| 摘要 |
PROBLEM TO BE SOLVED: To provide a modem communication method with an effective data transfer rate equalized when performing fallback control. SOLUTION: A plurality of modem devices A, B, C... are connected to a power line transmission channel 1. Two of the modem devices which are paired to perform one-to-one communication using a common channel (frequency range). A transmission control part 5A has a fallback control (transmission rate control) function, a multi-access control function and an effective data transfer rate control function. The modem device A sends a transmission channel evaluation signal instead of transmission data to the modem device B. The modem device B performs transmission channel evaluation, determines an optimum fallback rate, and notifies the modem device A of the determined fallback rate. The modem device A sets a back-off period in CSMA/CA multi-access control to be suitable for the fallback rate (bit rate). COPYRIGHT: (C)2009,JPO&INPIT
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