• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.12A
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• pp.984-993
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• 2011

In this paper, we present a new method for efficient mobility management in infrastructure-based ad hoc networks. This type of network inherently takes the tree topology model in which an Internet gateway (IG) becomes a root. Accordingly, the nodes near the IG process get much more number of messages, thereby causing a bottleneck phenomenon that degrades network performance. This problem is known as a funneling effect. We present a method to maximize message aggregation in which the nodes in the networks form tree topology and perform skewed time synchronization according to the depths of the nodes during the tree construction process. We proved by resorting to simulation that the funneling effect is alleviated and network performance is improved greatly.

• Journal of KIISE:Computer Systems and Theory
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• v.28 no.5
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• pp.213-217
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• 2001

Excessive memory buffer requirement in continuous media playback is a serious impediment of wide spread usage of on-line multimedia service. Skewed access frequency of available video files provides an opportunity of re-using the date blocks which has been loaded by one session for later usage. We present novel algorithm which minimizes the buffer requirement in multiple sessions of multimedia playbacks. In continuous media playback originated from the disk, a certain amount of memory buffer is required to synchronize asynchronous disk. Read operation and synchronous playback operation. As aggregate playback bandwodth increases, larger amount of buffer needs to be allocated for this synchronization purpose. The focus of this work is to study the asymptotic behavior of the synchronization buffer requirement and to develop an algorithm coping with this excessive buffer requirement under bandwidth congestioon. We argue that in a large scale continuous media server, it may not be necessary to read the blocks for each session directly from the disk. The beauty of our work lies in the fact that it dynamically adapts to disk utilization of the server and finds the optimal way of servicinh the individual sessions while minimizing the overall buffer space requirement. Optimality of the proposed algorithm is shown by proof. The effectiveness and performance of the proposed scheme is examined via simulation.