A method for determining a mode of transmission between two nodes of a power line communication network, the method comprising transmitting a first message from the first node to the second node in at least two frequency bands, said first message comprising, in each of the at least two frequency bands, information according to which a channel estimate is requested; the first node receiving at least one second message transmitted from the second node and comprising information representative of a channel estimate of at least one of the frequency bands in response to the first message; and determining a transmission mode for transmitting a third message to be transmitted based on the information received from the second node in response to the first message. The invention also relates to a device configured so as to execute the method.