5337049 - Contention-Aware Data Caching in Wireless...

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Contention-Aware Data Caching in Wireless Multihop Ad Hoc Networks Xiaopeng Fan, Jiannong Cao Department ofComputing Hong Kong Polytechnic University Kowloon, Hong Kong {csxpfan, csjcao}@comp.polyu.edu.hk Abstract-Data caching is one of the attractive techniques that can increase the efficiency of data access in wireless multi-hop ad hoc networks. However, it is still a challenging task to achieve an optimal trade-off between the total traffic cost and average access delay by properly selecting cache nodes, i.e, cache placement. In this paper, we address the problem of cache placement in wireless multi-hop ad hoc networks. We consider dynamic networks, in which there is a data source that stores one data item and other client nodes require accessing the data item. We define the cache placement problem on a dynamic network topology as Dynamic Cache Placement (DCP). Most of the existing cache placement algorithms use hop counts to measure the total cost of caching systems. Due to the impact of contentions in wireless networks, one hop delay is different from each other and it varies with the traffic load. Thus the previous algorithms cannot achieve their expected performance. We propose two heuristic cache placement algorithms, named Centralized Contention-Aware Caching Algorithm (CCCA) and Distributed Contention-aware Caching Algorithm (DCCA), which detect the variation of contentions to evaluate the benefit of selecting a node as cache node. Simulation results show that the proposed algorithms achieve better performance than other alternative ones in terms of average query delay, caching overheads, and query success ratio. Keywords-contention-aware; cache placement; wireless ad hoc network I. INTRODUCTION With the rapid growth of interest in mobile computing, wireless multi-hop ad hoc networks are used to provide radio devices with many services anywhere and anytime, such as Internet access. One of the most important merits of such networks is to enable users to spontaneously form a dynamic communication system. Users can access these services offered by the fixed network through multi-hop communications, without requiring infrastructure in the users' proximity. However, there are several challenging issues to improve the efficiency of data access in wireless ad hoc networks. First, wireless networks are notorious for the scarcity of communication bandwidth and resources. For example, sensor networks can only have at most a gross data rate with 250kbps [1] in the physical layer. Second, more and more applications require transmitting more datum than before, which dramatically increase the traffic load of networks. In wireless 978-1-4244-5113-5/09/$25.00 ©2009 IEEE WeigangWu Department ofComputer Science Sun Vat-sen University Guangzhou, China wuweig@mail.sysu.edu.cn mesh networks, streaming services are becoming much more popular, and some real-time applications require quality of services (QoS) guarantees, such as real-time surveillance.
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This note was uploaded on 03/19/2012 for the course CS 1313 taught by Professor Aman during the Spring '12 term at Punjab Engineering College.

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5337049 - Contention-Aware Data Caching in Wireless...

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