Browsing by Author "Chiang, ML"

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Cleaning policies in mobile computers using flash memory
(1999-11-01)
Chiang, ML
;
Chang, RC
;
資訊工程學系
;
Department of Computer Science
Flash memory is small, lightweight, shock-resistant, nonvolatile, and consumes little power. Flash memory therefore shows promise for use in storage devices for consumer electronics, mobile computers and embedded systems. However, flash memory cannot be overwritten unless erased in advance. Erase operations are slow that usually decrease system performance, and consume power. The number of erase cycles is also limited. For power conservation, better system performance, and longer flash memory lifetime, system support for erasure management is necessary. In this paper, we use the non-update-in-place scheme to implement a flash memory server and propose a new cleaning policy to reduce the number of erase operations needed and to evenly wear out flash memory. The policy uses a fine-grained method to effectively cluster hot data and cold data in order to reduce cleaning overhead. A wear-leveling algorithm is also proposed. Performance evaluations show that erase operations are significantly reduced and flash memory is evenly worn, Though the proposed fine-grained separation scheme is targeted at flash memory-based systems, it can be applied to other storage systems as well. (C) 1999 Elsevier Science Inc. All rights reserved.
Implementation of wireless network environments supporting inter access point protocol and dual packet filtering
(2005-06-01)
Hwang, LY
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Chiang, ML
;
Chang, RC
;
資訊工程學系
;
Department of Computer Science
With advances in wireless technologies, future internetworks will include large numbers of mobile hosts roaming across wireless cells. The goal of this paper is to provide a wireless network communication environment, in which mobile hosts can roam among various access points (wireless cells) and across different subnets. For this purpose, we develop methods to implement and integrate the communication mechanisms of Mobile IP and Inter Access Point Protocol (IAPP). For efficient transmission, we also devise a dual packet filtering technique to filter out unnecessary packet transmission, thereby reducing traffic on wireless networks. Such filtering is especially important because of the limited bandwidth of wireless links. Our work can serve as the reference once IAPP has been approved as standard. (c) 2004 Elsevier Inc. All rights reserved.
Managing flash memory in personal communication devices
(1997)
Chiang, ML
;
Lee, PCH
;
Chang, RC
;
資訊工程學系
;
Department of Computer Science
This paper describes a Flash Memory Server (FMS) for personal communication devices and embedded home information systems, such as set-top boxes and internet phones. Flash memory is small, lightweight, shock-resistant, nonvolatile, and requires little power. Writing to flash memory segments requires erasing the segment in advance. However, erase operations are slow and power-wasting that usually decrease system performance. The number of erase cycle is also limited. To reduce the number of erase operations needed and to evenly wear flash memory, a new flash memory management scheme has been designed. A new cleaning policy is also proposed to reduce cleaning overhead. Performance evaluations show that erase operations can be reduced by 55%.
Using data clustering to improve cleaning performance for flash memory
(1999-03-01)
Chiang, ML
;
Lee, PCH
;
Chang, RC
;
資訊工程學系
;
Department of Computer Science
Flash memory offers attractive features for storage of data, such as non-volatility, shock resistance, fast access speed, and low power consumption. However, it requires erasing before it can be overwritten. The erase operations are slow and consume comparatively a great deal of power, Furthermore, flash memory can only be Erased a limited number of times. To overcome hardware limitations, we use the non-in-place update mechanism that requires a cleaner to reclaim space occupied by obsolete data. To improve cleaning performance and prolong hash memory lifetime, we propose a new data reorganization method. By this method, data in flash memory are dynamically classified and clustered together according to their accessing frequencies, Experimental results show that this clustering technique significantly improved the cleaning performance for a variety of cleaning algorithms. The number of erase operations performed is greatly reduced and flash memory lifetime is prolonged. Even wearing is ensured as well, Copyright (C) 1999 John Wiley & Sons, Ltd.