| Summary: | 碩士 === 國立交通大學 === 資訊工程研究所 === 83 === The communication infrastructure of a mobile computing
environment can be built on the basis of a cellular/
microcellular telephone system or a PCS network. Under this
circumstance, the occurences of handoffs cannot be avoided.
With the occurences of handoffs, wireless links held by mobile
computers crossing cell boundaries may be forced terminated.
The forced termination probability of handoff access requests
has a significant effect on the performance of a mobile
computing environment. Moreover, the blocking probability of
initial access requests is also an important metric of
performance measurement. Several researches have been done on
the analysis of the initial and handoff accesses in cellular/
microcellular telephone systems and PCS networks. However, the
analytical models used in these researches are not appropriate
for mobile computing since each telephone uses only one channel
but a mobile computer may use several channels. In this thesis,
we develop an analytical model to analyze the initial and
handoff accesses in a mobile computing environment. This model
is constructed with a multi-dimensional continuous time Markov
chain. The accuracy of this model is verified by simulation.
Besides, we also develop another simulation model to examine
the effects of frequent disconnections. The simulation results
show that increasing the probability that a wireless link will
be disconnected may seriously degrade the performance of a
mobile computing system. Furthermore, we provide an approach to
balance the initial access blocking probability and the task
incompletion probability.
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