Chih-Lin Hu

Dynamic data broadcasting with traffic awareness

Data dissemination has significantly served as a scalable data delivery mechanism in wireless networks. However, even though the broadcast traffic has the nature of dynamic changes, most previous research efforts were elaborated upon the premise of static workloads and access patterns without having proper traffic awareness. In this paper, we address the existence of client impatience and accordingly devise an online traffic awareness mechanism based on a novel selective deferment and reflection (SDR) technique to estimate the dynamic workloads and access patterns in a granularity of a broadcast cycle. In comparison with prior probing and feedback approaches, our design is of practical usefulness in that it has low complexity and is light-weight without performance degradation. With various dynamic traffic scenarios, the experimental results show that with an increasing/decreasing workload, the real access frequency distribution is bounded by two specific estimated distributions. This fact in turn suggests us to employ a trigonometric tuning method to further enhance the estimation. In addition, we examine that the mean difference between the estimated access frequency distribution and the real one is very small, consequently indicating the feasibility and reliability of our proposed data broadcast mechanism with traffic awareness.

A mobile agent-based active network architecture for intelligent network control

The innovation and evolution of network technologies and services to enhance network functionality have traditionally encountered the problems of backward-compatibility and standardization. To resolve the related issues, active networks have been introduced to enable specific customization of network functionality without the lengthy standard-mediated committee processes. In this paper, we exploit the capability of mobile agent technology to construct an active network architecture. We argue that the mobile agent can be a building block for specific network customizations, and introduction of new network functionality. Both integrated and discrete operational models of network customizations can be supported in our prototype implementation. For the service development and deployment, an abstract service structure and a service loading mechanism are presented. Furthermore, we provide an agent management/control mechanism and devise a service management/control mechanism, which is either not available or incomplete in the other related work. The proposed architecture allows new service introduction, and as a result, achieves improved network functionality.

Online Scheduling Sequential Objects with Periodicity for Dynamic Information Dissemination

The scalability of data broadcasting has been manifested by prior studies on the base of the traditional data management systems where data objects, mapped to a pair of state and value in the database, are independent, persistent, and static against simple queries. However, many modern information applications spread dynamic data objects and process complex queries for retrieving multiple data objects. Particularly, the information servers dynamically generate data objects that are dependent and can be associated into a complete response against complex queries. Accordingly, the study in this paper considers the problem of scheduling dynamic broadcast data objects in a clients-providers-servers system from the standpoint of data association, dependency, and dynamics. Since the data broadcast problem is NP-hard, we derive the lower and the upper bounds of the mean service access time. In light of the theoretical analyses, we further devise a deterministic algorithm with several gain measure functions for the approximation of schedule optimization. The experimental results show that the proposed algorithm is able to generate a dynamic broadcast schedule and also minimize the mean service access time to the extent of being very close to the theoretical optimum.

Adaptive balanced hybrid data delivery for multi-channel data broadcast

With the proliferation of wireless information applications and services, data broadcasting known from radio networks has become an important mechanism for mobile data access in wireless communication networks. Two data delivery techniques, push and pull, and their hybrid combination bad been introduced to satisfy mobile user demands. However, most previous research efforts were elaborated upon the premise of a single channel with static workload and access pattern. The emergence of a multi-channel broadcast paradigm has attracted much research attention in the data broadcast community. We design an adaptive balanced scheme (ABS) which performs a heuristic search in pursuit of a fair balance of access time for a hybrid data delivery in a multi-channel data broadcast environment. The experimental results show that at the balanced point exploited by ABS, the result of channel partition and data item classification is very close to the optimal balance, and consequently, we are able to obtain the lowest mean access time in both push and pull channels simultaneously.

Adaptive multichannel data dissemination: support of dynamic traffic awareness and push-pull time balance

Data dissemination by the use of periodic broadcast is a viable scalable mechanism due to the explosion of information services in wireless networks. Many research works have exploited the data broadcast methodologies, however, upon the premise that the broadcast traffic is static on a single broadcast channel. In practice, the broadcast traffic changes dynamically and multiple broadcast channels can be utilized for efficient data dissemination. Accordingly, in this paper we devise an adaptive multichannel data-dissemination mechanism, including two components: the multichannel traffic-awareness and the deterministic balance search techniques. The multichannel traffic-awareness technique performs a cyclic estimation of dynamic access frequency distribution in response to traffic dynamics. With the measured estimation, the deterministic balance search technique adjusts channel allocation and item classification to further minimize and balance the push access and the pull response time. The experimental results show that the proposed mechanism is able to attain the result of channel partition and item classification very close to the optimum and, thus, minimize the mean access time in both push and pull channels simultaneously. Therefore, the reliability of broadcast contents is guaranteed.

