Energy-efficient caching for wireless mobile computing
IBM1
26 Feb 1996-pp 336-343
TL;DR: An energy-efficient cache invalidation method, called GCORE (Grouping with COld update-set REtention), that allows a mobile computer to operate in a disconnected mode to save the battery while still retaining most of the caching benefits after a reconnection is presented.
Abstract: Caching can reduce the bandwidth requirement in a mobile computing environment. However, due to battery power limitations, a wireless mobile computer may often be forced to operate in a doze (or even totally disconnected) mode. As a result, the mobile computer may miss some cache invalidation reports broadcast by a server, forcing it to discard the entire cache contents after waking up. In this paper, we present an energy-efficient cache invalidation method, called GCORE (Grouping with COld update-set REtention), that allows a mobile computer to operate in a disconnected mode to save the battery while still retaining most of the caching benefits after a reconnection. We present an efficient implementation of GCORE and conduct simulations to evaluate its caching effectiveness. The results show that GCORE can substantially improve mobile caching by reducing the communication bandwidth (or energy consumption) for query processing.
Citations
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01 Jan 2002
TL;DR: This paper proposes three caching strategies in which clients cooperatively cache broadcast data items that shorten the average response time for data access by replacing cached items based on their access frequencies, the network topology, and the time remaining until each item is broadcast next.
Abstract: Recent advances in computer and wireless communication technologies have increased interest in push-based information systems in which a server repeatedly broadcasts data to clients through a broadband channel. In this paper, assuming an environment where clients in push-based information systems construct ad hoc networks, we propose three caching strategies in which clients cooperatively cache broadcast data items. These strategies shorten the average response time for data access by replacing cached items based on their access frequencies, the network topology, and the time remaining until each item is broadcast next. We also show the results of simulation experiments conducted to evaluate the performance of our proposed strategies.
Dissertation•
01 Jan 2008
TL;DR: In a mobile computing environment, a potentially large number of mobile and fixed users may simultaneously access shared data; therefore, there is a need to provide a means to allow concurrent management of transactions, and three common execution strategies for mobile transactions are evaluated.
Abstract: As technological advances are made in software and hardware, the feasibility of
accessing information "any time, anywhere" is becoming a reality. In a mobile
computing environment, a potentially large number of mobile and fixed users may
simultaneously access shared data; therefore, there is a need to provide a means to
allow concurrent management of transactions. Specific characteristics of mobile
environments make traditional transaction management techniques no longer
appropriate. This is due to a fact that the ACID properties of transactions are not
simply followed, in particular the atomicity property. Thus, transaction management models adopting weaker forms of atomicity are needed.
In the first part of this thesis, a performance evaluation of three common
execution strategies for mobile transactions, the mobile host strategy (MHS), the
fixed host strategy (FHS), and the combined host strategy (CHS), is conducted. [Continues.]
TL;DR: Simulation results show that the cache invalidation scheme effectively increases cache reusability since the cost functions respect update rates at a server, broadcast intervals, the communication bandwidth, and data sizes as well as disconnection time.
Abstract: Summary In a wireless client-server environment, data broadcasting is an efficient data dissemination method and some of the broadcast data are often cached at each mobile client’s cache. Data broadcasting and caching save communication bandwidth, resource usage, and data access time. A server also broadcasts invalidation reports (IRs) to maintain the consistency between server data and clients’ cached data. Most existing cache invalidation policies simply purge the entire cache after a client has been disconnected long enough to miss a certain number (window size) of IRs. We present a cache invalidation scheme to increase the reusability of the data in mobile clients’ caches after long disconnection. Instead of clearing the entire cache regardless of its consistency after long disconnection, a client estimates the relative cost of purging all data and the cost of a selective purge. If a selective purge is cheaper, the client sends server an uplink message to ask the validity of data whose update rate is low to salvage as many valid data as possible. Simulation results show that our scheme effectively increases cache reusability since our cost functions respect update rates at a server, broadcast intervals, the communication bandwidth, and data sizes as well as disconnection time. Copyright © 2007 John Wiley & Sons, Ltd.
18 May 2003
TL;DR: This paper proposes a hybrid concurrency control scheme based on broadcast invalidation report that achieves high transaction throughput, because it uses of re-ordering and locking.
Abstract: Limitation of bandwidth, restriction of resources and frequent disconnection are main characteristics of ubiquitous computing environments. To reduce these kinds of problems, a new form of data delivery was proposed in which the server broadcasts data to mobile hosts that listen to the broadcast channel. In this paper, we propose a hybrid concurrency control scheme based on broadcast invalidation report. The scheme achieves high transaction throughput, because it uses of re-ordering and locking. By simulation experiments, we show that our scheme consistently demonstrates excellent performance with low space overhead in all parameter settings.
