| 摘要 |
PURPOSE:To obtain high transmitting efficiency in average even in any transmitting frequency by dividing a transmitting request frequency from respective transmitting equipments into the low frequency and the high frequency, switching over a CSMA/CD system having a high transmitting efficiency and CSMA/CA system to use them properly in respective cases. CONSTITUTION:After the signal from a sharing transmission line 1 is received at a receiving circuit part 3, the signal is sent to a signal frequency measuring part 4-1 as a carrier sense and a traffic signal. Then, when an access method discriminating part 4-2 maintains and exceeds a certain specified frequency for a certain specified time based upon the information from the signal frequency measuring part 4-1, an indication to change over the access method of the self-transmitting equipment to a CSMA/CA system advantageous when the signal frequency is high (high traffic) is outputted to an access control part 4-3. When the part is maintained and decreased from a certain specified frequency for a certain specified time, the indication to change over the access method of the self-transmitting equipment to a CSMA/CD system advantageous when the signal frequency is low (low traffic) is outputted to a media access control part 4-3. The control part 4-3 controls a media access by the CSMA/CD system based upon the discriminating signal from an access method discriminating part 4-2.
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