User-provided multimedia content distribution architecture in mobile and ubiquitous communication networks

The network convergence of wired, wireless, and mobile systems creates a ubiquitous network environment where modern networking devices feature multiple networking interfaces and can connect to different networks simultaneously. Mobile users in ubiquitous networks expect to access information services anytime, and from anywhere. This paper presents a mobile content sharing scenario in which a networked device can discover neighboring devices and share multimedia content in a convenient, networked manner. This ideal scenario differs from the traditional usage which requires the tedious manual operations of connection setup and file transfer. To achieve this goal, this study proposes a user-provided multimedia content distribution architecture for a mobile and ubiquitous network environment. The proposed architecture integrates several specific mechanisms, including device discovery, asynchronous content delivery, secure access control, and virtual file system. This design addresses several inherent limitations in wireless and mobile networks, and enables mobile users to transfer media content in a secure, mobile, and energy-saving way. The proof-of-concept prototype and performance evaluation in this study confirm that the proposed architecture not only provides better user experience, but also achieves a lightweight design without compromising performance.

Adaptive information dissemination: an extended wireless data broadcasting scheme with loan-based feedback control

The dissemination of numerous information broadcast services, gives rise to the scalability issue in wireless networks. Previous researchers have shown that the push-based data broadcast mechanism is efficient in reducing message traffic. However, most research efforts are dedicated to the dissemination of static information contents. In practice, information broadcast services can produce and deliver dynamic information contents. To efficiently convey the dynamic data, we device, in this paper, an adaptive information dissemination mechanism by exploiting the functionality of data broadcasting, to support the dissemination of static and dynamic information services simultaneously. In our design, both static and dynamic information services are subsumed as service groups, i.e. the building blocks with the uniform representation of structure and group popularity and, thus, the conventional scenario becomes a special case of our framework. Furthermore, in order to tolerate the broadcast traffic dynamics, we design an online load-based slot allocation and feedback control technique to deal with the adaptation of the service group classification, bandwidth allocation, and broadcast schedule so as to avoid performance degradation. It is shown by the experimental study that the proposed adaptive information dissemination mechanism associated with the online loan-based feedback control is able to achieve a substantial reduction of message traffic for dynamic dissemination in wireless networks.

Design of mobile group communication system in ubiquitous communication network

The advent of ubiquitous IP networks enables users to freely move and continue network services anytime, anywhere by means of mobile handheld devices. This paper exploits network ubiquity and advanced device capability to develop a novel mobile group communication system. Our work presents the design and implementation of a proof-of-concept software system. This system architecture consists of four components: central tracking, handheld tracking, handheld messaging and Web-based administration subsystems. Their functional integration thus fulfills both location tracking and mobile messaging services in support of mobile group communication. After prototype and demonstration, the proposed system is able to offer a variety of novel location-aware and text/voice communication scenarios to mobile social communities in ubiquitous IP network environments.

RSS watchdog: an instant event monitor on real online news streams

This paper introduces the RSS Watchdog system, which is capable of news clustering and instant event monitoring over multiple real and online RSS news streams. We briefly mention software architecture design, technical implementation, and prototype demonstration. In addition, the results of real case studies are presented to notice the RSS Watchdogs functionality

Multicast Complement for Efficient UPnP Eventing in Home Computing Network

The UPnP technology is widely employed to enable networked devices interconnected in home computing environments. The UPnP eventing protocol on top of HTTP over TCP performs in a unicast manner, however, suffering from scalability problem and performance degradation against highly frequent event notifications. This paper devises an efficient event multicast mechanism to mitigate above circumstances. The proposed mechanism can group service subscribers of the same access interest and synchronously inform all subscribers in a group of event notifications through a specific administratively scoped multicast delivery. Its design is compliable with GENA specification and so is able to coexist with the original UPnP eventing method. The experimental prototype shows that this mechanism is lightweight and does not complicate the UPnP system design.