TL;DR: The UTSM-ARM method which uses caching and broadcast method, and allows update transactions in mobile client, and makes efficiently use of the asymmetric bandwidth of broadcast environment and can Increase the transaction throughput.
Abstract: A broadcast method in mobile computing environments which have very large client populations solves the problem of low bandwidth. But most of previous proposed concurrency control protocols are restricted to read-only transactions from mobile client. In this paper, we propose the UTSM-ARM method which uses caching and broadcast method, and allows update transactions in mobile client. The UTSM-ARM decides the validation of cache data consistency with the dynamic update pattern ratio of accessed cached data. Also, the timestamps of accessed cached data and transaction in mobile client guarantee the serializable execution of mobile transactions. As a result, UTSM-ARM makes efficiently use of the asymmetric bandwidth of broadcast environment and can Increase the transaction throughput.
References
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622 citations
Proceedings Article•
01 Jan 1995
TL;DR: In this paper, a taxonomy of different cache invalidation strategies and study the impact of client's disconnection times on their performance is presented, and the authors determine that for the units which are often disconnected (sleepers) the best cache invalidization strategy is based on signatures previously used for efficient file comparison.
Abstract: In the mobile wireless computing environment of the future a large number of users equipped with low powered palm-top machines will query databases over the wireless communication channels. Palmtop based units will often be disconnected for prolonged periods of time due to the battery power saving measures; palmtops will also frequencly relocate between different cells and connect to different data servers at different times. Caching of frequently accessed data items will be an important technique that will reduce contention on the narrow bandwidth wireless channel. However, cache invalidation strategies will be severely affected by the disconnection and mobility of the clients. The server may no longer know which clients are currently residing under its cell and which of them are currently on. We propose a taxonomy of different cache invalidation strategies and study the impact of client's disconnection times on their performance. We determine that for the units which are often disconnected (sleepers) the best cache invalidation strategy is based on signatures previously used for efficient file comparison. On the other hand, for units which are connected most of the time (workaholics), the best cache invalidation strategy is based on the periodic broadcast of changed data items.
509 citations
24 May 1994
TL;DR: A taxonomy of different cache invalidation strategies is proposed and it is determined that for the units which are often disconnected (sleepers) the best cache invalidations strategy is based on signatures previously used for efficient file comparison, and for units which is connected most of the time (workaholics), the best Cache invalidation strategy isbased on the periodic broadcast of changed data items.
Abstract: In the mobile wireless computing environment of the future a large number of users equipped with low powered palm-top machines will query databases over the wireless communication channels. Palmtop based units will often be disconnected for prolonged periods of time due to the battery power saving measures; palmtops will also frequencly relocate between different cells and connect to different data servers at different times. Caching of frequently accessed data items will be an important technique that will reduce contention on the narrow bandwidth wireless channel. However, cache invalidation strategies will be severely affected by the disconnection and mobility of the clients. The server may no longer know which clients are currently residing under its cell and which of them are currently on. We propose a taxonomy of different cache invalidation strategies and study the impact of client's disconnection times on their performance. We determine that for the units which are often disconnected (sleepers) the best cache invalidation strategy is based on signatures previously used for efficient file comparison. On the other hand, for units which are connected most of the time (workaholics), the best cache invalidation strategy is based on the periodic broadcast of changed data items.
454 citations
24 May 1994
TL;DR: This work describes two methods, (1,m) Indexing and Distributed Indexing, for organizing and accessing broadcast data and demonstrates that the proposed algorithms lead to significant improvement of battery life, while retaining a low access time.
Abstract: We consider wireless broadcasting of data as a way of disseminating information to a massive number of users. Organizing and accessing information on wireless communication channels is different from the problem of organizing and accessing data on the disk. We describe two methods, (1,m) Indexing and Distributed Indexing, for organizing and accessing broadcast data. We demonstrate that the proposed algorithms lead to significant improvement of battery life, while retaining a low access time.
421 citations
TL;DR: The author begins by discussing the background, defining key terms and showing how wireless information systems can be viewed as a natural evolution of computing's relentless march toward greater distribution and ubiquity of access.
Abstract: The author begins by discussing the background, defining key terms and showing how wireless information systems can be viewed as a natural evolution of computing's relentless march toward greater distribution and ubiquity of access. Next, the research issues faced by designers of wireless information systems are detailed, and some large-scale engineering challenges for such designers are presented. The existing cellular system architecture, evolved from telephony, is compared with an alternative architecture more closely integrated with a computer networking view of wireless systems. Existing wireless systems are reviewed, and the final section presents the author's summary and conclusions, and charts the future of wireless information systems. >
321 citations