首页> 外文期刊>IEEE transactions on mobile computing >Optimal callback with two-level adaptation for wireless data access
【24h】

Optimal callback with two-level adaptation for wireless data access

机译:具有两级自适应功能的最佳回调,用于无线数据访问

获取原文
获取原文并翻译 | 示例

摘要

Strongly consistent callback cache mechanisms have been studied for data access in wireless networks. In cache access mechanisms, update information is extremely important since an updated data object in a remote server makes the corresponding data objects invalidated in mobile terminals (MTs), and the data object cache hit information in those MTs becomes almost useless. In this paper, we propose an adaptive access mechanism, called optimal callback with two-level adaptation. In the first-level adaptation, cache size in an MT is adaptively adjusted based on update-to-access-ratio (UAR), defined as the average number of updates per data object access. The range of the cache size is [O, M], where M is the maximum physical cache size of the MT. Two extreme cases are given as follows: 1) when the UAR is very large so that objects in the cache are always obsolete, the cache should not be used and, therefore, the cache size should be set to zero; 2) when the UAR is zero so that every object in the cache is valid, the cache size should be set to M. Under other situations, the cache size is dynamically changed between O and M. Define U-threshold of the UAR for any object, a particular important threshold, as a UAR value, beyond which the object should be not cached at all. The idea of the second-level adaptation is that if an object size is small, sending back the object may be a better choice than sending back an invalidation message when the object is updated. Therefore, when an object is updated at the server, it is sent directly to MTs if the object size is smaller than a threshold, called push threshold (T); otherwise, an invalidation message is sent to the MTs. We analytically model cost function for the proposed adaptive scheme as the total traffic involved between the server and an MT per data object access, and the optimal cache size and the optimal T value are obtained simultaneously to minimize the cost function. Furthermore, U-threshold is derived analytically. Both simulations and analytical results are used to study and compare the performance of the proposed scheme with several others under many different scenarios.
机译:对于无线网络中的数据访问,已经研究了非常一致的回调缓存机制。在缓存访问机制中,更新信息极为重要,因为远程服务器中的更新数据对象使相应的数据对象在移动终端(MT)中失效,并且这些MT中的数据对象缓存命中信息几乎变得无用。在本文中,我们提出了一种自适应访问机制,称为具有两级自适应的最佳回调。在第一级适配中,根据访问率更新(UAR)(定义为每次数据对象访问的平均更新次数)来自适应调整MT中的缓存大小。缓存大小的范围是[O,M],其中M是MT的最大物理缓存大小。两种极端情况如下:1)当UAR很大时,缓存中的对象总是过时的,则不应使用缓存,因此,缓存大小应设置为零。 2)当UAR为零以使高速缓存中的每个对象均有效时,应将高速缓存大小设置为M。在其他情况下,高速缓存大小将在O和M之间动态更改。为任何UAR定义UAR的U阈值对象,一个特别重要的阈值,作为UAR值,超过该阈值就不应完全缓存该对象。二级适应的思想是,如果对象大小较小,则与更新对象时发送无效消息相比,发送回对象可能是更好的选择。因此,当在服务器上更新对象时,如果对象大小小于阈值(称为推入阈值(T)),则会将其直接发送给MT。否则,将无效消息发送到MT。我们对所提出的自适应方案的成本函数进行了分析建模,因为每次数据对象访问服务器与MT之间涉及的总流量,并且同时获得了最佳缓存大小和最佳T值,以使成本函数最小化。此外,U阈值是通过分析得出的。仿真和分析结果都用于研究和比较该方案与许多其他方案在许多不同情况下的性能。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱:kefu@zhangqiaokeyan.com

京公网安备:11010802029741号 ICP备案号:京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有
  • 客服微信

  • 服务号