Proposal and Evaluation of a Hybrid Access Control Method for Improving the Delay of Bus Topology LANs (特集:マルチメディアネットワークシステム)

概要

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LANs, applied in different conditions, are of different performance characteristics. For plant control and factory automation, a time critical communication is important for real-time control, though the transmission speed of LANs today has been enhanced to be very high. As a standard, CSMA/CD is one of the most popular underlying technologies of LAN. By CSMA/CD, as load increases, the delay quickly becomes long and transmission time cannot be guaranteed. Here, we propose a Hybrid Access Control Method (HACM) based on CSMA/CD to improve its efficiency and integrate it with Token Bus just by changing the algorism in the MAC layer. In this paper, we propose improving CSMA/CD method to suit not only in the case of a low load but also in the case of a comparatively high load by exchanging to Token Bus according to the communication situation on LANs. As a main performance index of LAN, the delay can be estimated by an approximate formula for theory analysis, but for deciding by which mode is better dynamically, obtaining and processing information are somehow complex and analysis results have some difference from practice. Therefore, considering facility and practicability, we select indexes which can be easily obtained for the proposed HACM. The indexes are proved to be appropriate, and the proposed HACM is efficient according to the results of simulations.
一般社団法人情報処理学会の論文
2001-02-15