Joe Chun-Hung Yuen

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In this paper, we propose a cache invalidation scheme called Invalidation by Absolute Validity Interval (IAVI) for mobile computing systems. In IAVI, we define an absolute validity interval (AVI), for each data item based on its dynamic property such as the update interval. A mobile client can verify the validity of a cached item by comparing the last(More)
In a mobile computing system, caching data items at the mobile clients is important to reduce the data access delay in a unreliable and low bandwidth mobile network. However, efficient methods must be used to ensure the coherence between the cached items and the data items at the database server. In this paper, by exploring the real-time properties of the(More)
In this paper, we study the bandwidth allocation problem for serving video requests in a mobile real-time video player system. One of the main issues to maintain the quality of services (QoS) in mobile video playback is to ensure sufficient number of video frames available at the client side while a video is being played. However, due to the limited(More)
In this paper, we study the data dissemination problem in time-constrained mobile computing systems (TCMCS) in which maximizing data currency (minimizing staleness) and meeting transaction deadlines are of equal importance as providing consistent data items to transactions. We first investigate what are the performance problems of the multi-version data(More)
Rapid advances in mobile communication technology have spawned many new mobile applications. A key element in many of these systems is the need to distribute real-time information from a database server to mobile clients. While data broadcast has been shown to be an efficient data dissemination technique, many issues such as selection of broadcast data and(More)
In this paper, we propose broadcast algorithms, based on the policies proposed in previous studies, to disseminate data items to time-constrained read-only transactions. In the proposed algorithms, the number of data items requested by a transaction will be considered explicitly in selecting the data items for broadcast. The purpose of the algorithms is to(More)
Kam-yiu Lam, Edward Chan and Joe Chun-Hung Yuen Department of Computer Science City University of Hong Kong 83 Tat Chee Avenue, Kowloon Hong Kong Fax: 852-2788-8614 Email: {cskylam|csedchan|csjyuen} Abstract. Although data broadcast has been shown to be an efficient data dissemination technique for mobile computing systems, many issues such as(More)
In this paper, we propose an Adaptive Buffer Sensitive (ABS) protocol for scheduling the transmission of video streams over a mobile network. Two important considerations in the design of ABS are: (1) to minimize the impact of transient overloading and communication errors on video playback; and (2) to minimize the impact of a video playback by other video(More)
1 The work described in this paper was partially supported by a grant from the Research Grants Council of Hong Kong SAR, China [Project No. CityU 1097/99E]. Abstract In this paper, we propose the Adaptive Buffer Sensitive (ABS) algorithm for scheduling the transmission of video packets from multiple video streams in a mobile multimedia system. Two important(More)
In this paper, we study the admission and bandwidth allocation problems in real-time video streaming in a cellular network. Admission control in a cellular network is a complex issue due to the mobility of the clients, and the additional workload imposed by incoming clients could exceed the network capacity of a cell and seriously degrade the quality of(More)