PROBLEM TO BE SOLVED: To suppress, by an easier manner, the communication interference from G.fast to DSL and the decrease in transmission rate of G.fast per se when DSL and G.fast communications overlapping with each other in usable frequency band are present with their metal circuits placed close to each other.;SOLUTION: When a DSL communication system uses a first frequency band, second frequency bands which a G.fast communication system can use includes: (a)a G.fast-specific frequency band higher, in frequency, than an upper limit of the first frequency band; (b)of frequency bands that overlap with the first frequency band, a multiplex interference frequency band including a division band of frequency division duplex, which is the uppermost band in frequency descending order; and (c)of frequency bands overlapping with the first frequency band, a frequency band of small interference which is lower, in frequency, than a lower limit of the multiplex interference frequency band. While suppressing the use of the frequency band of (b), the frequency band of (a) and the frequency band of (c) are used for transmission.;SELECTED DRAWING: Figure 7;COPYRIGHT: (C)2018,JPO&INPIT
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