| Summary: | 碩士 === 國立中興大學 === 電機工程學系 === 89 === In this thesis, we introduce the International Mobile Telecommunication 2000 (IMT — 2000) and discuss the effect of the random access scheme in each personal mobile communication system. The mobile host starts the initial transmission between base and itself must communicates by using the random access scheme. In order to satisfy the multiple access service and multimedia service, a priority mechanism in transmission is added. However, in the first or second generation personal communication systems, they do not effectively offer a priority mechanism in random access scheme to guarantee the QoS for different packet source. In Third Generation personal communication system, using the WCDMA technology, it can offer the better performance of packet transmission of different access service source. The Third Generation Personal Communication System uses a preamble to initiate a call before the packet transmitting. The transmitted preamble is specified to the class of the packet source, hence support the priority of different packet source. From this idea we propose an access algorithm to improve the random access performance. We also adjust the parameters and change the flow of priority mechanism, and compare to the original 3G system. Using the proposed algorithm, we can ensure the priority of transmission for each random access attempt of different Access Service Class.
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