Choonhwa Lee

Enabling smart spaces with OSGi

Todays pervasive computing spaces are developed primarily with proprietary technology and seem to lack a long-term vision of evolution and interoperation. The future pervasive computing environment will comprise a wide variety of devices and services from different manufacturers and developers. We must therefore achieve platform and vendor independence as well as architecture openness before pervasive computing spaces become common places. The Open Services Gateway Initiative attempts to meet these requirements by providing a managed, extensible framework to connect various devices in a local network such as in a home, office, or automobile. By defining a standard execution environment and service interfaces, OSGi promotes the dynamic discovery and collaboration of devices and services from different sources. Moreover, the framework is designed to ensure smooth space evolution over time and to support connectivity to the outside world, allowing remote control, diagnosis, and management. We present the OSGi technology and examine several OSGi development toolkits and products. We also share our experience in using OSGi to build an open, assistive environment that supports independent living for elders.

Building an Integrated Service Management Platform for Ubiquitous Cities

As one of the frontrunners in the race to build smarter cities, South Korea is pushing the envelope by promoting the development of a standard architecture for a service management platform that integrates ubiquitous computing and green technologies.

Effect of localized optimal clustering for reader anti-collision in RFID networks: fairness aspects to the readers

This paper proposes an adaptive and dynamic localized scheme unique to hierarchical clustering in RFID networks, while reducing the overlapping areas of clusters and consequently reducing collisions among RFID readers. Drew on our LLC scheme that adjusts cluster coverage to minimize energy consumption, low-energy localized clustering for RFID networks (LLCR) addresses RFID reader anti-collision problem in this paper. LLCR is a RFID reader anti-collision algorithm that minimizes collisions by minimizing overlapping areas of clusters that each RFID reader covers. LLCR takes into account each RFID readers energy state as well as RFID reader collisions. For the energy state factor, we distinguish homogeneous RFID networks from heterogeneous ones according to computing power of each RFID reader. Therefore, we have designed efficient homo-LLCR and hetero-LLCR schemes for each case. Our simulation-based performance evaluation shows that LLCR minimizes energy consumption and overlapping areas of clusters of RFID readers.

Universal interactions with smart spaces

A critical challenge facing the pervasive computing research community is the need to manage complex interactions among numerous interconnected computers and devices. In such a pervasive space, a given applications functionalities are partitioned and distributed across several computing devices that are spontaneously discovered and used. In recent years, researchers have devoted much attention to universal interactions with diverse devices in richly networked settings. We can categorize the numerous approaches explored into two groups: universal user interface languages and user interface remoting. We review recent noteworthy efforts for universal interactions using these two approaches. Such efforts aim to raise interoperability in interactive smart spaces by standardizing user interface languages or communication protocols.

An architecture for wireless LAN/WAN integration

To allow a seamless integration between wireless LANs and wireless WANs, we developed a full stack adaptation model and a simple subnet architecture that superimposes Mobile-IP on cellular-type wireless LANs. The idea is to use Mobile IP as an integrative layer atop different LAN/WAN networks. While Mobile-IP is widely used in wireless WANs, it is not known how well it performs under a wireless LAN environment, against native MAC-level handoff. Through experimentation using the 802.11 W-LAN, we found that under practical values of handoff frequencies, the performance of Mobile IP based W-LAN handoff is almost identical to the performance of W-LAN handoff. Further performance studies show the suitability of Mobile-IP as an integrative layer in this architecture.

QoS-aware Internet access schemes for wireless mobile ad hoc networks

Recently, the idea of integrating mobile ad hoc networks (MANETs) and the Internet are being explored to expand the reach of the Internet to MANET access networks. It will get us one step closer to the goal of ubiquitous Internet which is accessible anytime and anywhere. Among others, Internet gateway discovery and selection schemes pose more fundamental challenge to the problem. In this paper, we propose a load-adaptive access gateway discovery protocol and a QoS-enabled access gateway selection scheme that can exploit relevant network conditions. The gateway discovery protocol dynamically adjusts its proactive area according to network traffic. Among a set of the discovered candidate gateways, one is selected based on the number of hops to and the capability of them. Our performance evaluation study shows that the load-adaptive access gateway discovery and QoS-enabled selection schemes outperform existing mechanisms over various simulation scenarios.

Efficient peer-to-peer overlay networks for mobile IPTV services

With recent advance in wireless networks and advent of powerful mobile devices such as smart phones, IPTV services become feasible in mobile platforms. Peer-to- Peer streaming techniques are expected be a promising solution to a large-scale mobile IPTV services by providing low cost and high scalability. On the other hand, the major concern for designing mobile IPTV systems is that mobile devices have the limited battery capacity. To address this concern, in this paper, we therefore develop energy-efficient overlay networks in mobile P2P IPTV systems. In our overlay network for data delivery, mobile peers can reduce the number of data packets and control messages significantly by receiving video data from stationary peers only in a push manner. In our social network for video searching, mobile peers can further reduce a large number of control messages by sending the searching request to only one peer. By extensive simulations, we show that our proposed overlay network structure can decrease the energy consumptions of mobile peers in proportion to the reduced number of data packets and control messages.

Context-aware service composition for mobile network environments

Recent advances in wireless and mobile networking technology pose a new set of requirements and challenges that are not previously thought of, when it comes to smart space middleware design. Leading the list is how to embrace diversity and unpredictability inherent in mobile computing environments. Service-oriented computing is being recognized as one of viable solutions to the problem. According to the paradigm, dynamic service discovery and composition should be able to handle the dynamism and diversity in the environments. However, most current service frameworks do not provide sufficient support to mask the complexity from having to deal with the uncertainty by ourselves. Therefore, building an application via qualified service composition still remains a cumbersome and daunting task. In this paper, we present a smart space middleware architecture designed to hide the complexity involved with context-aware, automated service composition. We also report our prototype implementations as an effort to validate the effectiveness and feasibility of the architecture.

Toward an Ecosystem for Developing and Programming Assistive Environments

The first cohort of “baby boomers” are now 65 years or older, presaging a massive wave of aging “boomers” that could degrade health care and elder care over the next quarter-century. Cost-effective, high-impact technologies for aging, disabilities and independent living are urgently needed. In this paper, we present our experience in building “assistive environments” for older adults-the Gator Tech Smart House (GTSH) project. Numerous R&D efforts similar to ours are either underway or have recently been conducted. In most of these projects, prototypes have been built to achieve independence, well being, and in general, good quality of life. But prototyping a technology is one thing; commercial proliferation and creating a vibrant industry around such technology is an altogether different proposition. From the lessons learned in the GTSH, we analyze the impediments hindering the emergence of products and services for assistive environments, and present the blueprints of an ecosystem based on requirements drawn from the lessons learned. We believe the proposed ecosystem is an important beginning to providing better conditions for an accelerated proliferation of next-generation smart homes and assistive environments.

LAID: load-adaptive internet gateway discovery for ubiquitous wireless internet access networks

Ubiquitous Internet connectivity is to connect all devices to the Internet at any time and any place To achieve this ubiquitous Internet connectivity, we consider integrating the Internet and mobile ad-hoc networks One of the most important issues in the ubiquitous Internet connectivity is to find an efficient and reliable Internet gateway We propose a load-adaptive Internet gateway discovery approach that can exploit network conditions The load-adaptive Internet gateway discovery scheme dynamically adjusts a proactive area according to network traffic Among the candidates, a serving gateway is selected based on offered load The simulation results show that our discovery scheme outperforms existing discovery schemes.