; the elements of both oligopolistic and monopolistic competition; very short product life cycle; considerable product differentiation; and using product quality, versioning and price discrimination as planning and marketing tools. Secondly, a model of consumers’ decision making in such markets is suggested on the assumption that a choice is to be made between the following options: to continue using the existing version of the product, to upgrade it with the current provider or to switch to another provider. Product price, quality characteristics, switching costs and network effects are demonstrated to be the variables affecting consumers’ decisions and therefore, these variables should be considered by competing providers when they choose production and marketing strategies. In conclusion, the results of the empirical study are discussed in the context of their possible application to other information and high technology markets.

Route maintenance using mobility prediction for mobile ad hoc networks

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)

Distributed power control in cellular mobile radio systems with time-varying link gains

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.

Mobile location based services

Mobility has become a key factor around the world, as the use of ubiquitous devices, including laptops, personal digital assistants (PDAs), and mobile phones, are increasingly becoming part of daily life (Steinfield, 2004). Adding mobility to computing power, and with advanced personalization of technologies, new business applications are emerging in the area of mobile communications (Jagoe, 2003). The fastest growing segment among these applications is location-based services. This article offers a brief overview of services and their supporting technologies, and provides an outlook for their future.

Dynamic route construction for mobile collectors in wireless sensor networks

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.