Editorial: Mobile and Pervasive Computing

The proliferation of wireless handheld devices, advances in network technologies, and the desire to stay connected anytime and anywhere, have ushered in the era of mobile and pervasive computing. Wireless mobile phones that also serve as personal digital assistants will soon become the norm in everyday life. People carrying these devices will be surrounded by intelligent and networked devices and embedded computing appliances: at home and work, in cars, public spaces, and even in their clothes and on their bodies. The fact that they exist everywhere drastically changes the way we use computers, imposes new requirements on computing and communications, and creates unique opportunities for ubiquitous services and applications. This special issue aims to bring together innovative research ideas and advances in the field of mobile and pervasive computing to address these challenges and opportunities. Mobile computing concerns the mobility of users, data and systems, and information organization and access methods for data services and management in mobile systems. Pervasive computing builds on mobile computing techniques and is concerned with the creation of environments populated with human beings, wireless networking devices and physical objects to satisfy the properties of physical integration and instantaneous interoperation. This issue includes seven papers that report state-of-the-art research results in mobile and pervasive computing. The papers are organized into three groups. The first group addresses networking and QoS support at the network layer. Wireless local area networks (WLANs) have become widely used thanks to the success of WLAN technologies such as IEEE 802.11 and Bluetooth. Feng et al. propose a solution for integrating WLANs and 3G UMTS mobile wireless services, allowing a mobile customer to access 3G packet-switched services over a WLAN without modifying the existing 3G network components. They propose and evaluate a novel mechanism to dynamically push service applications to a mobile customer in a WLAN to further reduce energy consumption and computational complexity in the mobile client station. The authors discuss their experience with a prototype they have implemented. Law and So propose active network techniques in support of pervasive computing. They describe an active pervasive network model in which ingress and egress agents adapt content delivery according to the available network resources and user requirements. In pervasive computing environments, connectivity properties of the network will impact service availability and performance. Bettstetter presents a derivation of the probabilities of node isolation and k-connectivity for ad hoc networks with inhomogeneous, non-uniform node distributions. Bettstetter also develops an analytical framework to study the effect of node mobility on connectivity. The second group addresses middleware and system level support. Tseng et al. study location tracking of moving objects in infrastructure-less wireless sensor networks. The authors describe a novel approach to track a moving object using a mobile agent that dynamically chooses and cooperates with the sensors closest to the moving object to track the object. They describe an experimental prototype based on IEEE 802.11 that demonstrates the efficiency and feasibility. Koloniari and Pitoura investigate and analyse service discovery mechanisms based on filters to route service discovery queries to appropriate nodes in mobile ad hoc environments. Their experimental results show that organizing filter nodes based on content similarity is more efficient for service discovery than organizing such nodes based on network proximity. Kang et al. describe the concept of ‘smart messages’, which are user-defined distributed programs that can migrate and execute on nodes specified by properties rather than by name. Smart messages are intended for use in networks of embedded systems that characterize large and dynamic pervasive computing environments. Analysis of an example application and performance results obtained from a prototype implementation point to the feasibility of this alternative to traditional message passing with static processes. The third group contains a paper by Raskovic et al. at the application layer. It describes the use of wearable computing for medical applications and presents a taxonomy that differentiates key features of different applications and identifies requirements for different classes of applications. The authors consider wearable devices that record data, process and act on data, correct medical conditions, and replace some natural function. Mobile and pervasive computing is still in its infancy. The papers presented advance the state of the art and open up avenues for research that may lead to the ubiquity of mobile and pervasive computing technologies. We would like to thank all reviewers and authors contributing to this special issue.