Siu Nam Chuang

Dynamic QoS Adaptation for Mobile Middleware

Computation and networking resources in mobile operating environments are much scarcer and more dynamic than in desktop operating environments. Mobile applications can leverage on the benefits of adaptive computing to optimize the QoS delivery based on contextual situations. Fuzzy control models have been successfully applied to various distributed network QoS management systems. However, existing models are either application-specific or limited to abstract modeling and simple conceptual scenarios which do not take into account overall model scalability. Specifically, the large number of QoS parameters in a mobile operating environment causes an exponential increase in the number of rules correspondingly increases the demand for processing power to infer the rules. Hierarchical fuzzy systems were introduced to reduce the number of rules using hierarchical fuzzy control, in which correlated linguistic variables are hierarchically inferred and grouped into abstract linguistic variables. In this paper, we propose a mobile QoS management framework that uses a hierarchical fuzzy control model to support a highly extensible and structured adaptation paradigm. The proposed framework integrates several levels of QoS abstractions derived from user-perceived requirements.

Dynamic service reconfiguration for wireless web access

This paper describes a dynamic service reconfiguration model where the proxy is composed of a chain of service objects called mobilets (pronounced as mo-be-lets), which can be deployed onto the network actively. This model offers flexibility because the chain of mobilets can be dynamically reconfigured to adapt to the vigorous changes in the characteristics of the wireless environment, without interrupting the service provision for other mobile nodes. Furthermore, mobilets can also be migrated to a new proxy server when the mobile node moves to a different network domain. We have realized the dynamic service reconfiguration model by crafting its design into a programmable infrastructure that forms the baseline architecture of the WebPADS (short for Web Proxy for Actively Deployable Services) system.

Actively deployable mobile services for adaptive Web access

The proliferation of mobile devices in wireless environments has put special requirements on the ability to access the Web seamlessly. To address the impact of varying contextual characteristics on mobile access, the authors developed the WebPADS framework, which can actively deploy new mobile services. Moreover, WebPADS can dynamically reconfigure its services and migrate them to adapt to the vigorous changes in the wireless environment.

An Event-Driven Middleware for Mobile Context Awareness

The formulation of a context-aware middleware requires researchers to devise suitable control mechanisms that allow applications to directly participate in resource adaptation in response to dynamic operating environments. This paper describes the design and implementation of an event model for a highly adaptive mobile middleware, Web Proxy for Actively Deployable Services (WebPADS) platform. The event model provides a highly composable event notification framework that uses multiple levels of environment monitors to provide a complex setup of composite events. Based on the event model and the dynamic reconfiguration feature WebPADS supports context awareness and a high level of adaptation to contextual changes through reconfiguration and migration of services.

Active Service for Mobile Middleware

Abstract This paper describes a dynamic service reconfiguration model where the proxy is composed of a chain of service objects called mobilets (pronounced as mo-be-lets), which can be actively deployed onto a network. This model offers flexibility because the chain of mobilets can be dynamically reconfigured to adapt to dynamic changes in the wireless environment, without interrupting service provision for other mobile nodes. We have realized the dynamic service reconfiguration model by crafting its design into a programmable infrastructure that forms the baseline architecture of the WebPADS (short for Web Proxy for Actively Deployable Services) system.

CRL: a context-aware request language for mobile computing

This paper introduces an XML-based generic Context Request Language (CRL), whose construction is part of a web services framework in the domain of mobile context sensing. The paper describes an implementation of the technique that is in accordance with the formal mathematical representational model, using first-order temporal language [6]. The language is an attempt to introduce intelligence into context-aware computing by defining context-sensing elements into logical entities. The use of first-order calculus in this language definition serving on web service technology allows users to utilize context aggregation and to embed user control in contextual information. By carrying out on-the-fly context inferences at the middleware level, we can achieve a complete separation of concerns between user application and context sensing. Moreover, the declaration of contextual knowledge based on situations and events within the predicate domain allows users to express changes in contextual information and to quantify these elements among times and durations.

Towards a Programmable Mobile IP

This paper describes the design and implementation of a highly configurable and robust Mobile IP framework that employs active networking principles. Through the provision of open programmable interfaces and execution environment, new mobile services or application-specific customized services can be rapidly developed and deployed within the Mobile IP networking environment. ANTS [11] is being employed as the baseline active network execution environment for the implementation of our programmable Mobile IP framework. In particular, we have extended ANTS considerably to export mobile IP native interfaces to support mobile specific functionalities. The design of our active Mobile IP framework is currently implemented over the Linux operating system. The programmable framework is applied to the Mobile IP agent nodes namely, the mobile node, foreign agent, home agent and correspondent node. To demonstrate the ease of designing and deploying new mobile services, this paper describes the setup of an experiment to implement an active route optimization service.