| Summary: | 碩士 === 國立交通大學 === 電子工程系 === 87 === Among the second-generation indoor wireless communication systems, the DECT
has received wide acceptance in Europe. DECT employs dynamic channel
allocation and mobile-controlled handover. In the ETSI DECT Recommendations,
the channel allocation and handover procedures are not standardized, thus
the system manufactures and operators have considerable freedom in
specifying the details of these functions. In this thesis, we examine the
parameters defined in the DECT documents that are related to channel
allocation and handover, and we study the performance of some channel
allocation method and handover criteria in the DECT framework.
In our study of the channel allocation algorithms, we gear at finding
techniques that yield high CIR and low GOS measured in terms of call
blocking and call dropping probabilities. The considered channel allocation
and handover
algorithms are all based on measurement of the CIR if
the signal strengths to different base statios, deciding on
handover if the CIR is lower than a predefined threshold or the signal strength
to another base station is stronger than a predefined threshold than current
base station.
The details differ for different algorithms, for example, the difference of
channel order and the length of the handover delay time. The
performance measure in our study is the GOS values and the handover
numbers when a portable initiates an initial or a handover call.
The larger the GOS value, the poor the system performance.
And the larger the handovr numbers, the heavier the system loading.
Simulations results show that the methods in this thesis perform a litte
better than the method according to DECT specification.
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