Vol. 27 · No. 5

There has been an increasing interest in wireless sensor networks as a new technology to realize ubiquitous computing, and demands for internetworking technology between the wireless sensor networks and the Internet which is based on IP address. For this purpose, this paper proposes and implements the internetworking scheme which assigns IP addresses to the sensor nodes and internetworks based on the gateway-based integration for internetworking between the wireless sensor networks and the Internet. That is, the proposed scheme makes the access to the wireless sensor networks be serviced as like the Web service with internetworking Internet IP address and ZigBee address which is allocated to the sensor node in wireless sensor networks. For validating the proposed scheme, we made experiments using Berkeley TinyOS, Mica Motes, dual protocol stack based on ZigBee and IP, and showed the service result using browser (IE) and IPv6 address based on DNS.

In mobile and ubiquitous computing environments, acquisition of contextual information about a user situation is necessary to provide useful services. Although the definition of user context may change according to the situation or the service used, contextual information about who, where, and when are considered to be essential. We have built a test bed with multiple sensors: floor pressure sensors, RFID (radio frequency identification) tag systems, and cameras, to carry out experiments to detect the positions of users and track their movement. The conventional background subtraction method by using cameras was used for moving object detection and tracking. In this paper, we propose knowledge application and parameter adaptation in the background subtraction method. The results are presented to show that the proposed method decreases the detection errors.

Because most CAD drawings are composed of a collection of files with various extensions, there exist problems associated with the processing speed and the accuracy of CAD files encryption (decryption) using file based secure methods. In this study, an innovative system of securing CAD files based on the workplace against illegal piracy of design knowledge in ubiquitous environment is presented. The proposed technology is to store all design files in the secure workplace which can be accessed by the authorized users and design applications only using Application Programming Hooking at user level and System Service Table at kernel level. The technology is demonstrated in this paper using its implementation example in an automobile company to verify it and CAD files can be shared among users without a concern of its leakage to the competitors by internal user.

As wireless sensor networks grow, so does the need for effective security mechanisms. We propose a cryptographic key-management protocol, called energy-efficient key-management (EEKM) protocol. Using a location-based group key scheme, the protocol supports the revocation of compromised nodes and energy-efficient rekeying. The design is motivated by the observation that unicast-based rekeying does not meet the security requirements of periodic rekeying in long-lived wireless sensor networks. EEKM supports broadcast-based rekeying for low-energy key management and high resilience. In addition, to match the increasing complexity of encryption keys, the protocol uses a dynamic composition key scheme. EEKM also provides group-management protocols for secure group communication. We analyzed the energy efficiency and security of EEKM and compared it to other key-management protocols using a network simulator.

This paper extends our previous framework for digital photo annotation by adding noble approach of indoor/mixed/outdoor image classification. We propose the best feature vectors for a support vector machine based indoor/mixed/ outdoor image classification. While previous research classifies photographs into indoor and outdoor, this study extends into three types, including indoor, mixed, and outdoor classes. This three-class method improves the performance of outdoor classification. This classification scheme showed 5–10

Wireless sensor networks generally support users that send queries and receive data via the sinks. The user and the sinks are mostly connected to each other by infrastructure networks. The users, however, should receive the data from the sinks through multi-hop communications between disseminating sensor nodes if such users move into the sensor networks without infrastructure networks. To support mobile users, previous work has studied various user mobility models. Nevertheless, such approaches are not compatible with the existing routing algorithms, and it is difficult for the mobile users to gather data efficiently due to their mobility. To improve the shortcomings, we propose a view of mobility for wireless sensor networks and propose a model to support a user mobility that is independent of sinks.

Transaction management for mobile and ubiquitous computing (MUC) aims at providing mobile users with reliable and transparent services anytime anywhere. Traditional mobile transaction models built on client-proxy-server architecture cannot make this vision a reality because 1) in these models, base stations (proxy) are the prerequisite for mobile hosts (client) to connect with databases (server), and 2) few models considered context-based transaction management. In this paper, we propose a new network architecture for MUC transactions, with the goal that people can get online network access and transaction even while moving around; and design a context-aware transaction model and a context-driven coordination algorithm adaptive to dynamically changing MUC transaction context. The simulation results have demonstrated that our model and algorithm can significantly improve the successful ratio of MUC transactions.

Though the MANET concept exists for decades and that many researches were carried out, such networks suffer from extremely low adoption. The main reason is the security or more precisely, lack thereof. This paper defines what a MANET should be for a real use, it explains what are the security challenges and analyzes the problems of the existing proposals to secure such network. Our main assumption is that security problems as we expose them should be addressed globally and not in a fragmented manner as currently. This paper aims at defining a state of the art that will be useful to propose a practical and global solution.

Media streams distribution over a wired network to static hosts can be realized by Client/Server mode or Peer-to-Peer overlay networks. However, if the end hosts are mobile over heterogeneous wireless access networks, one needs to consider many operational issues such as network detection, handoff, join and leave latency, and desired level of quality of service, as well as caching. In the latest researches, one popular P2P live streaming system, called AnySee, over the wired network, has been deployed and widely used. Based on the AnySee system, this paper proposed and implemented one hybrid live streaming system, AnySee-Mobile, under wired and wireless environment. In the system, one wireless peer will be selected to act as an agent. One agent has two main functions, to request media from P2P overlay network as a normal peer, and to multicast media to WLAN as a multicast source. In this paper we study, how to elect one multicast agent in WLAN. Several experimentations have been made and proved that the system has good user experiences and performances.