Time-threshold Caching Scheme for Mobile Networks

C.W. Pyo, J. Li, and H. Kameda (Japan)

Keywords

Timethreshold caching scheme, Mobile networks, Call delivery, LRU replacement

Abstract

A caching scheme is useful to reduce the call delivery time in distributed mobile networks. However, the per formance of the caching scheme significantly depends on the cache memory capacity and mobile user mobil ity patterns. The key issues of the caching scheme in mobile networks are to improve the cache memory uti lization under the various mobile user mobility patterns. This paper introduces a time-threshold caching scheme for mobile networks. The time-threshold is used to de termine whether cached entries are obsolete or not. The cached entries are not allowed to reside over the pre defined time, time-threshold, in a cache memory. This paper shows that the cost for delivering a call can be ex pressed by a function of the time-threshold. We obtain an optimal residing time through minimizing the call deliv ery cost, and that time logarithmically increases as the relative network link cost increases. Furthermore, we propose the enhanced LRU (Least Recently Used) re placement method with the time-threshold to replace the obsolete cached data. Simulation studies show the com parison of our time-threshold LRU replacement to the ex isting simple LRU replacement changing the parameters which are user mobility, calling patterns, the cache size, and the network link cost.

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