行動隨意無線網路是一種不需事先的基礎建設，由節點(如筆記型電腦及行動電話)所組成，節點具有移動性，網路拓樸一直在改變，由於節點的可攜性，所以有能源上的限制，如運算能力、記憶體空間及電力等。
在行動隨意無線網路上資料會是異動的，所以越來越多的研究關注於資料的一致性探討。我們提出了一個以網格為基底的方法，稱作以網格為基礎的快取驗證策略，藉由每個網格內選出一個節點當作代理人節點(proxy)，負責和資料庫伺服器(database server)溝通，協助網格內其他節點快取資料。模擬實驗結果顯示，與現有的ACOD及MTS快取策略相比，我們的方法能降低查詢的反應時間及能源消耗。

A Mobile Ad hoc Network (MANET) is a wireless network composed of mobile nodes such as laptops and mobile phones without any pre-existing infrastructure. Mobile nodes move freely in a particular area. Due to mobility of the mobile nodes, links between mobile nodes can be disconnected frequently. This phenomenon causes the unsteady network topology. Furthermore, mobile nodes in a MANET usually have restricted resources such as slower computation ability, smaller memory size and scarcer energy power.
In a MANET data items are allowed to be updated, which necessitates algorithms to maintain the consistency of the cached data items. In this thesis, we propose a cache consistency strategy, called Region-Based Cache Invalidation Scheme (RCIS). In this strategy, a proxy is elected for each region, which handles queries from mobile nodes in the same region in lieu of the database server. A proxy will cache the required data items for all the mobile nodes in its region. When data items are updated in the server, the corresponding cached data in the proxy will be called back and all the requests for the called back data items are redirected to the database server. The performance of the RCIS, ACOD and MTS schemes are compared through performance simulation. The results show that the RCIS scheme attains lower access delay and lower energy consumption, compared with the ACOD and the MTS schemes.

[1] J. Cao, Y. Zhang, G. Cao, and L. Xie, “Data consistency for cooperative caching in mobile environments,” Computer, vol. 40, no. 4, pp. 60–66, April 2007.
[2] Y. Leu, J.-J. Hung, and M.-B. Lin, “A new cache invalidation and searching policy for mobile ad hoc networks,” WSEAS Transactions on Computers Research, vol. 2, pp. 66–72, 2007.
[3] W. Li, E. Chan, Y. Wang, and D. Chen, “Cache invalidation strategies for mobile ad hoc networks,” Sept. 2007, pp. 57–57.
[4] Sunho Lim, Wang-Chien Lee, Guohong Cao, and Chita R. Das, “Cache invalidation strategies for internet-based mobile ad hoc networks,”Computer Communications, vol. 30, no. 8, pp. 1854 – 1869, 2007.
[5] Takahiro Hara and Sanjay K. Madria, Thomas F. La Porta, “Consistency Management Strategies for Data Replication in Mobile Ad Hoc Networks,” Mobile Computing, IEEE Transaction on, vol. 8, no. 7, pp.950-967, July 2009.
[6] G. Karumanchi, S. Muralidharan, and R. Prakash, “Information dissemination in partitionable mobile ad hoc networks,” Proc. SRDS’99, pp.4-13, 1999.
[7] J. Luo, J.P. Hubaux, and P. Eugster, “PAN: Providing reliable storage in mobile ad hoc networks with probabilistic quorum systems,” Proc. ACM MobiHoc 2003, pp.1-12, 2003.

[8] Aravindhan Venkateswaran, Venkatesh Sarangan, Thomas F. La Porta, “A Mobility-Prediction-Based Relay Deployment Framework for Conserving Power in MANETs,” Mobile Computing, IEEE Transaction on, vol. 8, no. 6, pp.750-765, June 2009.
[9] L. Breslau, P. Cao, L. Fan, G. Phillips, and S. Shenker, “Web Caching and Zipf-Like Distributions: Evidence and Implication,” Proc. IEEE INFOCOM ’99, pp. 126-134, 1999.
[10] G. Zipf, Human Behavior and the Principle of Least Effort. Addison Wesley, 1949.
[11] V. D. Tracy Camp, Jeff Beleng, “A survey of mobility models for ad hoc network research,” Wireless Communications and Mobile Computing, vol. 2, pp. 483-502, 2002.
[12] L. Feeney and M. Nilsson, “Investigating the Energy Consumption of a Wireless Network Interface in an Ad Hoc Networking Environment,” in Proceedings of IEEE INFOCOM, Anchorage, AK, 2001.
[13] Y.C Tseng et al. “The broadcast storm problem in a mobile ad hoc network, ” Wireless Networks, Volume 8, Issue 2/3, PP. 153 - 167, 2002.